Environmental Protection Agency Reference Dose Research Articles

Polybrominated diphenyl ethers in student dormitory microenvironments: Concentrations, sources, and human exposure

Microenvironments, such as student dormitories, differ from general residential environments. They are characterized by small spaces, poor air circulation, high personnel densities, and electronic products, such as computers that are turned on for extended periods, leading to increased pollution concentrations. The limited space and poor air circulation reduce migration of contaminants, such as polybrominated diphenyl ethers (PBDEs), making it easier for PBDEs to accumulate. However, few studies have been conducted on small group dwellings, including student dormitory dwellings. We collected dust samples from student dormitories of a university to analyze the characteristics and traceability of PBDEs in dormitory microenvironments. The results showed that PBDE congeners were widely present in university dormitories and the order of median concentration of ∑10PBDEs was as follows: male old-fashioned dormitory (273 ng/g) > female four-person dormitory (132 ng/g) > female two-person dormitory (132 ng/g) > male two-person dormitory (96.2 ng/g) > female old-fashioned dormitory (91.6 ng/g) > male four-person apartment (51.8 ng/g). BDE-209 was the most abundant PBDE congener, followed by BDE-47, and BDE-28. PBDEs were also found in typical electrical appliances, with higher concentrations in laptops than in desktops, and higher concentrations in desktops than in idle ones. According to Spearman correlation and Principal Component Analysis (PCA), we also found that boards and wallpaper materials were common sources of contamination in the microenvironment of student dormitories, and that female dormitories had more sources of PBDE emissions. Human exposure to PBDEs in students is below the US Environmental Protection Agency reference dose. Although exposure to PBDEs generated in dormitories does not pose a significant health risk, the potential hazards of PBDEs to the reagent environment remain to be investigated.

Sociodemographic Disparities in Mercury Exposure from United States Coal-Fired Power Plants.

Hazardous air pollutants emitted by United States (U.S) coal-fired power plants have been controlled by the Mercury and Air Toxics Standards (MATS) since 2012. Sociodemographic disparities in traditional air pollutant exposures from U.S. power plants are known to occur but have not been evaluated for mercury (Hg), a neurotoxicant that bioaccumulates in food webs. Atmospheric Hg deposition from domestic power plants decreased by 91% across the contiguous U.S. from 6.4 Mg in 2010 to 0.55 Mg in 2020. Prior to MATS, populations living within 5 km of power plants (n = 507) included greater proportions of frequent fish consumers, individuals with low annual income and less than a high school education, and limited English-proficiency households compared to the US general population. These results reinforce a lack of distributional justice in plant siting found in prior work. Significantly greater proportions of low-income individuals lived within 5 km of active facilities in 2020 (n = 277) compared to plants that retired after 2010, suggesting that socioeconomic status may have played a role in retirement. Despite large deposition declines, an end-member scenario for remaining exposures from the largest active power plants for individuals consuming self-caught fish suggests they could still exceed the U.S. Environmental Protection Agency reference dose for methylmercury.

Bioaccessibility, exposure and risk assessment of potentially toxic elements and essential micronutrients in ayurvedic, traditional Chinese and Ghanaian medicines.

Potentially toxic constituents in traditional medicines remain a concern due to health risks posed to consumers. Thirty-six traditional medicines (TM) consisting of 14 Indian Ayurvedic Medicines, 11 Chinese Traditional Medicines and eleven Ghanaian Traditional Medicines were evaluated using Total Reflection X-ray Fluorescence Spectrometer (T-XRF) after microwave assisted acid digestion. Physiologically Based Extraction Test (PBET) was used to obtain bioaccessible elemental concentrations. Merck XVI multi-element standard were used to evaluate the accuracy of the analytical method. The concentrations of the elements were quantified in (mg kg-1): Cr (0.01-698), Mn (0.01-1140), Fe (15-73300), Ni (1-1340), Cu (3-8160), Zn (0.01-224). The greatest bioaccessible concentrations of arsenic was 0.80mgkg-1 and 0.44mgkg-1 in the gastric and intestinal phases respectively. In order to evaluate the human health risks from ingesting these TM, the Acceptable Daily Intake (ADI) was calculated for each medicine based on element-specific bioaccessibility-adjusted concentrations and results compared with the United States Environmental Protection Agency (USEPA) Reference Dose (RfD) limits. The Acceptable Daily Intake (ADI) values for risks were within the USEPA RfD. Hazard quotients (HQ) of TM were < 1, meaning elemental concentrations do not pose non-carcinogenic risks to adult consumers. In summary the methods applied in the study gives a new insight on human health risks of potentially toxic and essential micronutrients elements in TM.

