Concentrations Of Organophosphate Metabolites Research Articles

The Association Between Urinary Concentrations of Organophosphate Metabolites and Asthma-Related Outcomes Among Schoolchildren From Informal Settlements.

Objectives: There is inconsistent evidence on the relationship between pesticide exposure and childhood respiratory outcomes in non-agricultural settings. This study investigated the association between organophosphate (OP) pesticide exposure and asthma-related outcomes in children residing in four informal settlements. Methods: The study was a longitudinal study of 590 schoolchildren, with a 12months follow-up period. A standardised questionnaire adopted from the International Study of Asthma and Allergies in Childhood was administered to caregivers for child's respiratory symptoms and household characteristics. Spirometry and fractional-exhaled nitric oxide, including a phadiatop test (atopy status) and urinary dialkyl phosphate (DAP) metabolites were measured at baseline and follow-up. DAP metabolites included diethylphosphate (DEP) and dimethyl phosphate (DMP) measured at baseline and follow-up and dimethylthiophosphate (DMTP) measured only at baseline. Results: The mean ages of schoolchildren were 9.9 ± 0.91years and the overal incidence proportions of new doctor diagnosed asthma was 2.2%. No consistent patterns of increased risk of asthma outcomes with increasing DAP concentrations was found in multivariate analysis. Conclusion: Future studies with longer follow-up periods and repeated OP biomonitoring are recommended.

Characterization of Urinary Pesticide Metabolite Concentrations of Pregnant Women in Suriname.

Prenatal exposure to pesticides and the association with adverse health outcomes have been examined in several studies. However, the characterization of pesticide exposure among Surinamese women during pregnancy has not been assessed. As part of the Caribbean Consortium of Research in Environmental and Occupational Health research program, 214 urine samples were collected from pregnant women living in three regions in Suriname with different agricultural practices: capital Paramaribo, the rice producing district Nickerie, and the tropical rainforest, the Interior. We used isotope dilution tandem mass spectrometry to quantify urinary concentrations of biomarkers of three pesticide classes, including phenoxy acid herbicides and organophosphate and pyrethroid insecticides, all of which are commonly used in agricultural and residential settings in Suriname. We observed that participants residing in Nickerie had the highest urinary metabolite concentrations of 2,4-dichlorophenoxyacetic acid and pyrethroids compared to those from Paramaribo or the Interior. Paramaribo had the highest concentrations of organophosphate metabolites, specifically dialkyl phosphate metabolites. Para-nitrophenol was detected in samples from Paramaribo and the Interior. Samples from Nickerie had higher median urinary pesticide concentrations of 2,4-dichlorophenoxyacetic acid (1.06 μg/L), and the following metabolites, 3,5,6-trichloro-2-pyridinol (1.26 μg/L), 2-isopropyl-4-methyl-6-hydroxypyrimidine (0.60 μg/L), and 3-phenoxybenzoic acid (1.34 μg/L), possibly due to residential use and heavy rice production.

The association between urinary concentrations of organophosphate metabolites and asthma-related outcomes at 12-month follow-up among children from informal settlements in Western Cape, South Africa

BACKGROUND AND AIM: There is limited evidence on the relationship between pesticide exposure and child respiratory outcomes in non-agricultural settings. This study investigated the association between organophosphate pesticide (OP) exposure and child asthma-related outcomes among children from four informal settlements. METHODS: This study was a longitudinal study of 590 schoolchildren, with a 12-month follow-up period. A standardised questionnaire adopted from the International Study of Asthma and Allergies in Childhood (ISAAC) was administered to caregivers on child’s respiratory symptoms and household characteristics. Spirometry and fractional-exhaled nitric oxide (FeNO), including a phadiatop test (atopy status) and urinary concentrations of dialkyl phosphate (DAP) metabolites diethylphosphate (DEP), dimethylthiophosphate (DMTP)] were measured at baseline and follow-up. Dimethylphosphate (DMP) was measured only at baseline. RESULTS: The mean age of schoolchildren were 9.9 ± 0.91 years and median sum DAP was 32.9 ng/ml (18.4 – 52.9 ng/ml) at baseline. Incidence proportions of new asthma outcome cases at 12-months were 2.2 % doctor diagnosed asthma, 17.8 % asthma-symptom score ≥ 2, 14.5 % forced expiratory volume 1< lower limit of normal, and 5.9 % airway inflammation across all areas. In the linear mixed and fixed effect model, no consistent patterns of increased risk of new asthma-associated outcomes at the 12-month was found. However, there was a significant increase in airway inflammation (β:2.99 (95% CI: 0.48 - 5.50) in the 3rd DEP quintile (1.9 – 3.0 ng/mL) compared to the reference quintile (1.10 ng/ml). CONCLUSION: DAP concentrations were higher than those of children in other settings. However, the study did not find consistent associations between urinary concentrations of DAP metabolites and asthma related outcomes over a 12-month follow-up period among schoolchildren. Future studies with a longer follow-up period and repeated OP pesticide biomonitoring are recommended. KEYWORDS: Pesticides, organophosphates, asthma, children, informal settlements, dialkyl phosphates, South Africa

