Last data update: Jan 27, 2025. (Total: 48650 publications since 2009)
Records 1-30 (of 39 Records) |
Query Trace: Barr DB[original query] |
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Systematic review of microplastics and nanoplastics in indoor and outdoor air: identifying a framework and data needs for quantifying human inhalation exposures
Eberhard T , Casillas G , Zarus GM , Barr DB . J Expo Sci Environ Epidemiol 2024 BACKGROUND: Humans are likely exposed to microplastics (MPs) in a variety of places including indoor and outdoor air. Research to better understand how exposure to MPs correlates to health is growing. To fully understand the possible impacts of MPs on human health, it is necessary to quantify MP exposure and identify what critical data gaps exist. OBJECTIVES: The current paper provides a human exposure assessment of microplastics in the air using systematically reviewed literature that provided concentration of MPs in air as well as doses used in toxicology studies to calculate inhalation exposure dose. METHODS: All published peer-reviewed journal articles, non-published papers, and grey literature that focused on micro- or nano-plastics in indoor and outdoor air were systematically searched using PRISMA guidelines. Literature that defined specific concentrations and size of MPs in air or exposed to human lung cells, animals, or humans with measurable health impacts were included in data extraction. Inhalational exposures were calculated for different age groups using published MP concentrations from the included literature using exposure dose equations and values from U.S. ATSDR and EPA. RESULTS: Calculated mean indoor inhalational exposures from passive sampling methods were higher than those calculated from active sampling methods. When comparing indoor and outdoor sampling, calculated inhalation exposures from indoor samples were greater than those from outdoor samples. Inhalation exposures of MPs differed between age groups with infants having the highest calculated dose values for all locations followed by preschool age children, middle-school aged children, pregnant women, adolescents, and non-pregnant adults. MP doses used in toxicology studies produced higher calculated mean inhalational exposures than those from environmental samples. IMPACT: This study is the first known systematic review of inhalational MP exposure from indoor and outdoor air. It also provides inhalational exposures calculated from previously published environmental samples of MPs as well as from toxicology studies. |
Interpreting biomonitoring data: Introducing the international human biomonitoring (i-HBM) working group's health-based guidance value (HB2GV) dashboard.
Nakayama SF , St-Amand A , Pollock T , Apel P , Bamai YA , Barr DB , Bessems J , Calafat AM , Castaño A , Covaci A , Duca RC , Faure S , Galea KS , Hays S , Hopf NB , Ito Y , Jeddi MZ , Kolossa-Gehring M , Kumar E , LaKind JS , López ME , Louro H , Macey K , Makris KC , Melnyk L , Murawski A , Naiman J , Nassif J , Noisel N , Poddalgoda D , Quirós-Alcalá L , Rafiee A , Rambaud L , Silva MJ , Ueyama J , Verner MA , Waras MN , Werry K . Int J Hyg Environ Health 2022 247 114046 ![]() Human biomonitoring (HBM) data measured in specific contexts or populations provide information for comparing population exposures. There are numerous health-based biomonitoring guidance values, but to locate these values, interested parties need to seek them out individually from publications, governmental reports, websites and other sources. Until now, there has been no central, international repository for this information. Thus, a tool is needed to help researchers, public health professionals, risk assessors, and regulatory decision makers to quickly locate relevant values on numerous environmental chemicals. A free, on-line repository for international health-based guidance values to facilitate the interpretation of HBM data is now available. The repository is referred to as the "Human Biomonitoring Health-Based Guidance Value (HB2GV) Dashboard". The Dashboard represents the efforts of the International Human Biomonitoring Working Group (i-HBM), affiliated with the International Society of Exposure Science. The i-HBM's mission is to promote the use of population-level HBM data to inform public health decision-making by developing harmonized resources to facilitate the interpretation of HBM data in a health-based context. This paper describes the methods used to compile the human biomonitoring health-based guidance values, how the values can be accessed and used, and caveats with using the Dashboard for interpreting HBM data. To our knowledge, the HB2GV Dashboard is the first open-access, curated database of HBM guidance values developed for use in interpreting HBM data. This new resource can assist global HBM data users such as risk assessors, risk managers and biomonitoring programs with a readily available compilation of guidance values. |
Measuring environmental exposure to enteric pathogens in low-income settings: Review and recommendations of an interdisciplinary working group
Goddard FGB , Ban R , Barr DB , Brown J , Cannon J , Colford JM Jr , Eisenberg JNS , Ercumen A , Petach H , Freeman MC , Levy K , Luby SP , Moe C , Pickering AJ , Sarnat JA , Stewart J , Thomas E , Taniuchi M , Clasen T . Environ Sci Technol 2020 54 (19) 11673-11691 Infections with enteric pathogens impose a heavy disease burden, especially among young children in low-income countries. Recent findings from randomized controlled trials of water, sanitation, and hygiene interventions have raised questions about current methods for assessing environmental exposure to enteric pathogens. Approaches for estimating sources and doses of exposure suffer from a number of shortcomings, including reliance on imperfect indicators of fecal contamination instead of actual pathogens and estimating exposure indirectly from imprecise measurements of pathogens in the environment and human interaction therewith. These shortcomings limit the potential for effective surveillance of exposures, identification of important sources and modes of transmission, and evaluation of the effectiveness of interventions. In this review, we summarize current and emerging approaches used to characterize enteric pathogen hazards in different environmental media as well as human interaction with those media (external measures of exposure), and review methods that measure human infection with enteric pathogens as a proxy for past exposure (internal measures of exposure). We draw from lessons learned in other areas of environmental health to highlight how external and internal measures of exposure can be used to more comprehensively assess exposure. We conclude by recommending strategies for advancing enteric pathogen exposure assessments. |
Urinary organophosphate insecticide metabolite concentrations during pregnancy and children's interpersonal, communication, repetitive, and stereotypic behaviors at 8 years of age: The home study