Quantitative Measurement of Phthalate Exposure Biomarker Levels in Diaper-Extracted Urine of Japanese Toddlers and Cumulative Risk Assessment: An Adjunct Study of JECS Birth Cohort.

Phthalate exposure monitoring and risk assessment in non-toilet-trained children are rarely reported. This adjunct study of the Japan Environment and Children's Study assessed cumulative health risks in 1.5-year-old toddlers in the Aichi regional subcohort by biomonitoring 16 urinary metabolites of eight phthalate plasticizers. Overnight urine was extracted from toddlers' diapers (n = 1077), and metabolites were quantified using ultraperformance liquid chromatography coupled with tandem mass spectrometry. The analyses' quality was assured by running quality control samples. The highest geometric mean concentration was found for mono-(2-ethyl-5-carboxypentyl) phthalate, followed by mono-isobutyl phthalate (23 and 21 μg/L, respectively). Di-2-ethylhexyl phthalate (DEHP) and di-butyl phthalate exhibited higher risks [hazard quotient (HQ) > 1] than the cutoff level in a small proportion of toddlers; 8 and 14% of toddlers were at cumulative risk of multiple phthalates beyond the cutoff level [hazard index, (HI) > 1], based on the tolerable daily intake of the European Food Safety Authority and the United States Environmental Protection Agency Reference Dose. HI > 1 for antiandrogenicity in creatinine-unadjusted and -adjusted estimations were exhibited by 36 and 23% of the children, respectively. Thus, identifying exposure sources and mitigating exposure are necessary for risk management. Additionally, continuous exposure assessment and evaluation of health outcomes, especially antiandrogenic effects, are warranted.

Fish consumption habits of pregnant women in Itaituba, Tapajós River basin, Brazil: risks of mercury contamination as assessed by measuring total mercury in highly consumed piscivore fish species and in hair of pregnant women.

The Tapajós River basin in the Amazon region, Brazil is one of the most active gold mining areas in the world. In this study, we evaluated fish consumption habits and mercury exposure in 110 pregnant women in the city of Itaituba by measuring their total hair mercury concentrations. In addition, we investigated seasonal differences in mercury concentrations in two highly consumed piscivorous fish species, tucunaré (Cichla spp.) and pescada (Plagioscion squamosissimus). Total fish mercury concentrations (THg) during the dry season were 0.62±0.07 mg/kg for Cichla spp. and 0.73±0.08 mg/kg for P. squamosissimus. During the rainy season they were 0.39±0.04 and 0.84±0.08 mg/ kg, respectively. Of our participants 44 % declared that they ate Cichla spp. and 67 % P. squamosissimus. Mean mercury concentration in their hair was 1.6±0.2 mg/kg and was above the US Environmental Protection Agency (US EPA) reference dose of 1 mg/kg in 48 % of them. Mean fish THg concentrations were also above the joint Food and Drug Administration and US EPA safety limit of 0.5 mg/kg for P. squamosissimus during both seasons and for Cichla spp. during the dry season only. These results show that pregnant women should avoid consumption of these piscivorous fish species during pregnancy and call for a regular programme to monitor Hg levels in that area.

Cumulative risk assessment of dietary exposure to phthalates in pregnant women in Beijing, China.

