Chlropyrifos-methyl shows anti-androgenic activity without estrogenic activity in rats

Bacillus thuringiensis affects reproductive capacity of adult rat offspring

We investigated the effects of B. thuringiensis-based biological insecticides, XenTari and Dipel, and deltamethrin on the reproductive development of pups of pregnant rats. Twenty 90-day-old pregnant rats were divided randomly onto four equal groups: control group (GC) administered only water; XenTari group (GX) administered 1 mg XenTari (containing Cry1Ac toxin of B. thuringiensis)/100 g body weight; Dipel group (GDi) administered 1 mg Dipel (containing Cry1Aa, Cry1Ab and Cry1Ac toxins of B. thuringiensis)/100 g body weight; and a deltamethrin group (GDe) administered 2 mg deltamethrin (0.08 ml Keshet 25EC)/kg body weight as a positive control. Insecticides were administered by gavage at doses of 1 mg/100 g/day (GX and GDi), and 2 mg/kg/day (GDe) during pregnancy and lactation. Treatment with both biologic and synthetic insecticides reduced the weight gain of the mothers. The biological insecticides reduced the number, weight and length, and increased malformation and mortality of the offspring. In female offspring for all three groups administered insecticides, opening of the vagina was delayed, metestrus was increased and estrogen and progesterone levels were reduced compared to proestrus, estrus and metestrus of the cycle. The ovaries of female offspring of all three groups administered insecticides contained numerous tertiary and atretic follicles, few corpora lutea, primary and secondary follicles, and reduced estrogen receptors compared to controls. In male offspring, all three groups exposed to insecticides exhibited reduced testosterone levels. Histopathological changes in the testes including vacuolation and desquamation of the seminiferous epithelium were observed only in the GX and GDi groups. The number of androgen receptors was reduced significantly in the testes and testicular morphometry revealed reduced tubule diameter, height of the seminiferous epithelium and total tubule length compared to the control. The biological insecticides, XenTari and Dipel, administered in sublethal doses to pregnant rats, caused reproductive changes in the offspring similar to those of the insecticide, deltamethrin.

Endocrine disrupting potential of selected azole and organophosphorus pesticide products through suppressing the dimerization of human androgen receptor in genomic pathway

Several pesticides widely used in agriculture have been considered to be endocrine disrupting chemicals through their binding affinities to estrogen or androgen receptors. This study was conducted to clarify the human androgen receptor (hAR)-mediated genomic endocrine disrupting mechanism of eight selected pesticide products by in vitro assay providing the Organization for Economic Co-operation and Development Test Guideline No. 458, 22Rv1/MMTV_GR-KO AR transcriptional activation assay and a homo-dimerization confirmation assay. None of the tested pesticide products showed an AR agonistic effect, whereas they were all determined to be AR antagonists at non-toxic concentrations. Also, the eight pesticide products were verified as true AR antagonists through a specificity control test. In the Bioluminescence Resonance Energy Transfer-based AR homo-dimerization confirmation assay, the eight pesticide products did not induce AR homo-dimerization. Additionally, western blotting revealed that none of the eight pesticide products induced AR translocation from the cytoplasm to the nucleus. In conclusion, we found for the first-time evidence to understand the AR-mediated endocrine disrupting mechanisms induced by selected azole and organophosphorus pesticide products.

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

BACKGROUND

Few studies have examined the adverse birth sizes of preconception exposure to organophosphate pesticides (OPs) in women undergoing in vitro fertilization (IVF).

OBJECTIVES

We investigated the relationship of preconception OP exposure with birth sizes among Chinese women undergoing IVF.

METHODS

This 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.

RESULTS

Women 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).

CONCLUSION

Preconception DEP concentration was associated with shortened gestational age and increased risk of preterm birth, and the association was more pronounced among boys than girls.

A comprehensive review on chlorpyrifos toxicity with special reference to endocrine disruption: Evidence of mechanisms, exposures and mitigation strategies

Chlorpyrifos (CPF) is a broad-spectrum chlorinated organophosphate (OP) pesticide used for the control of a variety of insects and pathogens in crops, fruits, vegetables, as well as households, and various other locations. The toxicity of CPF has been associated with neurological dysfunctions, endocrine disruption, and cardiovascular diseases (CVDs). It can also induce developmental and behavioral anomalies, hematological malignancies, genotoxicity, histopathological aberrations, immunotoxicity, and oxidative stress as evidenced by animal modeling. Moreover, eye irritation and dermatological defects are also reported due to CPF toxicity. The mechanism of action of CPF involves blocking the active sites of the enzyme, acetylcholinesterase (AChE), thereby producing adverse nervous system effects. Although CPF has low persistence in the body, its active metabolites, 3,5,6-trichloro-2-pyridinol (TCP), and chlorpyrifos-oxon (CPO) are comparatively more persistent, albeit equally toxic, and thus produce serious health complications. The present review has been compiled taking into account the work related to CPF toxicity and provides a brief compilation of CPF-induced defects in animals and humans, emphasizing the abnormalities leading to endocrine disruption, neurotoxicity, reproductive carcinogenesis, and disruptive mammary gland functionality. Moreover, the clinical signs and symptoms associated with the CPF exposure along with the possible pharmacological treatment are reported in this treatise. Additionally, the effect of food processing methods in reducing CPF residues from different agricultural commodities and dietary interventions to curtail the toxicity of CPF has also been discussed.

