Biomarkers Of Pesticide Exposure Research Articles

Biomarkers of Pesticide Exposure in a Traditional Brazilian Amazon Community

In 2008, Brazil became the country with the highest pesticide use in the world, with over one billion liters of pesticides applied to crops in 2009. The impacts of these products on public health are wide-ranging. Vast territories are affected, involving different population groups, such as workers in various fields of activity, the population that consumes contaminated food, and people living around factories, such as traditional communities. This study aimed to assess human exposure to pesticides through epidemiological and laboratory data of residents of the Santo Antônio quilombola community in Concórdia do Pará, Amazon region, Brazil. Epidemiological data were collected using a semi-structured questionnaire, which included factors such as sex, age, length of residence, and level of exposure to pesticides. The modified Ellman method was used to assess the activity of cholinesterases, and flow cytometry was performed for cytokine analysis. Analysis of collected blood samples showed that, in most cases, there was no significant reduction in the activity of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) compared to other studies in the scientific literature. Meanwhile, there was an increase in the levels of IFN-γ cytokines, especially IL-6, in all groups. The findings of this study highlight the urgent need for a comprehensive monitoring program, considering that some conditions other than pesticide exposure can alter the activities of the biomarkers used in this study.

Observations on populations of a small insectivorous bird,

The use of chemical pesticides to manage locust populations in natural ecosystems is likely to impact non-target arthropods and their predators. However, the relative effects of different locust control applications on Australian birds are unknown. Aerial applications of fipronil and fenitrothion are examples of two pesticides used in locust control in semiarid Australia. To test the relative impacts of pesticides on non-target fauna, pesticides were applied to replicate sites using aerial ultra-low-volume application methods. The body condition and biomarkers of pesticide exposure in resident white-winged fairy wrens (Malurus leucopterus leuconotus) at treatment and control sites were measured for two weeks before and after treatments. No measures suggested negative impacts of pesticide applications. However, birds monitored at treatment sites gained mass, possibly due to indirect impacts of pesticides on bird feeding patterns or the availability or behaviour of insect prey. Bird mass measures remained high at fipronil sites, whereas the mass of birds at fenitrothion sites returned to baseline levels within one week. As this study was conducted during dry conditions, when locust plagues are less likely, future insecticide research should also consider the availability of insect prey, its effect on insectivore feeding behaviour and the interaction of rainfall events.

Association between pesticide exposure and sleep health among a representative sample of US adults: evidence from NHANES 2009\u20132014

BackgroundData suggest that pesticides interact with the melatonin receptor, which may influence sleep. However, the link between pesticides and sleep remains unexplored among the general adult population. This study evaluated unstratified and sex-stratified associations between urinary pesticide exposure (N = 4,478) and self-reported acute household pesticide exposure (N = 14,956), with sleep health outcomes within a nationally representative sample of US adults.MethodsData from the National Health and Nutrition Examination Surveys (NHANES) 2009–2014 were combined for analysis of aim 1 and aim 2. Urinary pesticide metabolite concentrations served as biomarkers of pesticide exposure. Acute household pesticide exposure (if any chemical products were used in the home in the past seven days to control pests) was self-reported (yes/no). Insufficient sleep duration (< 7 h/night) and trouble sleeping (yes/no) were self-reported. Log-binomial regression models that accounted for complex survey weights and adjusted for confounders were used to compute prevalence ratios and 95% CI.ResultsLog urinary 3-phenoxybenzoic acid (3-PBA) was related to a higher probability of insufficient sleep [1.09 (95% CI: 1.00, 1.20), p = 0.04] and trouble sleeping [1.14 (95% CI: 1.02, 1.27), p = 0.02] among males. Self-reported acute household pesticide exposure was associated with a higher probability of insufficient sleep duration [1.16 (95% CI: 1.02, 1.32), p = 0.03] and trouble sleeping [1.20 (95% CI: 1.01, 1.44), p = 0.04] in the unstratified sample. Sex-stratified findings showed that associations between acute household pesticide exposure and trouble sleeping only persisted among males [1.69 (95% CI: 1.27, 2.24), p < .001].ConclusionsIn summary, acute pesticide exposure may be detrimental to adult sleep health, particularly among US males.