Millenson ME , Braun JM , Calafat AM , Barr DB , Huang YT , Chen A , Lanphear BP , Yolton K . Environ Res 2017 157 9-16 BACKGROUND: Prenatal exposure to organophosphate insecticides may be associated with autism spectrum disorders and related behaviors. This association may be modified by single nucleotide polymorphisms in the paraoxonase (PON1) enzyme. OBJECTIVE: We examined the relationship of prenatal organophosphate insecticide biomarkers with reciprocal social, repetitive, and stereotypic behaviors in 8-year old children, and modification of this relationship by child PON1 polymorphisms. METHODS: Among 224 pregnant women, we quantified concentrations of six nonspecific dialkyl phosphate (DAP) metabolites of organophosphate insecticides in two urine samples collected at ~16 and ~26 weeks gestation. When children were eight years old, we administered the Social Responsiveness Scale (SRS), a continuous measure of various dimensions of interpersonal behavior, communication, and repetitive/stereotypic behaviors. We estimated the association between a 10-fold increase in the sum of six DAP concentrations (SigmaDAP) and SRS scores. We examined whether child PON1192 and PON1-108 genotypes modified this association. RESULTS: After covariate adjustment, SigmaDAP concentrations were not associated with SRS scores [beta=-1.2; 95% confidence interval (CI): -4.0, 1.6]. Among children with the PON1-108TT genotype, SigmaDAP concentrations were associated with 2.5-point higher (95% CI: -4.9, 9.8) SRS scores; however, the association was not different from the 1.8-point decrease (95% CI: -5.8, 2.2) among children with PON1-108CT/CC genotypes (SigmaDAP x PON1-108 p-value =0.54). The association between SigmaDAP concentrations and SRS scores was not modified by PON1192 (SigmaDAP x PON1192 p-value =0.89). CONCLUSIONS: In this cohort, prenatal urinary DAP concentrations were not associated with children's social behaviors; these associations were not modified by child PON1 genotype. |
Biological matrix effects in quantitative tandem mass spectrometry-based analytical methods: advancing biomonitoring
Panuwet P , Hunter RE Jr , D'Souza PE , Chen X , Radford SA , Cohen JR , Marder ME , Kartavenka K , Ryan PB , Barr DB . Crit Rev Anal Chem 2016 46 (2) 93-105 The ability to quantify levels of target analytes in biological samples accurately and precisely in biomonitoring involves the use of highly sensitive and selective instrumentation such as tandem mass spectrometers and a thorough understanding of highly variable matrix effects. Typically, matrix effects are caused by co-eluting matrix components that alter the ionization of target analytes as well as the chromatographic response of target analytes, leading to reduced or increased sensitivity of the analysis. Thus, before the desired accuracy and precision standards of laboratory data are achieved, these effects must be characterized and controlled. Here we present our review and observations of matrix effects encountered during the validation and implementation of tandem mass spectrometry-based analytical methods. We also provide systematic, comprehensive laboratory strategies needed to control challenges posed by matrix effects in order to ensure delivery of the most accurate data for biomonitoring studies assessing exposure to environmental toxicants. |
A prospective study of prepregnancy serum concentrations of perfluorochemicals and the risk of gestational diabetes
Zhang C , Sundaram R , Maisog J , Calafat AM , Barr DB , Buck Louis GM . Fertil Steril 2014 103 (1) 184-9 OBJECTIVE: To examine preconception serum concentrations of perfluorooctanoic acid (PFOA) and six other PFCs in relation to gestational diabetes (GDM) risk. DESIGN: Prospective cohort with longitudinal follow-up. SETTING: Not applicable. PATIENT(S): Among 501 women recruited upon discontinuing contraception for the purpose of becoming pregnant, 258 (51%) became pregnant and were eligible for the study, of which 28 (11%) reported having physician-diagnosed GDM during follow-up. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): The odds ratios (ORs) and 95% confidence intervals (CIs) of GDM associated with each standard deviation (SD) increment of preconception serum PFOA concentration (ng/mL, log-transformed) and six other PFCs were estimated with the use of logistic regression after adjusting for age, prepregnancy body mass index, smoking, and parity conditional on gravidity. RESULT(S): Preconception geometric mean (95% CI) PFOA concentrations (in ng/mL) were higher for women with than without GDM (3.94 [3.15-4.93] vs. 3.07 [2.83-3.12], respectively). Each SD increment in PFOA was associated with a 1.87-fold increased GDM risk (adjusted OR 1.86 [95% CI 1.14-3.02]). A slightly increased risk associated with each SD increment for the six other PFCs was observed as well (all ORs >1.0, range 1.06-1.27), although the associations were not statistically significant. CONCLUSION(S): Our findings suggested that higher environmentally relevant concentrations of PFOA were significantly associated with an increased risk of GDM. If corroborated, these findings may be suggestive of a possible environmental etiology for GDM. |
Higher urinary lignan concentrations in women but not men are positively associated with shorter time to pregnancy
Mumford SL , Sundaram R , Schisterman EF , Sweeney AM , Barr DB , Rybak ME , Maisog JM , Parker DL , Pfeiffer CM , Louis GM . J Nutr 2014 144 (3) 352-8 Phytoestrogens have been associated with subtle hormonal changes, although effects on fecundity are unknown. Our objective was to evaluate the association between male and female urinary phytoestrogen (isoflavone and lignan) concentrations and time to pregnancy (TTP) in a population-based cohort of 501 couples desiring pregnancy and discontinuing contraception. Couples were followed for 12 mo or until pregnancy. Fecundability ORs (FORs) and 95% CIs were estimated after adjusting for age, body mass index, race, site, creatinine, supplement use, and physical activity in relation to female, male, and joint couple concentrations. Models included the phytoestrogen of interest and the sum of the remaining individual phytoestrogens. FORs <1 denote a longer TTP and FORs >1 a shorter TTP. Urinary lignan concentrations were higher, on average, among female partners of couples who became pregnant during the study compared with women who did not become pregnant (median enterodiol: 118 vs. 80 nmol/L; P < 0.10; median enterolactone: 990 vs. 412 nmol/L; P < 0.05) and were associated with significantly shorter TTP in models based on both individual and couples' concentrations (couples' models: enterodiol FOR, 1.13; 95% CI: 1.02, 1.26; enterolactone FOR, 1.11; 95% CI: 1.01, 1.21). Male lignan concentrations were not associated with TTP, nor were isoflavone concentrations. Sensitivity analyses showed that associations observed are unlikely to be explained by potential unmeasured confounding by lifestyle or other nutrients. Our results suggest that female urinary lignan concentrations at levels characteristic of the U.S. population are associated with a shorter TTP among couples who are attempting to conceive, highlighting the importance of dietary influences on fecundity. |
Associations of prenatal exposure to organophosphate pesticide metabolites with gestational age and birth weight
Rauch SA , Braun JM , Barr DB , Calafat AM , Khoury J , Montesano AM , Yolton K , Lanphear BP . Environ Health Perspect 2012 120 (7) 1055-60 BACKGROUND: Prenatal exposure to organophosphate (OP) insecticides, a widely used class of pesticides, may be associated with decreased gestational age and lower birth weight. Single nucleotide polymorphisms in paroxanase (PON1) enzyme genotypes may modify the relationships between OP exposure and perinatal outcomes. OBJECTIVE: We examined the relationship of prenatal OP insecticide exposure, measured using urinary dialkyl phosphate (DAP) metabolite concentrations, with gestational age and birth weight. METHODS: We measured the concentrations of six nonspecific DAP metabolites of OP insecticides in two maternal spot urine samples collected in a prospective birth cohort. We performed multivariable regression to examine associations between the sum of six DAP concentrations (SigmaDAP) with gestational age and birth weight. We also examined whether these associations differed according to infant PON1192 and PON1-108 genotypes. RESULTS: Among 306 mother-infant dyads, a 10-fold increase in SigmaDAP concentrations was associated with a decrease in covariate-adjusted gestational age [-0.5 weeks; 95% confidence interval (CI): -0.8, -0.1] and birth weight (-151 g; CI: -287, -16); the decrements in birth weight were attenuated after adjusting for gestational age. The relationship between SigmaDAP concentrations and gestational age was stronger for white (-0.7 weeks; CI: -1.1, -0.3) than for black (-0.1 weeks; 95% CI: -0.9, 0.6) newborns. In contrast, there was a greater decrease in birth weight with increasing urinary SigmaDAP concentrations for black (-188 g; CI: -395, 19) than for white (-118 g; CI: -296, 60) newborns. Decrements in birth weight and gestational age associated with SigmaDAP concentrations were greatest among infants with PON1192QR and PON-108CT genotypes. CONCLUSIONS: Prenatal urinary SigmaDAP concentrations were associated with shortened gestation and reduced birth weight in this cohort, but the effects differed by race/ethnicity and PON1192/108 genotypes. |