Organophosphate Pesticide Exposure and Breast Cancer Risk: A Rapid Review of Human, Animal, and Cell-Based Studies

BACKGROUND

Organophosphate pesticides (OPs) are one of the most commonly used classes of insecticides in the U.S., and metabolites of OPs have been detected in the urine of >75% of the U.S.

POPULATION

While studies have shown that OP exposure is associated with risk of neurological diseases and some cancers, the relationship between OP exposure and breast cancer risk is not well understood.

METHODS

The aim of this rapid review was to systematically evaluate published literature on the relationship between OP exposure and breast cancer risk, including both epidemiologic and laboratory studies. Twenty-seven full-text articles were reviewed by searching on Pubmed, EMBASE, and Cochrane databases.

RESULTS

Some human studies showed that malathion, terbufos, and chlorpyrifos were positively associated with human breast cancer risk, and some laboratory studies demonstrated that malathion and chlorpyrifos have estrogenic potential and other cancer-promoting properties. However, the human studies were limited in number, mostly included agricultural settings in several geographical areas in the U.S., and did not address cumulative exposure.

CONCLUSIONS

Given the mixed results found in both human and laboratory studies, more research is needed to further examine the relationship between OP exposure and breast cancer risk, especially in humans in non-agricultural settings.

A case-control study of breast cancer risk and ambient exposure to pesticides

Background:

While the estrogenic properties of certain pesticides have been established, associations between pesticide exposure and risk of breast cancer have been inconsistently observed. We investigated the relation between pesticide exposure and breast cancer risk using methods capable of objectively assessing exposure to specific pesticides occurring decades before diagnosis.

Methods:

A case–control study was conducted to evaluate the risk of postmenopausal breast cancer associated with historic pesticide exposure in California’s Central Valley, the most agriculturally productive region in the United States where pesticide drift poses a major source of nonoccupational exposure. Residential and occupational histories were linked to commercial pesticide reports and land use data to determine exposure to specific chemicals. Cases (N = 155) were recruited from a population-based cancer registry, and controls (N = 150) were obtained from tax assessor and Medicare list mailings.

Results:

There was no association between breast cancer and exposure to a selected group of organochlorine pesticides thought to have synergistic endocrine-disrupting potential; however, breast cancer was three times as likely to occur among women exposed to chlorpyrifos compared with those not exposed, after adjusting for exposure to other pesticides including organochlorines (OR = 3.22; 95% CI = 1.38, 7.53).

Conclusions:

Organophosphate pesticides, such as chlorpyrifos, have rarely been evaluated in studies of breast cancer risk. Additional research is needed to confirm these findings and to better understand the underlying mechanisms given that chlorpyrifos has been detected in local air monitoring at levels of concern for residents living in the agricultural regions where it is used.

Molecular and clinical aspects of embryotoxicity induced by acetylcholinesterase inhibitors

Acetylcholinesterase inhibitors are widely used for a variety of medical, agricultural and public health purposes. Consequently, exposure is highly possible during lifetime. However, their systematic use raises concerns for the potential impact on the fetus and newborn since these substances may affect angiogenesis, the neonatal and maternal intensive care, neuroimmune function and response, mammary growth/lactation via cholinergic/non-cholinergic central and peripheral neuroendocrine pathways. New methodologies, neuroscientific technologies and research studies are needed to harness existing knowledge along with the proper management, availability for new acetylcholinesterase inhibitors, with stable pharmacodynamics and clinical outcomes.

Magnetic dispersive micro solid-phase extraction and gas chromatography determination of organophosphorus pesticides in strawberries

Magnetic nanoparticles (MNPs) with different sizes and characteristics were synthesized to be used as a QuEChERS sorbents for the determination of seven organophosphorus pesticides (OPPs) in strawberries by gas chromatography analysis with flame photometric and mass spectrometry detection. To achieve the optimum conditions of modified QuEChERS procedure several parameters affecting the cleanup efficiency including the amount of the sorbents and cleanup time were investigated. The results were compared with classical QuEChERS methodologies and the modified QuEChERS procedure using MNPs showed the better performance. Under the optimum conditions of the new methodology, three spiking levels (25, 50 and 100 μg kg^-1) were evaluated in a strawberry sample. The results showed that the average recovery was 93% and the relative standard deviation was less than 12%. The enrichment factor ranged from 111 to 145%. The good linearity with coefficients of determination of 0.9904-0.9991 was obtained over the range of 25-250 μg kg^-1 for 7 OPPs. It was determined that the MNPs have an excellent function as sorbent when purified even using less amount of sorbents and the magnetic properties allowed non-use of the centrifugation in cleanup step. The new methodology was applied in strawberry samples from conventional and organic farming. The new sorbents were successfully applied for extraction and determination of OPPs in strawberries.

Toxicological evaluation of flumequine in pubertal male rats after oral administration for six weeks

Introduction

Veterinarians use flumequine (FLU) widely but its toxicological effects are still unclear.

