Elemental carbon - An efficient method to measure occupational exposure from materials in the graphene family

Graphene is a 2D-material with many useful properties such as flexibility, elasticity, and conductivity among others. Graphene could therefore become a material used in many occupational fields in the future, which can give rise to occupational exposure. Today, exposure is unknown, due to the lack of efficient measuring techniques for occupational exposure to graphene. Readily available screening techniques for air sampling and -analysis are either nonspecific or nonquantitative. Quantifying materials from the broad graphene family by an easy-to-use method is important for the large-scale industrial application of graphene, especially when for the safety of working environment. Graphene consists primarily of elemental carbon, and the present study evaluates the organic carbon/elemental carbon (OC/EC)-technique for exposure assessment. The purpose of this work is to evaluate the OC/EC analysis technique as an efficient and easy-to-use method for quantification of occupational exposure to graphene. Methods that can identify graphene would be preferable for screening, but they are time consuming and semi-quantitative and therefore not suited for quantitative work environment assessments. The OC/EC-technique is a thermal optical analysis (TOA), that quantitively determines the amount of and distinguishes between two different types of carbon, organic and elemental. The technique is standardised, well-established and among other things used for diesel exposure measurements (ref standard). OC/EC could therefore be a feasible measuring technique to quantitively determine occupational exposure to graphene. The present evaluation of the technique provides an analytical method that works quantitatively for graphene, graphene oxide and reduced graphene oxide. Interestingly, the TOA technique makes it possible to distinguish between the three graphene forms used in this study. The technique was tested in an industrial setting and the outcome suggests that the technique is an efficient monitoring technique to be used in combination with characterisation techniques like for example Raman spectroscopy, scanning electron microscopy and atomic force microscopy.

Current methods for evaluating people's exposure to green space: A scoping review

People's exposure to green space is a critical link between urban green space and urban residents' health. Since green space may affect human health through multiple pathways regarding diverse human health outcomes, the measurement of people's exposure to green space must be tailored to concrete study contexts and research questions. In this scoping review, we systematically categorized the available green space representations and metrics in the last two decades that can be used to derive people's exposure to green space regarding different research topics. A three-phase systematic review was conducted after a generalized search of relevant research articles from the three most-used publication databases, namely Scopus, the Web of Science, and PubMed. We identified 260 research articles that particularly discuss green space representations and metrics. We further developed a multi-pathway framework to articulate the complicated context issues in green space studies. We categorized the most relevant green space representations and metrics into five groups, including green space indices, the delineation, inventory, and usage of green space, the spatiotemporal evolution of green space, the attributes and components of green space, and the green space landscape and fragmentation. Finally, we discussed the inter-conversion between different green space representations and metrics, the "mobility-turn" in green space studies and how it may affect the derivation of people's exposure to green space, and other potential methodological issues in measuring people's exposure to green space. Our scoping review provides the most comprehensive framework and categories for deriving people's exposure to green space to date, which may strongly support a broad range of studies that concern green space's health effects.

Personal care products: Demographic characteristics and maternal hormones in pregnant women from Puerto Rico

Personal care products (PCPs) refer to a wide variety of items commonly characterized as health or beauty products. PCPs contain a number of ingredients, often including a wide range of endocrine disrupting chemicals such as phthalates and parabens. The present study examines the association between self-reported PCP use and prenatal sex-steroids and thyroid hormones levels in women from Puerto Rico. We recruited pregnant women (n = 1070) through the Puerto Rico PROTECT Cohort and collected blood, demographic and pregnancy-related data at recruitment and subsequent visits. PCP use in the 48-h preceding the blood sample was collected through self-reported questionnaires. Nine hormones (corticotropin-releasing hormone [CRH], sex-hormone binding globulin [SHBG], estriol [E3], progesterone, testosterone, thyroid-stimulating hormone [TSH], total triiodothyronine [T3], total thyroxine [T4], and free thyroxine [fT4]) were measured in maternal serum samples at two points during pregnancy. Linear mixed models with random intercepts were used to examine associations between PCP use and serum hormone levels. Use of cosmetics significantly increased with age, household income and education level (p < 0.01). Use of hair products, such as hair dyes and bleach, relaxers, and mousse, was associated with lower levels of all sex steroid hormones compared to non-use: SHBG (%Δ = -7.1, 95%CI: -12.4,-1.8), E3 (%Δ = -23.2, 95%CI: -32.2,-13.0), progesterone (%Δ = -21.5, 95%CI: -29.4,-12.9) and testosterone (%Δ = -21.5, 95%CI: -33.1,-7.8) adjusted for maternal age, education and pre-pregnancy body mass index. Our findings suggest that household income and education level influence PCP use among pregnant women in this study. Use of certain hair products was associated with lower concentrations of sex steroid hormones. Although there are limitations to questionnaire data, characterizing PCP use is inexpensive and may represent exposure from multiple classes of chemicals, including chemicals that may not specifically appear on product labels and/or have not been tested for endocrine disrupting potential, making it a useful complement to chemical biomarker data.