Heavy metals and couple fecundity, the LIFE Study
Buck Louis GM , Sundaram R , Schisterman EF , Sweeney AM , Lynch CD , Gore-Langton RE , Chen Z , Kim S , Caldwell KL , Barr DB . Chemosphere 2012 87 (11) 1201-7 The effect of heavy metals at environmentally relevant concentrations on couple fecundity has received limited study despite ubiquitous exposure. In 2005-2009, couples (n=501) desiring pregnancy and discontinuing contraception were recruited and asked to complete interviews and to provide blood specimens for the quantification of cadmium (mcgL(-1)), lead (mcgdL(-1)) and mercury (mcgL(-1)) using inductively coupled plasma-mass spectrometry. Couples completed daily journals on lifestyle and intercourse along with menstruation and pregnancy testing for women. Couples were followed for 12 months or until pregnant. Fecundability odds ratios (FORs) and 95% confidence intervals (CIs) were estimated adjusting for age, body mass index, cotinine, and serum lipids in relation to female then male exposures. FORs <1 denote a longer time to pregnancy. In adjusted models, reduced FORs were observed for both female cadmium (0.78; 95% CI 0.63-0.97) and male lead (0.85; 95% CI 0.73-0.98) concentrations. When jointly modeling couples' exposures, only male lead concentration significantly reduced the FOR (0.82; 95% CI 0.68, 0.97), though the FOR remained <1 for female cadmium (0.80; 95% CI 0.64, 1.00). This prospective couple based cohort with longitudinal capture of time to pregnancy is suggestive of cadmium and lead's reproductive toxicity at environmentally relevant concentrations. |
Menstrual cycle characteristics and reproductive hormone levels in women exposed to atrazine in drinking water
Cragin LA , Kesner JS , Bachand AM , Barr DB , Meadows JW , Krieg EF , Reif JS . Environ Res 2011 111 (8) 1293-301 Atrazine is the most commonly used herbicide in the U.S. and a wide-spread groundwater contaminant. Epidemiologic and laboratory evidence exists that atrazine disrupts reproductive health and hormone secretion. We examined the relationship between exposure to atrazine in drinking water and menstrual cycle function including reproductive hormone levels. Women 18-40 years old residing in agricultural communities where atrazine is used extensively (Illinois) and sparingly (Vermont) answered a questionnaire (n=102), maintained menstrual cycle diaries (n=67), and provided daily urine samples for analyses of luteinizing hormone (LH), and estradiol and progesterone metabolites (n=35). Markers of exposures included state of residence, atrazine and chlorotriazine concentrations in tap water, municipal water and urine, and estimated dose from water consumption. Women who lived in Illinois were more likely to report menstrual cycle length irregularity (odds ratio (OR)=4.69; 95% confidence interval (CI): 1.58-13.95) and more than 6 weeks between periods (OR=6.16; 95% CI: 1.29-29.38) than those who lived in Vermont. Consumption of >2 cups of unfiltered Illinois water daily was associated with increased risk of irregular periods (OR=5.73; 95% CI: 1.58-20.77). Estimated "dose" of atrazine and chlorotriazine from tap water was inversely related to mean mid-luteal estradiol metabolite. Atrazine "dose" from municipal concentrations was directly related to follicular phase length and inversely related to mean mid-luteal progesterone metabolite levels. We present preliminary evidence that atrazine exposure, at levels below the US EPA MCL, is associated with increased menstrual cycle irregularity, longer follicular phases, and decreased levels of menstrual cycle endocrine biomarkers of infertile ovulatory cycles. |
Urinary concentrations of dialkylphosphate metabolites of organophosphorus pesticides: National Health and Nutrition Examination Survey 1999-2004
Barr DB , Wong LY , Bravo R , Weerasekera G , Odetokun M , Restrepo P , Kim DG , Fernandez C , Whitehead RD Jr , Perez J , Gallegos M , Williams BL , Needham LL . Int J Environ Res Public Health 2011 8 (8) 3063-98 Organophosphorus (OP) insecticides were among the first pesticides that EPA reevaluated as part of the Food Quality Protection Act of 1996. Our goal was to assess exposure to OP insecticides in the U.S. general population over a six-year period. We analyzed 7,456 urine samples collected as part of three two-year cycles of the National Health and Nutrition Examination Survey (NHANES) from 1999-2004. We measured six dialkylphosphate metabolites of OP pesticides to assess OP pesticide exposure. In NHANES 2003-2004, dimethylthiophosphate was detected most frequently with median and 95th percentile concentrations of 2.03 and 35.3 mcg/L, respectively. Adolescents were two to three times more likely to have diethylphosphate concentrations above the 95th percentile estimate of 15.5 mcg/L than adults and senior adults. Conversely, for dimethyldithiophosphate, senior adults were 3.8 times and 1.8 times more likely to be above the 95th percentile than adults and adolescents, respectively, while adults were 2.1 times more likely to be above the 95th percentile than the adolescents. Our data indicate that the most vulnerable segments of our population-children and older adults-have higher exposures to OP pesticides than other population segments. However, according to DAP urinary metabolite data, exposures to OP pesticides have declined during the last six years at both the median and 95th percentile levels. |
Quantification of riboflavin in human urine using high performance liquid chromatography-tandem mass spectrometry
Bishop AM , Fernandez C , Whitehead Jr RD , Morales AP , Barr DB , Wilder LC , Baker SE . J Chromatogr B Analyt Technol Biomed Life Sci 2011 879 (20) 1823-6 We developed a selective method to measure riboflavin in human urine. Sample preparation involved solid phase extraction and concentration of the target analyte in urine. The urine concentrate was analyzed using high performance liquid chromatography-tandem mass spectrometry. Riboflavin concentrations were quantified using an isotopically labeled internal standard. The limit of detection was 11ng/mL, and the linear range was 4.4-20,000ng/mL. The relative standard deviation at 100, 1000, and 5000ng/mL was 17%, 17%, and 12%, respectively. The accuracy was 90%. On average, 100 samples, including calibration standards and quality control samples, were prepared per day. Using our method, we measured concentrations of riboflavin in human urine samples that were collected from participants in a study where riboflavin was used as a surrogate chemical to simulate exposure to an environmental toxicant. |
Variability and predictors of urinary bisphenol A concentrations during pregnancy
