Potential biomarkers for monitoring the toxicity of long-term exposure to atrazine in rat by metabonomic analysis.

1. Herbicide atrazine (ATR) poses harmful effects on human health. The purpose of this study is to study potential biomarkers used for monitoring the toxic effects after chronic exposure to ATR by studying urine metabolites. 2. Rats were assigned into clinical chemistry and metabonomics arms, and each arm was divided into low-dose, high-dose and control groups. ATR was administered to rats along with their feed. At the end of 16, 20 and 24 weeks, clinical parameters and histopathologic changes was assessed to monitor the toxic effects. Twenty-four hour urine samples was analyzed by UPLC-MS, to find the significant alterations in metabolic profiling. 3. The body weight of rats in ATR group was lower than that of control starting from 12th week; abnormal levels of serum biochemistry and histopathologic alterations of organs were found initially from 16th and 20th week, respectively. Five exogenous and five endogenous metabolites were found which showed significant differences between ATR groups and control group at above-mentioned time points. 4. These metabolites may be used as potential indicators to monitor ATR toxicity, and also may provide some clues for understanding the mechanism of toxicity of ATR. The exact relationship between endogenous metabolites and ATR toxicity needs further investigation.

In utero exposure to atrazine analytes and early menarche in the Avon Longitudinal Study of Parents and Children Cohort.

BACKGROUND: Evidence from experimental studies suggests that atrazine and its analytes alter the timing of puberty in laboratory animals. Such associations have not been investigated in humans. OBJECTIVE: To determine the association between in utero exposure to atrazine analytes and earlier menarche attainment in a nested case-control study of the population-based Avon Longitudinal Study of Parents and Children. METHODS: Cases were girls who reported menarche before 11.5 years while controls were girls who reported menarche at or after 11.5 years. Seven atrazine analyte concentrations were measured in maternal gestational urine samples (sample gestation week median (IQR): 12 (8-17)) during the period 1991-1992, for 174 cases and 195 controls using high performance liquid chromatography-tandem mass spectrometry. We evaluated the study association using multivariate logistic regression, adjusting for potential confounders. We used multiple imputation to impute missing confounder data for 29% of the study participants. RESULTS: Diaminochlorotriazine (DACT) was the most frequently detected analyte (58%>limit of detection [LOD]) followed by desethyl atrazine (6%), desethyl atrazine mercapturate (3%), atrazine mercapturate (1%), hydroxyl atrazine (1%), atrazine (1%) and desisopropyl atrazine (0.5%). Because of low detection of other analytes, only DACT was included in the exposure-outcome analyses. The adjusted odds of early menarche for girls with DACT exposures≥median was 1.13 (95% Confidence Interval [95% CI]:0.82, 1.55) and exposure

PBPK Model for Atrazine and Its Chlorotriazine Metabolites in Rat and Human.

The previously-published physiologically based pharmacokinetic model for atrazine (ATZ), deisopropylatrazine (DIA), deethylatrazine (DEA), and diaminochlorotriazine (DACT), which collectively comprise the total chlorotriazines (TCT) as represented in this study, was modified to allow for scaling to humans. Changes included replacing the fixed dose-dependent oral uptake rates with a method that represented delayed absorption observed in rats administered ATZ as a bolus dose suspended in a methylcellulose vehicle. Rate constants for metabolism of ATZ to DIA and DEA, followed by metabolism of DIA and DEA to DACT were predicted using a compartmental model describing the metabolism of the chlorotriazines by rat and human hepatocytesin vitro Overall, the model successfully predicted both the 4-day plasma time-course data in rats administered ATZ by bolus dose (3, 10, and 50 mg/kg/day) or in the diet (30, 100, or 500 ppm). Simulated continuous daily exposure of a 55-kg adult female to ATZ at a dose of 1.0 µg/kg/day resulted in steady-state urinary concentrations of 0.6, 1.4, 2.5, and 6.0 µg/L for DEA, DIA, DACT, and TCT, respectively. The TCT (ATZ + DEA + DIA + DACT) human urinary biomonitoring equivalent concentration following continuous exposure to ATZ at the chronic point of departure (POD = 1.8 mg/kg/day) was 360.6 µg/L.

Multiresidue analysis of pesticides in urine of healthy adult companion dogs.

