A pilot evaluation on the toxicokinetics and bioaccumulation of polychlorinated naphthalenes in laying hens

Historically Polluted Area Increases Human Exposure Risks to Polychlorinated Naphthalenes through Waterfowl Egg Consumption

Polychlorinated naphthalenes (PCNs), which are ubiquitous in the environment, are listed as persistent organic pollutants under the Stockholm Convention. Poultry can be exposed to PCNs via feed and breeding environments, leading to PCNs accumulation in eggs. However, information on PCNs in eggs from waterfowl raised in contaminated regions is scarce. In this study, waterfowl and chicken eggs were collected from a historically polluted area in Hunan Province, China. In addition, waterfowl eggs were collected from Guangxi Province as a control. The mean concentrations of Σ75PCNs in waterfowl (30.8 pg/g wet weight [ww]) and chicken eggs (26.1 pg/g ww) from Hunan were significantly higher than in waterfowl eggs (15.6 pg/g ww) from Guangxi. The PCN homologue profiles in poultry eggs from the two regions varied, but both were dominated by lower chlorinated CNs. Correlation analysis showed that breeding environment made a greater contribution to PCNs in waterfowl eggs. Interestingly, PCNs and polychlorinated biphenyls (PCBs) showed a significant positive correlation in samples from Hunan, but not in those from Guangxi. Human exposure to PCNs and PCBs was higher through consumption of poultry eggs from historically contaminated areas.

Organophosphate esters and their metabolites in Beijing total diets: Occurrence, time trend, and dietary exposure assessment

Organophosphate esters (OPEs) and their metabolites (mOPEs) are emerging pollutants. In this study, 18 OPEs and 10 mOPEs were measured in the 6th and 7th Beijing total diet studies (TDSs), and the dietary intakes of these pollutants by Beijing adults were estimated to assess related health concerns. Most OPEs and mOPEs had high detecting frequencies in both TDSs, which indicated that various foods in Beijing have been universally contaminated with OPEs and mOPEs. Statistical analysis further confirmed that the levels of both ∑OPEs and ∑mOPEs in the 7th Beijing TDS were significantly higher than those in the 6th study, indicating heavier contamination of both OPEs and their metabolites with time. Along with increasing OPE/mOPE contamination level and food consumption values, significant increases of EDIs were observed during the two studies, with the average EDIs of ∑OPEs increasing from 5.07 to 24.1 ng/kg bw/day, and that of ∑mOPEs increasing from 2.07 to 7.23 ng/kg bw/day. Although a comparison between EDIs and reference of doses (RfDs) indicated that current intakes of OPEs could still not cause significant health risks, the sharply increasing contamination levels and EDIs suggested the necessity to continuously monitor these emerging food contaminants.

Concentrations of polychlorinated naphthalenes in food and human dietary exposure: A review of the scientific literature

In general, for most environmental persistent organic pollutants (POPs), dietary intake is the main way of exposure. Polychlorinated naphthalenes (PCNs) are a family of two-ringed aromatic compounds, which are ubiquitous environmental contaminants, being structurally similar to PCDD/Fs and PCBs. Although the production and use of PCNs were banned in the USA and Europe some decades ago, due to their persistent properties, PCNs remain still present in the environment, being able to enter the food chain. The present paper was aimed at reviewing the results of the studies focused on determining the levels of PCNs in foods. The human dietary intake of these compounds was also reviewed with the few available data. The information on the levels of PCNs in foodstuffs is currently more abundant than that found in a previous review (Domingo, 2004). Since then, China is the country that has contributed with the greatest number of studies. The results of most surveys seem to suggest that human health risks of PCNs due to dietary exposure should not be worrying. However, because of the important differences in the methodology of the published studies, the comparison of the results is not easy, although there seems to be a general trend towards a decrease in the levels of PCNs in foods. In the next few years, a continued reduction of the environmental levels of PCNs is still expected. Therefore, a direct repercussion of the concentrations of these pollutants in foodstuffs must be also noted. Consequently, a reduction of the dietary exposure to PCNs should be expected. Anyway, to establish the tolerable dietary intake of PCNs is a key issue for assessing human health risks of these pollutants.