Effects of Chlorpyrifos Ethyl on Cholinesterase and Growth of Silver Barb (Barbonymus gonionotus)

Chlorpyrifos ethyl is a popular insecticide widely used in agriculture within the Vietnamese Mekong delta, including for rice farming. Here, local farmers often apply pesticides at very high rates which leads to contamination of the surrounding environment. Silver barb (Barbonymus gonionotus) is a fish species indigenous to the delta, which resides in a variety of water bodies and is also commonly cultivated in rice–fish systems. As a result, this species is at high risk of exposure to chlorpyrifos ethyl. This study aims to determine the lethal concentration (LC50) of chlorpyrifos ethyl, as well as the effects of sub-lethal concentrations on the activity of cholinesterase and growth of Silver barb. Lethal concentration testing was conducted in a static non-renewed system. Three concentrations of chlorpyrifos ethyl (1%, 10% and 20% LC50-96 h) were conducted in triplicate to assess the effects of chlorpyrifos ethyl on the brain cholinesterase (ChE) of fingerling fish for 15 days, and on their growth for 60 days. Results showed that chlorpyrifos ethyl was highly toxic to fingerling Silver barb with a LC50-96 h of 0.119 ppm. The lowest observed effect concentration (LOEC) was 1%LC50-96 h for ChE and 10%LC50-96 h for growth. No observed effect concentration (NOEC) of chlorpyrifos ethyl for growth was 1%LC50-96 h. The result from this study suggests that ChE activity is significantly inhibited at environmentally realistic concentrations in the Vietnamese Mekong delta and can be used as a biomarker of pesticide exposure. Further study in the rice fields as well as in the canals or rivers is required.

Understanding Challenges to Well-Being among Latina FarmWorkers in Rural Idaho Using in an Interdisciplinary, Mixed-Methods Approach.

The aim of this study was to identify social, cultural and workplace-related risk factors affecting well-being among Latina farmworkers in rural Idaho. We recruited 70 Latina farmworkers from southwestern Idaho in 2019. We employed an inter-disciplinary, mixed-methods approach—including surveys, focus groups, interviews, and pesticide biomonitoring—to characterize multiple domains that influence well-being, including food security and access, housing conditions, social supports, access to medical care, and workplace safety. Six major themes emerged as primary challenges to Latina farmworkers’ well-being. In the public sphere, study participants identified these challenges as long working hours, concerns regarding pesticide exposure, and lack of enforcement of regulatory protections. Participants’ concerns regarding pesticide exposure were underscored by biological sampling results; multiple biomarkers of pesticide exposure were detected in all samples, with the highest concentrations measured in samples collected from women who reported mixing, loading or applying pesticides. Within the private sphere, food security and provisioning, childcare responsibilities, and social isolation were identified as significant challenges to well-being. Gender, ethnicity, and geography emerged as important, intersecting statuses that shaped the life experiences of these agricultural workers. Our findings suggest that gender may play a particularly critical role in the unique challenges facing Latina farmworkers. As a result, the services and regulations needed to support well-being in this population may be highly specific, and almost certainly include attention to work–family dynamics, pesticide exposure, and social connections.

Determinants of pesticide exposure among workers in floriculture industry in rural Maharashtra

Background: Pesticides are extensively used in floriculture where workers are mostly unskilled and may not have appropriate knowledge about safety. Acute accidents during spraying are reported, chronic exposure goes unnoticed. There are not many Indian studies regarding health risks and safety practices among floriculture workers in India. Hence this study to assess pesticide exposure, to find their determinants and suggest appropriate preventive measures.Methods: Study was cross sectional in Floriculture Park, Talegaon (D), Pune, Maharashtra, India using cluster sampling from February 2018 to July 2019. Prevalence of morbidities being 63% sample size was calculated as 111 (allowable error 15%). Socio-demographic, work and health related variables were recorded using a pretested structured questionnaire. Clinical examination and laboratory investigations were done by medical experts.Results: A total of 118 workers participated. Only half (51.2%) were using personal protective devices. None were following reentry guidelines. 13.3% males and 4.1% females had low serum cholinesterase level which is a biomarker of pesticide exposure. Sprayers had significantly high risk of low serum cholinesterase levels (OR=3.31) as compared to others. With exposed subjects which included both sprayers as well as polyhouse workers the association increased with OR=4.27. However association was not significant when working in polyhouse alone was considered as a risk factor (OR=1.256).Conclusions: Presence of exposure was the only factor that had a statistically significant association with low Serum Cholinesterase levels. Safe occupational practices like use of personal protective devices, rotation of exposed workers, monitoring of serum cholinesterase levels and health education of workers should be undertaken.

