Organophosphite Antioxidants in Indoor Dust Represent an Indirect Source of Organophosphate Esters

Independent and combined effects of exposure to organophosphate esters on thyroid hormones in children and adolescents

Toxicological studies suggest that organophosphate esters (OPEs) may impair thyroid function. Epidemiological evidence, related to children and adolescents, has not been reported, and little is known about the combined effects of exposure to OPE mixtures. In this study, we collected information of 1156 children and adolescents (aged 6-18 years, 48.4% males) from a cross-sectional study in Liuzhou, China, and measured the levels of 15 urinary OPE metabolites and 5 serum thyroid hormones. Multivariate linear regression and quantile g-computation (QGC) approach were used to examine the associations which adjusted for demographic and lifestyle characteristics. Few participants had levels of triiodothyronine (T3) and free thyroxine (FT4) outside age-specific pediatric ranges. QGC analyses showed that individuals in the second, third, and fourth quartiles (Q2-Q4) of exposure had 3.93% (2.14%, 5.75%), 8.01% (4.32%, 11.8%), and 12.3% (6.54%, 18.3%) higher T3 than those in the first quartile (Q1), with similar pattern for free triiodothyronine (FT3). Individuals in Q2 and Q3 had higher thyroid-stimulating hormone (TSH) than those in Q1, but no differences were observed in TSH between Q1-Q4. In contrast, compared to the lowest quartile, FT4 was lower for those in Q2 (- 1.54%; 95% CI: - 3.02%, -0.04%), Q3 (-3.07%; 95% CI: -5.95%, -0.09%), and Q4 (-4.56%; 95% CI: - 8.80%, - 0.13%). These associations were consistent with the results from multivariate linear regression. When stratified by sex, OPE exposure (individual or mixtures) was associated with increased T3 and FT3 in males and decreased FT4 in females. This study provides the first evidence to characterize the thyroid-disrupting effects of OPE exposure in children and adolescents.

Occurrences and migration of organophosphite and organophosphate esters into food simulants from single-use food packaging in China

Organophosphite antioxidants (OPAs) and organophosphate esters (OPEs) are used as additives in food packaging. Because these chemicals have been found in various foods, they have caused increasing concern about potential health risks through food intake. Little information is available about the migration behaviors of OPAs and OPEs from single-use food packaging into food. In the present study, four OPAs and 23 OPEs were analyzed in paper and plastic single-use food packaging (n = 312), which are widely used for take-out food in China. The total concentrations of OPAs and OPEs in the packaging samples were 1966 and 189 ng/g, respectively. Tris (2,4-di-tert-butylphenyl) phosphite (AO168) was the dominant compound. OPAs and OPEs were present at higher concentrations in the plastic packaging than in the paper packaging. In a migration test, four OPAs and 15 OPEs were found in food simulants (4% acetic acid, 10% ethanol, and hexane). Higher levels of individual and total OPAs were found in hexane than the other food simulants, especially for AO168 migration from plastic packaging. The amounts of OPEs in the food simulants increased from the aqueous simulants (4% acetic acid and 10% ethanol) to the fatty food simulant (hexane). The migration efficiencies of the OPAs were higher than those of the OPEs. Preliminary calculations suggest that dietary exposure to OPAs and OPEs because of migration will be low for the population in China.

Profiles of novel high-molecular-weight synthetic antioxidants in urine and associated child exposure in China

The aim of this study is to investigate the exposure of novel high-molecular-weight (HMW) synthetic antioxidants (AOs), including nine synthetic phenolic antioxidants (SPAs), one low-molecular-weight (LMW) SPA, two organophosphite antioxidants (OPAs) as well as one transformation product in children's urine from eastern (n = 82) and western (n = 105) China. For the first time, all analytes were detected in children's urine such as the representative HMW SPAs pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate) (AO1010, median = 0.447 ng/mL), octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate (AO1076, median = 0.0300 ng/mL), and 1,3,5-tris[(3,5-di-tert-butyl-4-hydroxyphenyl)methyl]-1,3,5-triazinane-2,4,6-trione(1,2-dioxoethylene)bis(iminoethylene) (AO3114, median = 0.0166 ng/mL) and representative OPAs bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite (AO626, median = 0.00216 ng/mL), tris(2,4-di-tert-butylphenyl) phosphite (AO168, median = 0.0296 ng/mL) as well as its transformation product tris(2,4-di-tert-butylphenyl) phosphate (AO168O, median = 1.53 ng/mL). Significant differences were observed in the concentrations of AO1010, AO3114, AO168, and AO168O between urine samples from eastern and western China (p < 0.01). The high-frequency combination of AOs from binary to a mixture of six AOs was acquired, which would provide a better investigation of the mixture toxicity. The high estimated daily intakes of AO1010 (85.4 ng/kg/day), AO1076 (10.2 ng/kg/day), AO3114 (4.50 ng/kg/day), and AO168 (1231 ng/kg/day) were less than the values of the tolerable daily intake (3,020,000, 1,500,000, 10,000,000, and 580,000 ng/kg/day for AO1010, AO1076, AO3114, and AO168, respectively), indicating low health risk to children. Our findings showed the co-occurrence of those novel AOs and transformation products in children, the overall risks associated with the mixture of transformation products and the mixture with other emerging pollutants need to be considered when assessing the risks of AOs in further studies.

The Minderoo-Monaco Commission on Plastics and Human Health

Background

Plastics have conveyed great benefits to humanity and made possible some of the most significant advances of modern civilization in fields as diverse as medicine, electronics, aerospace, construction, food packaging, and sports. It is now clear, however, that plastics are also responsible for significant harms to human health, the economy, and the earth's environment. These harms occur at every stage of the plastic life cycle, from extraction of the coal, oil, and gas that are its main feedstocks through to ultimate disposal into the environment. The extent of these harms not been systematically assessed, their magnitude not fully quantified, and their economic costs not comprehensively counted.

Goals

The goals of this Minderoo-Monaco Commission on Plastics and Human Health are to comprehensively examine plastics' impacts across their life cycle on: (1) human health and well-being; (2) the global environment, especially the ocean; (3) the economy; and (4) vulnerable populations-the poor, minorities, and the world's children. On the basis of this examination, the Commission offers science-based recommendations designed to support development of a Global Plastics Treaty, protect human health, and save lives.

Report Structure

This Commission report contains seven Sections. Following an Introduction, Section 2 presents a narrative review of the processes involved in plastic production, use, and disposal and notes the hazards to human health and the environment associated with each of these stages. Section 3 describes plastics' impacts on the ocean and notes the potential for plastic in the ocean to enter the marine food web and result in human exposure. Section 4 details plastics' impacts on human health. Section 5 presents a first-order estimate of plastics' health-related economic costs. Section 6 examines the intersection between plastic, social inequity, and environmental injustice. Section 7 presents the Commission's findings and recommendations.

Plastics

Plastics are complex, highly heterogeneous, synthetic chemical materials. Over 98% of plastics are produced from fossil carbon- coal, oil and gas. Plastics are comprised of a carbon-based polymer backbone and thousands of additional chemicals that are incorporated into polymers to convey specific properties such as color, flexibility, stability, water repellence, flame retardation, and ultraviolet resistance. Many of these added chemicals are highly toxic. They include carcinogens, neurotoxicants and endocrine disruptors such as phthalates, bisphenols, per- and poly-fluoroalkyl substances (PFAS), brominated flame retardants, and organophosphate flame retardants. They are integral components of plastic and are responsible for many of plastics' harms to human health and the environment.Global plastic production has increased almost exponentially since World War II, and in this time more than 8,300 megatons (Mt) of plastic have been manufactured. Annual production volume has grown from under 2 Mt in 1950 to 460 Mt in 2019, a 230-fold increase, and is on track to triple by 2060. More than half of all plastic ever made has been produced since 2002. Single-use plastics account for 35-40% of current plastic production and represent the most rapidly growing segment of plastic manufacture.Explosive recent growth in plastics production reflects a deliberate pivot by the integrated multinational fossil-carbon corporations that produce coal, oil and gas and that also manufacture plastics. These corporations are reducing their production of fossil fuels and increasing plastics manufacture. The two principal factors responsible for this pivot are decreasing global demand for carbon-based fuels due to increases in 'green' energy, and massive expansion of oil and gas production due to fracking.Plastic manufacture is energy-intensive and contributes significantly to climate change. At present, plastic production is responsible for an estimated 3.7% of global greenhouse gas emissions, more than the contribution of Brazil. This fraction is projected to increase to 4.5% by 2060 if current trends continue unchecked.

Plastic Life Cycle

The plastic life cycle has three phases: production, use, and disposal. In production, carbon feedstocks-coal, gas, and oil-are transformed through energy-intensive, catalytic processes into a vast array of products. Plastic use occurs in every aspect of modern life and results in widespread human exposure to the chemicals contained in plastic. Single-use plastics constitute the largest portion of current use, followed by synthetic fibers and construction.Plastic disposal is highly inefficient, with recovery and recycling rates below 10% globally. The result is that an estimated 22 Mt of plastic waste enters the environment each year, much of it single-use plastic and are added to the more than 6 gigatons of plastic waste that have accumulated since 1950. Strategies for disposal of plastic waste include controlled and uncontrolled landfilling, open burning, thermal conversion, and export. Vast quantities of plastic waste are exported each year from high-income to low-income countries, where it accumulates in landfills, pollutes air and water, degrades vital ecosystems, befouls beaches and estuaries, and harms human health-environmental injustice on a global scale. Plastic-laden e-waste is particularly problematic.