Wrangling environmental exposure data: guidance for getting the best information from your laboratory measurements

BACKGROUND

Environmental health and exposure researchers can improve the quality and interpretation of their chemical measurement data, avoid spurious results, and improve analytical protocols for new chemicals by closely examining lab and field quality control (QC) data. Reporting QC data along with chemical measurements in biological and environmental samples allows readers to evaluate data quality and appropriate uses of the data (e.g., for comparison to other exposure studies, association with health outcomes, use in regulatory decision-making). However many studies do not adequately describe or interpret QC assessments in publications, leaving readers uncertain about the level of confidence in the reported data. One potential barrier to both QC implementation and reporting is that guidance on how to integrate and interpret QC assessments is often fragmented and difficult to find, with no centralized repository or summary. In addition, existing documents are typically written for regulatory scientists rather than environmental health researchers, who may have little or no experience in analytical chemistry.

OBJECTIVES

We discuss approaches for implementing quality assurance/quality control (QA/QC) in environmental exposure measurement projects and describe our process for interpreting QC results and drawing conclusions about data validity.

DISCUSSION

Our methods build upon existing guidance and years of practical experience collecting exposure data and analyzing it in collaboration with contract and university laboratories, as well as the Centers for Disease Control and Prevention. With real examples from our data, we demonstrate problems that would not have come to light had we not engaged with our QC data and incorporated field QC samples in our study design. Our approach focuses on descriptive analyses and data visualizations that have been compatible with diverse exposure studies with sample sizes ranging from tens to hundreds of samples. Future work could incorporate additional statistically grounded methods for larger datasets with more QC samples.

CONCLUSIONS

This guidance, along with example table shells, graphics, and some sample R code, provides a useful set of tools for getting the best information from valuable environmental exposure datasets and enabling valid comparison and synthesis of exposure data across studies.

Comparing REACH Chemical Safety Assessment information with practice-a case-study of polymethylmethacrylate (PMMA) in floor coating in The Netherlands

On June 1st, 2007 the European regulation on Registration, Evaluation and Restriction of Chemical substances (REACH) came into force. Aim of the regulation is safe use of chemicals for humans and for the environment. The core element of REACH is chemical safety assessment of chemicals and communication of health and safety hazards and risk management measures throughout the supply chain. Extended Safety Data Sheets (Ext-SDS) are the primary carriers of health and safety information. The aim of our project was to find out whether the actual exposure to methyl methacrylate (MMA) during the application of polymethylmethacrylate (PMMA) in floor coatings as assessed in the chemical safety assessment, reflect the exposure situations as observed in the Dutch building practice. Use of PMMA flooring and typical exposure situations during application were discussed with twelve representatives of floor laying companies. Representative situations for exposure measurements were designated on the basis of this inventory. Exposure to MMA was measured in the breathing zone of the workers at four construction sites, 14 full shift samples and 14 task based samples were taken by personal air sampling. The task-based samples were compared with estimates from the Targeted Risk Assessment Tool (v3.1) of the European Centre for Ecotoxicology and Toxicology of Chemicals (ECETOC-TRA) as supplied in the safety assessment from the manufacturer. For task-based measurements, in 12 out of 14 (86%) air samples measured exposure was higher than estimated exposure. Recalculation with a lower ventilation rate (50% instead of 80%) together with a higher temperature during mixing (40°C instead of 20°C) in comparison with the CSR, reduced the number of underestimated exposures to 10 (71%) samples. Estimation with the EMKG-EXPO-Tool resulted in unsafe exposure situations for all scenarios, which is in accordance with the measurement outcomes. In indoor situations, 5 out of 8 full shift exposures (62%) to MMA were higher than the Dutch occupational exposure limit of 205mg/m³ (8h TWA), which equals the DNEL. For semi-enclosed situations this was 1 out of 6 (17%). Exposures varied from 31 to 367mg/m³. The results emphasize that ECETOC-TRA exposure estimates in poorly controlled situations need better underpinning.