Braun JM , Kalkbrenner AE , Calafat AM , Bernert JT , Ye X , Silva MJ , Barr DB , Sathyanarayana S , Lanphear BP . Environ Health Perspect 2011 119 (1) 131-7 BACKGROUND: Prenatal bisphenol A (BPA) exposure may be associated with developmental toxicity, but few studies have examined the variability and predictors of urinary BPA concentrations during pregnancy. OBJECTIVE: Our goal was to estimate the variability and predictors of serial urinary BPA concentrations taken during pregnancy. METHODS: We measured BPA concentrations during pregnancy and at birth in three spot urine samples from 389 women. We calculated the intraclass correlation coefficient (ICC) to assess BPA variability and estimated associations between log10-transformed urinary BPA concentrations and demographic, occupational, dietary, and environmental factors, using mixed models. RESULTS: Geometric mean (GM) creatinine-standardized concentrations (micrograms per gram) were 1.7 (16 weeks), 2.0 (26 weeks), and 2.0 (birth). Creatinine-standardized BPA concentrations exhibited low reproducibility (ICC = 0.11). By occupation, cashiers had the highest BPA concentrations (GM: 2.8 mug/g). Consuming canned vegetables at least once a day was associated with higher BPA concentrations (GM = 2.3 mug/g) compared with those consuming no canned vegetables (GM = 1.6 mug/g). BPA concentrations did not vary by consumption of fresh fruits and vegetables, canned fruit, or store-bought fresh and frozen fish. Urinary high-molecular-weight phthalate and serum tobacco smoke metabolite concentrations were positively associated with BPA concentrations. CONCLUSIONS: These results suggest numerous sources of BPA exposure during pregnancy. Etiological studies may need to measure urinary BPA concentrations more than once during pregnancy and adjust for phthalates and tobacco smoke exposures. |
Pesticide exposure among pregnant women in Jerusalem, Israel: results of a pilot study
Berman T , Hochner-Celnikier D , Barr DB , Needham LL , Amitai Y , Wormser U , Richter E . Environ Int 2011 37 (1) 198-203 BACKGROUND: Pesticides have been shown to disrupt neurodevelopment in laboratory animals and in human populations. To date, there have been no studies on exposure to pesticides in pregnant women in Israel, despite reports of widespread exposure in other populations of pregnant women and the importance of evaluating exposure in this susceptible sub-population. METHODS: We measured urinary concentrations of organophosphorus (OP) insecticide metabolites and plasma concentrations of OP and other pesticides in 20 pregnant women, recruited in Jerusalem, Israel in 2006, and collected questionnaire data on demographic factors and consumer habits from these women. We compared geometric mean concentrations in subgroups using the Mann-Whitney U-test for independent samples. We compared creatinine-adjusted OP pesticide metabolite concentrations, as well as plasma pesticide concentrations, with other populations of pregnant women. RESULTS: Creatinine-adjusted total dimethyl (DM) metabolite concentrations were between 4 and 6 times higher in this population compared to other populations of pregnant women in the United States while total diethyl (DE) metabolite concentrations were lower. Dimethylphosphate (DMP) was detected in 74% of the urine samples whereas dimethylthiophosphate (DMTP) was detected in 90% of the urine samples. The carbamate bendiocarb was detected in 89% of the plasma samples, while the OP insecticide chlorpyrifos was detected in 42% of the samples. Mean plasma concentrations of bendiocarb and chlorpyrifos in our sample were 4.4 and 3.9 times higher, respectively, than that of an urban minority cohort from New York City. Twelve women (63%) reported using some form of household pest control during their pregnancy and five (26%) reported using household pest control during the past month. Women with a graduate degree had significantly higher geometric mean concentrations of total urinary DM metabolite concentrations compared to other women (P=0.006). Finally, one woman in the study had exceptionally high concentrations of DMP, DMTP, DMDTP compared to the other women in the study, despite reporting no current occupational exposure to OP pesticides and no other significant exposure sources. CONCLUSIONS: Pregnant women in the Jerusalem area are exposed to OP pesticides and to the carbamate pesticide bendiocarb. It is unclear why total DM metabolites concentrations were much higher in this population compared to other populations of pregnant women in the United States and Netherlands. Finally, the finding of very high DM metabolite concentrations in one woman who reported being moved from her regular laboratory work to administrative work upon becoming pregnant, raises questions about the adequacy of measures to protect pregnant women from pesticide exposures during pregnancy. |
Prenatal environmental tobacco smoke exposure and early childhood body mass index
Braun JM , Daniels JL , Poole C , Olshan AF , Hornung R , Bernert JT , Khoury J , Needham LL , Barr DB , Lanphear BP . Paediatr Perinat Epidemiol 2010 24 (6) 524-534 Maternal smoking during pregnancy is associated with increased risk of childhood overweight body mass index (BMI). Less is known about the association between prenatal secondhand tobacco smoke (SHS) exposure and childhood BMI. We followed 292 mother-child dyads from early pregnancy to 3 years of age. Prenatal tobacco smoke exposure during pregnancy was quantified using self-report and serum cotinine biomarkers. We used linear mixed models to estimate the association between tobacco smoke exposure and BMI at birth, 4 weeks, and 1, 2 and 3 years. During pregnancy, 15% of women reported SHS exposure and 12% reported active smoking, but 51% of women had cotinine levels consistent with SHS exposure and 10% had cotinine concentrations indicative of active smoking. After adjustment for confounders, children born to active smokers (self-report or serum cotinine) had higher BMI at 2 and 3 years of age, compared with unexposed children. Children born to women with prenatal serum cotinine concentrations indicative of SHS exposure had higher BMI at 2 (mean difference [MD] 0.3 [95% confidence interval -0.1, 0.7]) and 3 (MD 0.4 [0, 0.8]) years compared with unexposed children. Using self-reported prenatal exposure resulted in non-differential exposure misclassification of SHS exposures that attenuated the association between SHS exposure and BMI compared with serum cotinine concentrations. These findings suggest active and secondhand prenatal tobacco smoke exposure may be related to an important public health problem in childhood and later life. In addition, accurate quantification of prenatal secondhand tobacco smoke exposures is essential to obtaining valid estimates. |
Diethylene glycol in health products sold over-the-counter and imported from Asian countries
Schier JG , Barr DB , Li Z , Wolkin AF , Baker SE , Lewis LS , McGeehin MA . J Med Toxicol 2010 7 (1) 33-8 Diethylene glycol (DEG), a chemical that has been implicated in multiple medication-associated mass poisonings, can result in renal and neurological toxicity if ingested. Three previous such mass poisonings implicated Chinese manufacturers as the origin of contaminated ingredients. No literature exists on potential DEG or triethylene glycol (TEG), a related compound, contamination of health products imported from Asian countries to the USA. Our primary objective was to quantitatively assess the amount of DEG present in a convenience sampling of these health products. The study's secondary objectives were to: (1) evaluate for, and quantify TEG levels in these samples; (2) compare DEG and TEG levels in these products directly to levels in medications implicated in previous similar mass poisonings; and (3) to estimate DEG dose (in mg/kg) based on the manufacturer's instructions and compare these values to toxic doses from past mass poisonings and the literature. A quantitative assessment of DEG and TEG was performed in a convenience sampling of over-the-counter health products imported from Asian