The objective of this study was to determine the background exposures to pesticides as detected in urine from 21 healthy companion dogs in Northern Colorado. A panel of 301 pesticides was used to screen urine samples collected from dogs using an established ultraperformance liquid chromatography-mass spectrometry (UPLC-MS/MS) platform. Canine food intakes were controlled for one month on diets that were also screened for pesticide contents. Fifteen distinct pesticides were detected in urine. The most frequently detected compounds in canine urine samples collected over a 1 month period were atrazine, fuberidazole, imidacloprid, terbumeton, and clopyralid. Fuberidazole was the only pesticide detected in both the diets and urine. Companion dogs develop many similar chronic diseases as humans and represent a relevant model for biomonitoring combinations of environmental pesticide exposures, as well as for evaluating the potential relationships between environmental exposures and disease risk.

Environmental determinants of the urinary concentrations of herbicides during pregnancy: the PELAGIE mother-child cohort (France).

Herbicides are generally the most extensively used of the pesticides applied to agricultural crops. However, the literature contains little evidence useful in assessing the potential sources of the general population's exposure to herbicides, including by residential proximity to crops. The objective of this study was to take advantage of data from the PELAGIE mother-child cohort to identify the main determinants of the body burden of exposure to the chloroacetanilide and triazine herbicides commonly used on corn crops in Brittany, France, before 2006. Urine samples from a randomly selected subcohort of women in the first trimester of pregnancy (n=579) were assayed for herbicide metabolites. The residential exposure resulting from proximity to corn crops was assessed with satellite-image-based scores combined with meteorological data. Data on diet, drinking tap water (from the public water supply), occupations, and household herbicide use were collected by questionnaires. Herbicides were quantified in 5.3% to 39.7% of urine samples. Alachlor and acetochlor were found most frequently in the urine of women living in rural areas. The presence of dealkylated triazine metabolites in urine samples was positively associated with residential proximity to corn crops (OR=1.38, 95% CI: 1.05-1.80). Urinary metabolites of both atrazine and dealkylated triazine were correlated with tap water consumption (OR=2.94, 1.09-7.90, and OR=1.82, 1.10-3.03, respectively); hydroxylated triazine metabolites were correlated with fish intake (OR=1.48, 1.09-1.99). This study reinforces previous results that suggest that environmental contamination resulting from agricultural activities may contribute to the general population's exposure to herbicides.

Two-dimensional high performance liquid chromatography separation and tandem mass spectrometry detection of atrazine and its metabolic and hydrolysis products in urine.

Atrazine [6-chloro-N-ethyl-N'-(1-methylethyl)-1,3,5-triazine-2,4-diamine] is the most widely used herbicide in the United States. In recent years, there has been controversy about atrazine's potential endocrine/reproductive and neurological adverse effects in wildlife and humans. The controversy triggered several environmental and epidemiologic studies, and it generated needs for sensitive and selective analytical methods for the quantification of atrazine, atrazine metabolites, and degradation or hydrolysis products. We developed a two-dimensional high performance liquid chromatography (2D-HPLC) method with isotope dilution tandem mass spectrometry detection to measure atrazine in urine, along with 11 atrazine metabolites and hydrolysis products, including 6-chloro (Cl), 6-mercapto (Mer) and 6-hydroxy (OH) derivatives, and their desethyl, desisopropyl and diamino atrazine analogs (DEA, DIA and DAA, respectively). The 2D-HPLC system incorporated strong cation exchange and reversed phase separation modes. This versatile approach can be used for the quantitative determination of all 12 compounds in experimental animals for toxicological studies. The method requires only 10 µL of urine, and the limits of detection (LODs) range from 10 to 50 µg/L. The method can also be applied to assess atrazine exposure in occupational settings by measurement of 6-Cl and 6-Mer analogs, which requires only 100 µL of urine with LODs of 1-5 µg/L. Finally, in combination with automated off-line solid phase extraction before 2D-HPLC, the method can also be applied in non-occupational environmental exposure studies for the determination of -6-Cl and 6-Mer metabolites, using 500 µL of urine and LODs of 0.1-0.5 µg/L.

Urinary metabolites as biomarkers of human exposure to atrazine: atrazine mercapturate in agricultural workers.