Diet is an important exposure route for phthalates, such as di-iso-butyl phthalate (DiBP), dibutyl phthalate (DBP), bis(2-ethylhexyl) phthalate (DEHP), and benzyl butyl phthalate (BBP). In this study, we aimed to estimate phthalate exposure in the diet of pregnant women and assess the health risk. A total of 517 pregnant women in the first trimester were recruited, and food frequency questionnaires were collected. A simple distribution assessment method was used to estimate daily exposure, and the hazard index (HI) method was used to assess cumulative risk. The maximum daily dietary exposure to DEHP, DBP, DiBP, and BBP was 5.25, 3.17, 2.59, and 0.58μg/kg bw/day, respectively, and did not exceed the safety limit values. Cereals and vegetables were the main sources of the estimated daily intake (EDI) of phthalates in the diet. The cumulative risk assessment, based on the European Food Safety Authority tolerable daily intake (TDI) and the US Environmental Protection Agency reference dose (RfD), did not exceed the threshold of 1. DiBP, DBP, and DEHP had higher hazard quotient (HQ) values for cumulative health risk than BBP. In conclusion, a low health risk was posed by the cumulative dietary exposure to phthalates for pregnant women in Beijing.

Fluoride Pharmacokinetics in Urine and Plasma Following Multiple Doses of MK-8507, an Investigational, Oral, Once-Weekly Nonnucleoside Reverse Transcriptase Inhibitor.

MK‐8507 is an investigational HIV‐1 nonnucleoside reverse transcriptase inhibitor being developed for the treatment of HIV‐1 infection. MK‐8507 contains 2 trifluoromethyl groups that may result in fluoride release through metabolism, but the extent of MK‐8507–related fluoride release in humans has yet to be determined. This double‐blind, placebo‐controlled, 2‐period, parallel‐group, multiple‐dose trial in healthy participants without HIV‐1 who were administered a fluoride‐restricted diet and once‐weekly doses of MK‐8507 aimed to estimate the relationship between MK‐8507 dose and fluoride exposure. A total of 15 adult male and 3 adult female (of non‐childbearing potential) participants were randomized to receive MK‐8507 200 mg (n = 6), MK‐8507 800 mg (n = 6), or placebo (n = 6). Change from baseline in mean daily fluoride excretion averaged over 7 days following the administration of MK‐8507 200 mg resulted in a net mean increase of 19.8 μmol (90% confidence interval, 12.2‐27.4) relative to placebo and did not exceed 57 μmol, a threshold related to the mean difference between the daily reference dose set by the US Environmental Protection Agency and the average dietary fluoride intake in the United States. However, daily urinary fluoride excretion exceeded the threshold following administration of 800 mg MK‐8507 (75.1 μmol [90% confidence interval, 67.5‐82.7]). Assuming a linear relationship between MK‐8507 dose and estimated mean daily fluoride released at steady‐state, data interpolation suggests that the US Environmental Protection Agency reference dose for fluoride would not be exceeded in most patients when administering MK‐8507 at doses currently under clinical investigation (≤400 mg once weekly).

Prenatal methylmercury exposure is associated with decrease heart rate variability in children

BackgroundAlthough several epidemiological studies have suggested mercury (Hg) might be associated with cardiotoxicity, the impact of Hg exposure on cardiac autonomic activity and blood pressure in children has not been investigated at Hg exposure levels equivalent to the Environmental Protection Agency (EPA) reference dose. ObjectiveTo investigate the association between low dose prenatal and recent methylmercury (MeHg) exposures and cardiac autonomic function and blood pressure with adjustment for factors such as fish consumption among children from a high fish consumption coastal city. MethodsChildren aged 7–8 years were recruited from the birth cohort of our previous study. Heart rate variability (HRV), resting heart rate (RHR) and blood pressure were measured as surrogate markers of cardiac autonomic function. Cord blood and current whole blood Hg concentration were used as biomarkers of prenatal and recent MeHg exposure, respectively. Recent fish consumption information was estimated with a food frequency questionnaire. ResultsAmong 604 children, median cord blood and whole blood Hg concentrations were 45.9 nmol/L (IQR: 32.8–65.03 nmol/L) and 13.57 nmol/L (IQR: 9.29–19.72 nmol/L), respectively. Our results demonstrated that prenatal MeHg exposure was associated with decreased HRV (i.e. low CVRR, SDRR, and RMSSD), reflecting reduced parasympathetic activity (i.e. low CCVHF and HF), and a sympathovagal balance shift toward sympathetic predominance (i.e. high %LF and LF/HF ratio). Adjustment of recent fish consumption further increased the significance and magnitude of the adverse associations of MeHg. ConclusionThe results of this study suggest that prenatal MeHg exposure is associated with decreased parasympathetic modulation of cardiac autonomic function in children.

