Pesticide exposures and fetal death: a review of the epidemiologic literature

Harmful Effect of Intrauterine Smoke Exposure on Neuronal Control of "Fetal Breathing System" in Stillbirths

This article is aimed to contribute to the current knowledge on the role of toxic substances such as nicotine on sudden intrauterine unexplained deaths’ (SIUDS’) pathogenetic mechanisms. The in-depth histopathological examination of the autonomic nervous system in wide groups of victims of SIUDS (47 cases) and controls (20 cases), with both smoking and no-smoking mothers, highlighted the frequent presence of the hypodevelopment of brainstem structures checking the vital functions. In particular, the hypoplasia of the pontine parafacial nucleus together with hypoplastic lungs for gestational age were observed in SIUDS cases with mothers who smoked cigarettes, including electronic ones. The results allow us to assume that the products of cigarette smoke during pregnancy can easily cross the placental barrier, thus entering the fetal circulation and damaging the most sensitive organs, such as lungs and brain. In a non-negligible percentage of SIUDS, the mothers did not smoke. Furthermore, based on previous and ongoing studies conducted through analytical procedures and the use of scanning electron microscopy, the authors envisage the involvement of toxic nanoparticles (such as agricultural pesticides and nanomaterials increasingly used in biomedicine, bioscience and biotechnology) in the death pathogenesis, with similar mechanisms to those of nicotine.

Selection in utero and population health: Theory and typology of research

Public health researchers may assume, based on the fetal origins literature, that "scarring" of birth cohorts describes the population response to modern-day stressors. We contend, based on extensive literature concerned with selection in utero, that this assumption remains questionable. At least a third and likely many more of human conceptions fail to yield a live birth. Those that survive to birth, moreover, do not represent their conception cohort. Increasing data availability has led to an improved understanding of selection in utero and its implications for population health. The literature describing selection in utero, however, receives relatively little attention from social scientists. We aim to draw attention to the rich theoretical and empirical literature on selection in utero by offering a typology that organizes this diverse work along dimensions we think important, if not familiar, to those studying population health. We further use the typology to identify important gaps in the literature. This work should interest social scientists for two reasons. First, phenomena of broad scholarly interest (i.e., social connectivity, bereavement) affect the extent and timing of selection in utero. Second, the life-course health of a cohort depends in part on the strength of such selection. We conclude by identifying new research directions and with a reconciliation of the apparent contradiction between the "fetal origins" literature and that describing selection in utero.

Study of the Effects of Diazinon on Fetal Liver in BALB/c Mice

Background

Diazinon is an organophosphate that is broadly used as a pesticide to control insects and environmental pollutions. This toxic material is absorbed via inhalation, contact, or digestion and affects different tissues.

Objectives

This research was a histomorphometric and immunohistochemical study of the fetal liver of mice after exposure to Diazinon.

Materials and Methods

Twenty-five pregnant BALB/c mice (25 - 30 gr) were divided into five equal groups in the animal lab of Baqiyatallah University of Medical Sciences, Tehran, Iran. The normal group was without any intervention, and two sham groups received an emulsifier as 0.52 and 5.2 μL/volume (5000 cc in desiccator) and two experimental groups received Diazinon 1.3 and 13μL/volume from the seventh to eighteenth days of pregnancy every other day via forty minutes of inhalation. The pregnant mice were killed on the eighteenth day of gestation and their fetuses were removed and evaluated for fetal growth and liver development. Five fixed fetuses were dehydrated through a series of graded ethanol, embedded in paraffin wax and their whole bodies were sectioned sagittally and stained via the hematoxylin-eosin method. Quantitative computer-assisted morphometric studies were done on the fetal liver tissues occupied by hepatocytes, blood islands, liver sinusoids, and apoptosis.

Results

The mean crown-rump of the fetuses and their mean weight were increased in the experimental group as compared to the sham and normal groups, but the differences were not significant. The mean percentage of the hepatocyte area significantly increased in the experimental group as compared to the sham and control groups (P < 0.0001). However, the mean sinusoid area significantly decreased in the experimental group as compared to the sham and control groups. The mean percentage of the area occupied by apoptotic hepatocytes in the experimental group - 13 μL /volume (8.6143 ± 1.00945) and 1.3 μL /volume (6.1091 ± 0.93093) - significantly increased as compared to the normal and sham groups (P < 0.0001).

Conclusions

Our data showed that inhalation of Diazinon during pregnancy increased the hepatocyte area and hepatocyte apoptosis while it decreased the sinusoid area of the fetal liver.