Toxicokinetics and bioavailability of indoxacarb enantiomers and their new metabolites in rats

Indoxacarb is a chiral insecticide that consists of two enantiomers, S-(+)-indoxacarb and R-(-)-indoxacarb, of which only S-(+)-indoxacarb has insecticidal activity. Previous enantioselective toxicology studies of indoxacarb focused mostly on simple environmental model organisms. The lack of a toxicology evaluation of indoxacarb conducted in a mammalian system could mean that the extent of the potential health risk posed by the insecticide to humans is not adequately known. In this study, we reported on a new pair of enantiomers, S-IN-RM294 and R-IN-RM294, derived from the metabolic breakdown of S-(+)-indoxacarb and R-(-)-indoxacarb, respectively, in rats. The toxicokinetics of S-(+)-indoxacarb, R-(-)-indoxacarb, S-IN-RM294, and R-IN-RM294 in rats were evaluated to provide a more comprehensive risk assessment of these molecules. The bioavailability and excretion rates of both S-(+)-indoxacarb and R-(-)-indoxacarb were relatively low, which may be due to their faster metabolism and accumulation in the tissues. In addition, there were significant differences in the metabolism and distribution between the two indoxacarb enantiomers and their metabolites in vivo. S-(+)-Indoxacarb was found to be more easily metabolized in the blood compared with R-(-)-indoxacarb, as shown by the differences in pharmacokinetic parameters between oral and intravenous administration. Analysis of their tissue distribution showed that S-(+)-indoxacarb was less likely to accumulate in most tissues. The results obtained for the two metabolites were consistent with those of the two parent compounds. S-IN-RM294 was more readily cleared from the blood and less likely to accumulate in the tissues compared with R-IN-RM294. Therefore, whether from the perspective of insecticidal activity or from the perspective of mammalian and environmental friendliness, the application of optically pure S-(+)-indoxacarb in agriculture may be a more efficient and safer strategy.

Organophosphate esters and their metabolites in silver pomfret (Pampus argenteus) of the Vietnamese coastal areas: Spatial-temporal distribution and exposure risk

A large number of studies on organophosphate esters (tri-OPEs) in marine organisms have not assessed the simultaneous occurrence of tri-OPEs and their metabolites (di-OPEs) in these species. This research investigated the concentration and geographical distribution of 15 tri-OPEs and 7 di-OPEs in 172 samples of Pampus argenteus that were collected annually from 2021 to 2023 at three distinct locations along the Vietnamese coast. As a result, tri-OPEs and di-OPEs were detected in numerous fish samples, indicating their widespread spatial and temporal occurrence in marine fish and pointing out the importance of monitoring their levels. The tri-OPEs and di-OPEs ranged within 2.1-38.9 ng g-1 dry weight (dw) and 3.2-263.4 ng g-1 dw, respectively. The mean concentrations of tri-OPEs ranged from 0.4 (TIPrP) to 5.4 ng g-1 dw (TBOEP), with TBOEP and TEHP having the highest mean values. In addition, the profiles of tri-OPEs in fish exhibited a descending order: Σalkyl OPEs > ΣCl-alkyl OPEs > Σaryl OPEs. The di-OPEs, namely BEHP and DMP, had the highest mean levels, measuring 33.4 ng g-1 dw and 23.8 ng g-1 dw, respectively. Furthermore, there have been significant findings of strong positive correlations between di-OPEs and tri-OPE pairs (p < 0.05). It is worth noting that there is a noticeable difference in the composition of tri-OPEs between the North and other regions. Despite these findings, the presence of OPE-contaminated fish did not pose any health risks to Vietnam's coastal population.

Emerging organic contaminants in drinking water systems: Human intake, emerging health risks, and future research directions