Material and Methods

FLU doses of 53, 200, or 750 mg/kg were administered orally for six weeks to pubertal male rats for evaluation of their toxicity.

Results

Weight gain was poorer after seven days of exposure to FLU 750, but relative weights of the brain, adrenal and thyroid glands, and testes were notably higher. Haematological and lipid profile parameters, cardiac markers, and inorganic phosphate significantly increased in the FLU 750 group. Blood glucose, oestradiol and serum concentrations of immunoglobulins G (IgG) and E (IgE) significantly decreased after treatment. The levels of interleukins 10 (IL-10) and 6 (IL-6) fell significantly in the FLU 200 and FLU 750 groups. Cytochrome P450, family 1, subfamily A, polypeptide 1 (CYP1A1) and cyclooxygenase-2 (Cox-2) expression amplified after treatment. Serum levels of free triiodothyronine (fT3) and free thyroxine (fT4) reduced in the FLU 200 and FLU 750 groups without changes in total T3 or T4 level. All doses of FLU significantly depressed concentrations of thyroid-stimulating hormone (TSH) and testosterone. Histopathology of thyroid glands from rats treated with FLU 750 showed degeneration and depletion of thyroid follicular epithelial cells. Expression of 8-hydroxydeoxyguanosine (8-OHdG) was increased in a dose-dependent manner in the brain, but decreased in the testes. Expression of CYP1A1 increased in the adrenal and pituitary glands.

Conclusion

The results of this study suggest that the toxicity of FLU in rats is an effect of its disruptive influence on the pituitary-thyroid hormonal system and on the dysfunction of the immune system.

Interactions of organophosphorus pesticides with solute carrier (SLC) drug transporters

1. Organophosphorus pesticides (OPs) are known to interact with human ATP-binding cassette drug efflux pumps. The present study was designed to determine whether they can also target activities of human solute carrier (SLC) drug transporters. 2. The interactions of 13 OPs with SLC transporters involved in drug disposition, such as organic cation transporters (OCTs), multidrug and toxin extrusion proteins (MATEs), organic anion transporters (OATs) and organic anion transporting polypeptides (OATPs), were mainly investigated using transporter-overexpressing cell clones and fluorescent or radiolabeled reference substrates. 3. With a cut-off value of at least 50% modulation of transporter activity by 100 µM OPs, OAT1 and MATE2-K were not impacted, whereas OATP1B1 and MATE1 were inhibited by two and three OPs, respectively. OAT3 activity was similarly blocked by three OPs, and was additionally stimulated by one OP. Five OPs cis-stimulated OATP2B1 activity. Both OCT1 and OCT2 were inhibited by the same eight OPs, including fenamiphos and phosmet, with IC₅₀ values however in the 3-30 µM range, likely not relevant to environmental exposure. 4. These data demonstrated that various OPs inhibit SLC drug transporter activities, especially those of OCT1 and OCT2, but only when used at high concentrations not expected to occur in environmentally-exposed humans.

Toxicological Evaluation of Flumequine in Pubertal Male Rats After Oral Administration for Six Weeks

INTRODUCTION

Veterinarians use flumequine (FLU) widely but its toxicological effects are still unclear.

MATERIAL AND METHODS

FLU doses of 53, 200, or 750 mg/kg were administered orally for six weeks to pubertal male rats for evaluation of their toxicity.

RESULTS

Weight gain was poorer after seven days of exposure to FLU 750, but relative weights of the brain, adrenal and thyroid glands, and testes were notably higher. Haematological and lipid profile parameters, cardiac markers, and inorganic phosphate significantly increased in the FLU 750 group. Blood glucose, oestradiol and serum concentrations of immunoglobulins G (IgG) and E (IgE) significantly decreased after treatment. The levels of interleukins 10 (IL-10) and 6 (IL-6) fell significantly in the FLU 200 and FLU 750 groups. Cytochrome P450, family 1, subfamily A, polypeptide 1 (CYP1A1) and cyclooxygenase-2 (Cox-2) expression amplified after treatment. Serum levels of free triiodothyronine (fT3) and free thyroxine (fT4) reduced in the FLU 200 and FLU 750 groups without changes in total T3 or T4 level. All doses of FLU significantly depressed concentrations of thyroid-stimulating hormone (TSH) and testosterone. Histopathology of thyroid glands from rats treated with FLU 750 showed degeneration and depletion of thyroid follicular epithelial cells. Expression of 8-hydroxydeoxyguanosine (8-OHdG) was increased in a dose-dependent manner in the brain, but decreased in the testes. Expression of CYP1A1 increased in the adrenal and pituitary glands.

CONCLUSION

The results of this study suggest that the toxicity of FLU in rats is an effect of its disruptive influence on the pituitary-thyroid hormonal system and on the dysfunction of the immune system.