Urinary organophosphate metabolite concentrations and birth sizes among women conceiving through in vitro fertilization in Shanghai, China

BackgroundFew studies have examined the adverse birth sizes of preconception exposure to organophosphate pesticides (OPs) in women undergoing in vitro fertilization (IVF). ObjectivesWe investigated the relationship of preconception OP exposure with birth sizes among Chinese women undergoing IVF. MethodsThis study included 302 couples seeking infertility treatment in the China National Birth Cohort Study, from Shanghai, China, who gave birth to singleton infants between 2018 and 2021. Clinical data were collected from medical records. We measured the concentrations of six nonspecific dialkyl phosphates (DAP) metabolites of OPs [diethylthiophosphate (DETP), diethylphosphate (DEP), diethyldithiophosphate (DEDTP), dimethyldithiophosphate (DMTP), dimethylphosphate (DMP), and dimethyldithiophosphate (DMDTP)] in maternal urine. DMDTP and DEDTP were precluded from further analyses due to the low detection rates. Generalized linear models (GLMs) and weighted quantile sum (WQS) regression analyses were performed to examine the individual and joint effects of OP exposures on gestational age, birth weight, body length, and ponderal index. Odder ratio (OR) of preterm birth were estimated using logistic regression models. ResultsWomen in the highest as compared with lowest quartile of DEP had shorter gestational age (β = - 0.68; 95% CI = −1.24, −0.11). The association was modified by sex, with boys showing larger decreases in gestational age (β = - 0.86; 95% CI = −1.60, −0.13). No associations were found between other DAP metabolites and birth sizes. Results from linear models with individual DAP metabolites were corroborated by the WQS regression where DEP had the largest contribution to the overall mixture effect on gestational age (weight = 0.70). Moreover, DEP concentration was associated with an elevated risk of preterm birth (OR = 1.35, 95% CI = 1.11, 2.25). ConclusionPreconception DEP concentration was associated with shortened gestational age and increased risk of preterm birth, and the association was more pronounced among boys than girls.

Urinary Organophosphate Metabolite Concentrations and Pregnancy Outcomes among Women Conceiving through in Vitro Fertilization in Shanghai, China.

Background:Animal studies suggest that pesticide exposure elicits endocrine changes, increases embryo implantation failure, and decreases litter size. However, only a few epidemiological studies have evaluated the effects of pesticides on the outcomes of in vitro fertilization (IVF) pregnancies.Objectives:This study examined the associations between preconception organophosphate pesticides (OP) exposure and pregnancy outcomes among women undergoing IVF in a Chinese population.Methods:This study included 522 women with infertility who underwent IVF. Women were recruited from a prospective study, the China National Birth Cohort (CNBC), from Shanghai, China, between July 2017 and December 2018. Demographic and clinical information were collected from medical records and through questionnaires. Preconception exposure to OP was assessed by measuring six nonspecific dialkylphosphate (DAP) metabolites [diethylthiophosphate (DETP), diethylphosphate (DEP), diethyldithiophosphate (DEDTP), dimethylthiophosphate (DMTP), dimethylphosphate (DMP), dimethyldithiophosphate (DMDTP)] in urine samples collected at recruitment. Generalized estimating equation (GEE) models were used to evaluate the associations between OP and pregnancy outcomes.Results:Compared with women in the lowest quartile () of individual DEP and (the sum of DMP, DMTP, DEP, and DETP), women in the highest quartile () had lower odds of successful implantation, clinical pregnancy, and live birth, and most of the negative trends were significant (). There were no significant associations between urinary DAP concentrations and early IVF outcomes, including total and mature oocyte counts, best embryo quality, fertilization, trigger levels, and endometrial wall thickness.Conclusion:Preconception OP exposure was inversely associated with successful implantation, clinical pregnancy, and live birth in women who underwent IVF. https://doi.org/10.1289/EHP7076