countries. Results were converted to volume to volume (v/v) % and compared with DEG levels in medications implicated in previous mass poisonings. Estimated doses (based on the manufacturer's instructions) of each product with detectable levels of DEG for a 70 kg adult were compared to toxic doses of DEG reported in the literature. Seventeen of 85 (20%) samples were not able to be analyzed for DEG or TEG due to technical reasons. Fifteen of 68 (22%) samples successfully tested had detectable levels of DEG (mean, 18.8 mug/ml; range, 0.791-110.1 mug/ml; and volume to volume (v/v) range, 0.00007-0.01%). Two of 68 (3%) samples had TEG levels of 12.8 and 20.2 mug/ml or 0.0012% and 0.0018% TEG v/v. The product with the highest DEG% by v/v was 810 times less than the product involved in the Panama DEG mass poisoning (8.1%). The lowest reported toxic dose from a past DEG mass poisoning (14 mg/kg) was more than 150 times higher than the highest daily dose estimated in our study (0.09 mg/kg). Sixty-eight of 85 (80%) samples were able to be successfully analyzed for DEG and TEG. DEG and TEG were detectable in 15/68 (22%) and 2/68 (3%) samples, respectively. Based on current standards, these levels probably do not represent an acute public health threat. Additional research focusing on why DEG is found in these products and on the minimum amount of DEG needed to result in toxicity is needed. |
Non-dioxin-like polychlorinated biphenyls and risk of endometriosis
Trabert B , De Roos AJ , Schwartz SM , Peters U , Scholes D , Barr DB , Holt VL . Environ Health Perspect 2010 118 (9) 1280-5 BACKGROUND: Endometriosis, a gynecologic disorder affecting 8-10% of reproductive-age women in the United States, is defined as the presence of endometrial tissue outside the uterus and is linked to pelvic pain and infertility. Environmental contaminants, including polychlorinated biphenyls (PCBs), are hypothesized to contribute to endometriosis risk through effects on steroid hormones. OBJECTIVE: We evaluated serum concentrations of certain noncoplanar PCBs, which have no or only weak dioxin-like properties, as risk factors for endometriosis. METHODS: In a case-control study of Group Health enrollees in western Washington State, 20 PCB congeners were measured in serum from surgically confirmed endometriosis cases that were newly diagnosed between 1996 and 2001 (n = 251) and from female controls matched for age and reference year (n = 538). RESULTS: Summed and estrogenic PCB concentrations were not associated with endometriosis risk [summed: odds ratio (OR) = 1.3; 95% confidence interval (CI), 0.8-2.2; estrogenic: OR = 1.1; 95% CI, 0.8-1.4]. Although several congener-specific ORs were statistically above or below the null (PCB 170: third quartile vs. lowest: OR = 0.5; 95% CI, 0.3-0.9; PCB 196: third quartile vs. lowest: OR = 0.4; 95% CI, 0.2-0.7; PCB 201: second vs. lowest: OR = 0.5; 95% CI, 0.3-0.8; third quartile vs. lowest: OR = 0.4; 95% CI, 0.2-0.7), there were no overall consistent patterns of endometriosis risk. CONCLUSIONS: Taken in context with other North American studies, our findings suggest that noncoplanar PCB concentrations consistent within the range of exposure currently observed in western Washington State do not contribute meaningfully to endometriosis risk. |
High-throughput sample preparation for the quantitation of acephate, methamidophos, omethoate, dimethoate, ethylenethiourea, and propylenethiourea in human urine using 96-well-plate automated extraction and high-performance liquid chromatography-tandem mass spectrometry
Jayatilaka NK , Montesano AM , Whitehead Jr RD , Schloth SJ , Needham LL , Barr DB . Arch Environ Contam Toxicol 2010 61 (1) 59-67 Acephate, methamidophos, o-methoate, and dimethoate are organophosphorus pesticides, and ethylenethiouria and propylenethiourea are two metabolites from the bisdithiocarbamate fungicide family. They are some of the most widely used pesticides and fungicides in agriculture both domestically and abroad. The existing high-performance liquid chromatography (HPLC)-tandem mass spectrometry (MS/MS) method for the measurement of these compounds in human urine was improved by using a 96-well plate format sample preparation; the use of HPLC-MS/MS was comparable with a concentration range of 0.125 to 50 ng/ml. Deuterium-labeled acephate, ethylenethiouria, and methamidophos were used as internal standards. The sample preparation procedure, in the 96-well format with a 0.8-ml urine sample size, uses lyophilization of samples, followed by extraction with dichloromethane. The analytes were chromatographed on a Zorbax SB-C3 (4.6 x 150 mm, 5.0-mum) column with gradient elution by using 0.1% formic acid in aqueous solution (solvent A) and 0.1% formic acid in methanol (solvent B) mobile phase at a flow rate of 1 ml/min. Quantitative analysis was performed by atmospheric pressure chemical ionization source in positive ion mode using multiple-reaction monitoring of the precursor-to-product ion pairs for the analytes on a TSQ Quantum Ultra HPLC-MS/MS. Repeated analyses of urine samples spiked with high (15 ng/ml), medium (5 ng/ml), and low (1 ng/ml) concentrations of the analytes gave relative SDs of <13%. The limits of detection were in the range of 0.004-0.01 ng/ml. The method also has high accuracy, high precision, and excellent extraction recovery. Furthermore, the improved sample preparation method decreased the cost and labor required while effectively doubling the analytic throughput with minimal matrix effect. |
Quantification of cyanuric acid residue in human urine using high performance liquid chromatography-tandem mass spectrometry
Panuwet P , Wade EL , Nguyen JV , Montesano MA , Needham LL , Barr DB . J Chromatogr B Analyt Technol Biomed Life Sci 2010 878 (28) 2916-22 Concern has increased about the resulting health effects of exposure to melamine and its metabolic contaminant, cyanuric acid, after infants in China were fed baby formula milk products contaminated with these compounds. We have developed a selective and sensitive analytical method to quantify the amount of cyanuric acid in human urine. The sample preparation involved extracting free-form cyanuric acid in human urine using anion exchange solid phase extraction. Cyanuric acid was separated from its urinary matrix components on the polymeric strong anion exchange analytical column; the analysis was performed by high performance liquid chromatography-tandem mass spectrometry using negative mode electrospray ionization interface. Quantification was performed using isotope dilution calibration covering the concentration range of 1.00-200ng/mL. The limit of detection was 0.60ng/mL and the relative standard deviations were 2.8-10.5% across the calibration range. The relative recovery of cyanuric acid was 100-104%. Our method is suitable to detect urinary concentrations of cyanuric acid caused by either environmental exposures or emerging poisoning events. |
Job demands and pesticide exposure among immigrant Latino farmworkers
Grzywacz JG , Quandt SA , Vallejos QM , Whalley LE , Chen H , Isom S , Barr DB , Arcury TA . J Occup Health Psychol 2010 15 (3) 252-66 The goal of this study was to understand the potential threat of job stressors to farmworker health. To accomplish this goal we studied pesticide exposure, an issue with immediate and long-term health consequences, and predictions from the Demands-Control model of occupational stress. Longitudinal, self-report data and urine samples were collected at monthly intervals from a cohort of Latino farmworkers (N = 287) during the 2007 agricultural season. The primary hypothesis was that greater exposure to psychological demands, physical exertion, and hazardous work conditions are associated with greater odds of detecting dialkylphosphate (DAP) urinary pesticide metabolites, biomarkers indicating exposure to pesticides. Contrary to this hypothesis, results indicated that none of the elements of the Demands-Control model were independently associated with detection of DAP urinary pesticide metabolites. However, analyses produced several interaction effects, including evidence that high levels of control may buffer the effects of physical job demands on detection of DAP urinary pesticide metabolites. |