A preliminary study for conducting a rational assessment of radon exposure levels

The aim of this study was to determine the factors that go into a highly reliable estimate of radon exposure levels for use in setting up the case-control study. To this end, the present study conducted a multi-faceted investigation of the distribution of radon concentrations in the bedrooms and living rooms of 400 households in the target areas during the winter months from December 2014 to February 2015. We determined that taking the mean value of the radon concentration levels detected in the bedroom and living room as the representative value of residential concentration is appropriate, given the usability of previous research data and the difference in the concentration levels between the two. In terms of detector placement, we found that detectors should not inconvenience residents or be affected by an air current. Further, we found that housing type should distinguish between regular housing (single-detached, row, and multiplex housing) and apartments but that the building type was not a key factor in the assessment of radon exposure levels. Houses should be classified into those constructed with soil (red clay) and those with constructed with general building materials for the assessment of radon exposure levels.

The Hokkaido Birth Cohort Study on Environment and Children's Health: cohort profile-updated 2017

The Hokkaido Study on Environment and Children’s Health is an ongoing study consisting of two birth cohorts of different population sizes: the Sapporo cohort and the Hokkaido cohort. Our primary study goals are (1) to examine the effects of low-level environmental chemical exposures on birth outcomes, including birth defects and growth retardation; (2) to follow the development of allergies, infectious diseases, and neurobehavioral developmental disorders and perform a longitudinal observation of child development; (3) to identify high-risk groups based on genetic susceptibility to environmental chemicals; and (4) to identify the additive effects of various chemicals, including tobacco smoking. The purpose of this report is to update the progress of the Hokkaido Study, to summarize the recent results, and to suggest future directions. In particular, this report provides the basic characteristics of the cohort populations, discusses the population remaining in the cohorts and those who were lost to follow-up at birth, and introduces the newly added follow-up studies and case-cohort study design. In the Sapporo cohort of 514 enrolled pregnant women, various specimens, including maternal and cord blood, maternal hair, and breast milk, were collected for the assessment of exposures to dioxins, polychlorinated biphenyls, organochlorine pesticides, perfluoroalkyl substances, phthalates, bisphenol A, and methylmercury. As follow-ups, face-to-face neurobehavioral developmental tests were conducted at several different ages. In the Hokkaido cohort of 20,926 enrolled pregnant women, the prevalence of complicated pregnancies and birth outcomes, such as miscarriage, stillbirth, low birth weight, preterm birth, and small for gestational age were examined. The levels of exposure to environmental chemicals were relatively low in these study populations compared to those reported previously. We also studied environmental chemical exposure in association with health outcomes, including birth size, neonatal hormone levels, neurobehavioral development, asthma, allergies, and infectious diseases. In addition, genetic and epigenetic analyses were conducted. The results of this study demonstrate the effects of environmental chemical exposures on genetically susceptible populations and on DNA methylation. Further study and continuous follow-up are necessary to elucidate the combined effects of chemical exposure on health outcomes.

Assessment of different route choice on commuters' exposure to air pollution in Taipei, Taiwan

The purposes of this study are to develop a healthy commute map indicating cleanest route in Taipei metropolitan area for any given journey and to evaluate the pollutant doses exposed in different commuting modes. In Taiwan, there are more than 13.6 million motorcycles and 7.7 million vehicles among the 23 million people. Exposure to traffic-related air pollutants can thus cause adverse health effects. Moreover, increasing the level of physical activity during commuting and longer distances will result in inhalation of more polluted air. In this study, we utilized air pollution monitoring data (CO, SO₂, NO₂, PM₁₀, and PM_2.5) from Taiwan EPA's air quality monitoring stations in Taipei metropolitan area to estimate each pollutant exposure while commuting by different modes (motorcycling, bicycling, and walking). Spatial interpolation methods such as inverse distance weighting (IDW) were used to estimate each pollutant's distribution in Taipei metropolitan area. Three routes were selected to represent the variety of different daily commuting pathways. The cleanest route choice was based upon Dijkstra's algorithm to find the lowest cumulative pollutant exposure. The IDW interpolated values of CO, SO₂, NO₂, PM₁₀, and PM_2.5 ranged from 0.42-2.2 (ppm), 2.6-4.8 (ppb), 17.8-42.9 (ppb), 32.4-65.6 (μg/m³), and 14.2-38.9 (μg/m³), respectively. To compare with the IDW results, concentration of particulate matter (PM₁₀, PM_2.5, and PM₁) along the motorcycle route was measured in real time. In conclusion, the results showed that the shortest commuting route for motorcyclists resulted in a much higher cumulative dose (PM_2.5 3340.8 μg/m³) than the cleanest route (PM_2.5 912.5 μg/m³). The mobile personal monitoring indicated that the motorcyclists inhaled significant high pollutants during commuting as a result of high-concentration exposure and short-duration peaks. The study could effectively present less polluted commuting routes for citizen health benefits.