Environmental Findings

Plastics and plastic-associated chemicals are responsible for widespread pollution. They contaminate aquatic (marine and freshwater), terrestrial, and atmospheric environments globally. The ocean is the ultimate destination for much plastic, and plastics are found throughout the ocean, including coastal regions, the sea surface, the deep sea, and polar sea ice. Many plastics appear to resist breakdown in the ocean and could persist in the global environment for decades. Macro- and micro-plastic particles have been identified in hundreds of marine species in all major taxa, including species consumed by humans. Trophic transfer of microplastic particles and the chemicals within them has been demonstrated. Although microplastic particles themselves (>10 µm) appear not to undergo biomagnification, hydrophobic plastic-associated chemicals bioaccumulate in marine animals and biomagnify in marine food webs. The amounts and fates of smaller microplastic and nanoplastic particles (MNPs <10 µm) in aquatic environments are poorly understood, but the potential for harm is worrying given their mobility in biological systems. Adverse environmental impacts of plastic pollution occur at multiple levels from molecular and biochemical to population and ecosystem. MNP contamination of seafood results in direct, though not well quantified, human exposure to plastics and plastic-associated chemicals. Marine plastic pollution endangers the ocean ecosystems upon which all humanity depends for food, oxygen, livelihood, and well-being.

Human Health Findings

Coal miners, oil workers and gas field workers who extract fossil carbon feedstocks for plastic production suffer increased mortality from traumatic injury, coal workers' pneumoconiosis, silicosis, cardiovascular disease, chronic obstructive pulmonary disease, and lung cancer. Plastic production workers are at increased risk of leukemia, lymphoma, hepatic angiosarcoma, brain cancer, breast cancer, mesothelioma, neurotoxic injury, and decreased fertility. Workers producing plastic textiles die of bladder cancer, lung cancer, mesothelioma, and interstitial lung disease at increased rates. Plastic recycling workers have increased rates of cardiovascular disease, toxic metal poisoning, neuropathy, and lung cancer. Residents of "fenceline" communities adjacent to plastic production and waste disposal sites experience increased risks of premature birth, low birth weight, asthma, childhood leukemia, cardiovascular disease, chronic obstructive pulmonary disease, and lung cancer.During use and also in disposal, plastics release toxic chemicals including additives and residual monomers into the environment and into people. National biomonitoring surveys in the USA document population-wide exposures to these chemicals. Plastic additives disrupt endocrine function and increase risk for premature births, neurodevelopmental disorders, male reproductive birth defects, infertility, obesity, cardiovascular disease, renal disease, and cancers. Chemical-laden MNPs formed through the environmental degradation of plastic waste can enter living organisms, including humans. Emerging, albeit still incomplete evidence indicates that MNPs may cause toxicity due to their physical and toxicological effects as well as by acting as vectors that transport toxic chemicals and bacterial pathogens into tissues and cells.Infants in the womb and young children are two populations at particularly high risk of plastic-related health effects. Because of the exquisite sensitivity of early development to hazardous chemicals and children's unique patterns of exposure, plastic-associated exposures are linked to increased risks of prematurity, stillbirth, low birth weight, birth defects of the reproductive organs, neurodevelopmental impairment, impaired lung growth, and childhood cancer. Early-life exposures to plastic-associated chemicals also increase the risk of multiple non-communicable diseases later in life.

Economic Findings

Plastic's harms to human health result in significant economic costs. We estimate that in 2015 the health-related costs of plastic production exceeded $250 billion (2015 Int$) globally, and that in the USA alone the health costs of disease and disability caused by the plastic-associated chemicals PBDE, BPA and DEHP exceeded $920 billion (2015 Int$). Plastic production results in greenhouse gas (GHG) emissions equivalent to 1.96 gigatons of carbon dioxide (CO2e) annually. Using the US Environmental Protection Agency's (EPA) social cost of carbon metric, we estimate the annual costs of these GHG emissions to be $341 billion (2015 Int$).These costs, large as they are, almost certainly underestimate the full economic losses resulting from plastics' negative impacts on human health and the global environment. All of plastics' economic costs-and also its social costs-are externalized by the petrochemical and plastic manufacturing industry and are borne by citizens, taxpayers, and governments in countries around the world without compensation.

Social Justice Findings

The adverse effects of plastics and plastic pollution on human health, the economy and the environment are not evenly distributed. They disproportionately affect poor, disempowered, and marginalized populations such as workers, racial and ethnic minorities, "fenceline" communities, Indigenous groups, women, and children, all of whom had little to do with creating the current plastics crisis and lack the political influence or the resources to address it. Plastics' harmful impacts across its life cycle are most keenly felt in the Global South, in small island states, and in disenfranchised areas in the Global North. Social and environmental justice (SEJ) principles require reversal of these inequitable burdens to ensure that no group bears a disproportionate share of plastics' negative impacts and that those who benefit economically from plastic bear their fair share of its currently externalized costs.

Conclusions

It is now clear that current patterns of plastic production, use, and disposal are not sustainable and are responsible for significant harms to human health, the environment, and the economy as well as for deep societal injustices.The main driver of these worsening harms is an almost exponential and still accelerating increase in global plastic production. Plastics' harms are further magnified by low rates of recovery and recycling and by the long persistence of plastic waste in the environment.The thousands of chemicals in plastics-monomers, additives, processing agents, and non-intentionally added substances-include amongst their number known human carcinogens, endocrine disruptors, neurotoxicants, and persistent organic pollutants. These chemicals are responsible for many of plastics' known harms to human and planetary health. The chemicals leach out of plastics, enter the environment, cause pollution, and result in human exposure and disease. All efforts to reduce plastics' hazards must address the hazards of plastic-associated chemicals.

Recommendations

To protect human and planetary health, especially the health of vulnerable and at-risk populations, and put the world on track to end plastic pollution by 2040, this Commission supports urgent adoption by the world's nations of a strong and comprehensive Global Plastics Treaty in accord with the mandate set forth in the March 2022 resolution of the United Nations Environment Assembly (UNEA).International measures such as a Global Plastics Treaty are needed to curb plastic production and pollution, because the harms to human health and the environment caused by plastics, plastic-associated chemicals and plastic waste transcend national boundaries, are planetary in their scale, and have disproportionate impacts on the health and well-being of people in the world's poorest nations. Effective implementation of the Global Plastics Treaty will require that international action be coordinated and complemented by interventions at the national, regional, and local levels.This Commission urges that a cap on global plastic production with targets, timetables, and national contributions be a central provision of the Global Plastics Treaty. We recommend inclusion of the following additional provisions:The Treaty needs to extend beyond microplastics and marine litter to include all of the many thousands of chemicals incorporated into plastics.The Treaty needs to include a provision banning or severely restricting manufacture and use of unnecessary, avoidable, and problematic plastic items, especially single-use items such as manufactured plastic microbeads.The Treaty needs to include requirements on extended producer responsibility (EPR) that make fossil carbon producers, plastic producers, and the manufacturers of plastic products legally and financially responsible for the safety and end-of-life management of all the materials they produce and sell.The Treaty needs to mandate reductions in the chemical complexity of plastic products; health-protective standards for plastics and plastic additives; a requirement for use of sustainable non-toxic materials; full disclosure of all components; and traceability of components. International cooperation will be essential to implementing and enforcing these standards.The Treaty needs to include SEJ remedies at each stage of the plastic life cycle designed to fill gaps in community knowledge and advance both distributional and procedural equity.This Commission encourages inclusion in the Global Plastic Treaty of a provision calling for exploration of listing at least some plastic polymers as persistent organic pollutants (POPs) under the Stockholm Convention.This Commission encourages a strong interface between the Global Plastics Treaty and the Basel and London Conventions to enhance management of hazardous plastic waste and slow current massive exports of plastic waste into the world's least-developed countries.This Commission recommends the creation of a Permanent Science Policy Advisory Body to guide the Treaty's implementation. The main priorities of this Body would be to guide Member States and other stakeholders in evaluating which solutions are most effective in reducing plastic consumption, enhancing plastic waste recovery and recycling, and curbing the generation of plastic waste. This Body could also assess trade-offs among these solutions and evaluate safer alternatives to current plastics. It could monitor the transnational export of plastic waste. It could coordinate robust oceanic-, land-, and air-based MNP monitoring programs.This Commission recommends urgent investment by national governments in research into solutions to the global plastic crisis. This research will need to determine which solutions are most effective and cost-effective in the context of particular countries and assess the risks and benefits of proposed solutions. Oceanographic and environmental research is needed to better measure concentrations and impacts of plastics <10 µm and understand their distribution and fate in the global environment. Biomedical research is needed to elucidate the human health impacts of plastics, especially MNPs.

Summary

This Commission finds that plastics are both a boon to humanity and a stealth threat to human and planetary health. Plastics convey enormous benefits, but current linear patterns of plastic production, use, and disposal that pay little attention to sustainable design or safe materials and a near absence of recovery, reuse, and recycling are responsible for grave harms to health, widespread environmental damage, great economic costs, and deep societal injustices. These harms are rapidly worsening.While there remain gaps in knowledge about plastics' harms and uncertainties about their full magnitude, the evidence available today demonstrates unequivocally that these impacts are great and that they will increase in severity in the absence of urgent and effective intervention at global scale. Manufacture and use of essential plastics may continue. However, reckless increases in plastic production, and especially increases in the manufacture of an ever-increasing array of unnecessary single-use plastic products, need to be curbed.Global intervention against the plastic crisis is needed now because the costs of failure to act will be immense.

Organophosphite Antioxidants and Novel Organophosphate Esters in Dust from China: Large-Scale Distribution and Heterogeneous Phototransformation

A large-scale survey was conducted by measuring five organophosphite antioxidants (OPAs) and three novel organophosphate esters (NOPEs) in 139 dust samples across China. The median summed concentrations of OPAs and NOPEs in outdoor dust were 33.8 ng/g (range: 0.12-53,400 ng/g) and 7990 ng/g (2390-27,600 ng/g), respectively. The dust concentrations of OPAs associated with the increasing economic development and population density from western to eastern China, whereas the NOPE concentration in Northeast China (median, 11,900 ng/g; range, 4360-16,400 ng/g) was the highest. Geographically, the distribution of NOPEs was significantly associated with annual sunshine duration and precipitation at each sampling site. Results of laboratory experiments further revealed that the simulated sunlight irradiation promoted the heterogeneous phototransformation of OPAs in dust, and this process was accelerated with the existence of reactive oxygen species and enhanced relative humidity. Importantly, during this phototransformation, the hydroxylated, hydrolyzed, dealkylated, and methylated products, e.g., bis(2,4-di-tert-butylphenyl) methyl phosphate, were identified by nontargeted analysis, part of which were estimated to be more toxic than their parent compounds. The heterogeneous phototransformation pathway of OPAs was suggested accordingly. For the first time, the large-scale distribution of OPAs and NOPEs and the phototransformation of these "new chemicals" in dust were revealed.