Few earlier reviews on emerging organic contaminants (EOCs) in drinking water systems (DWS) focused on their detection, behaviour, removal and fate. Reviews on multiple exposure pathways, human intake estimates, and health risks including toxicokinetics, and toxicodynamics of EOCs in DWS are scarce. This review presents recent advances in human intake and health risks of EOCs in DWS. First, an overview of the evidence showing that DWS harbours a wide range of EOCs is presented. Multiple human exposure to EOCs occurs via ingestion of drinking water and beverages, inhalation and dermal pathways are discussed. A potential novel exposure may occur via the intravenous route in dialysis fluids. Analysis of global data on pharmaceutical pollution in rivers showed that the cumulative concentrations (μg L-1) of pharmaceuticals (mean ± standard error of the mean) were statistically more than two times significantly higher (p = 0.011) in South America (11.68 ± 5.29), Asia (9.97 ± 3.33), Africa (9.48 ± 2.81) and East Europe (8.09 ± 4.35) than in high-income regions (2.58 ± 0.48). Maximum cumulative concentrations of pharmaceuticals (μg L-1) decreased in the order; Asia (70.7) had the highest value followed by South America (68.8), Africa (51.3), East Europe (32.0) and high-income regions (17.1) had the least concentration. The corresponding human intake via ingestion of untreated river water was also significantly higher in low- and middle-income regions than in their high-income counterparts. For each region, the daily intake of pharmaceuticals was highest in infants, followed by children and then adults. A critique of the human health hazards, including toxicokinetics and toxicodynamics of EOCs is presented. Emerging health hazards of EOCs in DWS include; (1) long-term latent and intergenerational effects, (2) the interactive health effects of EOC mixtures, (3) the challenges of multifinality and equifinality, and (4) the Developmental Origins of Health and Disease hypothesis. Finally, research needs on human health hazards of EOCs in DWS are presented.

Uptake and elimination of methylsiloxanes in hens after oral exposure: Implication for risk estimation

Methylsiloxanes are accumulated easily in aquatic organisms and may pose potential risks. However, available information on their uptake and accumulation in terrestrial species remains scarce. This study investigated the uptake, elimination and accumulation of eight typical methylsiloxanes in hens after a single oral exposure. At 1440 min after oral exposure, methylsiloxanes were mainly accumulated in kidney, liver and ovary, representing for 29.5 %, 20.4 % and 17.4 % of the summed methylsiloxanes in all tissues, respectively; all investigated chemicals were also detected in brains and unformed yolks. We found much higher mass uptake fractions (MUFs) of cyclic (27.5-66.5 %) than linear chemicals (9.9-17.3 %) by hens via this exposure, and the observed MUFs of individual cyclic congeners were comparable to the higher values of those reported for rats or fish previously. However, the metabolic half-life (t1/2) of these chemicals in hen tissues were in the range of 1.04-57.5 h based on kinetic analyses, indicating higher clearances in comparison with those reported for fish and rats. More research is needed on the metabolic mechanism of these chemicals in hens. Our findings provide important information for further understanding of transportation and transformation of these chemicals in terrestrial organisms and the associated potential risks.

The long-term spatial and temporal distributions of polychlorinated naphthalene air concentrations in Fildes Peninsula, West Antarctica

The knowledge of polychlorinated naphthalenes (PCNs) in the Antarctic atmosphere is quite limited compared to the Arctic. PCNs are a global concern because of their PBT characteristics (i.e., persistent, bioaccumulative, and toxic) and severe and often deadly biological effects on people and other animals. Therefore, the present study used a passive air sampling method to conduct long-term air monitoring of PCNs for almost a decade from 2013 to 2022, specifically on Fildes Peninsula, situated on King George Island, located in West Antarctica. The median sum of mono-CNs to octa-CN concentration (∑75PCNs) in the Antarctic atmosphere was 12.4 pg/m3. In terms of homologues, mono-CNs to tri-CNs predominated. Among these, the prevalent congeners observed were PCN-1 and PCN-2, originating from mono-CNs, followed by PCN-5/7 from di-CNs, and PCN-24/14 from tri-CNs, respectively. Between 2013 and 2022, the total levels of PCNs were found to have decreased approximately fourfold. Ratio analyses and principal component analysis (PCA) showed that the long-range atmospheric transport and combustion-related sources as the potential PCN sources in the study area. This paper provides the most up-to-date temporal trend analysis of PCNs in the Antarctic continent and is the first to document all 75 congeners (mono-CNs to octa-CN homologue groups).