Individual and combined effect of chlorpyrifos and cypermethrin on reproductive system of adult male albino rats

Commercial mixtures of chlorpyrifos and cypermethrin pesticides are widely used to enhance the toxic effects of cypermethrin on target insects. So, the purpose of the current study was to evaluate the individual and combined toxic effects of chlorpyrifos (CPF) and cypermethrin (CYP) on reproductive system of adult male albino rats. Forty adult male albino rats were randomized into main four groups: group I (control group) included 16 rats, subdivided into negative and positive control; group II (eight rats) received chlorpyrifos 6.75 mg/kg b.w./orally∕daily); group III (eight rats) (received cypermethrin 12.5 mg/kg b.w./orally∕daily); and group IV (eight rats) (received chlorpyrifos and cypermethrin at the same previously mentioned doses). All treatments were given by oral gavage for 12 weeks. We found that single CPF and CYP exposures significantly have adverse effects on reproductive function of adult male albino rats manifested by reduced testicular weight, decreased sperm count, motility and viability, significantly increased percent of morphologically abnormal spermatozoa, and significant increments in sperm DNA fragmentation index (DFI) with respect to control group. Furthermore, serum follicle stimulating hormone, luteinizing hormone, and testosterone levels were decreased significantly compared to control group. This was accompanied with histopathological changes in the testis of rats such as necrosis, degeneration, decreasing number of spermatogenic cells in some seminiferous tubules, edema, congested blood vessels, and exudate in interstitial tissue of the testis. Notably, all these changes were exaggerated in rats treated concomitantly with chlorpyrifos and cypermethrin rendering the mixture more toxic than the additive effects of each compound and causing greater damage on the reproductive system of male albino rats than the individual pesticides.

Enhancement of plasmonic resonance through an exchange reaction on the surface of silver nanoparticles: application to the highly selective detection of triazophos pesticide in food and vegetable samples

The proposed method is based on the aggregation of AgNPs due to the exchange of citrate ions from the surface of NPs with triazophos pesticide and causes the color change and red shift in LSPR of AgNPs in the UV-visible region used as sensing probe.

Effect on the H19 gene methylation of sperm and organs of offspring after chlorpyrifos-methyl exposure during organogenesis period

To elucidate the effect on the H19 gene methylation of sperm and organs in offspring by chlorpyrifos-methyl (CPM) exposure during organogenesis period, CPM was administered at doses of 4 (CPM4), 20 (CPM20), and 100 (CPM100) mg/kg bw/day from 7 days post coitum (d.p.c.) to 17 d.p.c. after mating CAST/Ei (♂) and B6 (♀). Anogenital distance (AGD) was measured at postnatal day (PND) 21. Clinical signs, body weights, feed and water consumption, organs weights, serum hormone values, and H19 methylation level of organ and sperm were measured at PND63. Body weights were significantly lower than control until PND6. AGD was significantly decreased in the CPM100 group in males and increased in the CPM20 group in females. The absolute weights of the thymus and epididymis were significantly increased for males in all of CPM treatment groups. In the CPM20 group, absolute weights of liver, kidney, heart, lung, spleen, prostate gland, and testes were significantly increased. Testosterone concentrations in serum were significantly increased by CPM treatment in males. H19 methylation level of liver and thymus showed decreased pattern in a dose-dependent manner in males. The levels of H19 methylation in sperm were 73.76 ± 7.16% (Control), 57.84 ± 12.94% (CPM4), 64.24 ± 3.79% (CPM20), and 64.24 ± 3.79% (CPM100). Conclusively, CPM exposure during organogenesis period can disrupt H19 methylation in sperm, liver, and thymus and disturb the early development of offspring.

Dialkyl phosphate urinary metabolites and chromosomal abnormalities in human sperm

BACKGROUND

The past decade has seen numerous human health studies seeking to characterize the impacts of environmental exposures, such as organophosphate (OP) insecticides, on male reproduction. Despite an extensive literature on OP toxicology, many hormone-mediated effects on the testes are not well understood.

OBJECTIVES

This study investigated environmental exposures to OPs and their association with the frequency of sperm chromosomal abnormalities (i.e., disomy) among adult men.

METHODS

Men (n=159) from a study assessing the impact of environmental exposures on male reproductive health were included in this investigation. Multi-probe fluorescence in situ hybridization (FISH) for chromosomes X, Y, and 18 was used to determine XX18, YY18, XY18 and total disomy in sperm nuclei. Urine was analyzed using gas chromatography coupled with mass spectrometry for concentrations of dialkyl phosphate (DAP) metabolites of OPs [dimethylphosphate (DMP); dimethylthiophosphate (DMTP); dimethyldithiophosphate (DMDTP); diethylphosphate (DEP); diethylthiophosphate (DETP); and diethyldithiophosphate (DEDTP)]. Poisson regression was used to model the association between OP exposures and disomy measures. Incidence rate ratios (IRRs) were calculated for each disomy type by exposure quartiles for most metabolites, controlling for age, race, BMI, smoking, specific gravity, total sperm concentration, motility, and morphology.

RESULTS

A significant positive trend was seen for increasing IRRs by exposure quartiles of DMTP, DMDTP, DEP and DETP in XX18, YY18, XY18 and total disomy. A significant inverse association was observed between DMP and total disomy. Findings for total sum of DAP metabolites concealed individual associations as those results differed from the patterns observed for each individual metabolite. Dose-response relationships appeared nonmonotonic, with most of the increase in disomy rates occurring between the second and third exposure quartiles and without additional increases between the third and fourth exposure quartiles.