Human exposure to atrazine and other triazine herbicides results in urinary excretion of traces of parent compounds and of their metabolites formed by N-dealkylation or conjugation with mercapturic acid. In contrast to N-dealkylated metabolites, which are not compound-specific, the measurement of atrazine mercapturate and unchanged atrazine provides an unambiguous confirmation of exposure to this herbicide. The aim of this study was to investigate the levels of these two compounds in a group of agricultural workers who may be considered representative for typical behaviour and procedures during the atrazine application in Croatia. The spot urine samples were collected at the beginning (samples A) and at the end (samples B) of a working day and 12h after exposure has ended (samples C). Atrazine and atrazine mercapturate were extracted from acidified urine samples (pH 2) with ethyl acetate and the extracts were analysed using high performance liquid chromatography-tandem mass spectrometry with a turbo ion spray (electrospray) ionization interface. The detection limits based on treatment of 2ml urine samples were 0.2ngml(-1) for both analytes. Atrazine was not detected in any of 27 analysed urine samples but traces of atrazine mercapturate were measured in about a third of pre-exposure and in all post-exposure urine samples in mass concentrations ranging from 0.3 to 10.4ngml(-1) (0.3 to 8.0µgg(-1) of creatinine). The metabolite concentrations in B and C group of post-exposure samples were not significantly different. The urinary atrazine mercapturate post-exposure concentrations were comparable to those reported for U.S. farmers engaged in a single field application of atrazine.

Urinary biomarkers of prenatal atrazine exposure and adverse birth outcomes in the PELAGIE birth cohort.

BACKGROUND: Despite evidence of atrazine toxicity in developing organisms from experimental studies, few studies--and fewer epidemiologic investigations--have examined the potential effects of prenatal exposure. OBJECTIVES: We assessed the association between adverse birth outcomes and urinary biomarkers of prenatal atrazine exposure, while taking into account exposures to other herbicides used on corn crops (simazine, alachlor, metolachlor, and acetochlor). METHODS: This study used a case-cohort design nested in a prospective birth cohort conducted in the Brittany region of France from 2002 through 2006. We collected maternal urine samples to examine pesticide exposure biomarkers before the 19th week of gestation. RESULTS: We found quantifiable levels of atrazine or atrazine mercapturate in urine samples from 5.5% of 579 pregnant women, and dealkylated and identified hydroxylated triazine metabolites in 20% and 40% of samples, respectively. The presence versus absence of quantifiable levels of atrazine or a specific atrazine metabolite was associated with fetal growth restriction [odds ratio (OR) = 1.5; 95% confidence interval (CI), 1.0-2.2] and small head circumference for sex and gestational age (OR = 1.7; 95% CI, 1.0-2.7). Associations with major congenital anomalies were not evident with atrazine or its specific metabolites. Head circumference was inversely associated with the presence of quantifiable urinary metolachlor. CONCLUSIONS: This study is the first to assess associations of birth outcomes with multiple urinary biomarkers of exposure to triazine and chloroacetanilide herbicides. Evidence of associations with adverse birth outcomes raises particular concerns for countries where atrazine is still in use.

A physiologically based pharmacokinetic model for atrazine and its main metabolites in the adult male C57BL/6 mouse.

Atrazine (ATR) is a chlorotriazine herbicide that is widely used and relatively persistent in the environment. In laboratory rodents, excessive exposure to ATR is detrimental to the reproductive, immune, and nervous systems. To better understand the toxicokinetics of ATR and to fill the need for a mouse model, a physiologically based pharmacokinetic (PBPK) model for ATR and its main chlorotriazine metabolites (Cl-TRIs) desethyl atrazine (DE), desisopropyl atrazine (DIP), and didealkyl atrazine (DACT) was developed for the adult male C57BL/6 mouse. Taking advantage of all relevant and recently made available mouse-specific data, a flow-limited PBPK model was constructed. The ATR and DACT sub-models included blood, brain, liver, kidney, richly and slowly perfused tissue compartments, as well as plasma protein binding and red blood cell binding, whereas the DE and DIP sub-models were constructed as simple five-compartment models. The model adequately simulated plasma levels of ATR and Cl-TRIs and urinary dosimetry of Cl-TRIs at four single oral dose levels (250, 125, 25, and 5mg/kg). Additionally, the model adequately described the dose dependency of brain and liver ATR and DACT concentrations. Cumulative urinary DACT amounts were accurately predicted across a wide dose range, suggesting the model's potential use for extrapolation to human exposures by performing reverse dosimetry. The model was validated using previously reported data for plasma ATR and DACT in mice and rats. Overall, besides being the first mouse PBPK model for ATR and its Cl-TRIs, this model, by analogy, provides insights into tissue dosimetry for rats. The model could be used in tissue dosimetry prediction and as an aid in the exposure assessment to this widely used herbicide.