Human health and ecological risk assessment of pesticides from rice production in the Babol Roud River in Northern Iran

Increasing agricultural activities result in increasing use of different pesticides in order to protect the products, but this is happening without paying attention to the consequences of the daily increase of using pesticides. Pesticides could affect human health and the environment at the same time. In this study three pesticides (diazinon, carbaryl and butachlor), which are used in rice production, were measured in the Babol Roud River located in Mazandaran province in Northern Iran. A large portion of the agricultural land use in this region is for rice production. Water samples were collected from 8 sampling points along the river during 4 seasons throughout the year, since planting of rice is conducted twice a year in this region. Mean concentrations for diazinon are 367.7 and 354.5 μgL−1 in October 2018 and June 2019, respectively. Also, concentrations of carbaryl are 197 and 211.1 μgL−1 and butachlor are 299.6 and 413.2 μgL−1 in 2018 and 2019, respectively. Moreover, hazard quotient (HQ) for non-carcinogenic health risk of these pesticides were calculated based on the United States Environmental Protection Agency reference dose (RfD) and the European Union's acceptable daily intake (EU ADI). HQs for adult based on RfD are 4.3, 0.3 and 0.1 and for children are 8.6, 0.08 and 0.03 for diazinon, butachlor and carbaryl, respectively. Also, HQs for adults based on the EU ADI are 15, 0.05 and 0.1 and for children are 30, 0.1 and 0.4 for diazinon, butachlor and carbaryl, respectively. The probabilistic ecological risk assessment indicated that diazinon in the river represents a considerable risk to invertebrate and vertebrate communities, carbaryl to invertebrate communities, and butachlor to primary producer communities. The 5th centile of the species sensitivity distributions for each of these communities of biota are exceeded in more than 75% of samples.

Dietary exposure to mercury and its relation to cytogenetic instability in populations from “La Mojana” region, northern Colombia

Fish consumption and chronic exposure to low doses of mercury (Hg) seems to activate several molecular mechanisms leading to carcinogenic and/or teratogenic processes. However, Hg genotoxic effects on humans are not completely described. In the present study, we assessed cytogenetic damage in isolated human peripheral lymphocytes using the cytokinesis-block micronucleus cytome assay (CBMN-Cyt), micronucleus formation with anti-kinetochore antibody (CREST staining), levels of total Hg in hair (T-Hg), fish consumption, and estimated Hg dose. The study comprised 39 non-exposed, and 73 residents from La Mojana region, an area with a well-documented Hg contamination. Data showed a significant increase in micronuclei (MNBN), nucleoplasmic bridges (NPB), and necrotic and apoptotic cell frequencies in residents of “La Mojana.” The overall mean T-Hg level in hair for exposed residents was 1.12 ± 0.94 mg kg−1 and 0.15 ± 0.05 in individuals from the reference area. Approximately 40% of analyzed individuals showed T-Hg levels that exceeded US Environmental Protection Agency (USEPA) reference dose. Increased T-Hg levels in hair were related to increased MNBN frequencies and high fish consumption. Other cellular markers, such as necrotic and apoptotic cell frequencies, were also correlated with high fish intake and T-Hg contents. Results of the CREST staining demonstrated that in vivo exposure to Hg induces genetic instability by chromosome fragment loss (clastogenic). Additionally, a high average intake of some fish species, particularly with carnivorous habits like Caquetaia kraussii, Hoplias malabaricus, and Sorubin cuspicaudus, seems to increase MNBN frequencies significantly.