The partitioning and distribution of neonicotinoid insecticides in human blood

The burden of neonicotinoid insecticides (neonics) in humans has attracted widespread attention in recent years due to the potential adverse effects. Nonetheless, information on the partitioning behavior and distribution in human blood is still limited. Herein, we obtained 115 adult whole blood and plasma specimens for analysis of eight neonics to better understand neonics' partitioning and distribution in human blood. At least one neonic was detected in 49.6% of the red blood cells and 55.7% of the plasma. In red blood cells, the highest detection rate and concentration was thiamethoxam (THI) with 19.1% and 3832 ng/L, respectively. Imidacloprid had the highest detection rate with 26.1% in the plasma. The mass fraction (Fp) of neonics detected indicates that thiacloprid, imidacloprid, and dinotefuran are mostly resided in plasma upon entering into human blood, while thiamethoxam is mostly present in red blood cells. The distribution of clothianidin and acetamiprid between plasma and red blood cells is similar. The mass fraction (Fp) values for THI were significantly different compared to other neonics, and the effect of age and gender on THI partitioning concluded that there may not be significant variability in the distribution of THI in the sampled population. Overall, this study was the first to investigate neonics residuals in red blood cells and provided fundamental information on the partitioning and distribution of neonics in human blood.

Pollution profiles, influencing factors, and source apportionment of target and suspect organophosphate esters in ambient air: A case study in a typical city of Northern China

Organophosphate esters (OPEs) are attracting attention because they pose risks to biota, including humans. Little research has been performed into the environmental fates of OPEs in the atmosphere. Here, target/suspect OPEs were determined in 122 atmosphere samples (gas phase (n = 31), PM_2.5 (n = 30), PM₁₀ (n = 30), and total suspended particles (n = 31)) from a city in Northern China. Pollution profiles were established, influencing factors identified, and sources apportioned. We found 12 target OPEs and 29 suspect OPEs. The target and suspect OPE concentrations in the ambient air samples were 2.2-172.5 and 0.7-53.9 ng/m³, respectively. Tris(chloroethyl) phosphate, tris(1-chloro-2-propyl) phosphate, and tris(2,4-di-t-butylphenyl) phosphate were the dominant OPEs in all samples. The OPEs were not in equilibrium, indicated by a multi-parameter linear free energy relationship model. The air quality index and OPE concentrations significantly correlated, indicating that OPE pollution is often more serious during weather with worse air quality. The target and suspect screening strategy and a positive matrix factorization model allowed OPE sources to be apportioned, improving our understanding of OPE sources. The four dominant sources were (1) construction, (2) indoor emissions, (3) the plastic industry and industrial activities, and (4) traffic emissions, textiles, and foam products.

Catalyst-Free Oxidation Reactions in a Microwave Plasma Torch-Based Ion/Molecular Reactor: An Approach for Predicting the Atmospheric Oxidation of Pollutants

The atmospheric oxidation of chemicals has produced many new unpredicted pollutants. A microwave plasma torch-based ion/molecular reactor (MPTIR) interfacing an online mass spectrometer has been developed for creating and monitoring rapid oxidation reactions. Oxygen in the air is activated by the plasma into highly reactive oxygen radicals, thereby achieving oxidation of thioethers, alcohols, and various environmental pollutants on a millisecond scale without the addition of external oxidants or catalysts (6 orders of magnitude faster than bulk). The direct and real-time oxidation products of polycyclic aromatic hydrocarbons and p-phenylenediamines from the MPTIR match those of the long-term multistep environmental oxidative process. Meanwhile, two unreported environmental compounds were identified with an MPTIR and measured in the actual water samples, which demonstrates the considerable significance of the proposed device for both predicting the environmental pollutants (non-target screening) and studying the mechanism of atmospheric oxidative processes.

Discovery of 18 Organophosphate Esters and 3 Organophosphite Antioxidants in Food Contact Materials Using Suspect and Nontarget Screening: Implications for Human Exposure

In this study of extracts of 100 food contact material (FCM) samples collected from South China, we identified 21 organophosphate esters (OPEs) by suspect screening and seven novel OPEs by characteristic fragments-based nontarget screening. Six organophosphite antioxidants (OPAs) were further identified using a suspect list derived from these identified OPEs. Of these compounds, 18 OPEs and 3 OPAs were found for the first time in the extracts of FCMs. (Semi-)quantification revealed that seven of the OPEs [triphenyl phosphate, tris(2,4-di-tert-butylphenyl) phosphate (TDtBPP), bis(2,4-di-tert-butylphenyl) methyl phosphate, (2,4-di-tert-butylphenyl)pentaerythritol phosphate, triethyl phosphate, 2-ethylhexyl-diphenyl phosphate, and trimethyl phosphate] and two of the OPAs [tris(2,4-di-tert-butylphenyl) phosphite (TDtBPPi) and pentabutylated triphenyl phosphite] were present in more than 50 FCM samples and that TDtBPP and TDtBPPi were the dominant OPE and OPA in FCMs, respectively [with median concentrations of 7260 ng/g (range: <8.50-103,879 ng/g) and 31,920 ng/g (range: <9.80-657,399 ng/g), respectively]. A migration test revealed that the migration efficiencies of compounds from a plastic coffee cup to food simulants in the cup increased as the ethanol/water ratio in the food simulants increased. This study significantly enhanced our understanding on the diversity and occurrences of OPEs and OPAs in FCMs used in China and their FCM-to-food migration risk.

Potential adverse outcome pathways with hazard identification of organophosphate esters

Data-driven analysis and pathway-based approaches contribute to reasonable arrangements of limited resources and laboratory tests for continuously emerging commercial chemicals, which provides opportunities to save time and effort for toxicity research. With the widespread usage of organophosphate esters (OPEs) on a global scale, the concentrations generally reached up to micromolar range in environmental media and even in organisms. However, potential adverse effects and toxicity pathways of OPEs have not been systematically assessed. Therefore, it is necessary to review the current situation, formulate the future research priorities, and characterize toxicity mechanisms via data-driven analysis. Results showed that the early toxicity studies focused on neurotoxicity, cytotoxicity, and metabolic disorders. Then the main focus shifted to the mechanisms of cardiotoxicity, endocrine disruption, hepatocytes, reproductive and developmental toxicity to vulnerable sub-populations, such as infants and embryos, affected by OPEs. In addition, several novel OPEs have been emerging, such as bis(2-ethylhexyl)-phenyl phosphate (HDEHP) and oxidation derivatives (OPAsO) generated from organophosphite antioxidants (OPAs), leading to multiple potential ecological and human health risks (neurotoxicity, hepatotoxicity, developmental toxicity, etc.). Notably, in-depth statistical analysis was promising in encapsulating toxicological information to develop adverse outcome pathways (AOPs) frameworks. Subsequently, network-centric analysis and quantitative weight-of-evidence (QWOE) approaches were utilized to construct and evaluate the putative AOPs frameworks of OPEs, showing the moderate confidences of the developed AOPs. In addition, frameworks demonstrated that several events, such as nuclear receptor activation, reactive oxygen species (ROS) production, oxidative stress, and DNA damage, were involved in multiple different adverse outcome (AO), and these AOs had certain degree of connectivity. This study brought new insights into facilitating the complement of AOP efficiently, as well as establishing toxicity pathways framework to inform risk assessment of emerging OPEs.

Suspect and nontarget screening of known and unknown organophosphate esters (OPEs) in soil samples

Ninety-five soil samples (n = 95) were analyzed using an integrated suspect and non-target organophosphate ester (OPE) screening strategy. This suspect and non-target screening strategy allowed us to fully or tentatively identify 26 OPEs or OPE-like substances. Among these 26 newly identified contaminants, bisphenol A bis(diphenylphosphate) (BPABDP) exhibited the highest detection frequency of 83.2 %, with a concentration range of ND - 385 ng/g dry weight (dw). We also observed that BPABDP was significantly correlated with all other OPEs (p < 0.001 in all pairs), suggesting that BPABDP is widely used as a plasticizer and flame retardant in various commercial products. Another interesting finding was the discovery of four novel OPE structures with tentatively proposed chemical structures. Among these four non-target OPEs, (tert-butyl) phenyl bis(2,4-di-tert-butylphenyl) phosphate (TBPBDTBPP) shared a backbone structure very similar to that of the well-known OPE, tris(2,4-di-tert-butylphenyl) phosphate (TDTBPP). Detection frequency of this newly discovered OPE was high, up to 69.5 %, and it was significantly correlated with isodecyl diphenyl phosphate (IDDP), BPABDP, diphenyl 2-isopropylphenyl phosphate (2IPPDPP), and tricresyl phosphate (TCrP, p < 0.05 in all pairs), respectively. This study reported the most comprehensive suite of OPEs in soil samples, and 16 out of them were recognized in soil for the first time.