Associations of acetylcholinesterase activity with depression and anxiety symptoms among adolescents growing up near pesticide spray sites.

The cholinergic system has an important role in mood regulation. Cholinesterase inhibitor pesticides (e.g. organophosphates) appear to increase depression and anxiety symptoms in the few existing animal and human studies. Human studies have not described such associations using biomarkers of exposure and studies among children are needed. We studied 529 adolescents (ages 11-17y) in agricultural communities in the Ecuadorian Andes (ESPINA study). Acetylcholinesterase (AChE) activity was measured in a finger-stick sample. Anxiety and depression symptoms were assessed using the CDI-2 and MASC-2 (greater scores reflect greater internalizing symptoms). Models adjusted for age, gender, hemoglobin, income among others. The median age was 14.38y and 51% were female. The mean (SD) of the following parameters were: AChE 3.7 U/mL (0.55), depression T-score 53.0 (9.4) and anxiety T-score: 57.6 (9.8). Lower AChE activity (reflecting greater cholinesterase inhibitor exposure) was associated with higher depression symptoms (difference per SD decrease of AChE [β [95% CI:]]: 1.09 [0.02, 2.16]), was stronger among girls (β = 1.61) than boys (β = 0.69), and among younger (<14.38y, β = 1.61) vs. older children (β = 0.57). The associations were strongest among girls <14.38y (β = 3.30 [0.54, 6.05], OR for elevated symptoms per SD decrease in AChE = 2.58 [1.26, 5.27]). No associations were observed with anxiety scores. Analyses of AChE change between 2008 and 2016 concurred with these findings. We observed associations between a biomarker of pesticide exposure and children's depression symptoms. Lower AChE activity may create risk for depression in teenagers, particularly among girls during early adolescence.

Assessment of genotoxicity and cholinesterase activity among women workers occupationally exposed to pesticides in tea garden

To assess the effects of exposure to pesticides in tea garden women workers, the present study evaluated the activities of erythrocyte acetylcholinesterase (AChE) and plasma butyrylcholinesterase (BChE) as biomarkers of pesticide exposure and DNA damage by comet assay as a biomarker of genotoxicity in peripheral blood lymphocytes. We examined 143 women subjects including 77 women workers exposed to pesticide in tea garden (exposed) and 66 women subject with no history of occupational exposure to pesticides (non-exposed). The two groups had similar mean ages, BMI and personal habits. The results revealed that exposed group had lower activity of AChE (2.86 ± 0.75 vs. 3.93 ± 0.87 U/ml) BChE (2.02 ± 0.74 vs. 2.60 ± 0.74 U/ml, p < 0.001) than those of non-exposed group. The mean comet parameters such as tail length (TL), % DNA in tail, tail moment (TM) and olive tail moment (OTM) used to measure DNA damage were significantly elevated in exposed workers compared to non-exposed (p < 0.001). There was no variation observed in Cholinesterase (ChEs) activity and Comet assay parameter based on age, personal habits, years of exposure and use of personal protective equipments (PPEs) except BChE activity. The multiple regression analysis showed no association of confounding factors on end points measured except slight negative association of BMI with tail length. Therefore this study suggests that the workers in tea garden might have exposed to pesticide through their occupation on a regular interval. Although this study could able to associate it with their occupational exposure, the role of other DNA damaging factors cannot be ruled out. Our study finding indicate the necessity of periodic monitoring of these biomarkers along with imparting education and training to minimise the risk.

β-Glucuronidase and Its Relationship With Clinical Parameters and Biomarkers of Pesticide Exposure.