CONCLUSIONS

This is the first epidemiologic study of this size to examine the relationship between environmental OP exposures and human sperm disomy outcomes. Our findings suggest that increased disomy rates were associated with specific DAP metabolites, suggesting that the impacts of OPs on testis function need further characterization in epidemiologic studies.

Malathion-induced hepatotoxicity in male Wistar rats: biochemical and histopathological studies

The increasing use of organophosphorus pesticides in the environment constitutes an ecotoxicological hazard especially for humans and non-target animals. Hereby, we analyzed the toxic effects of malathion on the histological structure of liver and biochemical parameters in male rats. Three groups received daily different amounts of malathion: 1/1000, 1/100, and 1/10 LD50 for 30 days. The weights of treated rat's liver have increased. Analyzed tissues showed centrilobular and sinusoidal congestion, hepatocyte hypertrophy, cellular vacuolization, anucleated hepatocytes, depletion of organelles affecting the majority of cells, and presence of necrotic foci into the hepatic parenchyma. Histological sections of the liver showed important hepatocyte glycogen storage. We conclude that malathion stimulates the filing of glycogen in a dose-dependent manner. Biochemical parameters showed that alanine transaminase (ALT), aspartate transaminase (AST), gamma glutamyl transpeptidase (GGT), lactate dehydrogenase (LDH), and alkaline phosphatase (ALP) levels increased in the treated groups when the level of total protein decreased in intoxicated groups.

Organophosphate insecticide use and cancer incidence among spouses of pesticide applicators in the Agricultural Health Study

OBJECTIVES

Organophosphates (OPs) are among the most commonly used insecticides. OPs have been linked to cancer risk in some epidemiological studies, which have been largely conducted in predominantly male populations. We evaluated personal use of specific OPs and cancer incidence among female spouses of pesticide applicators in the prospective Agricultural Health Study cohort.

METHODS

At enrolment (1993-1997), spouses provided information about ever use of specific pesticides, including 10 OPs, demographic information, reproductive health history and other potential confounders. We used Poisson regression to estimate relative risks (RRs) and 95% CIs for all cancers diagnosed through 2010 for North Carolina and through 2011 for Iowa.

RESULTS

Among 30,003 women, 25.9% reported OP use, and 718 OP-exposed women were diagnosed with cancer during the follow-up period. Any OP use was associated with an elevated risk of breast cancer (RR=1.20, 95% CI 1.01 to 1.43). Malathion, the most commonly reported OP, was associated with increased risk of thyroid cancer (RR=2.04, 95% CI 1.14 to 3.63) and decreased risk of non-Hodgkin lymphoma (RR=0.64, 95% CI 0.41 to 0.99). Diazinon use was associated with ovarian cancer (RR=1.87, 95% CI 1.02 to 3.43).

CONCLUSIONS

We observed increased risk with OP use for several hormonally-related cancers, including breast, thyroid and ovary, suggesting potential for hormonally-mediated effects. This study represents the first comprehensive analysis of OP use and cancer risk among women, and thus demonstrates a need for further evaluation.

Effect of nonpersistent pesticides on estrogen receptor, androgen receptor, and aryl hydrocarbon receptor

Nonpersistent pesticides are considered less harmful for the environment, but their impact as endocrine disruptors has not been fully explored. The pesticide Switch was applied to grape vines, and the maximum residue concentration of its active ingredients was quantified. The transactivation potential of the pesticides Acorit, Frupica, Steward, Reldan, Switch, Cantus, Teldor, and Scala and their active compounds (hexythiazox, mepanipyrim, indoxacarb, chlorpyrifos-methyl, cyprodinil, fludioxonil, boscalid, fenhexamid, and pyrimethanil) were tested on human estrogen receptor α (ERα), androgen receptor (AR) and arylhydrocarbon receptor (AhR) in vitro. Relative binding affinities of the pure pesticide constituents for AR and their effect on human breast cancer and prostate cancer cell lines were evaluated. Residue concentrations of Switch's ingredients were below maximum residue limits. Fludioxonil and fenhexamid were ERα agonists (EC50 -values of 3.7 and 9.0 μM, respectively) and had time-dependent effects on endogenous ERα-target gene expression (cyclin D1, progesterone receptor, and nuclear respiratory factor 1) in MCF-7 human breast cancer cells. Fludioxonil, mepanipyrim, cyprodinil, pyrimethanil, and chlorpyrifos-methyl were AhR-agonists (EC50 s of 0.42, 0.77, 1.4, 4.6, and 5.1 μM, respectively). Weak AR binding was shown for chlorpyrifos-methyl, cyprodinil, fenhexamid, and fludioxonil. Assuming a total uptake which does not take metabolism and clearance rates into account, our in vitro evidence suggests that pesticides could activate pathways affecting hormonal balance, even within permitted limits, thus potentially acting as endocrine disruptors.