Prediction of Collision Cross-Section Values for Extractables and Leachables from Plastic Products

The use of ion mobility separation (IMS) in conjunction with high-resolution mass spectrometry has proved to be a reliable and useful technique for the characterization of small molecules from plastic products. Collision cross-section (CCS) values derived from IMS can be used as a structural descriptor to aid compound identification. One limitation of the application of IMS to the identification of chemicals from plastics is the lack of published empirical CCS values. As such, machine learning techniques can provide an alternative approach by generating predicted CCS values. Herein, experimental CCS values for over a thousand chemicals associated with plastics were collected from the literature and used to develop an accurate CCS prediction model for extractables and leachables from plastic products. The effect of different molecular descriptors and machine learning algorithms on the model performance were assessed. A support vector machine (SVM) model, based on Chemistry Development Kit (CDK) descriptors, provided the most accurate prediction with 93.3% of CCS values for [M + H]⁺ adducts and 95.0% of CCS values for [M + Na]⁺ adducts in testing sets predicted with <5% error. Median relative errors for the CCS values of the [M + H]⁺ and [M + Na]⁺ adducts were 1.42 and 1.76%, respectively. Subsequently, CCS values for the compounds in the Chemicals associated with Plastic Packaging Database and the Food Contact Chemicals Database were predicted using the SVM model developed herein. These values were integrated in our structural elucidation workflow and applied to the identification of plastic-related chemicals in river water. False positives were reduced, and the identification confidence level was improved by the incorporation of predicted CCS values in the suspect screening workflow.

Nine alkyl organophosphate triesters newly identified in house dust

Owing to increasing concerns about the toxicity of alkyl organophosphate triesters (OPTEs), it is necessary to comprehensively profile alkyl OPTEs in the environment. In this study, we conducted a nontarget analysis using high-resolution mass spectrometry to newly identify alkyl OPTEs in house dust samples collected in North China. Data-independent acquisition mode directed by the characteristic phosphate fragment was used. Nine alkyl OPTEs were newly identified, namely tridecyl phosphate (TDeP), dioctyl tetradecyl phosphate, tridodecyl phosphate (TDoP), dioctyl butoxyethoxyethyl phosphate (DOBEEP), dioctyl (oxo)butoxypropyl phosphate (DOOBPP), dioctyl hydroxyethoxyethoxyethyl phosphate (DOHEEEP), didodecyl hydroxyethoxyethyl phosphate (DDoHEEP), tetradecyl dodecyl hydroxyethoxyethyl phosphate (TDoHEEP), and bis(2-butoxyethyl) hydroxyethyl phosphate (BBOEHEP). BBOEHEP was fully identified by comparison to an authentic standard, and the others were tentative structures (level 3). Eight of them (not DOHEEEP) exhibited detection frequencies between 89% and 100% in the 45 samples, and (semi-)quantitation revealed that their median concentrations and ranges were: TDoP (35.1 ng/g, 8.21-111 ng/g), DOBEEP (29.3 ng/g, 2.56-5191 ng/g), DOOBPP (13.6 ng/g, 1.38-2128 ng/g), BBOEHEP (5.79 ng/g, not detected (ND)-861 ng/g), TDeP (4.10 ng/g, 1.34-39.2 ng/g), DDoHEEP (3.26 ng/g, ND-41.5 ng/g), TDoHEEP (2.09 ng/g, ND-29.5 ng/g), and DOTP (0.93 ng/g, ND-169 ng/g). Moreover, TDeP, TDoP, DOBEEP, DOOBPP, and BBOEHEP were found in SRM2585 (standard house dust). These data revealed the widespread occurrence of alkyl OPTEs with high concentrations in the indoor environment.

Penetration of Organophosphate Triesters and Diesters across the Blood-Cerebrospinal Fluid Barrier: Efficiencies, Impact Factors, and Mechanisms

The penetration of organophosphate triesters (tri-OPEs) and diesters (di-OPEs) across the blood-brain barrier and their influencing factors remain unclear in humans. In this study, 21 tri-OPEs and 8 di-OPEs were measured in 288 paired serum and cerebrospinal fluid (CSF) samples collected in Jinan, China. Six tri-OPEs were frequently detected in both serum and CSF, with median concentrations ranging from 0.062 to 1.62 and 0.042-1.11 ng/mL, respectively. Their penetration efficiencies across the blood-CSF barrier (BCSFB) (R_CSF/serum, C_CSF/C_serum) were calculated at 0.667-2.80, and these efficiencies first increased and then decreased with their log K_ow values. The reduced penetration efficiencies of triphenyl phosphate (TPHP) and 2-ethylhexyl diphenyl phosphate (EHDPP) may be attributed to their strong binding affinities for human serum albumin and p-glycoprotein due to their high hydrophobicity and aryl structure, as indicated by molecular docking. This suggests that active efflux transport may be involved in the penetration of TPHP and EHDPP in addition to passive diffusion similar to the other four tri-OPEs. Di-OPEs were found in few serum samples and even fewer CSF samples, indicating their limited BCSFB permeability. This may be due to their high polarity, low hydrophobicity, and ionic state in blood. This study has important implications for understanding the neurotoxicity of tri-OPEs and di-OPEs and the underlying mechanisms.

Low-level alternative halogenated flame retardants (AHFRs) in indoor dust from Adelaide, South Australia decades since national legislative control on polybrominated diphenyl ethers (PBDEs)

Since commercial polybrominated diphenyl ethers (PBDEs) have been globally banned or restricted in 2000s, alternative halogenated flame retardants (AHFRs) appear increasingly dominant over PBDEs in many countries/regions. In this study, low levels of AHFRs were unexpectedly observed in the indoor dust from Adelaide, South Australia. Anti-dechlorane plus (anti-DP) was the most frequently detected AHFR with a median concentration of 1.28 ng/g, while other AFHRs were less detected (detection frequency < 50%). The levels of ΣPBDEs (496 ng/g, median) and ΣAHFRs (160 ng/g) and the ratio of ΣAHFRs/ΣPBDEs (0.32) were much lower than those investigated in Australian indoor dust previously. The findings were different to the trend for PBDEs and AHFRs from other countries over the past two decades. No significant correlation was determined between DP and PBDE congeners, indicating their different sources in dust. The human exposure assessment suggested that dust ingestion was the predominant pathway of PBDEs and AHFRs exposure for toddlers, while dermal absorption may be the dominant pathway for adults. The estimated daily intake (EDI) suggested low health risks via dust ingestion and dermal contact for general populations in Adelaide. This study contributes to the knowledge on region-specific FR contamination in indoor environments and related human exposure risk.

Elevated concentration and high Diversity of organophosphate esters (OPEs) were Discovered in Sediment from Industrial, and E-Waste Recycling Areas

Aquatic environments in industrial, and e-waste recycling areas might undergo severe contamination; however, there are few studies comprehensively assessing the pollution status of organophosphate esters (OPEs) in these two areas. Here, we applied both atmospheric pressure chemical ionization (APCI) and electron spray ionization (ESI) sources in our target, suspect, and functional group-dependent screening strategy, which enhanced the confidence for confirmation on precursor ions of OPEs. Then, n=53 sediment samples (30 from the industrial area, and 23 from the e-waste recycling area) were analyzed. Twenty-three out of 30 target OPEs were quantifiable in these analyzed samples. Total OPE concentrations (Σ₃₀OPEs) in samples from e-waste recycling area range from 12.8 to 9250 ng/g dry weight (dw), that are statistically significantly greater (t-test, p < 0.001) than those from industrial area (25.1-5520 ng/g dw). Σ₃₀OPEs in the sediments from industrial, or e-waste recycling area are statistically significantly greater (one-way ANOVA, p < 0.001) as compared to those (32.0-369 ng/g dw) from Taihu Lake in our previous study. In sediment from three areas, suspect and non-target analysis fully or tentatively identified other 20 OPEs. Four of them have not been recorded or registered in any of online chemical databases, and they are tentatively named as ((methoxy(phenoxy)phosphoryl)oxy)phenyl diphenyl phosphate (mPPODP), (tert-butyl)phenyl (ethyne-oxidane) bis(2,4-di-tert-butylphenyl) phosphate (TPBDTP), bis(dichlorophenyl) propane-1,3-diyl bis(hexylated phosphate) (BDCBHP), and bis(2-hexadecoxyethyl) ethyl phosphate (BHEPP). Overall, this study provided new insights regarding both analytical methodology and pollution status of OPEs, and highlights that elevated concentrations and high diversity of OPEs exist in sediments from industrial, and e-waste recycling areas.

Concentrations of bisphenols, benzophenone-type ultraviolet filters, triclosan, and triclocarban in the paired urine and blood samples from young adults: Partitioning between urine and blood

Bisphenols (BPs), benzophenone-type UV filters (BP-type UV filters), triclosan (TCS), and triclocarban (TCC) are endocrine-disrupting chemicals (EDCs) and commonly used in consumer and personal care products. In the present study, seven BPs, eight BP-type UV filters, TCS, and TCC were quantified in 196 paired urine and blood samples collected from young adults in South China. Benzophenone-7 and benzophenone-9 were not detected in all samples, while other target compounds were widely detected in 39%-96% of the urine and 14%-96% of the blood samples, and the median concentrations ranged from <0.02 (specific gravity adjusted: < 0.02) to 2.33 (2.05) ng/mL and <0.01-2.66 ng/mL in the urine and blood samples, respectively. Females had higher levels of most target analytes, and gender-related differences (p < 0.05) were found in the blood levels of benzophenone-2 (females vs. males: 0.84 vs. <0.01 ng/mL), ΣBP (sum of BP-type UV filters; 1.61 vs. 0.98 ng/mL), TCS (3.89 vs. 1.69 ng/mL), and ΣTC (sum of TCS and TCC; 5.77 vs. 3.02 ng/mL). We calculated the portioning of the target compounds between blood and urine (B/U ratios). The B/U ratios of bisphenol F, benzophenone-2, benzophenone-6, 4-hydroxy benzophenone, TCS, and TCC were higher than 1, showing that these analytes have higher enrichment capacities in human blood. To the best of our knowledge, this is the first study to simultaneously analyze the concentrations of BPs, BP-type UV filters, TCS, and TCC in the paired urine and blood samples of young adults in South China.