Estimating daily intakes of manganese due to breast milk, infant formulas, or young child nutritional beverages in the United States and France: Comparison to sufficiency and toxicity thresholds

BackgroundAlthough manganese (Mn) is an essential nutrient, recent research has revealed that excess Mn in early childhood may have adverse effects on neurodevelopment. MethodsWe estimated daily total Mn intake due to breast milk at average body weights by reviewing reported concentrations of breast milk Mn and measurements of body weight and breast milk intake at 3 weeks, 4.25 months, 7 months, and 18 months. We compared these figures to the Mn content measured in 44 infant, follow-up, and toddler formulas purchased in the United States and France. We calculated Mn content of formula products made with ultra-trace elemental analysis grade water (0 μg Mn/L) and with water containing 250 μg Mn/L, a concentration which is relatively high but less than the World Health Organization Health-based value of 400 μg Mn/L or the United States Environmental Protection Agency Health Advisory of 350 μg Mn/L. ResultsEstimated mean daily Mn intake from breast milk ranged from 1.2 μg Mn/kg/day (3 weeks) to 0.16 μg Mn/kg/day (18 months), with the highest intakes at the youngest age stage we considered, 3 weeks. Estimated daily Mn intake from formula products reconstituted with 0 μg Mn/L water ranged from 130 μg Mn/kg/day (3 weeks) to 4.8 μg Mn/kg/day (18 months) with the highest intakes at 3 weeks. Formula products provided 28–520 times greater than the mean daily intake of Mn from breast milk for the 4 age stages that we considered. Estimated daily Mn intake from formula products reconstituted with water containing 250 μg Mn/L ranged from 12 μg Mn/kg/day to 170 μg Mn/kg/day, which exceeds the United States Environmental Protection Agency Reference Dose of 140 μg Mn/kg/day for adults. ConclusionsMn deficiency is highly unlikely with exclusive breast milk or infant formula feeding, but established tolerable daily intake levels for Mn may be surpassed by some of these products when following labeled instructions.

Hair mercury levels and dietary exposure of mercury in relation to fish consumption among coastal population in Negombo, Sri Lanka

Consumption of contaminated fish is the major source of the human exposure to total mercury (T-Hg) and methyl mercury. This study reports the fish consumption habits of three groups based on the age category and their occupation; “Children” (age 9-20 years) and two groups of “Adults” (age above 21 years) based on their occupation; “Adults-Fishermen” (fishermen) and “Adults-Other”. Hair T-Hg levels were measured from 30 individuals (age 9-48 years) from Negombo area in Sri Lanka. All individuals in this survey consumed fish at least six servings per week, which belongs to the high fish consumer category (> 3 servings/week) according to World Health Organization (WHO) guidelines. The main fish groups consumed by the respondents were mainly yellow-fin tuna (YFT), skipjack tuna (SKT), kawakawa and frigate tuna and small fish such as sardines (spotted sardines, goldstripe sardine, other sardines, scads and trevallies). The majority consumed an equal amount of big fish and small fish. The average weekly fish consumption per individual varied depending on the test group (Children; 1270 g/week per person, Adults-other; 1078 g/week per person and Adults-fishermen 1852 g/week per person) which exceeded United States Food & Drug Administration (USFDA) recommended level of 340 g/ week of seafood containing low concentration of Hg. The mean hair T-Hg of respondents of Negombo population was 4.89±3.23 µg/g (range 1.60-13.38 µg/g), which exceeded the United States Environmental Protection Agency (USEPA) reference dose (1 µg/g) for T-Hg level of hair. The total hair mercury in three respondent groups (Children 3.33±1.36 µg/g, Adults-other 2.89±1.26 µg/g and Adults-Fishermen 6.08±3.62 µg/g), were not significantly different (p>0.05) from each other. Real exposure value of three respondent groups were not significantly different (p>0.05). There was a low strength positive correlation (r=0.353, p>0.05) between hair T-Hg levels with the weekly large fish consumption.

Expression of Genes Involved in Stress, Toxicity, Inflammation, and Autoimmunity in Relation to Cadmium, Mercury, and Lead in Human Blood: A Pilot Study.

There is growing evidence of immunotoxicity related to exposure to toxic trace metals, and an examination of gene expression patterns in peripheral blood samples may provide insights into the potential development of these outcomes. This pilot study aimed to correlate the blood levels of three heavy metals (mercury, cadmium, and lead) with differences in gene expression in 24 participants from the Long Island Study of Seafood Consumption. We measured the peripheral blood mRNA expression of 98 genes that are implicated in stress, toxicity, inflammation, and autoimmunity. We fit multiple linear regression models with multiple testing correction to correlate exposure biomarkers with mRNA abundance. The mean blood Hg in this cohort was 16.1 µg/L, which was nearly three times the Environmental Protection Agency (EPA) reference dose (5.8 µg/L). The levels of the other metals were consistent with those in the general population: the mean Pb was 26.8 µg/L, and the mean Cd was 0.43 µg/L. The expression of three genes was associated with mercury, four were associated with cadmium, and five were associated with lead, although none were significant after multiple testing correction. Little evidence was found to associate metal exposure with mRNA abundance for the tested genes that were associated with stress, toxicity, inflammation, or autoimmunity. Future work should provide a more complete picture of physiological reactions to heavy metal exposure.