Organophosphate metabolite concentrations in maternal urine during pregnancy

The burden of organophosphate (OP) pesticides in pregnant women from Tarragona (n = 157), a Mediterranean area of intense agricultural activity, has been assessed from the study of hydroxylated organic metabolites in urine samples in the three trimesters of pregnancy. 2-Diethylamino-6-methylpyrimidin-4-ol (DEAMPY), a metabolite of pirimiphos, was the compound found in higher concentration, medians 0.66–2.8 μg/g creatinine. 4-Nitrophenol (PNP), a metabolite of parathion, medians 0.24–0.41 μg/g creatinine, was the second most abundant compound. 2-Isopropyl-6-methyl-4-pyrimidol (IMPY), a metabolite of diazinon, was also present but in lower concentrations. Except for DEAMPY, the concentrations found in this cohort were lower than those reported in studies from other countries.Intraclass correlation coefficients (ICCs) were calculated for the compounds found in more than the 35% of the samples, the reliability between trimesters was poor (<0.40) to fair (0.40–0.60). Statistically significant differences were observed for the creatinine adjusted concentrations of the most abundant OP metabolites in these trimesters when examined with the Wilcoxon signed rank test for paired data.In general, no association was found between urinary OP metabolites and most demographic and lifestyle predictors. However, a positive significant association was observed for women with vegetarian diet and for women of higher economic status and eventual consumption of organic food which showed higher PNP concentrations. These results suggest that higher fruit and vegetable consumption may involve higher OP pesticide ingestion but the overall association was weak.

Prenatal exposure to organophosphate pesticides and risk of autism spectrum disorders and other non-typical development at 3 years in a high-risk cohort.

Organophosphates are widely used pesticides that have been shown to affect child neurodevelopment. Previous studies that explored their potential effects on Autism Spectrum Disorder (ASD) relied either on proxies of external exposure or on questionnaires completed by the parents to identify autism-like behaviors but did not provide a clinical diagnosis of ASD. We studied the associations between prenatal biologic markers for exposure to organophosphate pesticides and the risk of having a child with ASD or other developmental concerns (ODC). We analyzed 203 mother-child pairs of the ongoing MARBLES (Markers of Autism Risk in Babies - Learning Early Signs) mother-child cohort, which enrolls mothers who are either pregnant or planning a pregnancy and whose expected child has an elevated risk to develop ASD. Seven metabolites of organophosphate pesticides were assessed in repeated urine samples collected during pregnancy. At 36 months, children were assessed with intruments measuring cognitive function and adaptive behaviors, and with two gold-standard diagnostic instruments for ASD: the Autism Diagnostic Observation Schedule and the Autism Diagnostic Interview-Revised. Children were classified in one of the following groups: ASD (n = 46), ODC (n = 55) and typically developing (TD, n = 102). After adjustment for potential confounders, organophosphate metabolite concentrations were not associated with an increased risk of ASD or ODC when boys and girls were studied together. After stratification by sex, dimethylthiophosphate (DMTP) pregnancy concentration tended to be associated with an increased ASD risk among girls (OR for a doubling in the DMTP concentration: 1.64 (95%CI, 0.95; 2.82)) but not among boys (OR: 0.84, 95%CI: 0.63; 1.11). This is the first study of clinically confirmed diagnoses of ASD that utilized repeated measurements of organophosphate metabolites during pregnancy to explore the associations between these pesticides and ASD risk in children. The association we observed among girls, as well as the lack of association in boys, need to be replicated in further studies with similar design and larger sample size. In light of the higher baseline risk for ASD in this cohort, generalizability to children lacking a first degree relative affected by ASD is unknown.

Behavioural disorders in 6-year-old children and pyrethroid insecticide exposure: the PELAGIE mother–child cohort

ObjectiveThe potential impact of environmental exposure to pyrethroid insecticides on child neurodevelopment has only just started to receive attention despite their widespread use. We investigated the associations between prenatal and...