High-Resolution Mass Spectrometry Screening of Emerging Organophosphate Esters (OPEs) in Wild Fish: Occurrence, Species-Specific Difference, and Tissue-Specific Distribution

There is a dearth of information regarding the pollution status of emerging organophosphate esters (OPEs) in wild fish. Here, we optimized and validated a quick, easy, cheap, effective, rugged, and safe (QuEChERS) pretreatment method, which was further applied for target, suspect, and nontarget screening of OPEs in n = 48 samples of wild fishes from Taihu Lake (eastern China). This integrated technique allows us to fully identify 20 OPEs, and 9 out of them are emerging OPEs detected in wild fish for the first time. Importantly, some of the emerging OPEs, i.e., tris(2,4-di-tert-butylphenyl) phosphate (TDtBPP), 4-tert-butylphenyl diphenyl phosphate (BPDP), and 2-isopropylphenyl diphenyl phosphate (IPDP), exhibited greater or at least comparable contamination levels as compared to traditional ones. There were no statistically significant interspecies (n = 6) differences regarding OPE concentrations. However, we observed significant differences on OPE concentrations among different tissues of silver carp (Hypophthalmichthys molitrix), for which the intestine has the highest OPE mean concentration (46.5 ng/g wet weight (ww)), followed by the liver (20.1 ng/g ww) ≈ brain (20.0 ng/g ww) > gill (14.8 ng/g ww) > muscle (11.4 ng/g ww). An interesting exception is IPDP, which presents an unexpectedly high concentration in the brain (0.510 ng/g ww). Collectively, this study expands our understanding of OPE contamination in wild fish and clearly shows that emerging TDtBPP, IPDP, and BPDP could play an equally important role as traditional OPEs in contribution of OPE pollution in wild fish samples.

Occurrence of novel organophosphate esters derived from organophosphite antioxidants in an e-waste dismantling area: Associations between hand wipes and dust

Electronic waste (e-waste) is a well-known source of plastic additives in the environment. However, the e-waste-related occupational exposure to organophosphite antioxidants (OPAs) and the relevant oxidation products-novel organophosphate esters (NOPEs)-via different pathways is still unknown. In this study, six OPAs and three NOPEs were measured in 116 dust and 43 hand-wipe samples from an e-waste dismantling area in Central China. The median concentrations of ΣOPAs and ΣNOPEs were 188 and 13,900 ng·g^-1 in workshop dust and 5,250 ng·m^-2 and 53,600 ng·m^-2 on workers' hands, respectively. The increasing concentrations of dust in the form of triphenyl phosphate (TPHP) (p < 0.01) and tris(2,4-di-tert-butylphenyl) phosphate (AO168 = O) (p < 0.05) were strongly associated with the corresponding concentration on workers' hands. Furthermore, men had significantly lower levels of NOPEs on their hands than did women (p < 0.01). Moreover, the hand wipe levels of AO168 = O (41,600 ng·m^-2) was significantly higher than that of the typical OPE (TPHP, 7370 ng·m^-2), and the hand-to-mouth contact (ΣOPAs, 9.48 ng·kg bw^-1·day^-1; ΣNOPEs, 109 ng·kg bw^-1·day^-1) was a more significant and integrated pathway than dust ingestion (ΣOPAs, 0.10 ng·kg bw^-1·day^-1; ΣNOPEs, 5.01 ng·kg bw^-1·day^-1) of e-waste related occupational exposure to these "new" chemicals.

Profiles of parabens, benzophenone-type ultraviolet filters, triclosan, and triclocarban in paired urine and indoor dust samples from Chinese university students: Implications for human exposure

Parabens, benzophenone (BP)-type UV filters, triclosan (TCS), and triclocarban (TCC) are commonly used in personal care products. Human exposure to these compounds has received increasing concern because of their adverse health effects. However, the levels of these chemicals in paired urine and indoor samples have never been simultaneously measured. In this work, eight parabens, eight BP-type UV filters, TCS, and TCC were measured in paired urine and indoor dust samples collected from university students and their dormitories in South China. The target analytes were commonly measured in urine (71%-100%) and indoor dust (30%-98%), with median concentrations ranging from 0.16 ng/mL to 19.3 ng/mL in urine and from <0.01 ng/g to 3700 ng/g in indoor dust samples. Females had high levels of most of these target compounds, and gender-related differences were found in the levels of most target analytes. Positive correlations were found in the levels of methylparaben, ethyl paraben, benzophenone-3, and TCS between urine and indoor dust samples. This finding suggested that indoor dust is an important source for human exposure to these compounds. The estimated daily intake (EDI) of these analytes in paired samples was also evaluated. The median EDI_-urine values of target analytes varied in the range of 4.02-59,280 ng/kg bw/day. Females had higher median EDI_-urine values for most of target analytes than males. In addition, the median EDI_{-indoor dust} values of most target analytes in dust from female dormitories were higher than those in dust from male dormitories. Indoor dust ingestion only had minor contribution (<0.5%) to the total exposure. To the best of the authors' knowledge, this study is the first to simultaneously analyze the concentrations of parabens, BP-type UV filters, TCS, and TCC in the paired urine and indoor samples from university students in South China.

Identifying Citric Acid Esters, a Class of Phthalate Substitute Plasticizers, in Indoor Dust via an Integrated Target, Suspect, and Characteristic Fragment-Dependent Screening Strategy

Citrate acid esters (CAEs) have been proposed as a class of phthalate substitute plasticizers; however, information on their occurrence in indoor environments is rare. By using liquid chromatography coupled with a quadrupole-Orbitrap mass spectrometer, we developed an integrated strategy that can be applied for target, suspect, and characteristic fragment-dependent screening of CAEs. In n = 50 indoor dust samples collected from Nanjing City (China), three CAEs, namely, acetyl tributyl citrate (ATBC; mean: 412,000 ng/g), tributyl citrate (TBC, 11,600 ng/g), and triethyl citrate (TEC, 10,900 ng/g), exhibited the greatest contamination levels. Total concentrations of CAEs (∑₈CAEs) were statistically significantly (p < 0.01) greater than those of common organophosphate triesters (OPTEs), a class of ubiquitous contaminants in dust. Suspect and characteristic fragment-dependent screening (m/z 111.0078 ([C₅H₃O₃]⁺) and m/z 129.0181 ([C₅H₅O₄]⁺)) of CAEs were further conducted for the same batch of samples. We tentatively identified six novel CAEs, and the most frequent and abundant CAE was fully identified as tributyl aconitate (TBA). Statistically significant correlation relationships were observed on dust levels between TBA vs ATBC (r = 0.650; p < 0.01) and TBA vs TBC (r = 0.384; p < 0.01), suggesting their similar sources in dust samples.

Occurrence of organophosphate esters in surface water and sediment in drinking water source of Xiangjiang River, China

In this study, we investigated the occurrence of organophosphate esters (OPEs) in the surface water and sediments of the Xiangjiang (XJ) River, a drinking water source of Changsha City. The total concentrations of five detected OPEs (Σ₅OPEs) in surface water and tap water were 6.07-25.3 ng L^-1 (average 14.9 ± 4.98 ng L^-1), and 23.6 ng L^-1, respectively, and four detected OPEs (Σ₄OPEs) in sediments were 3.74-27.5 ng g^-1 dw (average 12.1 ± 6.48 ng g^-1 dw). Tris-2-chloroisopropyl phosphate (TCIPP) was the dominant contributor in water and sediment samples, accounting for over 40% of ΣOPEs. A particular flood event during July-August 2020 reduced the level of OPEs in river water, leading to generally uniform OPE concentrations in surface water and sediment samples from the upper, middle, and lower reaches of XJ. Principal component analysis-multiple linear regression (PCA-MLR) results indicated that the main sources of OPEs in the surface water and sediments of XJ were emissions of waste-water treatment plants and anthropocentric activities. The results of ecological and human health risk assessments indicated that all OPEs posed a low or negligible ecological risk for algae, daphnia, and fish, and negligible risk for human health. Interestingly, the concentration and human health risk of OPEs in a composite tap water sample was generally higher than those in river water samples, indicating possible OPE contamination from water treatment processes or transportation through pipe networks.

Occurrence and distribution of neonicotinoids and characteristic metabolites in paired urine and indoor dust from young adults: Implications for human exposure

Neonicotinoid insecticides (NEOs) are widely used for pest control worldwide. The profile of NEOs in paired urine and indoor dust has not yet been reported in China. In this study, 40 paired samples (i.e., 160 urine and 40 indoor dust) were collected from university students and dormitories from Guangzhou City of China to measure the concentrations of six NEOs and their three metabolites. Target analytes were frequently detected in paired urine (81%-98%) and indoor dust (75%-95%) samples, with median concentrations ranging from 0.02 [specific gravity (SG) adjusted: 0.02] to 2.08 (SG-adjusted: 2.38) ng/mL in urine and from 0.05 to 2.74 ng/g in indoor dust. 5-Hydroxy-imidacloprid was predominant in urine, while N-desmethyl acetamiprid was predominant in indoor dust samples, accounting for 56% and 37%, respectively. 1-Methyl-3-(tetrahydro-3-furylmethyl) urea, a dinotefuran degradate, was measured for the first time in indoor dust, with the median level of 1.02 ng/g. Significant gender-related differences (p < 0.05) in the urinary concentrations of most NEOs were found. We calculated the estimated daily intake (EDI) of target compounds from urine and indoor measurements. The EDIs of target analytes varied among all urine and indoor dust samples, with median values ranging from 0.51 (SG-adjusted: 0.56) to 51.6 (SG-adjusted: 52.8) ng/kg bw/day and from 0.04 to 2.10 pg/kg bw/day, respectively. Moreover, the median EDIs_urine of most target analytes in females were significantly higher than (p < 0.05) those in males. The median EDIs_dust of target compounds in dust from female dormitories were slightly higher than that in dust from male dormitories. These findings indicated that females were more exposed to NEO than males. Thus, the potential health risks of exposure to NEOs and their metabolites in female adults should be addressed in future studies. To our knowledge, this study is the first to report the profiles of NEOs and their metabolites in paired urine and indoor dust samples from young adults in China.