Comparison of current-use pesticide and other toxicant urinary metabolite levels among pregnant women in the CHAMACOS Cohort and NHANES
Castorina R , Bradman A , Fenster L , Barr DB , Bravo R , Vedar MG , Harnly ME , McKone TE , Eisen EA , Eskenazi B . Environ Health Perspect 2010 118 (6) 856-63 BACKGROUND: We measured 34 metabolites of current-use pesticides and other precursor compounds in urine samples collected twice during pregnancy from 538 women living in the Salinas Valley of California, a highly agricultural area (1999-2001). Precursors of these metabolites included fungicides, carbamate, organochlorine, organophosphorus (OP), and pyrethroid insecticides, and triazine and chloroacetanilide herbicides. We also measured ethylenethiourea, a metabolite of the ethylene-bisdithiocarbamate fungicides. Repeat measurements of the compounds presented here have not been reported in pregnant women previously. To understand the impact of the women's regional environment on these findings, we compared metabolite concentrations from the CHAMACOS (Center for the Health Assessment of Mothers and Children of Salinas) cohort with U.S. national reference data for 342 pregnant women sampled by the National Health and Nutrition Examination Survey (1999-2002). RESULTS: The eight metabolites detected in > 50% of samples [2,4-dichlorophenol (2,4-DCP); 2,5-dichlorophenol (2,5-DCP); 1- and 2-naphthol; ortho-phenylphenol (ORTH); para-nitrophenol (PNP); 2,4,6-trichlorophenol (2,4,6-TCP); and 3,4,6-trichloro-2-pyridinol (TCPy)] may be related to home or agricultural pesticide use in the Salinas Valley, household products, and other sources of chlorinated phenols. More than 78% of women in this study had detectable levels of at least one of the OP pesticide-specific metabolites that we measured, and > 30% had two or more. The 95th percentile values of six of the most commonly detected (> 50%) compounds were significantly higher among the CHAMACOS women after controlling for age, race, socioeconomic status, and smoking [(2,4-DCP; 2,5-DCP; ORTH; PNP; 2,4,6-TCP; and TCPy); quantile regression p < 0.05]. CONCLUSIONS: Findings suggest that the CHAMACOS cohort has an additional burden of precursor pesticide exposure compared with the national sample, possibly from living and/or working in an agricultural area. EDITOR'S SUMMARY: Few studies have investigated maternal exposures during pregnancy to pesticides currently in use. Castorina et al. (p. 856) measured metabolites of current-use pesticides and other precursor compounds in urine samples collected twice during pregnancy from 538 California women enrolled in the Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS) cohort. Precursors of these metabolites included fungicides; carbamate, organochlorine, organophosphorus (OP), and pyrethroid insecticides; and triazine and chloroacetanilide herbicides. The authors also measured ethylenethiourea, a metabolite of the ethylene-bisdithiocarbamate fungicides. To understand the impact of the women's regional environment on these findings, they compared metabolite concentrations from the CHAMACOS cohort with U.S. national reference data for pregnant women sampled by the National Health and Nutrition Examination Survey (1999-2002). Eight metabolites detected in > 50% of samples may be related to home or agricultural pesticide use in the Salinas Valley, household products, and other sources of chlorinated phenols. Over 78% of women in this study had detectable levels of at least one of the OP pesticide-specific metabolites and > 30% had two or more. The 95th percentile values of five of the most commonly detected (> 50%) compounds were significantly higher among the CHAMACOS women than the NHANES sample after controlling for age, race, socioeconomic status, and smoking. The authors conclude that the CHAMACOS cohort has an additional burden of precursor pesticide exposure compared with the national sample, possibly from living and/or working in an agricultural area. |
Urinary concentrations of metabolites of pyrethroid insecticides in the general U.S. population: National Health and Nutrition Examination Survey 1999-2002
Barr DB , Olsson AO , Wong LY , Udunka S , Baker SE , Whitehead RD , Magsumbol MS , Williams BL , Needham LL . Environ Health Perspect 2010 118 (6) 742-8 BACKGROUND: Pyrethroid insecticides are the most commonly used residential insecticides in the United States. OBJECTIVES: Our objective was to assess human exposure via biomonitoring to pyrethroid insecticides in a representative sample of the general U.S. population ≥ 6 years of age. METHODS: By using isotope-dilution high-performance liquid chromatography/electrospray chemical ionization/tandem mass spectrometry, we measured five urinary metabolites of pyrethroid insecticides in 5,046 samples collected as a part of the 1999-2002 National Health and Nutrition Examination Survey (NHANES). Univariate, multivariate, and Pearson correlation analyses were performed using SUDAAN and SAS software, incorporating the appropriate sample weights into the analyses. Multivariate analyses included age, sex, race/ethnicity, creatinine, fasting status, and urine collection time as covariates. RESULTS: We detected 3-phenoxybenzoic acid (3PBA), a metabolite common to many pyrethroid insecticides, in more than 70% of the samples. The least-squares geometric mean (LSGM) concentration (corrected for covariates) of 3PBA and the frequency of detection increased from 1999-2000 (0.292 ng/mL) to 2001-2002 (0.318 ng/mL) but not significantly. Non-Hispanic blacks had significantly higher LSGM 3PBA concentrations than did non-Hispanic whites and Mexican Americans in the 2001-2002 survey period and in the combined 4-year survey periods but not in the 1999-2000 survey period. Children had significantly higher LSGM concentrations of 3PBA than did adolescents in both NHANES periods and than adults in NHANES 1999-2000. Cis- and trans-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid were highly correlated with each other and with 3PBA, suggesting that urinary 3PBA was derived primarily from exposure to permethrin, cypermethrin, or their degradates. CONCLUSIONS: Pyrethroid insecticide exposure in the U.S. population is widespread, and the presence of its metabolites in the urine of U.S. residents indicates that children may have higher exposures than adolescents and adults. EDITOR'S SUMMARY: Synthetic pyrethroid insecticides are being used with greater frequency in the United States to replace residential and some agricultural organophosphorus (OP) and carbamate insecticides. The pyrethroids are considered to be less toxic to humans than the OPs and carbamates, but like many other classes of insecticides, they are acute neurotoxicants. Barr et al. (p. 742) assessed human exposure to pyrethroid insecticides in a representative sample of the general U.S. population ≥ 6 years of age. 3-Phenoxybenzoic acid (3PBA), a metabolite common to many pyrethroid insecticides, was detected in > 70% of urine samples tested. Non-Hispanic blacks had significantly higher 3BPA concentrations than non-Hispanic whites and Mexican Americans, and children had significantly higher concentrations of 3PBA than adolescents and adults. Cis- and trans-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid were highly correlated with each other and with 3PBA, suggesting that urinary 3PBA was primarily derived from exposure to permethrin, cypermethrin, or their degradates. The authors conclude that pyrethroid insecticide exposure in the U.S. population is widespread and that children may have higher exposures than adolescents and adults. |