This study determined β-glucuronidase activity and its relationship with clinical, biochemical, and pesticide-exposure biomarkers in workers occupationally exposed mainly to OP insecticides. A cross-sectional study was conducted in pesticide applicators. Three study groups were established: reference group, moderate-exposure group, and high-exposure group. Blood samples were obtained to determine the activity of β-glucuronidase. Clinical analysis was conducted in a certified laboratory. The activity of β-glucuronidase was associated with clinical variables such as glucose, cholesterol, triglycerides, LDL, VLDL, HDL, atherogenic index, transaminases, and BuChE activity, but not with AChE activity. The activity of this enzyme exhibited a significant increase in the group of moderate exposure to pesticides but not in the group of high exposure. β-Glucuronidase activity is a sensitive biomarker under certain scenarios of OP exposure.

Associations of Acetylcholinesterase Activity with Depression and Anxiety Symptoms among Adolescents Growing Up near Pesticide Spray Sites

Background:Self-reports of pesticide exposures have been associated with increased depression and anxiety symptoms among adult agricultural workers; research among children and adolescents is lacking and no studies have described these associations using biomarkers of exposure. Methods:Methods: We estimated the associations among 516 adolescents (ages 12-19y) in 2016 living in floricultural communities in Ecuador: the ESPINA study. Children&amp;#8217;s acetylcholinesterase (AChE) activity (lower values reflect greater organophosphate or carbamate pesticide exposure) was measured in a finger-stick sample. Anxiety and depression symptoms were assessed using the CDI-2 and MASC-2 (greater t-scores reflect greater internalizing symptoms). Models adjusted for age, gender, hemoglobin and anthropometric measures. Results:51% of participants were female; the median age was 14.4y. The mean (SD) of the following parameters were: AChE 3.7 U/mL (0.55), depression t-score 53.0 (9.4) and anxiety t-score: 57.6 (9.8). AChE activity was inversely related to depression score (difference per SD decrease of AChE [&amp;#946;]: 0.87 units [95%CI: -0.18, 1.91]); the OR for moderately elevated depression score (&amp;gt;55) per SD decrease of AChE was 1.28 [1.00, 1.62]. The association was stronger among children &amp;lt;14.4y (&amp;#946;: 2.00 units [0.22, 3.78]; OR: 1.41 [1.02, 1.96]) than among older adolescents (&amp;#946;: 0.28 units [-1.03, 1.60], OR: 1.17 [0.85, 1.62]). These associations were strengthened after accounting for 2008 AChE values. Among children &amp;lt;14.4y, the associations were stronger in girls (OR: 1.91 [1.00, 3.65]) than boys (OR: 0.90 [0.40, 2.03]). No associations were observed with anxiety scores. Discussion: This is the first study to describe associations between a biomarker of pesticide exposure and depression symptoms, in one of the largest studies of its kind. Cholinesterase inhibition may affect the mood towards depression of non-agricultural-worker adolescents, particularly among girls during early adolescence.

The use of carboxylesterases as biomarkers of pesticide exposure in bivalves: A methodological approach

Bivalves are worldwide sentinels of anthropogenic pollution. The inclusion of biomarker responses in chemical monitoring is a recommended practise that has to overcome some difficulties. One of them is the time frame between sample collection and sample processing in order to ensure the preservation of enzymatic activities. In the present study, three bivalve species of commercial interest (mussel, Mytilus galloprovincialis, razor shell, Solen marginatus, and cockle, Cerastoderma edule) were processed within <2 h after being retrieved from their natural habitat, and 24 h after being transported in air under cold conditions (6–8 °C) to laboratory facilities. The enzymatic activities were compared in the three species submitted to both conditions revealing no differences in terms of carboxylesterase dependent activities (CEs) using different substrates: p-nitrophenyl acetate (pNPA), p-nitrophenyl butyrate (pNPB), 1-naphthyl acetate (1-NA), 1-naphthyl butyrate (1-NB) and 2-naphthyl acetate (2-NA). In mussels, three tissues were selected (haemolymph, gills and digestive gland). For comparative purposes, in razor shell and cockle only digestive gland was considered as it is the main metabolic organ. Baseline enzymatic activities for CEs were characterised in the digestive gland of the three bivalves using four out of the five selected CE substrates as well as the kinetic parameters (Vmax and Km) and catalytic efficiency. The in vitro sensitivity to the organophosphorus metabolite chlorpyrifos oxon was also calculated. IC50 values (pM-nM range) were lower than those obtained for vertebrate groups which suggest that bivalves have high protection efficiency against this pesticide as well as species dependent particularities.