Exposure of pregnant mice to chlorpyrifos-methyl alters embryonic H19 gene methylation patterns

The aim of this study was to identify whether chlorpyrifos methyl (CPM) exposure during pregnancy leads to changes in the methylation patterns of H19 gene. CPM 4, 20, 100 mg/kg bw/day was administered to 4 pregnant mice per group between 7 and 12 days post coitum (d.p.c.). Pregnant mice were killed at 13 d.p.c. The genomic methylation in primordial germ cells (PGCs) and fetal organs (the liver, intestine, and placenta) was examined. Four polymorphism sites in the H19 alleles of maternal (C57BL/6J) and paternal (CAST/Ei) alleles were identified at nucleotide position 1407, 1485, 1566, and 1654. The methylation patterns of 17 CpG sites were analyzed. The methylation level in male and female PGCs was not altered by CPM treatment in the maternal allele H19. The methylation level of the paternal H19 allele was altered in only male PGCs in response to the CPM treatment. The methylation level at a binding site for the transcriptional regulator CTCF2 was higher than that at the CTCF1 binding site in all CPM-treated groups. In the placenta, the aggregate methylation level of H19 was 56.89%in control group. But, those levels were ranged from 47.7% to 49.89% after treatment with increasing doses of CPM. H19 gene from the liver and intestine of 13 d.p.c. fetuses treated with CPM was hypomethylated as compared with controls, although H19 mRNA expression was unaltered. In the placenta, H19 expression was slightly increased in the CPM-treated group, although not significantly. IGF2 expression levels were not significantly changed in the placenta. In conclusion, CPM exposure during pregnancy alters the methylation status of the H19 gene in PGCs and embryonic tissues. We infer that these alterations are likely related to changes in DNA demethylase activity.

Mishandling and exposure of farm workers in Qatar to organophosphate pesticides

We used a combination of subjective (questionnaire) and objective (urinary metabolites) measurements to evaluate factors that can predict the exposure of farm workers in Qatar to organophosphate pesticides and to assess whether the levels of exposure are associated with any self-reported health outcomes. The results show that pesticides were being extensively mishandled in the farms. Very few (<2%) of the farm workers knew the names of the pesticide they were using, and about one-third of the participants did not know the amount of pesticides to be applied to the crops. Nearly all (96%) of the participants had participated in mixing pesticides together before use and few (29%) used protective clothing while engaged in this operation. A significant number of participants (18%) had no knowledge that pesticides are a health hazard. At least one dialkyllphosphate (DAP) metabolite was detected in every worker. The geometric mean (GM) concentration of the dimethylalkylphosphates (DMAP) was 108 nM (range, from below the limit of detection (LOD) to 351 nM), and the GM for the diethylalkylphosphates (DEAP) was 43 nM (range, LOD-180 nM). The GM for total concentration of the metabolites (DAP) of 146 nM (maximum value estimated to be 531 nM) is below the values that have been reported for farmers in some countries, but higher than the levels in the general populations of many countries. We explored the influence of metal exposure and found consistent and negative relationships between the DAP metabolites and the concentrations of most of the trace elements in the urine of the farm workers; the negative associations were statistically significant for Cr, Mn, Fe, Ni, As, and Pb. We suspect that the negative associations are not source-dependent but may be reflective of antagonistic relationships in human metabolism of OPPs and trace metals; hence we recommend that metals should be included as co-factors in assessing the health effects of OPP exposure.

Simultaneous Detection of Fenitrothion and Chlorpyrifos-Methyl with a Photonic Suspension Array

A technique was developed for simultaneous detection of fenitrothion (FNT) and chlorpyrifos-methyl (CLT) using a photonic suspension array based on silica colloidal crystal beads (SCCBs). The SCCBs were encoded with the characteristic reflection peak originating from the stop-band of colloidal crystal. This approach avoids the bleaching, fading or potential interference seen when encoding by fluorescence. SCCBs with a nanopatterned surface had increased biomolecule binding capacity and improved stability. Under optimal conditions, the proposed suspension array allowed simultaneous detection of the selected pesticides in the ranges of 0.25 to 1024 ng/mL and 0.40 to 735.37 ng/mL, with the limits of detection (LODs) of 0.25 and 0.40 ng/mL, respectively. The suspension array was specific and had no significant cross-reactivity with other chemicals. The mean recoveries in tests in which samples were spiked with target standards were 82.35% to 109.90% with a standard deviation within 9.93% for CLT and 81.64% to 108.10% with a standard deviation within 8.82% for FNT. The proposed method shows a potentially powerful capability for fast quantitative analysis of pesticide residues.

Health risk assessment of exposure to chlorpyrifos and dichlorvos in children at childcare facilities

The present study evaluated 168 childcare facilities from 6 cities in South Korea to assess exposure to organophosphorus pesticides (OPs) in children through 4 major pathways (indoor air, indoor dust, surface wipe of indoor objects, and hand wash water of children). The Excess Cancer Risk (ECR) was calculated based on the Cancer Potency Factor (CPF) and Age Dependent Adjustment Factor (ADAF) in adults. Dichlorvos residues were detected in the indoor air, indoor dust, surface wipes of indoor objects, and the hand wash water of children at frequencies of 47.4, 90, 100, and 100%, respectively. After revision based on the ADAF, total cancer risk in the 50th percentile was 3.99×10(-3) for inhalation, oral intake, and dermal contact in children ages 3 to 4 and 4.63×10(-4) in kindergarteners ages 5 to 6. Inhalation was the primary pathway of pesticide exposure in children in childcare facilities. Children ages 3 to 4 in daycare centers had a Hazard Quotient (HQ) of 0.5 for dichlorvos, which was 50% lower than the risk criterion level of 1 but was higher than the 95% percentile with a HQ of 1.9. This study postulates that children in childcare facilities may be exposed to specific OPs.