Effects of Paraoxonase 1 gene polymorphisms on organophosphate insecticide metabolism in Japanese pest control workers.

Paraoxonase 1 (PON1) in serum detoxifies organophosphate (OP) insecticides by hydrolysis. The present cross-sectional study aimed to clarify the relationship between PON1 single nucleotide polymorphisms (SNPs) and enzyme activities or OP metabolite concentrations in urine of workers occupationally exposed to low-level OPs. Among 283 workers in 10 pest control companies located in central Japan who underwent checkups, 230 subjects (male 199, female 31, average age 38.9 ± 11.1 years old) participated in the study. Q192R and L55M polymorphisms were determined by TaqMan assay. PON1 activity was measured using fenitrothion (FNT) oxon, chlorpyrifos-methyl (CPM) oxon, chlorpyrifos (CP) oxon, and phenyl acetate as substrates. Urinary OP metabolite concentrations were measured with gas chromatography-mass spectrometry. The maximum differences in enzyme activities between individuals were 64.6-, 6.3-, 7.7-, and 2.0-fold for FNT oxonase, CPM oxonase, CP oxonase, and arylesterase (ARE), respectively. The activities of CPM oxonase and ARE in workers having the RR genotype were 53.5% and 18.2% lower than in those with the QQ genotype, respectively. CP oxonase activity was 15.0% lower in those having the M allele (LM + MM compared with LL). Urinary metabolite concentrations were not associated with PON1 polymorphisms, but negative associations were observed between the concentrations and activities of FNT oxonase and ARE. While PON1 SNPs can explain differences in catalytic activities toward some OPs, differences in urinary concentrations of OP metabolites are not attributable to PON1 SNPs but instead are attributable to its serum activities. Its serum activities might be more sensitive biomarkers for estimation of individual susceptibility to OP toxicities.

Pyrethroid insecticide exposure and cognitive developmental disabilities in children: The PELAGIE mother–child cohort

Pyrethroid insecticides are widely used in agriculture and in homes. Despite the neurotoxicity of these insecticides at high doses, few studies have examined whether lower-level exposures could adversely affect children's neurodevelopment.The PELAGIE cohort included 3421 pregnant women from Brittany, France between 2002 and 2006. When their children reached their sixth birthday, 428 mothers from the cohort were randomly selected, successfully contacted and found eligible. A total of 287 (67%) mothers agreed to participate with their children in the neuropsychological follow-up. Two cognitive domains were assessed by the Wechsler Intelligence Scale for Children: verbal comprehension and working memory. Five pyrethroid and two organophosphate insecticide metabolites were measured in maternal and child first-void urine samples collected between 6 and 19 gestational weeks and at 6years of age, respectively. Linear regression models were used to estimate associations between cognitive scores and urinary pyrethroid metabolite concentrations, adjusting for organophosphate metabolite concentrations and potential confounders.Maternal prenatal pyrethroid metabolite concentrations were not consistently associated with any children's cognitive scores. By contrast, childhood 3-PBA and cis-DBCA concentrations were both negatively associated with verbal comprehension scores (P-trend=0.04 and P-trend<0.01, respectively) and with working memory scores (P-trend=0.05 and P-trend<0.01, respectively). No associations were observed for the three other childhood pyrethroid metabolite concentrations (4-F-3-PBA, cis-DCCA, and trans-DCCA).Low-level childhood exposures to deltamethrin (as cis-DBCA is its principal and selective metabolite), in particular, and to pyrethroid insecticides, in general (as reflected in levels of the 3-PBA metabolite) may negatively affect neurocognitive development by 6years of age. Whatever their etiology, these cognitive deficits may be of importance educationally, because cognitive impairments in children interfere with learning and social development. Potential causes that can be prevented are of paramount public health importance.

Association between urinary biomarkers of exposure to organophosphate insecticides and serum reproductive hormones in men from NHANES 1999-2002.