Estimated daily intake and cumulative risk assessment of phthalates in Taiwan military personnel

Background: Phthalate esters (PAEs), which may have potential adverse health effects, are widely used in industrial and consumer products. The public raised concerns of exposure to PAEs after di-2-ethylhexyl PAE (DEHP) had been illegally used in food products in Taiwan in 2011. However, there is little information regarding the exposure levels of PAEs among Taiwanese military personnel. Objective: Health risk assessment indicators, including daily intake (DI), hazard quotient (HQ), and hazard index (HI), were used to assess the distribution and trends of PAEs and cumulative risk in Taiwanese military personnel. Materials and Methods: We recruited 503 participants who participated in northern voluntary military service from June to August 2017. We calculated the DI of five PAEs, namely dimethyl PAE, diethyl PAE, dibutyl PAE (DBP), benzyl butyl phthalate, and DEHP, and selected the reference dose (RfD) described by the US Environmental Protection Agency (EPA) as an acceptable exposure reference value to compute the HQ and HI. We used statistical analysis to examine the differences and trends of PAE metabolites in urine and investigated the possible primary sources of PAEs with principal component analysis. Results: The detection rates of 7 PAE metabolite concentrations were ≥72.2%. All DIs, HQRfDs, and HIRfDs were not over the standard EPA RfD. For all participants, two principal components (PC) were extracted. Three DEHP metabolites and MBP were correlated with PC1, and MiBP and MnBP were correlated with PC2. Conclusions: The main potential sources of PAE exposure for Taiwanese military personnel are DEHP and DBP. Efforts to reduce exposure to environmental PAEs are necessary to maintain health within the military.

Integration of mechanistic and pharmacokinetic information to derive oral reference dose and margin-of-exposure values for hexavalent chromium.

The current US Environmental Protection Agency (EPA) reference dose (RfD) for oral exposure to chromium, 0.003 mg kg−1 day−1, is based on a no‐observable‐adverse‐effect‐level from a 1958 bioassay of rats exposed to ≤25 ppm hexavalent chromium [Cr(VI)] in drinking water. EPA characterizes the confidence in this RfD as “low.” A more recent cancer bioassay indicates that Cr(VI) in drinking water is carcinogenic to mice at ≥30 ppm. To assess whether the existing RfD is health protective, neoplastic and non‐neoplastic lesions from the 2 year cancer bioassay were modeled in a three‐step process. First, a rodent physiological‐based pharmacokinetic (PBPK) model was used to estimate internal dose metrics relevant to each lesion. Second, benchmark dose modeling was conducted on each lesion using the internal dose metrics. Third, a human PBPK model was used to estimate the daily mg kg−1 dose that would produce the same internal dose metric in both normal and susceptible humans. Mechanistic research into the mode of action for Cr(VI)‐induced intestinal tumors in mice supports a threshold mechanism involving intestinal wounding and chronic regenerative hyperplasia. As such, an RfD was developed using incidence data for the precursor lesion diffuse epithelial hyperplasia. This RfD was compared to RfDs for other non‐cancer endpoints; all RfD values ranged 0.003–0.02 mg kg−1 day−1. The lowest of these values is identical to EPA's existing RfD value. Although the RfD value remains 0.003 mg kg−1 day−1, the confidence is greatly improved due to the use of a 2‐year bioassay, mechanistic data, PBPK models and benchmark dose modeling.