Modeling the antioxidant properties of the eye reduces the false-positive rate of a nonanimal eye irritation test (OptiSafe)

We recently identified a group of chemicals that are misclassified by most, if not all, in vitro alternative ocular irritation tests, suggesting that nonanimal tests may not fully model the ocular environment in which these chemicals interact. To address this, we evaluated the composition of tears, the first defense against foreign substances, and identified the presence of antioxidants that could detoxify reactive chemicals that otherwise may be falsely identified as irritants in alternative irritation tests. In this study, we evaluated the effects of tear antioxidants on the ocular irritation scoring of commonly overclassified chemicals (false positives) using the OptiSafe™ ocular irritation test. Six tear-related antioxidants were individually added to the OptiSafe formulation, and the effects on test outcome were determined. Ascorbic acid, the most abundant water-soluble antioxidant in tears, specifically reduced the OptiSafe false-positive rate. Titration curves showed that this reduction occurs at in vivo concentrations and is specific to chemicals identified either as producing reactive oxygen species or as crosslinkers. Importantly, the addition of tear antioxidants did not impact the detection of true negatives, true positives, or other false positives unassociated with reactive oxygen species or crosslinking. These results suggest that the addition of tear antioxidants to in vitro alternative test systems may substantially reduce the false-positive rate and improve ocular irritant detection.

Profiles of neonicotinoid insecticides and characteristic metabolites in paired urine and blood samples: Partitioning between urine and blood and implications for human exposure

Neonicotinoid insecticides (NEOs) are widely used for pest control worldwide. However, only a few studies have analyzed NEOs and their metabolites in blood samples, and no study has measured the concentrations of NEOs and their metabolites in paired urine and blood samples. In this study, six NEOs and three characteristic metabolites were detected in 196 paired urine and blood samples collected from young adults from China. The NEOs and their metabolites were widely detected in paired urine (67%-91%) and blood (64%-97%) samples, and the median levels ranged within 0.01-1.15 ng/mL in urine and 0.08-0.80 ng/mL in blood. Olefin-imidacloprid (Of-IMI) and 1-methyl-3-(tetrahydro-3-furylmethyl) urea (UF) were the most abundant target compounds in the urine (32.4%) and blood (26.4%) samples, respectively. Gender-related differences were observed in the concentrations of most NEOs and their metabolites in the urine and blood samples. The partitioning of target analytes between blood and urine (NEOs-B/NEOs-U ratios) was also calculated in this study. The B/U ratios of most NEOs and their metabolites were below 1, and positive correlations were observed between urine and blood in most levels of NEOs and their metabolites. This finding indicates that urinary levels are good predictors of human exposure to NEOs and their metabolites. The estimated daily intake (EDI) and the imidacloprid-equivalent (IMI_eq) levels of NEOs and their metabolites in 196 young adults were also determined. The median EDI values (ng/kg bw/day) of ΣNEOs (sum of NEOs and their metabolites) and IMI_eq in females (194.9 and 458.2) were slightly higher than (p > 0.05) those in males (157.1 and 439.7). This finding shows young adults are extensively exposed to NEOs and their metabolites. To our knowledge, this study is the first to report about NEOs and their metabolites in paired samples of urine and blood in China.

Organophosphite Antioxidants in Mulch Films Are Important Sources of Organophosphate Pollutants in Farmlands

Organophosphite antioxidants (OPAs) are important auxiliary antioxidants used in plastic polymers and can be oxidized to organophosphate esters (OPEs) during production and processing. In this work, the occurrence of OPAs and OPEs in farmlands with or without mulch film applications was investigated. Six OPAs and five OPEs were detected, with the median concentrations of 2.66 ng/g (∑₆OPAs) and 100 ng/g (∑₅OPEs) in the film-mulching soil and 1.16 ng/g (∑₆OPAs) and 47.9 ng/g (∑₅OPEs) in the nonfilm-mulching soil, respectively. The oxidative derivative of AO168 (tris (2,4-di-tert-butylphenyl) phosphite), a typical OPA, AO168═O (tris (2,4-di-tert-butylphenyl) phosphate) was frequently detected in farmlands at the concentrations of 0-731 ng/g, which is much higher than that of the commercial OPEs (0-12.1 ng/g). This suggests that the oxidation derivatives of OPAs (OPAs═O) might be important OPE contaminants in soils. Mulch films could be their important source. According to the simulation migration experiment, the emission risk ranges of AO168 and AO168═O from mulch films to soils in China were estimated to be 3.96-87.6 and 10.5-95.3 tons/year, respectively, which were much higher than those of OPEs from sewage sludge applications. Simulation experiments also demonstrated that oxidation was the major pathway for OPAs in soils. OPAs with small substituent groups could be potential sources for organophosphate diesters. For the first time, the serious pollution of OPAs and OPAs═O in soils has been reported, and mulch films have been identified as their potential source.

Ornamental houseplants as potential biosamplers for indoor pollution of organophosphorus flame retardants

We investigated the occurrence, compositions, and partitioning behaviors of organophosphorus flame retardants (OPFRs) in indoor dust, air, and ornamental plants in Dalian, China, to evaluate the possibility of using houseplants as indoor biosamplers of OPFRs. The mean concentrations of OPFRs in the indoor air, dust, and plant samples were 14.9 ng/m³, 18,000 ng/g, and 345 ng/g, respectively. Tris(2-chloroisopropyl) phosphate (TCIPP) was the dominant congener in all kinds of samples. Significant correlation was found between the concentrations of tris(1,3-dichloroisopropyl) phosphate (TDCIPP) in indoor air and plants, suggesting that ornamental plant can be used as a sentinel for certain OPFRs in the indoor air. We developed a predictive model to assess the partitioning coefficients of OPFRs between indoor air and plant. The lipid content in leaf cuticle instead of leaf organic matter was used to improve the accuracy and reliability of this assessment. Using this model, we can estimate the OPFR concentrations in the indoor air based on their concentrations measured in the corresponding indoor plant. The estimated air concentrations were generally comparable with the measured concentrations, especially for those with octanol-air partition coefficient log K_oa <11.6. Indoor plants can also provide a more holistic understanding of OPFR occurrence within a home due to the relatively long-term air-foliage partitioning. The results suggest that under certain conditions indoor ornamental plants have the potential to be used as the biosamplers of OPFRs in the indoor environment due to their convenience and low-cost.

Printing ink related chemicals, including synthetic phenolic antioxidants, organophosphite antioxidants, and photoinitiators, in printing paper products and implications for human exposure

Although synthetic antioxidants (AOs) and photoinitiators (PIs) are known to be used in printing inks, there are little data on residual concentrations in printing paper products. In the present study, twenty-five PIs, ten AOs, and six transformation products were analyzed in two types of printing paper products, magazines and paperboard food packaging materials, both of which are unavoidable everyday products in our life. Nine AOs and six transformation products can be detected in food packaging materials with total concentrations (geometric mean, GM) of 1.16 × 10⁴ ng/dm². Twenty-two PIs were detected in food packaging materials with total concentrations (GM) of 1.76 × 10⁴ ng/dm². These chemicals were also detected in magazines, albeit at low concentrations (GM of AOs: 466 ng/dm², GM of PIs: 1.17 × 10³ ng/dm²). Magazine front covers were found to have much higher concentrations of the target compounds than magazine inside pages. Tris(2,4-di-tert-butylphenyl) phosphate (AO168O), 2,6-di-tert-butyl-4-methylphenol (BHT), bisphenol A (BPA), and benzophenone (BP) were among the predominant chemicals in those printing paper products. Preliminary calculations suggest that dermal exposure to AOs (GM: 6.25 ng/day) and PIs (GM: 17.0 ng/day) via contact with printing paper products is a minor exposure pathway compared to food intake/dust ingestion and is exceedingly unlikely to cause adverse health effects.

Profiles of neonicotinoid insecticides and their metabolites in paired saliva and periodontal blood samples in human from South China: Association with oxidative stress markers

Neonicotinoid insecticides (NEOs) are widely used around the world. The distribution of NEOs in paired saliva and periodontal blood samples was not previously documented in China. In this study, the concentrations of six NEOs and three corresponding metabolites were measured in 188 paired saliva and periodontal blood samples collected from South China. NEOs and their metabolites were frequently detected (68-94%) in paired saliva and periodontal blood, with median levels of 0.01-0.99 ng/mL. 1-Methyl-3-(tetrahydro-3-furylmethyl) urea was the most predominant NEO in paired saliva (39%) and periodontal blood (42%). Gender-related differences in NEOs and their metabolite concentrations were found: males showed lower levels than females. We calculated the concentration ratios between saliva and periodontal blood (S/PB ratios), and found that the median S/PB ratios of NEO and their metabolites were higher than 1, indicating that NEOs and their metabolites were easily excreted via saliva. 8-Hydroxy-2'-deoxyguanosine (8-OHdG) was measured in paired saliva and periodontal blood as a marker of oxidative stress. 8-OHdG concentrations in saliva and periodontal blood were significantly and positively correlated (p < 0.05) with the concentrations of most NEOs and their metabolites in saliva and periodontal blood samples. These findings indicated that exposure to NEOs and their metabolites is associated with oxidative stress. This study is the first to report NEOs and their metabolites in paired saliva and periodontal blood samples collected from South China.

Identification of Three Novel Chloroalkyl Organophosphate Triesters in House Dust Using Halogenation-Guided Nontarget Screening Combined with Suspect Screening

Several haloalkyl organophosphate triester (OPTE) flame retardants have been restricted in some countries due to their potential health risks, but the usage of alternative haloalkyl OPTEs is of concern. In this study, we comprehensively screened for haloalkyl OPTEs in house dust using high-resolution mass spectrometry. Through halogenation-guided nontarget screening, a rare chloroalkyl OPTE, diethylene glycol bis(bis(2-chloroisopropyl)phosphate) (DEGBBCPP), was unequivocally identified (Level 1) in house dust of Beijing, North China. In addition, by screening a suspect list of 61 haloalkyl OPTEs from the EPA's CompTox Chemicals Dashboard, we tentatively identified diethylene glycol bis(bis(2-chloroethyl)phosphate) (DEGBBCEP) and ethylene bis[bis(2-chloroethyl)phosphate] (EBBCEP) (Level 2). DEGBBCPP was detected in all 45 house dust samples, and the median concentration was 98.4 ng/g (13.6-6217 ng/g), that is, approximately one-half that of tris(1,3-dichloro-2-propyl) phosphate, a traditional high-production chloroalkyl OPTE. The detection frequencies of DEGBBCEP and EBBCEP were 96% and 98%, respectively, but at relatively low median concentrations of 10.6 ng/g (from not detected to 152 ng/g) and 3.79 ng/g (from not detected to 130 ng/g), respectively. In standard house dust SRM2585, DEGBBCEP and EBBCEP were detected at 160 ± 15.7 and 1897 ± 38.8 ng/g, respectively, but DEGBBCPP was not detected. Future studies should evaluate the potential adverse health effects of these emerging flame retardants.