Using in vitro high throughput screening assays to identify potential endocrine-disrupting chemicals

BACKGROUND

Over the past 20 years, an increased focus on detecting environmental chemicals that pose a risk of adverse effects due to endocrine disruption has driven the creation of the U.S. Environmental Protection Agency (EPA) Endocrine Disruptor Screening Program (EDSP). Thousands of chemicals are subject to the EDSP; thus, processing these chemicals using current test batteries could require millions of dollars and decades. A need for increased throughput and efficiency motivated the development of methods using in vitro high throughput screening (HTS) assays to prioritize chemicals for EDSP Tier 1 screening (T1S).

OBJECTIVE

In this study we used U.S. EPA ToxCast HTS assays for estrogen, androgen, steroidogenic, and thyroid-disrupting mechanisms to classify compounds and compare ToxCast results to in vitro and in vivo data from EDSP T1S assays.

METHOD

We implemented an iterative model that optimized the ability of endocrine-related HTS assays to predict components of EDSP T1S and related results. Balanced accuracy was used as a measure of model performance.

RESULTS

ToxCast estrogen receptor and androgen receptor assays predicted the results of relevant EDSP T1S assays with balanced accuracies of 0.91 (p < 0.001) and 0.92 (p < 0.001), respectively. Uterotrophic and Hershberger assay results were predicted with balanced accuracies of 0.89 (p < 0.001) and 1 (p < 0.001), respectively. Models for steroidogenic and thyroid-related effects could not be developed with the currently published ToxCast data.

CONCLUSIONS

Overall, results suggest that current ToxCast assays can accurately identify chemicals with potential to interact with the estrogenic and androgenic pathways, and could help prioritize chemicals for EDSP T1S assays.

Changes in male hormone profile after occupational organophosphate exposure. A longitudinal study

There is a growing concern about the endocrine effects of long-term, low-level exposure to organophosphate (OP) compounds. Studies on experimental animals have found that OP pesticides have an impact on the endocrine system and a few clinical and epidemiological studies have also shown that OPs may affect the male hormone profile, although results are inconsistent. We have evaluated the effect of exposure to OP pesticides, measured through urinary levels of six dialkylphosphate (DAP) metabolites, on male hormone profile in 136 floriculture workers from the State of Mexico and Morelos during two agricultural periods with different degree of pesticide exposure. Generalized estimated equations (GEE) models were developed and adjusted for several potential confounders, including PON1 enzyme activity, as a biomarker of susceptibility, and serum levels of p,p'-DDE, a metabolite of the pesticide DDT widely used in Mexico until 1999 for control of agricultural pests and malaria. Exposure of male floriculture workers to OP pesticides was associated with increased serum levels of follicle-stimulating hormone (FSH) and prolactin and with decreased serum testosterone and inhibin B levels. Among all DAPs tested, only DETP was inversely associated with luteinizing hormone (LH). Estradiol showed a marginally significant positive trend with DEP and DETP derivatives. In conclusion, OP pesticides may have an impact on the endocrine function because of their potential to modify the male hormone profile as a function of the type of pesticide used as well as the magnitude of exposure.

Does the home environment and the sex of the child modify the adverse effects of prenatal exposure to chlorpyrifos on child working memory?

Prenatal exposure to chlorpyrifos (CPF), an organophosphorus insecticide, has long been associated with delayed neurocognitive development and most recently with decrements in working memory at age 7. In the current paper, we expanded the previous work on CPF to investigate how additional biological and social environmental factors might create or explain differential neurodevelopmental susceptibility, focusing on main and moderating effects of the quality of the home environment (HOME) and child sex. We evaluate how the quality of the home environment (specifically, parental nurturance and environmental stimulation) and child sex interact with the adverse effects of prenatal CPF exposure on working memory at child age 7years. We did not observe a remediating effect of a high quality home environment (either parental nurturance or environmental stimulation) on the adverse effects of prenatal CPF exposure on working memory. However, we detected a borderline significant interaction between prenatal exposure to CPF and child sex (B (95% CI) for interaction term=-1.714 (-3.753 to 0.326)) suggesting males experience a greater decrement in working memory than females following prenatal CPF exposure. In addition, we detected a borderline interaction between parental nurturance and child sex (B (95% CI) for interaction term=1.490 (-0.518 to 3.499)) suggesting that, in terms of working memory, males benefit more from a nurturing environment than females. To our knowledge, this is the first investigation into factors that may inform an intervention strategy to reduce or reverse the cognitive deficits resulting from prenatal CPF exposure.