Exposure to organophosphate (OP) insecticides may alter reproductive hormone levels in men and increase the risk for poor reductive health and other adverse health outcomes. However, relevant epidemiology studies in men are limited. We evaluated urinary concentrations of OP metabolites (3,5,6-trichloro-2-pyridinol and six dialkyl phosphates) in relation to serum concentrations of testosterone (T) and estradiol among 356 men aged 20-55 years old from the U.S. National Health and Nutrition Examination Survey. Biomarkers were detected in greater than 50% of the samples, except for diethyldithiophosphate, dimethylphosphate, and dimethyldithiophosphate. In adjusted regression models, we observed a statistically significant inverse relationship between diethyl phosphate (DEP) and T when DEP was modeled as either a continuous or categorical variable. These findings add to the limited evidence that exposure to certain OP insecticides is linked to altered T in men, which may have important implications for male health.

The Influence of Urinary Concentrations of Organophosphate Metabolites on the Relationship between BMI and Cardiometabolic Health Risk.

The objective was to determine whether detectable levels of OP metabolites influence the relationship between BMI and cardiometabolic health. This cross-sectional study was conducted using 2227 adults from the 1999–2008 NHANES datasets. Urinary concentrations of six dialkyl phosphate metabolites were dichotomized to above and below the detection limit. Weighted multiple regression analysis was performed adjusting for confounding variables. Independent of BMI, individuals with detectable metabolites had higher diastolic blood pressure (for dimethylphosphate, diethylphosphate, and diethyldithiophosphate; P < 0.05), lower HDL (for diethyldithiophosphate; P = 0.02), and higher triglyceride (for dimethyldithiophosphate; P = 0.05) than those below detection. Contrarily, those with detectable dimethylthiophosphate had better LDL, HDL, and total cholesterol, independent of BMI. Individuals at a higher BMI range who had detectable diethylphosphate (interaction: P = 0.03) and diethylthiophosphate (interaction: P = 0.02) exhibited lower HDL, while little difference existed between OP metabolite detection statuses at lower BMIs. Similarly, individuals with high BMIs and detectable diethylphosphate had higher triglyceride than those without detectable levels, while minimal differences between diethylphosphate detection statuses were observed at lower BMIs (interaction: P = 0.02). Thus, cardiometabolic health outcome differs depending on the specific OP metabolite being examined, with higher BMIs amplifying health risk.

Simultaneous analysis of phthalate and organophosphate triesters’ metabolites in urine -Exposure assessment to plastisizer and flame retardants and their risk o

Background: We have reported the method to simultaneous analysis of eight metabolites of five phthalates in urine in ISES2012. ?We have established simultaneous analysis of three metabolites of organophosphate triesters in addition to phthalate metabolites. Methods: Target metabolites were eight phthalate metabolites (MEHP, 5oxo-MEHP, 5cx-MEPP, 2cx-MMHP, MnBP, MBzP, MiBP, and MCPP) and three organophosphate triesters (BEHP metabolite of TEHP,DBP of TBP,and DPhP of TPhP). Sample preparation consists of 1. deconjucation with an enzyme; ?-glucuronidase/arylsulfatase, 2. extraction with ethyl acetate, 3. dried by evaporation, 4. derivatization with N-Methyl-N-tert-Butyldimethylsilytrifluoroacetamide (MTBSTFA), and 5. GS/MS(SIM) analysis. A calibration curve was prepared by the simplified method of standard addition, that six different concentrations of standard solutions were spiked in urine (from 0 to 1.0?g/mL). Organophosphate trimesters were administered to mice and three main metabolites were examined. Results: Good linear correlations were obtained for eleven metabolites, and LOQs calculated as 10SD of five repeated measurement of standard solution in urine (0.01?g/mL) were between 0.006 to 0.053?g/mL. After deconjucation with an enzyme, concentration of phthalate metabolites were approximately 1.3 times higher than when deconjucation was not performed. On the other hand, concentrations of organophosphate metabolites were same levels at both with and without enzyme treatment.DBP was detected from urine samples of mice administered TBP, as well as DPhP from TPhP administered mice. However, BEHP was not detected from TEHP administered mice urine. Conclusion: Derivatization with MTBSTFA improves analytical sensitivity of simultaneous analysis. This research was supported by Environment Research and Technology Development Fund (C-1151) of the Ministry of the environment, Japan.