Current and historically used pesticides in residential soil from 11 homes in Atlanta, Georgia, USA
Riederer AM , Smith KD , Barr DB , Hayden SW , Hunter Jr RE , Ryan PB . Arch Environ Contam Toxicol 2010 58 (4) 908-17 We used a multiresidue, gas chromatography/mass spectrometry-based method to measure seven pyrethroid, five organophosphorus (OP), and six organochlorine pesticides in soil collected from 11 Atlanta homes in 2006. Our objective was to collect preliminary data for a larger study of pesticide exposures among Atlanta children. The pyrethroid insecticides (cis- and trans-permethrin, bioallethrin) were the most commonly detected analytes, giving evidence of widespread outdoor use among our study homes. Our pyrethroid insecticide detection frequencies were higher than those reported in a recent study of Ohio and North Carolina homes; however, our maximum values were approximately half of those reported. We detected the target OP pesticides in only a few samples, but we found two restricted-use OP pesticides--methyl parathion and terbufos--and thus possible evidence of illegal residential use or environmental persistence in soil. We also detected dichlorodiphenyltrichloroethane (DDT) and dichlorodiphenyldichloroethane (DDE) in samples from six homes. Although our small sample size limits comparison to other studies, our results provide evidence that residential soil is a potential source of human exposure to both current and historically used pesticides. |
Quantification of dialkylphosphate metabolites of organophosphorus insecticides in human urine using 96-well plate sample preparation and high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry
Odetokun MS , Montesano MA , Weerasekera G , Whitehead Jr RD , Needham LL , Barr DB . J Chromatogr B Analyt Technol Biomed Life Sci 2010 878 (27) 2567-74 Organophosphorus (OP) pesticides kill by disrupting a targeted pest's brain and nervous systems. But if humans and other animals are sufficiently exposed, OP pesticides can have the same effect on them. We developed a fast and accurate high-performance liquid chromatography-tandem mass spectrometry method for the quantitative measurement of the following six common dialkylphosphate (DAP) metabolites of organophosphorus insecticides: dimethylphosphate (DMP), dimethylthiophosphate (DMTP), dimethyldithiophosphate (DMDTP), diethylphosphate, (DEP), diethylthiophosphate (DETP), and diethyldithiophosphate (DEDTP). The general sample preparation included 96-well plate solid phase extraction using weak anion exchange cartridges. The analytical separation was performed by high-performance liquid chromatography with a HILIC column. Detection involved a triple quadrupole mass spectrometer with an ESI probe in negative ion mode using multiple reaction monitoring. Repeated analyses of urine samples spiked at 150, 90 and 32ng/mL with the analytes gave relative standard deviations of less than 22%. The extraction efficiency ranged from 40% to 98%. The limits of detection were in the range of 0.04-1.5ng/mL. The throughput is 1152 samples per week, effectively quadrupling our previous throughput. The method is safe, quick, and sensitive enough to be used in environmental and emergency biological monitoring of occupational and nonoccupational exposure to organophosphates. |
Predictors of 2,4-dichlorophenoxyacetic acid exposure among herbicide applicators
Bhatti P , Blair A , Bell EM , Rothman N , Lan Q , Barr DB , Needham LL , Portengen L , Figgs LW , Vermeulen R . J Expo Sci Environ Epidemiol 2010 20 (2) 160-8 To determine the major factors affecting the urinary levels of 2,4-dichlorophenoxyacetic acid (2,4-D) among county noxious weed applicators in Kansas, we used a regression technique that accounted for multiple days of exposure. We collected 136 12-h urine samples from 31 applicators during the course of two spraying seasons (April to August of 1994 and 1995). Using mixed-effects models, we constructed exposure models that related urinary 2,4-D measurements to weighted self-reported work activities from daily diaries collected over 5 to 7 days before the collection of the urine sample. Our primary weights were based on an earlier pharmacokinetic analysis of turf applicators; however, we examined a series of alternative weighting schemes to assess the impact of the specific weights and the number of days before urine sample collection that were considered. The derived models accounting for multiple days of exposure related to a single urine measurement seemed robust with regard to the exact weights, but less to the number of days considered; albeit the determinants from the primary model could be fitted with marginal losses of fit to the data from the other weighting schemes that considered a different numbers of days. In the primary model, the total time of all activities (spraying, mixing, other activities), spraying method, month of observation, application concentration, and wet gloves were significant determinants of urinary 2,4-D concentration and explained 16% of the between-worker variance and 23% of the within-worker variance of urinary 2,4-D levels. As a large proportion of the variance remained unexplained, further studies should be conducted to try to systematically assess other exposure determinants. |
Measurement of pyrethroid, organophosphorus, and carbamate insecticides in human plasma using isotope dilution gas chromatography-high resolution mass spectrometry
Perez JJ , Williams MK , Weerasekera G , Smith K , Whyatt RM , Needham LL , Barr DB . J Chromatogr B Analyt Technol Biomed Life Sci 2010 878 (27) 2554-62 We have developed a gas chromatography-high resolution mass spectrometry method for measuring pyrethroid, organophosphorus, carbamate and fipronil pesticides and the synergist piperonyl butoxide in human plasma. Plasma samples were extracted using solid phase extraction and were then concentrated for injection and analysis using isotope dilution gas chromatography-high resolution mass spectrometry. The limits of detection ranged from 10 to 158pg/mL with relative recoveries at concentrations near the LODs (e.g., 25 or 250pg/mL) ranging from 87% to 156% (9 of the 16 compounds were within +/-15% of 100%). The extraction recoveries ranged from 20% to 98% and the overall method relative standard deviations were typically less than 20% with some exceptions. Analytical characteristics were determined at 25, 250, and 1000pg/mL. |
An improved high-performance liquid chromatography-tandem mass spectrometric method to measure atrazine and its metabolites in human urine
Panuwet P , Restrepo PA , Magsumbol M , Jung KY , Montesano MA , Needham LL , Barr DB . J Chromatogr B Analyt Technol Biomed Life Sci 2010 878 957-62 We report an improved solid-phase extraction-high-performance liquid chromatography-tandem mass spectrometry method with isotope dilution quantification to measure seven atrazine metabolites in urine. The metabolites measured were hydroxyatrazine (HA), diaminochloroatrazine (DACT), desisopropylatrazine (DIA), desethylatrazine (DEA), desethylatrazine mercapturate (DEAM), atrazine mercapturate (ATZM), and atrazine (ATZ). Using offline mixed-mode reversed-phase/cation-exchange solid-phase extraction dramatically increased recovery and sensitivity by reducing the influence of matrix components during separation and analysis. DACT extraction recovery improved to greater than 80% while the other analytes had similar extraction efficiencies as previously observed. Limits of detection were lower than our previous method (0.05-0.19ng/mL) with relative standard deviations less than 10%. The total runtime was shorter (18min) than the previous on-line method, thus it is suitable for large-scale sample analyses. We increased the throughput of our method twofold by using the newer extraction technique. |