Erythrocyte acetylcholinesterase as biomarker of pesticide exposure: new and forgotten insights

Acetylcholinesterase (AChE) acts on the hydrolysis of acetylcholine, rapidly removing this neurotransmitter at cholinergic synapses and neuromuscular junctions as well as in neuronal growth and differentiation, modulation of cell adhesion ("electrotactins") and aryl-acylamidase activity (AAA). This enzyme is also found in erythrocyte, as 160kDa dimer that anchors to the plasma membrane via glycophosphatidylinositol. The function of this enzyme in erythrocytes has not yet been elucidated; however, it is suspected to participate in cell-to-cell interactions. Here, a review on erythrocyte AChE characteristics and use as biomarker for organophosphorus and carbamate insecticides is presented since it is the first specific target/barrier of the action of these pesticides, besides plasma butyrylcholinesterase (BChE). However, some past and current methods have disadvantages: (a) not discriminating the activities of AChE and BChE; (b) low accuracy due to interference of hemoglobin in whole blood samples. On the other hand, extraction methods of hemoglobin-free erythrocyte AChE allows: (a) the freezing and transporting of samples; (b) samples free of colorimetric interference; (c) data from only erythrocyte AChE activity; (d) erythrocyte AChE specific activity presents higher correlation with the central nervous system AChE than other peripheral ChEs; (e) slow spontaneous regeneration against anti-ChEs agents of AChE in comparison to BChE, thus increasing the chances of detecting such compounds following longer interval after exposure. As monitoring perspectives, hemoglobin-free methodologies may be promising alternatives to assess the degree of exposure since they are not influenced by this interfering agent.

DNA damage and circulating cell free DNA in greenhouse workers exposed to pesticides.

Pesticides widely used in agriculture and other applications have been linked to cancer and other diseases through several potential mechanisms. The goals of this study were to assess DNA damage in lymphocytes by the cytokinesis-block micronucleus assay (CBMN), and to measure circulating cell free DNA (ccf-DNA) in the blood of pesticide-exposed greenhouse workers and matched controls living in the same area. CBMN was applied to peripheral blood lymphocyte samples taken at different times (spring and autumn) for each individual. We measured plasma ccf-DNA levels using a Qubit® fluorometer. The results indicated that the MNL, BNMN, and NBUDs frequencies of pesticide-exposed individuals were significantly higher than non-exposed individuals. Apart from MNL, BNMN and CBPI, a season-related effect was found for the NPB and NBUD frequencies. With MNL and BNMN as the dependent variables, multiple regression analysis showed that age and gender affected MN formation. The ccf-DNA level in the pesticide-exposed group was significantly higher than the control group. There was no seasonal variation regarding the free DNA amount. Ccf-DNA in males was found to be higher than females. The MNL, BNMN, NPB, and CBPI did not correlate with the ccf-DNA amount. It can be concluded that pesticide exposure can modulate DNA integrity via different mechanisms. Also, elevated levels of ccf-DNA could be recommended as a biomarker of pesticide exposure. Environ. Mol. Mutagen. 59:161-169, 2018. © 2017 Wiley Periodicals, Inc.