Dietary human exposure to mercury in two artisanal small-scale gold mining communities of northwestern Colombia

Artisanal and small-scale gold mining (ASGM) is the largest anthropogenic source of mercury pollution worldwide, posing a grave threat to human health. The present study identifies current levels of mercury in the human population from mining areas of the Chocó Department, Colombia, through total mercury (THg) and methylmercury (MeHg) measurements in human hair. Mercury exposure of the local population was assessed in two towns affected by ASGM and was related to different variables of interest. Concentrations of THg in human hair ranged from 0.06 to 17.54ppm and the mean value for the subjects under study was 2.48ppm. Men had significantly higher levels than women in both towns (3.29ppm vs. 0.77ppm). Fish consumption was related to a marked increase of THg in hair, with mean values close to five times higher in frequent fish consumers (5–7 times/week) than in non-fish consumers (4.80ppm vs. 0.90ppm). A multiple linear regression model was fitted successfully (R=0.671) and reveals that gender, fish consumption and location of residence were significant indicators of Hg levels in hair, while no significant relationship was found for age. Approximately 60% of subjects tested had THg levels that exceeded the U.S. Environmental Protection Agency reference dose of 1.0ppm, while 25% surpassed that of the World Health Organization (2.2ppm).

Cumulative risk assessment of phthalates associated with birth outcomes in pregnant Chinese women: A prospective cohort study

A prospective cohort study of a Chinese population of mother–neonate pairs (n = 3103) was conducted to investigate the relationship between the cumulative hazard index (HI) of combined diethyl phthalate (DEP), dibutyl phthalate (DBP), dibenzyl phthalate (BBzP) and di(2-ethylhexyl) phthalate (DEHP) exposure and birth outcomes. The estimated HI for phthalates was based on phthalate metabolite concentrations in urine collected between 5th and 14th gestational weeks. The median HI values according to the European Food Safety Authority tolerable daily intake (HITDI) and U.S. Environmental Protection Agency reference dose (HIRfD) were 0.358 and 0.187, respectively. A total of 16.3% and 1.9% of the women exhibited HITDI and HIRfD exceeding the value of one, respectively. In unadjusted models, the categories (low < P25, median P25–P50, high > P75) of HITDI were associated with decreased birth weight (β = −26.34 g, p = 0.021) and head circumference (β = −0.09 cm, p = 0.029), whereas those for HIRfD were negatively associated with birth weight (β = −31.74 g, p = 0.005), birth length (β = −0.11 cm, p = 0.032), head circumference (β = −0.13 cm, p = 0.003) and chest circumference (β = −0.10 cm, p = 0.021) in all neonates. Adjustment for potential confounders revealed that HIRfD was inversely associated with head circumference (β = −0.10 cm, p = 0.020). Stratification by gender indicated that HIRfD was associated with decreased birth length (β = −0.17 cm, p = 0.041) in infant boys and HITDI was associated with decreased birth weight (β = −33.12 g, p = 0.036) and head circumference (β = −0.13 cm, p = 0.027) in girls. This is the first study on the cumulative risk assessment of phthalate exposures in pregnant Chinese women. We found that the HI values of multiple phthalate co-exposure were sex-specifically related to birth outcomes.

Low-level arsenic exposure and developmental neurotoxicity in children: A systematic review and risk assessment

Risk assessments of arsenic have focused on skin, bladder, and lung cancers and skin lesions as the sensitive cancer and non-cancer health endpoints, respectively; however, an increasing number of epidemiologic studies that can inform risk assessment have examined neurodevelopmental effects in children. We conducted a systematic review and risk assessment based on the epidemiologic literature on possible neurodevelopmental effects at lower arsenic exposures. Twenty-four cross-sectional, case-control, and cohort studies were identified that report on the association between low-level arsenic exposure (i.e., largely <100 μg/L of arsenic in drinking water) and neurological outcomes in children. Although the overall evidence does not consistently show a causal dose-response relationship at low doses, the most rigorously conducted studies from Bangladesh indicate possible inverse associations with cognitive function, predominantly involving concurrent arsenic exposure as measured by biomarkers (i.e., arsenic in urine or blood) and raw verbal test scores at ages 5-11 years. Issues such as non-comparability of outcome measures across studies; inaccuracies of biomarkers and other measures of inorganic arsenic exposure; potential effect modification by cultural practices; insufficient adjustment for nutritional deficiencies, maternal IQ, and other important confounders; and presence of other neurotoxicants in foreign populations limit generalizability to U.S. Of the few U.S. studies available, the most rigorously conducted study did not find a consistent dose-response relationship between arsenic concentrations in tap water or toenails and decrements in IQ scores. Assuming that the strongest dose-response relationship from the most rigorous evidence from Bangladesh is generalizable to U.S. populations, possible reference doses were estimated in the range of 0.0004-0.001 mg/kg-day. These doses are higher than the U.S. Environmental Protection Agency reference dose for chronic lifetime exposure, thus indicating protectiveness of the existing value for potential neurotoxicity in children. This reference dose is undergoing revision as EPA considers various health endpoints in the reassessment of inorganic arsenic health risks.