Urinary metabolites of organophosphate and pyrethroid pesticides and behavioral problems in children from the general Canadian population

Background: Exposure to organophosphate insecticides has been associated with neurobehavioral deficits in children, although data on low levels of exposure experienced by the general population is sparse. Pyrethroids are another class of insecticides rapidly gaining popularity, and epidemiological evidence on their potential effects are lacking. Aims: Our goal was to examine the association of organophosphate and pyrethroid insecticides exposure with behavioral problems in Canadian children aged 6 to 11 years. Methods: We used data on 1081 children ages 6 to 11 years from the Canadian Health Measures Survey (2007-2009). We performed logistic regression to examine odds of behavioral problems, indicated by high scores on the Strengths and Difficulties Questionnaire, in relation with pyrethroid and organophosphate insecticides metabolites in urine, adjusting for covariates, and accounting for the sampling design. Results: Urinary concentrations of organophosphate metabolites were not significantly associated with behavioral problems. Higher concentration of the pyrethroid metabolite cis-DCCA was associated with behavioral problems (p=0.03), and there was a trend for trans-DCCA (p=0.12). For a 10-fold increase in cis-DCCA and trans-DCCA concentrations, the odds ratios (ORs) were 2.0 (CI95%, 1.1 to 3.6) and 1.6 (CI95%, 0.9 to 3.0), respectively. Another metabolite common to many pyrethroids, 3-PBA, was associated with conduct disorders among girls (OR, 2.2 [CI95% 1.0, 4.9]) but not boys (OR, 0.6 [CI95%, 0.3, 1.4]), although this association did not remain significant after accounting for the complex design (p=0.10). Conclusion: We did not observe the previously reported association between organophosphate insecticides and behavioral problems in children. However, our findings suggest that pyrethroids were associated with these problems. This is the first study to suggest this, and further research is needed on potential risks of exposure to pyrethroid insecticides for children’s development.

PESTICIDES EXPOSURE AND THE RISK OF CHILDHOOD ACUTE LEUKEMIA

Background and Aims: Acute leukemia (AL) is one of the most common malignant tumors among children below the age of 15, and pesticide has been hypothesized as one of the risk factors for AL. In this study, the association between pesticide exposure and the risk of childhood AL is evaluated. Methods: A total of 248 patients with newly diagnosed AL were recruited from four pediatric hospitals in Shanghai between January 1, 2006 and December 31, 2010, and 111 controls were matched with the cases based on gender and age. Pesticide exposure was determined by questionnaire and by measuring of organophosphate pesticide (OP) metabolites including Diethyl phosphrate (DEP), Dimethyl phophrate (DMP), Dimethyl thiophosphrate (DMTP), Diethyl thiophosphrate (DETP) and Diethyl dithiophosphrate (DEDTP) in the subjects’ urine using gas chromatography with a flame photometric detector. Results: Total environmental chemical exposure of children [odds ratio (OR)= 9.320, 95% confidence interval (CI):2.842-30.568], maternal chemical exposure during pre-gestation and pregnancy (OR=3.333; 95%CI:1.524-7.289), household use of pesticides (OR=1.786; 95%CI:1.128-2.830), and household use of mosquito insecticides (OR=2.225; 95%CI:1.304-3.796) increased the risk of childhood AL. Median concentrations of organophosphate metabolites (DEP, DMP, DMTP, DETP and DEDTP) in the cases (5.7296, 9.6673, 14.0634, 4.3642, 3.8472µg/gCr respectively) were significantly higher than those in the controls (1.6901, 1.6828, 0.8451, 0.7221, 0.7221µg/gCr respectively) (P&lt;0.05). Conclusions: This study found that chemical exposure and household use of pesticides, especially mosquito insecticides, might be associated with childhood AL, based on higher urine OPs levels in children with AL compared with those in the controls. Our findings add some evidence to the hypothesis that pesticides might be a risk factor for childhood AL. This association of AL risk with pesticide exposure merits further studies to confirm the association.