Evaluation of circulating cell free DNA as biomarker of pesticide exposure

Evaluation of circulating cell free DNA as biomarker of pesticide exposure

Urinary microRNAs as potential biomarkers of pesticide exposure

MicroRNAs (miRNAs) are post-transcriptional regulators that silence messenger RNAs. Because miRNAs are stable at room temperature and long-lived, they have been proposed as molecular biomarkers to monitor disease and exposure status. While urinary miRNAs have been used clinically as potential diagnostic markers for kidney and bladder cancers and other diseases, their utility in non-clinical settings has yet to be fully developed. Our goal was to investigate the potential for urinary miRNAs to act as biomarkers of pesticide exposure and early biological response by identifying the miRNAs present in urine from 27 parent/child, farmworker/non-farmworker pairs (16FW/11NFW) collected during two agricultural seasons (thinning and post-harvest) and characterizing the between- and within-individual variability of these miRNA epigenetic regulators. MiRNAs were isolated from archived urine samples and identified using PCR arrays. Comparisons were made between age, households, season, and occupation. Of 384 miRNAs investigated, 297 (77%) were detectable in at least one sample. Seven miRNAs were detected in at least 50% of the samples, and one miRNA was present in 96% of the samples. Principal components and hierarchical clustering analyses indicate significant differences in miRNA profiles between farmworker and non-farmworker adults as well as between seasons. Six miRNAs were observed to be positively associated with farmworkers status during the post-harvest season. Expression of five of these miRNA trended towards a positive dose response relationship with organophosphate pesticide metabolites in farmworkers. These results suggest that miRNAs may be novel biomarkers of pesticide exposure and early biological response.

Cholinesterase Effects of Pesticides in Rabbit Embryos and their Potential for Use in Hazard Assessment

Cholinesterase are often taken as biomarkers of exposure and effect. Then acetylhydrolase isozymes and acylcholine acylhydrolase were examined for their suitability as biomarkers of pesticide exposure. The study of effects of embryos of the rabbit is already an accepted tool in monitor food waste levels, but effects of various groups of substances to the rabbit embryo remain to be studied. A 43% inhibition of acetylhydrolase enzyme activities was reached by 250 mg/kg malathion, while 35% inhibition of acylcholine acylhydrolase enzyme activities was reached by 500 mg/kg malathion indicating the possible use of these enzymes as biomarkers of exposure. There are found some significant specific activities of the acetylhydrolase ranged from 1.5-7.1 U mg−1 protein. The specific activity of acylcholine acylhydrolase in the range of 0.9-4.5 U mg−1 protein in the respective developmental stages. Substratespecificity was analyzed using specific inhibitors (iso-OMPA and BW284c51). The results showed that the observed cholinesterase’s activities in the whole embryo may be attributed mainly to acetylhydrolase with a partial capability to use butyrylthiocholine (BuSCh) as an additional substrate.

The Utility of Urinary Mirna Profiles as Biomarkers of Pesticide Exposure

The Utility of Urinary Mirna Profiles as Biomarkers of Pesticide ExposureAbstract Number:2746 Sara E. Pacheco, Brittany Weldon*, Tomomi Workman, Alex Artemenko, Beti Thompson, Elaine M. Faustman Sara E. Pacheco Institute for Risk Analysis and Risk Communication,University of Washington, United States, E-mail Address: [email protected] Search for more papers by this author , Brittany Weldon* Institute for Risk Analysis and Risk Communication,University of Washington, United States, E-mail Address: [email protected] Search for more papers by this author , Tomomi Workman Institute for Risk Analysis and Risk Communication,University of Washington, United States, E-mail Address: [email protected] Search for more papers by this author , Alex Artemenko Institute for Risk Analysis and Risk Communication,University of Washington, United States, E-mail Address: [email protected] Search for more papers by this author , Beti Thompson Fred Hutchinson Cancer Research Center, United States, E-mail Address: [email protected] Search for more papers by this author , and Elaine M. Faustman Institute for Risk Analysis and Risk Communication,University of Washington, United States, E-mail Address: [email protected] Search for more papers by this author AbstractBackground: MicroRNAs (miRNAs) are a class of post-transcriptional regulators that silence messenger RNAs. MiRNAs are stable at room temperature and are long lived, and these characteristics make them useful molecular biomarkers to monitor disease and exposure status. Urine miRNAs have been used clinically as potential diagnostic markers of bladder cancer. However, their utility in non-clinical settings has yet to be elucidated. Objective andMethods: The goal of this project was to identify the miRNAs present in urine field samples 27 parent/child, farmworker/non-farmworker pairs (n=107) collected during two seasons (non-spray and thinning) as part of our Children’s Health Center cohort study in Yakima Valley, WA and characterize the between- and within-individual variability of these miRNAs. MiRNAs were isolated from urine samples using previously optimized methods and identified using PCR-based microarrays. Comparisons were made between age, households, season, and occupation. Findings: Of the 380 miRNAs investigated on the array, 297 (78%) were expressed in at least one sample. In addition, there were 7 miRNAs present in at least 50% of the samples, and 1 miRNA (miR-223) was present in 97% of the samples. In general, households (parent and child combined) expressed fewer miRNAs in their urine during thinning than during non-spray (mean, 31 [range, 3-169] vs. 57 [6-197]). However, this difference was more drastic in adults (mean, 25 [range, 3-130] vs. 74 [6-169]) than children (mean, 38 [6-169] vs. 40 [9-173]) when analyzed separately. The other comparisons are in progress.Conclusions: Initial analyses suggest that there is high variation in the miRNAs present within individuals and households during different seasons. These results will provide valuable insight on the utility of archived field samples for the future development of urine biomarkers. Funded by HHSN2672007023C and HHSN2752008015C (NICHD), P01-ES009601 and P30-ES007033 (NIEHS) and RD-834514 (EPA).