Mercury Exposure Assessment and Spatial Distribution in A Ghanaian Small-Scale Gold Mining Community.

Mercury is utilized worldwide in artisanal and small-scale gold mining (ASGM) and may pose a risk for miners and mining communities. While a number of studies have characterized mercury in ASGM communities, most have focused on a single media and few have taken a holistic approach. Here, a multiple media exposure assessment and cross-sectional study of mercury was conducted in 2010 through 2012 in northeast Ghana with a small-scale gold mining community, Kejetia, a subsistence farming community, Gorogo, and an urban ASGM gold refinery in Bolgatanga. The objective was to assess mercury in a range of human (urine and hair) and ecological (household soil, sediment, fish, and ore) samples to increase understanding of mercury exposure pathways. All participants were interviewed on demographics, occupational and medical histories, and household characteristics. Participants included 90 women of childbearing age and 97 adults from Kejetia and 75 adults from Gorogo. Median total specific gravity-adjusted urinary, hair, and household soil mercury were significantly higher in Kejetia miners (5.18 µg/L, 0.967 µg/g, and 3.77 µg/g, respectively) than Kejetia non-miners (1.18 µg/L, 0.419 µg/g, and 2.00 µg/g, respectively) and Gorogo participants (0.154 µg/L, 0.181 µg/g, and 0.039 µg/g) in 2011. Sediment, fish, and ore Hg concentrations were below guideline values. Median soil mercury from the Bolgatanga refinery was very high (54.6 µg/g). Estimated mean mercury ingestion for Kejetia adults from soil and dust exceeded the U.S. Environmental Protection Agency reference dose (0.3 µg Hg/kg·day) for pica (0.409 µg Hg/kg·day) and geophagy (20.5 µg Hg/kg·day) scenarios. Most participants with elevated urinary and household soil mercury were miners, but some non-miners approached and exceeded guideline values, suggesting a health risk for non-mining residents living within these communities.

Mercurial exposure of residents of Santarém and Oriximiná cities (Pará, Brazil) through fish consumption.

A survey of the mercurial exposure of residents of Santarém and Oriximiná showed a differential mercurial impregnation between men and women. At the level of both cities, the mean hair mercury concentrations were 1.5 ± 0.5 (90th and 95th percentiles: 2.8 and 4.3) and 2.52 ± 0.09 μg g Hg/g (90th and 95th percentiles: 4.7 and 8.1) for women and men, respectively. The mercurial contamination appeared significantly closely linked to the daily amount of consumed fish. Carnivore species pescada branca (Plagioscion squamosissimus) and apapá (Pellona castelnaeana) and non-carnivore species pacú (Mylossoma duriventre) and aracú (Schizodon fasciatus) were consumed by 22, 19, 55 and 25% of people, respectively, and the mean mercury concentrations within fish flesh were 1.44 ± 0.11, 1.66 ± 0.19, 0.48 ± 0.09 and 0.49 ± 0.06 μg/g dry weight, respectively. Men aged above 35 were significantly more contaminated than those below. The mean hair concentrations of men were 5.20 ± 1.25 and 1.50 ± 0.22 μg/g, for those aged above 35 and below, respectively. The probability for women of childbearing age from both cities to present a hair mercury concentration above 1 μg Hg/g (corresponding to the US Environmental Protection Agency reference dose) was equal to 0.30 (95% confidence interval of 0.24-0.36). The probability of hair mercury concentration to be above the lowest observable adverse effect level (LOAEL) (0.3 μg Hg/g) was equal to 0.79 (95% confidence interval: 0.73-0.86).