Exposure to lambda-cyhalothrin, a synthetic pyrethroid, increases reactive oxygen species production and induces genotoxicity in rat peripheral blood

Lambda-cyhalothrin (LTC) is a synthetic pyrethroid with a broad spectrum of insecticidal and acaricidal activities used to control a wide range of insect pests in a variety of applications. However, there is little known about its adverse effects, in particular those related to its genotoxicity in humans. To elucidate the genotoxicity mechanisms of LTC, the micronuclei (MN) frequencies, the levels of reactive oxygen species (ROS), erythrocyte osmotic fragility, nitrite (NO) formation, protein carbonyl (PCO) levels and malondialdehyde (MDA) production were evaluated for a period of 7, 14 and 21 days. Our results show that exposure rat to LTC (1/10DL50 = 6.23 mg/kg) for a period of 7, 14 and 21 days induced a noticeable genotoxic effect in rat peripheral blood evidenced by a significant increase in the frequency of MN only at day 21 of treatment. Significant differences between the two groups were observed in erythrocyte osmotic fragility. Further, a significant (p < 0.01) increase in ROS contents, NO formation, PCO levels and lipid peroxidation in erythrocytes were observed at different times of treatments, suggesting the implication of oxidative stress in its toxicity. These results confirm the genotoxic and the pro-oxidant effects of LTC in rat peripheral blood.

Deltamethrin-induced oxidative stress and biochemical changes in tissues and blood of catfish (Clarias gariepinus): antioxidant defense and role of alpha-tocopherol

Background

The pyrethroid class of insecticides, including deltamethrin, is being used as substitutes for organochlorines and organophosphates in pest-control programs because of their low environmental persistence and toxicity. This study was aimed to investigate the impact of commonly used pesticides (deltamethrin) on the blood and tissue oxidative stress level in catfish (Clarias gariepinus); in addition to the protective effect of α-tocopherol on deltamethrin induced oxidative stress.

Catfish were divided into three groups, 1^st control group include 20 fish divided into two tanks each one contain 10 fish, 2^nd deltamethrin group, where Fish exposed to deltamethrin in a concentration (0.75 μg/l) and 3^rd Vitamin E group, Fish exposed to deltamethrin and vitamin E at a dose of 12 μg/l for successive 4 days.

Serum, liver, kidney and Gills were collected for biochemical assays. Tissue oxidative stress biomarkers malondialdhyde (MDA) and catalase activity in liver, kidney and gills tissues, serum liver enzymes (ALT and AST), serum albumin, total protein, urea and creatinine were analysed.

Results

Our results showed that 48 h. exposure to 0.75 μg/l deltamethrin significantly (p < 0.05) increased lipid peroxidation (MDA) in the liver, kidney and gills while catalase activity was significantly decreased in the same tissues. This accompanied by significant increase in serum ALT, AST activity, urea and creatinine and a marked decrease in serum albumin and total proteins.

Conclusions

It could be concluded that deltamethrin is highly toxic to catfish even in very low concentration (0.75 μg/l). Moreover the effect of deltamethrin was pronounced in the liver of catfish in comparison with kidneys and gills. Moreover fish antioxidants and oxidative stress could be used as biomarkers for aquatic pollution, thus helping in the diagnosis of pollution. Adminstration of 12 μg/l α-tocopherol restored the quantified tissue and serum parameters, so supplementation of α-tocopherol consider an effective way to counter the toxicity of deltamethrin in the catfish.

Maternal occupational pesticide exposure and risk of hypospadias in the National Birth Defects Prevention Study

BACKGROUND

Hypospadias is a common congenital malformation among men in which the urethral opening is ventrally displaced. Pesticide exposure has been suggested as a possible etiologic factor, but previous epidemiologic studies have produced inconsistent results.

METHODS

We used data from the National Birth Defects Prevention Study (NBDPS), a population-based case-control study, to examine maternal occupational exposure to fungicides, insecticides, and herbicides among 647 hypospadias case infants and 1496 unaffected male control infants with estimated delivery dates from October 1997 to December 2002. Periconceptional (1 month before conception through the first trimester of pregnancy) pesticide exposures were assigned by an expert rater, assisted by a job-exposure matrix (JEM), from a job history completed by mothers during a telephone interview. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated with multivariable logistic regression, and adjusted for relevant covariates.