An improved high-performance liquid chromatography-tandem mass spectrometric method to measure atrazine and its metabolites in human urine.

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 (0.05-0.19 ng/mL) with relative standard deviations less than 10%. The total runtime was shorter (18 min) 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.

Comparison of immunoassay and HPLC-MS/MS used to measure urinary metabolites of atrazine, metolachlor, and chlorpyrifos from farmers and non-farmers in Iowa.

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.

Disposition of the herbicide 2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine (Atrazine) and its major metabolites in mice: a liquid chromatography/mass spectrometry analysis of urine, plasma, and tissue levels.

2-Chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine (atrazine, ATR) is a toxicologically important and widely used herbicide. Recent studies have shown that it can elicit neurological, immunological, developmental, and biochemical alterations in several model organisms, including in mice. Because disposition data in mice are lacking, we evaluated ATR's metabolism and tissue dosimetry after single oral exposures (5-250 mg/kg) in C57BL/6 mice using liquid chromatography/mass spectrometry (Ross and Filipov, 2006). ATR was metabolized and cleared rapidly; didealkyl ATR (DACT) was the major metabolite detected in urine, plasma, and tissues. Plasma ATR peaked at 1 h postdosing and rapidly declined, whereas DACT peaked at 2 h and slowly declined. Most ATR and metabolite residues were excreted within the first 24 h. However, substantial amounts of DACT were still present in 25- to 48-h and 49- to 72-h urine. ATR reached maximal brain levels (0.06-1.5 microM) at 4 h (5-125 mg/kg) and 1 h (250 mg/kg) after dosing, but levels quickly declined to <0.1 microM by 12 h in all the groups. In contrast, strikingly high concentrations of DACT (1.5-50 microM), which are comparable with liver DACT levels, were detectable in brain at 2 h. Brain DACT levels slowly declined, paralleling the kinetics of plasma DACT. Our findings suggest that in mice ATR is widely distributed and extensively metabolized and that DACT is a major metabolite detected in the brain at high levels and is ultimately excreted in urine. Our study provides a starting point for the establishment of models that link target tissue dose to biological effects caused by ATR and its in vivo metabolites.

Exposure to atrazine and selected non-persistent pesticides among corn farmers during a growing season.

The aim was to develop quantitative estimates of farmers' pesticide exposure to atrazine and to provide an overview of background levels of selected non-persistent pesticides among corn farmers in a longitudinal molecular epidemiologic study. The study population consisted of 30 Agricultural Health Study farmers from Iowa and 10 non-farming controls. Farmers completed daily and weekly diaries from March to November in 2002 and 2003 on pesticide use and other exposure determinants. Urine samples were collected at 10 time points relative to atrazine application and other farming activities. Pesticide exposure was assessed using urinary metabolites and diaries. The analytical limit of detection (LOD) ranged between 0.1 and 0.2 microg/l for all pesticide analytes except for isazaphos (1.5 microg/l) and diazinon (0.7 microg/l). Farmers had higher geometric mean urinary atrazine mercapturate (AZM) values than controls during planting (1.1 vs

Quantification of atrazine and its metabolites in urine by on-line solid-phase extraction-high-performance liquid chromatography-tandem mass spectrometry.

We have developed a method using on-line solid-phase extraction-high-performance liquid chromatography-tandem mass spectrometry (SPE-HPLC-MS/MS) and isotope dilution quantification to measure atrazine and seven atrazine metabolites in urine. The metabolites measured were hydroxyatrazine, diaminochloroatrazine, desisopropylatrazine, desethylatrazine, desethylatrazine mercapturate, atrazine mercaturate and atrazine itself. Our method has good precision (relative standard deviations ranging from 4 to 20% at 5, 10 and 50 ng/mL), extraction efficiencies of 67 to 102% at 5 and 25 ng/mL, relative recoveries of 87 to 112% at 5, 25, 50 and 100 ng/mL limits of detection (LOD) ranging from 0.03 to 2.80 ng/mL. The linear range of our method spans from the analyte LOD to 100 ng/mL (40 ng/mL for atrazine and atrazine mercapturate) with R (2) values of greater than 0.999 and errors about the slope of less than 3%. Our method is rapid, cost-effective and suitable for large-scale sample analyses and is easily adaptable to other biological matrices. More importantly, this method will allow us to better assess human exposure to atrazine-related chemicals.

[Determination of atrazine and its metabolites in human urines using gas chromatography].