Tissue-Specific Variations of Esterase Activities in the Tadpoles and Adults of Pseudis paradoxa (Anura: Hylidae)

We determined basal levels of cholinesterase (ChE) and carboxylesterase (CbEs; two substrates: α-naphthyl acetate and 4-nitrophenylvalerate) in different tissues of tadpoles and adults of the frog Pseudis paradoxa and evaluated their use as complementary biomarkers of anti-cholinesterase pesticide exposure. ChE and CbEs sensitivity to malaoxon was also evaluated. Adults and tadpoles were collected with sweep net from temporary ponds located in natural riparian forests along the Parana River (Garay Department, Santa Fe province, Argentina). We found significant differences in B-esterase activities between adults and tadpoles and among different tissues. The in vitro inhibition tests indicated that ChE is more sensitive to inhibition than CbEs. Our results suggest that basal ChE and CbE (α-NA and 4-NPV) activities in different tissues of adult and tadpoles P. paradoxa would be suitable biomarkers of pesticide exposure, and this amphibian species could be used as sentinel in field monitoring.

Oregon Indigenous Farmworkers

To examine changes in health beliefs, pesticide safety knowledge, and biomarkers of pesticide exposure in indigenous farmworkers who received enhanced pesticide safety training compared with those receiving the standard training. Farmworkers in Oregon were randomly assigned to either a promotors pesticide safety training program or a standard video-based training. Spot urine samples were analyzed for dialkyl phosphate urinary metabolites. Pre-/postintervention questionnaires were used to measure pesticide safety knowledge, health beliefs, and work practices. Baseline to follow-up improvements in total pesticide knowledge scores were higher in the promotor group than in the standard video group. Pairwise differences in mean concentrations of dialkyl phosphate metabolite levels showed declines from baseline to follow-up for both intervention groups. Results showed reductions in pesticide exposure in indigenous-language speaking farmworkers who received enhanced pesticide safety training.

Modulation of the endogenous antioxidants paraoxonase-1 and urate by pesticide exposure and genetic variants of xenobiotic-metabolizing enzymes

This study evaluated the association between pesticide exposure in farmworkers and plasma levels of the endogenous antioxidants urate and paraoxonase-1 (PON1) enzyme activities (paraoxonase, arylesterase and diazoxonase, three substrate-specific assays for measuring PON1 function) by using generalized estimating equations (GEEs). Decreases in plasma and erythrocyte cholinesterases (BChE and AChE, respectively) were used as biomarkers of pesticide exposure. We also assessed the contribution of genetic polymorphisms of the pesticide-metabolising enzymes PON1, glutathione S-transferases (GST) and cholinesterase variants (BCHE) on plasma levels of endogenous antioxidants and potential gene-environment interactions. A dual effect was observed on paraoxonase depending on the pattern of pesticide exposure. Thus, exposure to anticholinesterase pesticides was associated with decreased paraoxonase activity and urate levels whereas long-term pesticide exposure showed an association with increased paraoxonase activity. Significant interactions were observed between BChE activity and PON1 regulatory region polymorphisms on arylesterase and diazoxonase activities, and between AChE activity (a biomarker for long-term pesticide exposure) and PON1192RR genotype on arylesterase activity. These findings suggest that pesticide exposure may affect plasma antioxidant potential and that relevant gene-pesticide interactions may play a mechanistic role in oxidative stress-induced diseases following pesticide exposure. Nonetheless, more studies are needed to better characterise these interactions.