Novel Organophosphate Esters in Airborne Particulate Matters: Occurrences, Precursors, and Selected Transformation Products

Organophosphate esters (OPEs) represent an important group of industrial additives with broad applications. However, their occurrences and fate in the atmospheric environment have not been sufficiently investigated. Our study focused on four novel OPEs, including tris(2,4-di-tert-butylphenyl) phosphate (AO168 = O), bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphate, triisodecyl phosphate, and trisnonylphenol phosphate, and characterized their organophosphite antioxidant (OPA) precursors and selected transformation products, in airborne fine particles from South China. House dust from South China was also studied for comparison. Among these four OPEs, exceedingly high concentrations were determined for AO168 = O (i.e., median: 25 500 ng/g in PM_2.5, 52 900 ng/g in PM_1.0, and 10 700 ng/g in indoor dust), reaching 1 order of magnitude greater than those of traditional OPEs. Their OPA precursors were not detectable in airborne particles but hypothesized as one of the sources for airborne OPEs. In addition, potential transformation products of AO168 = O, including bis(2,4-di-tert-butylphenyl) phosphate (B2,4DtBPP) and 2,4-di-tert-butylphenol (2,4DtBP), also exhibited broad distributions. The levels of 2,4DtBP even surpassed those of AO168 = O in particles. The links between OPAs, OPEs, and other transformation products indicate the complexity of OPE-related chemicals in atmospheric environments. These links should be taken into consideration for a better characterization of OPEs' environmental and health risks.

Synthetic Phenolic Antioxidants: A Review of Environmental Occurrence, Fate, Human Exposure, and Toxicity

Synthetic phenolic antioxidants (SPAs) are widely used in various industrial and commercial products to retard oxidative reactions and lengthen product shelf life. In recent years, numerous studies have been conducted on the environmental occurrence, human exposure, and toxicity of SPAs. Here, we summarize the current understanding of these issues and provide recommendations for future research directions. SPAs have been detected in various environmental matrices including indoor dust, outdoor air particulates, sea sediment, and river water. Recent studies have also observed the occurrence of SPAs, such as 2,6-di-tert-butyl-4-methylphenol (BHT) and 2,4-di-tert-butyl-phenol (DBP), in humans (fat tissues, serum, urine, breast milk, and fingernails). In addition to these parent compounds, some transformation products have also been detected both in the environment and in humans. Human exposure pathways include food intake, dust ingestion, and use of personal care products. For breastfeeding infants, breast milk may be an important exposure pathway. Toxicity studies suggest some SPAs may cause hepatic toxicity, have endocrine disrupting effects, or even be carcinogenic. The toxicity effects of some transformation products are likely worse than those of the parent compound. For example, 2,6-di-tert-butyl-p-benzoquinone (BHT-Q) can cause DNA damage at low concentrations. Future studies should investigate the contamination and environmental behaviors of novel high molecular weight SPAs, toxicity effects of coexposure to several SPAs, and toxicity effects on infants. Future studies should also develop novel SPAs with low toxicity and low migration ability, decreasing the potential for environmental pollution.

Beyond Traditional Organophosphate Triesters: Prevalence of Emerging Organophosphate Triesters and Organophosphate Diesters in Indoor Dust from a Mega E-waste Recycling Industrial Park in South China

Numerous studies have reported the environmental contamination with traditional organophosphate triesters (tri-OPEs), but there is very little information on emerging tri-OPEs and organophosphate diesters (di-OPEs), especially in e-waste recycling areas. In this study, we conducted a comprehensive survey to monitor a broad suite of 11 traditional tri-OPEs, 12 emerging OPEs, and 10 di-OPEs in indoor dust collected from the workshops of (n = 42) and residential homes adjacent to (n = 24) a mega e-waste recycling industrial park in South China. In addition to traditional tri-OPEs, all of the emerging OPEs and di-OPEs were frequently detected in the dust samples. Total concentrations of emerging tri-OPEs and di-OPEs were in the range of 1210-62 900 and 2010-55 600 ng/g in the workshop dust and 435-23 700 and 186-4350 ng/g in the local home dust, respectively, which were comparable to those of traditional tri-OPEs (1160-61 500 and 370-13 900 ng/g, respectively). Most OPEs exhibited significantly higher concentrations in workshop dust versus local home dust (p < 0.05), indicating that e-waste dismantling activities contributed to the high residues of OPEs in indoor dust. Correlation analysis revealed that tri-OPEs have some common emission sources, i.e., e-waste and household products, while di-OPEs could originate from different sources, e.g., tri-OPE degradation, direct commercial application, and impurities in tri-OPE formulas. For both occupational workers and local adults, the median estimated daily intake values of emerging tri-OPEs (7.5 and 1.7 ng/kg bw/day, respectively) and di-OPEs (3.9 and 0.2 ng/kg bw/day, respectively) were comparable to that of traditional tri-OPEs (4.3 and 1.0 ng/kg bw/day, respectively), which suggests the important contribution of the emerging tri-OPEs and di-OPEs to the overall risks of human external exposure to OPE chemicals.

Organic contaminants formed during fire extinguishing using different firefighting methods assessed by nontarget analysis

During a fire event, potentially hazardous chemicals are formed from the combustion of burning materials and are released to the surrounding environment, both via gas and soot particles. The aim of this investigation was to study if firefighting techniques influence the emission of chemicals in gas phase and soot particles. Five full-scale fire tests were extinguished using four different firefighting techniques. A nontarget chemical analysis approach showed that important contaminants in gas and soot separating the different tests were brominated flame retardants (BFRs), organophosphate flame retardants (OPFR), polycyclic aromatic hydrocarbons (PAHs) and linear hydrocarbons. Reproducibility was evaluated by a field replicate test and it was determined that the temperature curve during the event had a bigger impact on the released chemicals than the firefighting technique used. However, despite fire intensity being a confounding factor, multivariate statistics concluded that water mist with additive resulted in less BFR emissions compared to foam extinguishing. The analysis also showed that the conventional spray nozzle method released more PAHs compared with the water mist method. The comprehensive chemical analysis of gas and soot released during fire events was able to show that different firefighting techniques influenced the release of chemicals.

Nontarget Discovery of 11 Aryl Organophosphate Triesters in House Dust Using High-Resolution Mass Spectrometry

There is growing interest in the identification of novel aryl organophosphate triester (OPTE) congeners that may exist in the environment. In this study, we discovered 11 novel aryl OPTEs in north China house dust using a characteristic aryl phosphate fragment-guided high-resolution mass spectrometry method with data-independent acquisition. Tripentylated triphenyl phosphate (TPeTPhP), dicresyl phenyl phosphate (DCrPP), diisodecylphenyl phosphate (DIDPP), butoxyethoxyethyl octyl phenyl phosphate (BEEOPP), dioctyl nonylphenyl phosphate (DONPP), propoxypropyl bis(diphenyl phosphate) (PPBDPhP), octyl nonylphenyl phenyl phosphate (ONPPP), and (saturated mono-oxygen butoxybutyl) butoxyethoxyethyl phenyl phosphate (MBBPP) were detected in 84-100% of 45 samples. ONPPP was present in the highest median concentration of 69.0 ng/g, followed by DONPP (68.7 ng/g), DIDPP (50.3 ng/g), BEEOPP (42.5 ng/g), DCrPP (33.7 ng/g), PPBDPhP (25.0 ng/g), TPeTPhP (9.28 ng/g), and MBBPP (4.80 ng/g). Seven novel aryl OPTEs were also detected in standard house dust SRM2585, and the concentration of DIDPP (4375 ± 660 ng/g) was 4-fold higher than that (1048 ± 44.5 ng/g) of triphenyl phosphate, a typical aryl OPTE. The discovery of these novel OPTEs has significantly enriched our understanding of the aryl OPTEs present in house dust.

Tris(2,4-di-tert-butylphenyl)phosphate: An Unexpected Abundant Toxic Pollutant Found in PM2.5

A novel pollutant, tris(2,4-di-tert-butylphenyl)phosphate (I168O), was identified in urban fine particulate matter (PM_2.5) samples in a nontargeted screening based on mass spectrometry for the first time. I168O was detected in all samples collected from two typical cities far away from each other in China. The concentrations of I168O reached up to 851 (median: 153) ng/m³, indicating that it was a widespread and abundant pollutant in the air. The antioxidant Irgafos 168 [I168, tris(2,4-di-tert-butylphenyl)phosphite] popularly added in plastics was the most suspected source for the detected I168O. Simulation studies indicated that heating, UV radiation, and water contact might significantly (p < 0.05) transform I168 to I168O. In particular, I168O might be magnificently evaporated into the air at high temperatures. The outdoor inhalation exposure of I168O may exert substantial health risks.