Atrazine (ATZ) was widely used to control broadleaf weeds. Numerous animal experiments have proved that atrazine is a suspicious endocrine disruptor. Thus, further development of the ability to estimate low-dose human exposure to atrazine is requested in epidemiologic studies to correlate the toxicological effects associated with the concentrations of ATZ and its metabolites in human body. A method for detecting ATZ and its metabolites (deethylatrazine (DEA), deisopropylatrazine (DIA), deethyldeisopropylatrazine (DEDIA)) in human urines using gas chromatography was established. A urine sample was extracted by ethyl acetate, and purified using a Florisil column. Final concentrated extract was analyzed by a gas chromatograph-electron capture detector. The conditions of this method were optimized. The limits of detection were 0. 002 5 mg/L for DEDIA, 0. 005 mg/L for DEA, DIA and ATZ. The linear ranges were from 0.2 to 8 ng for all analytes. The atrazine concentrations in urine samples of the workers collected from an atrazine plant were determined by this method. The concentration ranges were 0.003 -0.301 mg/L for DEDIA, 0.005 -0.011 mg/L for DEA, 0.006 -0.276 mg/L for DIA, and 0.005 -0.012 mg/L for ATZ.

Assessing exposure to atrazine and its metabolites using biomonitoring.

BACKGROUND: Atrazine (ATZ) is the second most abundantly applied pesticide in the United States. When we assessed exposure to ATZ by measuring its urinary mercapturic acid metabolite, general population data indicated that < 5% of the population was exposed to ATZ-related chemicals (limit of detection < 0.8 ng/mL). OBJECTIVES: The aim of our study was to determine if we were underestimating ATZ exposure by measuring its urinary mercapturic acid metabolite and if the urinary metabole profile changed with the exposure scenario. METHODS: We conducted a small-scale study involving 24 persons classified as high- (n = 8), low(n = 5), and environmental- (n = 11) exposed to ATZ. Using online solid phase extraction high performance liquid chromatography-tandem mass spectrometry, we measured nine ATZ-related metabolites in urine that included dealkylated, hydroxylated, and mercapturic acid metabolites. RESULTS: We found that the urinary metabolite profiles varied greatly among exposure scenarios and among persons within each exposure scenario. Although diaminochlorotriazine (DACT) appeared to be the predominant urinary metabolite detected in each exposure category, the variation in proportion of total ATZ metabolites among persons was consistently large, suggesting that one metabolite alone could not be measured as a surrogate for ATZ exposure. CONCLUSIONS: We have likely been underestimating population-based exposures by measuring only one urinary ATZ metabolite. Multiple urinary metabolites must be measured to accurately classify exposure to ATZ and its environmental degradates. Regardless, DACT and desethylatrazine appear to be the most important metabolites to measure to evaluate exposures to ATZ-related chemicals.

Pesticide dose estimates for children of Iowa farmers and non-farmers.

Farm children have the potential to be exposed to pesticides. Biological monitoring is often employed to assess this exposure; however, the significance of the exposure is uncertain unless doses are estimated. In the spring and summer of 2001, 118 children (66 farm, 52 non-farm) of Iowa farm and non-farm households were recruited to participate in a study investigating potential take-home pesticide exposure. Each child provided an evening and morning urine sample at two visits spaced approximately 1 month apart, with the first sample collection taken within a few days after pesticide application. Estimated doses were calculated for atrazine, metolachlor, chlorpyrifos, and glyphosate from urinary metabolite concentrations derived from the spot urine samples and compared to EPA reference doses. For all pesticides except glyphosate, the doses from farm children were higher than doses from the non-farm children. The difference was statistically significant for atrazine (p<0.0001) but only marginally significant for chlorpyrifos and metolachlor (p = 0.07 and 0.1, respectively). Among farm children, geometric mean doses were higher for children on farms where a particular pesticide was applied compared to farms where that pesticide was not applied for all pesticides except glyphosate; results were significant for atrazine (p = 0.030) and metolachlor (p = 0.042), and marginally significant for chlorpyrifos (p = 0.057). The highest estimated doses for atrazine, chlorpyrifos, metolachlor, and glyphosate were 0.085, 1.96, 3.16, and 0.34 microg/kg/day, respectively. None of the doses exceeded any of the EPA reference values for atrazine, metolachlor, and glyphosate; however, all of the doses for chlorpyrifos exceeded the EPA chronic population adjusted reference value. Doses were similar for male and female children. A trend of decreasing dose with increasing age was observed for chlorpyrifos.