Biomonitoring data for 2,4-dichlorophenoxyacetic acid in the United States and Canada: interpretation in a public health risk assessment context using biomonitoring equivalents
Aylward LL , Morgan MK , Arbuckle TE , Barr DB , Burns CJ , Alexander BH , Hays SM . Environ Health Perspect 2010 118 (2) 177-81 Background: Several extensive studies of exposure to 2,4-dichlorophenoxyacetic acid (2,4-D) using urinary concentrations in samples from the general population, farm applicators, and farm family members are now available. Reference doses (RfDs) exist for 2,4-D, and Biomonitoring Equivalents (BEs; concentrations in urine or plasma that are consistent with those RfDs) for 2,4-D have recently been derived and published. Objective: We reviewed the available biomonitoring data for 2,4-D from the United States and Canada and compared them with BE values to draw conclusions regarding the margin of safety for 2,4-D exposures within each population group. Data sources: Data on urinary 2,4-D excretion in general and target populations from recent published studies are tabulated and the derivation of BE values for 2,4-D summarized. Data synthesis: The biomonitoring data indicate margins of safety (ratio of BE value to biomarker concentration) of approximately 200 at the central tendency and 50 at the extremes in the general population. Median exposures for applicators and their family members during periods of use appear to be well within acute exposure guidance values. Conclusions: Biomonitoring data from these studies indicate that current exposures to 2,4-D are below applicable exposure guidance values. This review demonstrates the value of biomonitoring data in assessing population exposures in the context of existing risk assessments using the BE approach. Risk managers can use this approach to integrate the available biomonitoring data into an overall assessment of current risk management practices for 2,4-D. Editor's Summary: Urinary concentrations of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) have been measured in general populations, farm applicators, and farm family members, but until recently it has not been possible to relate these biomonitoring data to reference dose (RfD) guidelines for acceptable levels of acute or chronic 2,4-D exposure. Aylward et al. (p. 177) compare published biomonitoring data with recently derived Biomonitoring Equivalents (BEs; urinary 2,4-D concentrations that correspond to RfDs) to determine whether population exposures appear consistent with current guidelines. The authors report that median urinary 2,4-D concentrations in general U.S. populations were approximately 200 times lower than the guideline value for chronic exposure. Median 2,4-D exposures reported for pesticide applicators and family members were 25 times lower than the guideline value for acute (occupational) exposure, although the highest urinary concentration reported was above the occupational BE. The authors conclude that findings support the value of the BE approach for assessing population risks based on biomonitoring data and suggest that current 2,4-D exposures are generally below reference values for acceptable exposure levels. |
Comparison of immunoassay and HPLC-MS/MS used to measure urinary metabolites of atrazine, metolachlor, and chlorpyrifos from farmers and non-farmers in Iowa
Curwin BD , Hein MJ , Barr DB , Striley C . J Expo Sci Environ Epidemiol 2010 20 (2) 205-12 Urine samples were collected from 51 participants in a study investigating pesticide exposure among farm families in Iowa. Aliquots from the samples were sent to two different labs and analyzed for metabolites of atrazine (atrazine mercapturate), metolachlor (metolachlor mercapturate) and chlorpyrifos (TCP) by two different analytical methods: immunoassay and high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS). HPLC-MS/MS methods tend to be highly specific, but are costly and time consuming. Immunoassay methods are cheaper and faster, but can be less sensitive due to cross reactivity and matrix effects. Three statistical methods were employed to compare the two analytical methods. Each statistical method differed in how the samples that had results below the limit of detection (LOD) were treated. The first two methods involved an imputation procedure and the third method used maximum likelihood estimation (MLE). A fourth statistical method that modeled each lab separately using MLE was used for comparison. The immunoassay and HPLC-MS/MS methods were moderately correlated (correlation 0.40-0.49), but the immunoassay methods consistently had significantly higher geometric mean (GM) estimates for each pesticide metabolite. The GM estimates for atrazine mercapturate, metolachlor mercapturate, and TCP by immunoassay ranged from 0.16-0.98 microg l(-1), 0.24-0.45 microg l(-1) and 14-14 microg l(-1), respectively and by HPLC-MS/MS ranged from 0.0015-0.0039 microg l(-1), 0.12-0.16 microg l(-1), and 2.9-3.0 microg l(-1), respectively. Immunoassays tend to be cheaper and faster than HPLC-MS/MS, however, they may result in an upward bias of urinary pesticide metabolite levels. |
Organophosphorus and pyrethroid insecticide urinary metabolite concentrations in young children living in a southeastern United States city
Naeher LP , Tulve NS , Egeghy PP , Barr DB , Adetona O , Fortmann RC , Needham LL , Bozeman E , Hilliard A , Sheldon LS . Sci Total Environ 2010 408 (5) 1145-53 Pesticide metabolites are routinely measured in the urine of children in the United States. Although the sources of these metabolites are believed to include residues in food from agricultural applications and residues from applications in everyday environments (e.g., homes), few studies have been able to demonstrate an association between indoor residential pesticide applications and pesticide metabolite concentrations. To better quantify the effects of potential risk factors related to demographics, household characteristics, occupation, and pesticide use practices on urinary biomarker levels, we performed a study in a city (Jacksonville, Florida) previously determined to have elevated rates of pesticide use. We enrolled a convenience sample of 203 children ranging in age from 4 to 6 years; their caregivers completed a questionnaire and the children provided a urine sample, which was analyzed for a series of organophosphorus and pyrethroid insecticide metabolites. The questionnaire responses substantiated much higher pesticide use for the study participants as compared to other studies. Urinary metabolite concentrations were approximately an order of magnitude higher than concentrations reported for young children in other studies. Few statistically significant differences (at the p<0.05 level) were observed, however, several trends are worth noting. In general, mean urinary pesticide metabolite concentrations were higher for males, Caucasians, and those children living in homes with an indoor pesticide application occurring within the past four weeks. Comparing the urinary pesticide metabolite concentrations in this study to those reported in the NHANES and GerES studies showed that the children living in Jacksonville had substantially higher pyrethroid pesticide exposures than the general populations of the United States and Germany. Further research is needed in communities where routine pesticide use has been documented to obtain information on the most important routes and pathways of exposure and to develop the most effective strategies for reducing pesticide exposures for children. |
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