A broad range of organophosphate tri- and di-esters in house dust from Adelaide, South Australia: Concentrations, compositions, and human exposure risks

This study aimed to investigate the occurrences of a suite of thirty-one organophosphate tri-esters (tri-OPEs) and six di-esters (di-OPEs) in house dust collected from Adelaide, South Australia. The results demonstrate ubiquitous presence of most OPEs in Adelaide house dust, with median concentration of 40,200 and 5260 ng/g dry weight for ∑tri-OPEs and ∑di-OPEs, respectively. A number of emerging OPEs with chemical structures resembling that of triphenyl phosphate (TPHP), including bisphenol A bis(diphenyl phosphate) (BPA-BDPP), cresyl diphenyl phosphate (CDP), isodecyl diphenyl phosphate (IDDPP), resorcinol-bis(diphenyl)- phosphate (RDP), as well as a suite of isopropylated or tert-butylated triarylphosphate ester isomers (ITPs or TBPPs), were frequently detected with combined levels surpassing that of TPHP. The investigated di-OPEs, predominated by DPHP, consisted of approximately 13% of the ∑tri-OPEs concentrations. Median concentration ratios of diphenyl phosphate (DPHP) and bis(2-ethylhexyl) phosphate (BEHP) to their respective tri-OPEs [i.e., TPHP and tris(2-ethylhexyl) phosphate (TEHP)] were determined to be 1.8 and 2.0, respectively, indicating possible commercial applications for these two di-OPEs. The estimated human intakes of dust-associated OPEs via dust ingestion and dermal contact were much lower than the reference doses. However, the risks of human exposure to OEPs may be complicated by quickly expanding family of OPEs containing various analogues and isomers as well as additional exposure pathways. Therefore, elucidation of human exposure to OPEs and associated risks requires extensive efforts in analytical, environmental, toxicological, and epidemiological investigations.

Biodegradation of triphenyl phosphate using an efficient bacterial consortium GYY: Degradation characteristics, metabolic pathway and 16S rRNA genes analysis

Triphenyl phosphate (TPHP) was frequently detected in various environment, which has caused wide attention out of its adverse effects on organisms. Hence, an effective and reasonable method is in urgent demand for removing TPHP. In this study, microbial consortium GYY with efficient capacity to degrade TPHP has been isolated, which could degrade 92.2% of TPHP within 4 h under the optimal conditions (pH 7, inoculum size 1 g/L wet weight, 30 °C, TPHP initial concentration 3 μmol/L). Some intermediate products such as diphenyl phosphate (DPHP), phenyl phosphate (PHP), OH-TPHP, and methoxylation products were identified, suggesting that TPHP was metabolized by hydrolysis, methoxylation after hydrolysis, and methoxylation after hydroxylation pathways. The sequencing analysis demonstrated that Pseudarthrobacter and Sphingopyxis were the dominant genera in consortium GYY during the process of TPHP biodegradation. Also, Sphingopyxis (GY-1) that degraded 98.9% of TPHP (3 μmol/L) within 7 days was further isolated and identified. Overall, this study provides a new insight on TPHP metabolic transformation by consortium and theoretical basis of developing bioremediation technology for TPHP contamination.

Functional Group-Dependent Screening of Organophosphate Esters (OPEs) and Discovery of an Abundant OPE Bis-(2-ethylhexyl)-phenyl Phosphate in Indoor Dust

There is increasing scientific interest in environmental pollution and the effect on public health caused by organophosphate esters (OPEs). Using liquid chromatography coupled to a hybrid quadrupole Orbitrap high-resolution mass spectrometer, a novel, robust, and untargeted screening strategy for the identification of novel OPEs in indoor dust samples was presently developed based on the characteristic molecular fragmentation pathways, and 12 previously reported OPEs and six previously unrecognized OPEs were detected in the combined extracts of indoor dust samples, collected in Nanjing, eastern China. One of the six detected OPEs, bis-(2-ethylhexyl)-phenyl phosphate (BEHPP), was identified by comparison of unique LC and MS characteristics with a synthesized pure standard. Accurate concentrations of BEHPP were determined in n = 50 individual indoor dust samples with 100% detection frequency with a median concentration range of 50-1530 ng/g dry weight, which were generally greater or at least comparable to traditional OPEs, that is, triphenyl phosphate and 2-ethylhexyl diphenyl phosphate (EHDPP), in the same dust samples. Statistically significant, positive correlations were found for log-transformed concentrations of BEHPP versus EHDPP (r² = 0.7884, p < 0.0001), and BEHPP versus tris(2-ethylhexyl)phosphate (r² = 0.4054, p < 0.0001), suggesting their similar commercial applications and sources in the environment.

Uptake, Deposition, and Metabolism of Triphenyl Phosphate in Embryonated Eggs and Chicks of Japanese Quail (Coturnix japonica)

The toxicokinetics of triphenyl phosphate (TPHP) in vivo including the uptake, deposition, and biotransformation into the metabolite diphenyl phosphate (DPHP) is presently reported in embryonated eggs and chicks of Japanese quail. Quail were dosed with TPHP at 3 concentrations by air cell egg injection on embryonic day 0, followed by daily oral dosing after chicks hatched (5 d). Vehicle-only exposed controls were also used. In dosed eggs, only 33% of the TPHP remained 2 d after injection (no hepatic development); after 10 d (post-hepatogenesis), only 2% remained. The estimated TPHP half-lives in the eggs ranged from 1.1 to 1.8 d for the 3 dosed groups. In all exposed eggs and chicks, DPHP significantly increased with dose (0.001 < p < 0.044). It appears that DPHP is an important metabolite in quail, making up 41 to 74% of all metabolites formed in embryonated eggs. In chicks, at medium and high doses, DPHP concentrations significantly exceeded those of TPHP (p ≤ 0.007), making up 67 and 76% of the total burden, respectively. Our findings suggest that rapid TPHP metabolism occurred in chicks and embryonated quail eggs but that this may vary with the age of the embryonated egg and the stage of embryo development, which should be considered when evaluating concentrations of TPHP and DPHP measured in eggs of wild birds. Environ Toxicol Chem 2020;39:565-573. © 2019 Her Majesty the Queen in Right of Canada. Environmental Toxicology and Chemistry © 2019 SETAC.

Estimating renal and hepatic clearance rates of organophosphate esters in humans: Impacts of intrinsic metabolism and binding affinity with plasma proteins

The renal and hepatic clearance rates of organophosphate esters (OPEs) in humans were estimated. Six OPEs and their corresponding diester metabolites (mOPEs) were quantified respectively in 30 paired human plasma and urine samples collected in Hengshui, Hebei province, China. The renal clearance rate (CL_renal) of triphenyl phosphate (TPHP), tris(chloroethyl) phosphate (TCEP) and tris(1,3-dichloro-isopropyl) phosphate (TDCIPP) was estimated to be 68.9, 50.9 and 33.3 mL/kg/day, respectively, while it was not calculated for other three OPEs due to the low detection frequencies in human samples. To estimate the clearance rates of the target OPEs, hepatic clearance rates (CL_h) of OPEs were extrapolated from their in vitro intrinsic clearance data in human liver microsomes (CL_HLM). The calculated CL_h values of TCEP and TDCIPP were comparable to their CL_renal, indicating that the in vitro extrapolation method was suitable for estimating the clearance rates of OPEs. The higher binding affinity of TDCIPP with plasma proteins could reduce its renal clearance. The estimated half-lives of Cl-OPEs in human were longer than those of the aryl- and alkyl-OPEs. This study provided a feasible in vitro method to predict the clearance and half-lives of OPEs in human, which is significant for their accurate health risk assessment.

Synthetic phenolic antioxidants and transformation products in dust from different indoor environments in Toronto, Canada

Synthetic phenolic antioxidants (SPAs) are a class of anthropogenic antioxidants that are widely used in a large variety of commercial products. Although several SPAs have been listed as targets for risk assessment by Environment and Climate Change Canada, little data are available on the occurrence of SPAs in the Canadian environment. In this study, eighty-three indoor dust samples were collected from offices and homes in Toronto. Eight SPAs were detected at concentrations ranging from 67.2 to 1.55e4 ng/g, with a geometric mean (GM) concentration of 1.49e3 ng/g, among which 2,6-di-tert-butyl-4-methylphenol (BHT) was the primary congener and had a GM concentration of 658 ng/g. Four BHT transformation products (TPs) were also detected in the indoor dust samples, with concentrations ranging from 40.4 to 1.27e4 ng/g and a GM concentration of 883 ng/g. No significant concentration difference was observed between the office and home dust samples for either the summed target SPA or TP concentrations (p > 0.05). The calculated estimated daily intakes of these chemical contaminants (0.004-10.0 ng/kg BW/day) suggest that they pose no immediate health risk to the Canadian population. To the best of our knowledge, this is the first report of the occurrence of these chemical contaminants and their transformation products in Canadian indoor environments, and furthermore the first detection of 4-tert-butyl-phenol in an environmental sample.

Identification of Photoinitiators, Including Novel Phosphine Oxides, and Their Transformation Products in Food Packaging Materials and Indoor Dust in Canada

Although photopolymerization is generally considered a green technology, the contamination of foodstuffs by photoinitiators (PIs), an essential component of photopolymerization systems, has recently attracted notice. Despite this interest, little attention has been paid to PI contamination in the environment. To date, only one study, performed in China, has reported the occurrence of PIs in the environment. In the present study, the occurrence of 25 PI additives with discrete molecular structures was investigated in food packaging materials and indoor dust. The PIs studied here include benzophenones (BZPs), thioxanthones (TXs), amine co-initiators (ACIs), and novel phosphine oxides (POs). Twenty-four PIs were detected in food packaging materials. Total concentrations of PIs (∑PIs) ranged between 122 and 44 113 ng/g, with a geometric mean (GM) of 3375 ng/g. The photodegradation of PIs in food packaging materials was investigated for the first time, and the half-lives of PIs in these materials were found to range from 32 to 289 h. These 24 PIs were also detected in indoor dust samples (GM of ∑PIs = 1483 ng/g). The relative abundances of different PIs were found to vary between the packaging materials and the indoor dust, which is attributed in part to the different stabilities of different PIs under simulated sunlight. Using standards synthesized in our lab, four TX transformation products (GM: 34.8 ng/g) were also detected in indoor dust. The concentrations of the transformation products were higher than the concentrations of the parent chemicals in indoor dust. Thus, further studies exploring human exposure to TXs should include these transformation products to avoid underestimation. This is the first report of PIs and relevant transformation products in the indoor environment in North America.