Quantification of atrazine, phenylurea, and sulfonylurea herbicide metabolites in urine by high-performance liquid chromatography-tandem mass spectrometry.

We developed a high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS-MS) method to measure metabolites of atrazine, phenylurea, and sulfonylurea herbicides in human urine. The metabolites measured in the method include atrazine mercapturate, desethyl atrazine, and desisopropyl atrazine as markers of atrazine exposure; dichlorophenyl urea, dichlorophenylmethyl urea, diuron, and linuron as markers of phenylurea herbicide exposure; and dimethoxypyrimidine, dimethylpyrimidine, and methoxymethyl triazine as markers for sulfonylurea herbicide exposure. The metabolites were extracted from urine by simple solid-phase extraction using a mixed-bed cartridge and were analyzed by HPLC-MS-MS. Quantification of the atrazine metabolites was achieved using isotope-dilution calibration. The remaining metabolites were quantified using similarly structured chemicals as internal standards. Extraction recoveries ranged from 88% to 104% (n = 5). Limits of detection for the entire method ranged from 0.125 to 1 ng/mL, and the average relative standard deviation of repeat measurements was about 13% (n = 30).

Urinary pesticide concentrations among children, mothers and fathers living in farm and non-farm households in iowa.

In the spring and summer of 2001, 47 fathers, 48 mothers and 117 children of Iowa farm and non-farm households were recruited to participate in a study investigating take-home pesticide exposure. On two occasions approximately 1 month apart, urine samples from each participant and dust samples from various rooms were collected from each household and were analyzed for atrazine, metolachlor, glyphosate and chlorpyrifos or their metabolites. The adjusted geometric mean (GM) level of the urine metabolite of atrazine was significantly higher in fathers, mothers and children from farm households compared with those from non-farm households (P < or = 0.0001). Urine metabolites of chlorpyrifos were significantly higher in farm fathers (P = 0.02) and marginally higher in farm mothers (P = 0.05) when compared with non-farm fathers and mothers, but metolachlor and glyphosate levels were similar between the two groups. GM levels of the urinary metabolites for chlorpyrifos, metolachlor and glyphosate were not significantly different between farm children and non-farm children. Farm children had significantly higher urinary atrazine and chlorpyrifos levels (P = 0.03 and P = 0.03 respectively) when these pesticides were applied by their fathers prior to sample collection than those of farm children where these pesticides were not recently applied. Urinary metabolite concentration was positively associated with pesticide dust concentration in the homes for all pesticides except atrazine in farm mothers; however, the associations were generally not significant. There were generally good correlations for urinary metabolite levels among members of the same family.

Mixed-effect models for evaluating multiple measures of atrazine exposure among custom applicators.

The exposure of custom (or commercial) applicators to the herbicide atrazine was measured in environmental (hand wash and dermal patch) and biological (urine and saliva) samples. Surrogate exposure data, such as amount of atrazine sprayed, were also collected. A systematic sampling design was used that included both spray and nonspray days. Fifteen applicators were sampled 5 to 7 days each during a 6-week spring spray season for a total of 89 sampled days. Mixed-effect regression modeling was used to examine the relationship among the surrogate, environmental, and biological atrazine exposure measures. Surrogate measures of atrazine application (either kg of atrazine sprayed or spray atrazine [yes/no]) were significantly associated with increased levels of atrazine or atrazine equivalents (eq) in hand wash, thigh patch, 4-6 p.m. saliva, and 24-hour urine samples. Two days of spraying information (day of sampling and day before sampling) were needed to optimally estimate atrazine biomarkers in the biological samples, whereas only 1 day of spraying information (day of sampling) was needed to estimate atrazine levels in the environmental samples. Thigh and hand atrazine exposures were significantly associated with increased atrazine and atrazine eq. levels in the 4-6 p.m. saliva and 24-hour urine samples, respectively. Levels of 4-6 p.m. salivary atrazine were also significantly associated with increased levels of 24-hour urinary atrazine eq. Atrazine levels in the 4-6 p.m. saliva samples tracked most closely with evening and next morning urinary atrazine eq. Number of days into the study at the time of sample collection predicted urinary and salivary atrazine levels independent of other fixed effects. These results indicate that either surrogate, environmental, or biological exposure measures can be used in appropriately specified models to estimate urinary and salivary atrazine biomarker levels.