Temporal Variability in Diet and Urinary Concentrations of Pyrethroid and Organophosphate Pesticide Metabolites in Adult Volunteers From a Large U.S. City

P-354 Introduction: We are investigating the validity of using urinary biomarkers to estimate dietary exposures to pyrethroid and organophosphate pesticides in a pilot sample of adult volunteers (n = 11) from a large urban area of the United States. This information is needed to help determine the most accurate way of measuring exposures to non-persistent pesticides among the general adult population. Methods: We collected four consecutive days of duplicate diet samples and 10 spot urine samples from each subject. First morning void and before bedtime spot urine samples were collected on each day of diet sampling. Additional spot urines were collected the night before the first day of diet sampling and the morning after the last day of diet sampling. Detailed diet information including food description, organic status, preparation details (e.g. raw vs. cooked, peeled vs. unpeeled, etc.) and weight (in grams) was collected for each item consumed over the four-day sampling period. The four-day protocol was repeated twice for each subject, once in summer (July–October 2005) and once in winter (January–March 2006), to examine seasonal differences. Urine samples are currently being analyzed for selected pyrethroid and organophosphate metabolites while method development is underway for quantifying parent pesticide residues in the duplicate diet samples. Results: We present findings on intra- and inter-subject variability in urinary metabolite concentrations across the four-day sampling period, and across the summer and winter sampling cycles. We also present results of multivariate longitudinal regression analyses to determine which food items are most significantly associated with urinary metabolite concentrations among subjects in our pilot sample. Discussion/conclusions: This is the first study we know of to date to measure food intake and urinary pyrethroid and organophosphate metabolites in a multi-day longitudinal sample of non-occupationally exposed adults. For food intakes showing no association, alternative strategies for measuring dietary exposure to non-persistent pesticides must be considered. For those displaying significant association, urinary levels offer a valid tool for estimating dietary exposures among similar adult populations. This study will also provide important reference data on short-term temporal variability in urinary pyrethroid and organophosphate metabolite concentrations among U.S. adults.

Agricultural task and exposure to organophosphate pesticides among farmworkers.

Little is known about pesticide exposure among farmworkers, and even less is known about the exposure associated with performing specific farm tasks. Using a random sample of 213 farmworkers in 24 communities and labor camps in eastern Washington State, we examined the association between occupational task and organophosphate (OP) pesticide residues in dust and OP metabolite concentrations in urine samples of adult farmworkers and their children. The data are from a larger study that sought to test a culturally appropriate intervention to break the take-home pathway of pesticide exposure. Commonly reported farm tasks were harvesting or picking (79.2%), thinning (64.2%), loading plants or produce (42.2%), planting or transplanting (37.6%), and pruning (37.2%). Mixing, loading, or applying pesticide formulations was reported by 20% of our sample. Workers who thinned were more likely than those who did not to have detectable levels of azinphos-methyl in their house dust (92.1% vs. 72.7%; p = 0.001) and vehicle dust (92.6% vs. 76.5%; p = 0.002). Thinning was associated with higher urinary pesticide metabolite concentrations in children (91.9% detectable vs. 81.3%; p = 0.02) but not in adults. Contrary to expectation, workers who reported mixing, loading, or applying pesticide formulations had lower detectable levels of pesticide residues in their house or vehicle dust, compared with those who did not perform these job tasks, though the differences were not significant. Future research should evaluate workplace protective practices of fieldworkers and the adequacy of reentry intervals for pesticides used during thinning.

A pilot study of global positioning system/geographical information system measurement of residential proximity to agricultural fields and urinary organophosphate metabolite concentrations in toddlers.

This pilot study enrolled 20 children between the ages of 11 and 17 months in Imperial County, California to assess children's pesticide exposure and residential proximity to agricultural fields. We compared parental self-report of residential proximity to agricultural fields to measurements using global positioning system/geographical information system (GPS/GIS) technology, and we assessed the relationship between residential proximity to agricultural fields and a biomarker of organophosphate (OP) pesticide exposure. Questionnaires were administered twice, 4 weeks apart, to determine self-reported residential proximity to agricultural fields. Urine samples were collected at each contact to measure OP metabolites. Actual residential proximity to the closest agricultural field and number of fields was within 1 mile to the west were measured using GPS/GIS. Self-report of living proximity to agricultural fields agreed with GPS/GIS measurement 75% of the time during the initial interview, compared to 66% agreement during the second interview. Presence of urinary metabolites suggests that OP exposure was ubiquitous: creatinine-adjusted total urinary dimethyl values ranged from 1.60 to 516.00 microg/g creatinine, and total diethyl ranged from 2.70 to 134.84 microg/g creatinine. No association was found between urinary OP metabolites and residential to field proximity. These results suggest that initial self-report of living proximity to agricultural fields may be more accurate than follow-up self-report. Limitations in this pilot study prevent determination of whether self-report is an accurate measure of proximity.