Cytotoxicity and DNA damage of five organophosphorus pesticides mediated by oxidative stress in PC12 cells and protection by vitamin E

Previous studies have demonstrated that pesticides could induce cytotoxicity and genotoxicity in vivo and in vitro, and that oxidative stress may be an important factor involved. However, investigations comparing the capability of different organophosphorous (OP) compounds to induce cytotoxicity, genotoxicity and oxidative stress are limited. Hence, the aim of this paper was to access the cytotoxic and genotoxic effects of five OPs or metabolites, Acephate (ACE), Methamidophos (MET), Chloramidophos (CHL), Malathion (MAT) and Malaoxon (MAO), and to clarify the role of oxidative stress, using PC12 cells. The results demonstrated that MET, MAT and MAO caused significant inhibition of cell viability and increased DNA damage in PC12 cells at 40 mg L(-1). MAO was more toxic than the other OPs. ACE, MET, MAT and MAO increased the levels of intracellular reactive oxygen species (ROS) and malondialdehyde (MDA), and decreased the activity of superoxide dismutase (SOD), catalase (CAT) and glutathione (GSH) at 20 mg L(-1) and 40 mg L(-1) to different degrees. Pre-treatment with vitamin E(600 μM)caused a significant attenuation in the cytotoxic and genotoxic effect; pre-treatment reversed subsequent OP-induced elevation of peroxidation products and the decline of anti-oxidant enzyme activities. These results indicate that oxidative damage is likely to be an initiating event that contributes to the OP-induced cytotoxicity.

Protective effects of vitamins C and E against hepatotoxicity induced by methyl parathion in rats

Male rats were given vitamins C+E, methyl parathion, or both daily via gavage for seven weeks. Body weight was decreased while liver weight increased significantly at the end of fourth and seventh weeks in the methyl parathion- and methyl parathion plus vitamin-treated groups. Serum total protein, albumin, triglyceride, low density lipoprotein-cholesterol (VLDL-cholesterol) levels decreased, and serum alkaline phosphatase (ALP), alanine aminotransferase (ALT), aspartate aminotransferase (AST), γ-glutamyl-transferase (GGT), lactate dehydrogenase (LDH), and total cholesterol levels increased significantly in the methyl parathion- and the methyl parathion plus vitamin-treated rats. There was a statistically significant difference for all biochemical parameters when the methyl parathion plus vitamin-treated group was compared with methyl parathion-treated group. In electron microscopic investigation, cytopathological alterations were observed in hepatocytes of the methyl parathion- and the methyl parathion plus vitamin-treated rats. As a result, methyl parathion-induced hepatotoxicity is reduced by vitamins C+E, but vitamins C+E did not provide complete protection.

Effect of endocrine disruptor pesticides: a review

Endocrine disrupting chemicals (EDC) are compounds that alter the normal functioning of the endocrine system of both wildlife and humans. A huge number of chemicals have been identified as endocrine disruptors, among them several pesticides. Pesticides are used to kill unwanted organisms in crops, public areas, homes and gardens, and parasites in medicine. Human are exposed to pesticides due to their occupations or through dietary and environmental exposure (water, soil, air). For several years, there have been enquiries about the impact of environmental factors on the occurrence of human pathologies. This paper reviews the current knowledge of the potential impacts of endocrine disruptor pesticides on human health.

The organophosphate Chlorpyrifos interferes with the responses to 17β-estradiol in the digestive gland of the marine mussel Mytilus galloprovincialis

Background

Many pesticides have been shown to act as endocrine disrupters. Although the potencies of currently used pesticides as hormone agonists/antagonists are low compared with those of natural ligands, their ability to act via multiple mechanisms might enhance the biological effect. The organophosphate Chlorpyrifos (CHP) has been shown to be weakly estrogenic and cause adverse neurodevelopmental effects in mammals. However, no information is available on the endocrine effects of CHP in aquatic organisms. In the digestive gland of the bivalve Mytilus galloprovincialis, a target tissue of both estrogens and pesticides, the possible effects of CHP on the responses to the natural estrogen 17β-estradiol (E₂) were investigated.

Methodology/Principal Findings

Mussels were exposed to CHP (4.5 mg/l, 72 hrs) and subsequently injected with E₂ (6.75 ng/g dw). Responses were evaluated in CHP, E₂ and CHP/E₂ treatment groups at 24 h p.i. by a biomarker/transcriptomic approach. CHP and E₂ induced additive, synergistic, and antagonistic effects on lysosomal biomarkers (lysosomal membrane stability, lysosome/cytoplasm volume ratio, lipofuscin and neutral lipid accumulation). Additive and synergistic effects were also observed on the expression of estrogen-responsive genes (GSTπ, catalase, 5-HTR) evaluated by RT-Q-PCR. The use of a 1.7K cDNA Mytilus microarray showed that CHP, E₂ and CHP/E₂, induced 81, 44, and 65 Differentially Expressed Genes (DEGs), respectively. 24 genes were exclusively shared between CHP and CHP/E₂, only 2 genes between E₂ and CHP/E₂. Moreover, 36 genes were uniquely modulated by CHP/E₂. Gene ontology annotation was used to elucidate the putative mechanisms involved in the responses elicited by different treatments.

Conclusions

The results show complex interactions between CHP and E₂ in the digestive gland, indicating that the combination of certain pesticides and hormones may give rise to unexpected effects at the molecular/cellular level. Overall, these data demonstrate that CHP can interfere with the mussel responses to natural estrogens.