Spatial and temporal trends of polychlorinated naphthalenes in the Arctic atmosphere at Ny-Ålesund and London Island, Svalbard

Polychlorinated naphthalenes (PCNs) are ubiquitous atmospheric pollutants that can even be found in the most remote region of the Arctic. However, temporal trend analysis and reports on mono- to octa-CN in the Arctic air are still scarce. In the present study, 8 years of atmospheric monitoring data of PCNs on Svalbard was investigated using XAD-2 resin passive air samplers (PASs) from 2011-2019. The concentrations of ∑₇₅ PCNs in the Arctic air ranged from 4.56 to 85.2 pg/m³, with a mean of 23.5 pg/m³. The mono-CNs and di-CNs were the dominant homologue groups accounting for 80 % of the total concentrations. The most abundant congeners were PCN-1, PCN-2, PCN-24/14, PCN-5/7, and PCN-3, respectively. A declining time trend of PCN concentration was observed from 2013 to 2019. The reduction in PCN concentrations is likely due to declining global emissions and banned production. However, no significant spatial difference was observed among the sampling sites. The total PCN toxic equivalency (TEQ) concentrations in the Arctic atmosphere ranged from 0.043 to 1.93 fg TEQ/m³ (mean 0.41 fg TEQ/m³). The fraction of combustion-related congeners to ∑PCNs (tri- to octa-CN) analysis results indicated that the sources of PCNs in the Arctic air were contributed mainly from reemissions of historical Halowax mixtures and combustion-related sources. To the best of our knowledge, this is the first research to report all 75 PCN congeners and homologue groups in Arctic air. Therefore, this study provides data on recent temporal trend analysis as well as all the 75 PCN congeners in the Arctic atmosphere.

Pilot study on the effect of secondary copper smelters on polychlorinated naphthalene contamination in surrounding agricultural areas

Polychlorinated naphthalenes (PCNs) are dioxin-like persistent organic pollutants that are primarily produced unintentionally during industrial thermal processes. These compounds are harmful to the environment and human health. This study investigated the occurrences of all 75 PCN congeners in agricultural areas near secondary copper smelters in China. The PCN concentrations in aquatic foods, eggs, crops, sediments and soils within 10 km of these smelters were higher than those in samples collected 20-30 km away from such facilities. In contrast, the PCN concentrations in compound animal feed samples collected at different distances from the secondary copper smelters were comparable to one another. Similar PCN homologue patterns were found in crop, egg, feed and soil samples collected at different distances from the smelters but the homologue profiles of PCNs in aquatic food and sediment samples collected from different distances varied. Lower chlorinated naphthalenes were the predominant homologues in most samples. The contamination of farm animals and crops with PCNs might result from the emission of these compounds from such sources into the surrounding environment. However, the health risks associated with human exposure to PCNs through food consumption are low for both distances (<10 km and 20-30 km) from secondary copper smelters.

Occurrence of polychlorinated naphthalenes in dairy cow farms in proximity to an iron smelting plant in China: A preliminary study

Animal derived foods are the primary pathway for human exposure to polychlorinated naphthalenes (PCNs), and various foodstuffs have been reported to contain PCNs. However, information on how PCN emission sources affect surrounding animal farms is scarce. The present study determined PCN levels in cow's milk, excrement, feed, plant and soil samples collected from four dairy farms situated within 10 km of an iron smelting plant in China. PCN concentrations in the milk samples from all four farms were in the range from 470 to 797 pg/g lipid weight while the PCN concentrations in the other specimens decreased in the order: plant > soil > excrement > feed. Higher PCN concentrations appeared in silage than in other feedstuffs, and the relationships between PCNs in milk, excrement and feed were closer than those in plant and soil. Human exposure risk to PCNs by consuming milk from this region was relatively higher than in less polluted areas.

A Review of the Impact That Healthcare Risk Waste Treatment Technologies Have on the Environment

Health-Care Risk Waste (HCRW) treatment protects the environment and lives. HCRW is waste from patient diagnostics, immunization, surgery, and therapy. HCRW must be treated before disposal since it pollutes, spreads illnesses, and causes harm. However, waste treatment increases the healthcare sector's carbon footprint, making the healthcare sector a major contributor to anthropogenic climate change. This is because treating HCRW pollutes the environment and requires a lot of energy. Treating HCRW is crucial, but its risks are not well-studied. Unintentionally, treating HCRW leads to climate change. Due to frequent climate-related disasters, present climate-change mitigation strategies are insufficient. All sectors, including healthcare, must act to mitigate and prevent future harms. Healthcare can reduce its carbon footprint to help the environment. All contributing elements must be investigated because healthcare facilities contribute to climate change. We start by evaluating the environmental impact of different HCRW treatment technologies and suggesting strategies to make treatments more sustainable, cost-effective, and reliable to lower the carbon footprint.