Human Exposure Assessment for Air Pollution

Assessment of human exposure to air pollution is a fundamental part of the more general process of health risk assessment. The measurement methods for exposure assessment now include personal exposure monitoring, indoor-outdoor sampling, mobile monitoring, and exposure assessment modeling (such as proximity models, interpolation model, air dispersion models, and land-use regression (LUR) models). Among these methods, personal exposure measurement is considered to be the most accurate method of pollutant exposure assessment until now, since it can better quantify observed differences and better reflect exposure among smaller groups of people at ground level. And since the great differences of geographical environment, source distribution, pollution characteristics, economic conditions, and living habits, there is a wide range of differences between indoor, outdoor, and individual air pollution exposure in different regions of China. In general, the indoor particles in most Chinese families comprise infiltrated outdoor particles, particles generated indoors, and a few secondary organic aerosol particles, and in most cases, outdoor particle pollution concentrations are a major contributor to indoor concentrations in China. Furthermore, since the time, energy, and expense are limited, it is difficult to measure the concentration of pollutants for each individual. In recent years, obtaining the concentration of air pollutants by using a variety of exposure assessment models is becoming a main method which could solve the problem of the increasing number of individuals in epidemiology studies.

Measuring the impact of manganese exposure on children's neurodevelopment: advances and research gaps in biomarker-based approaches

BACKGROUND

Children's exposure to manganese (Mn) is a public health concern and consistent policy guidelines for safe levels of Mn exposure is lacking. The complexity of establishing exposure thresholds for Mn partially relates to its dual role as an essential micronutrient with low levels required for good health, but also as a neurotoxin at high levels. Questions exist about the age-related susceptibility to excess Mn, particularly for children, and how best to measure chronic exposures. To address this concern we conducted a systematic review of studies examining children's exposure to Mn and neurodevelopmental outcomes focused on selection of biomarker-based and environmental measurements of Mn exposure to identify the scientific advances and research gaps.

METHODS

PubMed and EMBASE databases were searched through March 2016 for studies that were published in English, used a biomarker-based or environmental measurement of Mn exposure, and measured at least one neurological outcome for children aged 0-18 years. Ultimately, thirty-six papers from 13 countries were selected. Study designs were cross-sectional (24), prospective cohorts (9), and case control (3). Neurodevelopmental outcomes were first assessed for Mn exposure in infants (6 papers), toddlers or preschoolers (3 papers) and school-age children (27 papers).

RESULTS

Studies of school-aged children most frequently measured Intelligence Quotient (IQ) scores using Mn biomarkers of hair or blood. Higher hair concentrations of Mn were consistently associated with lower IQ scores while studies of blood biomarkers and IQ scores had inconsistent findings. Studies of infants and toddlers most frequently measured mental and psychomotor development; findings were inconsistent across biomarkers of Mn (hair, cord blood, tooth enamel, maternal or child blood and dentin). Although few studies measured environmental sources of Mn, hair biomarkers were associated with Mn in drinking water and infant formula. Only one paper quantified the associations between environmental sources of Mn and blood concentrations.

CONCLUSION

Hair-Mn was the more consistent and valid biomarker of Mn exposure in school-aged children. Accurate measurement of children's exposure to Mn is crucial for addressing these knowledge gaps in future studies. However, research on biomarkers feasible for fetuses and infants is urgently needed given their unique vulnerability to excessive Mn.

Within-person variability of urinary bisphenol-A in postmenopausal women

We evaluated the within-person variability of urinary BPA levels over two samples collected three years apart in 90 Women's Health Initiative participants. The intraclass correlation coefficient was 0.09 (95% CI 0.01-0.44), indicating high within-participant variability relative to the between-person variation. Concordance of BPA quartile over time was low (31.7%) and was unrelated to demographic, behavioral, or dietary factors. A single, or even several, measurements of BPA may not adequately classify long-term exposure in human studies.