RESULTS

Maternal periconceptional occupational exposure to any pesticides (yes/no) was not associated with an increased risk of hypospadias (OR = 0.78; 95% CI = 0.61-1.01). Maternal occupational periconceptional pesticide exposure type (insecticides, fungicides, and herbicides) and estimated quantity also showed no significantly increased risk of hypospadias and no evidence of a dose-response relationship; however, the estimated pesticide exposure levels in this population were low.

CONCLUSION

Using broad classes of insecticides, herbicides, and fungicides, we found no evidence that low intensity maternal periconceptional occupational pesticide exposure was a risk factor for hypospadias.

Residential insecticide usage in northern California homes with young children

Residential insecticide usage and actual application details were collected in a population-based sample of 477 households residing within 22 counties in northern California with at least one child of age ≤ 5 years between January 2006 and August 2008. Structured telephone interviews were conducted collecting information on residential use of insecticides, including outdoor sprays, indoor sprays, indoor foggers, applications by professionals, and pet flea/tick control during the previous year. Interviews also covered post-treatment behaviors, which influence post-application exposure levels. Altogether, 80% of the households applied some type of insecticide in the previous year, with half of this population using two or more application methods. Of the households using insecticides, half reported applying insecticides relatively infrequently (<4 times per year), whereas 11-13% reported high frequency of use (>24 times per year). Application frequency was temperature dependent, with significantly more applications during the warmer months from May through October. Spot treatments appeared to be the most prevalent application pattern for sprays. For one out of three of the indoor applications, children played in the treated rooms on the day of the application, and for 40% of the outdoor applications, pets played in the treated area on the day of the application. These findings describing the intensity of insecticide use and accompanying behaviors in families with young children may inform future insecticide exposure modeling efforts, and ultimately, risk assessments.

Living near agricultural pesticide applications and the risk of adverse reproductive outcomes: a review of the literature

Over the last decade, there has been growing concern about the possible health effects, including a number of adverse reproductive outcomes, from pesticide exposure of people living near agricultural fields. This systematic review evaluates the current epidemiological evidence on the association between living near agricultural pesticide applications and adverse reproductive outcomes, including congenital malformations, stillbirth, intrauterine growth retardation (IUGR), low birthweight, preterm birth and miscarriage. We identified and reviewed 25 studies from a systematic search of the main scientific databases and other sources published in 1950-2007. Study methods and main results were summarised and tabulated according to the year of study, design and type of adverse reproductive outcome. The levels of evidence for reproductive toxicity in humans contributed by each study were assessed and the main limitations associated with these studies discussed. Residential proximity to agricultural pesticide applications may be an important source of ambient environmental exposure, but because of the underlying methodological difficulties, the strength of evidence for its relationship with adverse reproductive outcomes is generally weak and varied between outcomes. The evidence suggested an association for congenital malformations, but because of methodological limitations, such as poor exposure measurement and potentially inadequate control of confounding, a firm conclusion remains beyond reach. For the other outcomes (stillbirth, IUGR, low birthweight, preterm birth and miscarriage) the evidence for any associations was equivocal at best, but some leads warrant further investigation. Improved exposure assessment methods are needed to obtain a more reliable assessment of any risks.

Effects of trichlorfon on maternal estrous cycle, oocyte maturation, and near-term fetal developmental outcome in mice

Trichlorfon (TCF) is a widely used broad-spectrum agricultural organophosphate (OP) pesticide. Few studies have evaluated the effects of TCF on reproductive toxicity after low-level exposure, especially after long-term exposure. This study assessed the direct effects of TCF on estrous cycle, oocyte maturation in female mice, and developmental outcome in near-term fetuses after 30 consecutive days of maternal exposure to 2, 10, or 50 mg/kg body weight/d TCF via drinking water. Both male and female fetuses in the 50 mg/kg/d TCF-treated group had significantly reduced body weights; but this did not occur in the 2 mg/kg/d and 10 mg/kg/d TCF-treated groups. No difference in oocyte maturation, including the percentages of germinal vesicle breakdown (GVBD) and first polar body (PB1) extrusion, or in estrous cycle was found between the control and TCF-treated groups. No increased incidence of fetal external malformations was observed in the TCF-treated groups. Significant decreases in maternal liver weights occurred in the 10 and 50 mg/kg/d TCF-treated groups in a dose-dependent manner. No significant changes were found in the weight of organs such as the ovaries, thymus, kidneys, spleen, lungs, heart or brain. The lack of effects of 2 mg/kg/d and 10 mg/kg/d TCF on any in vivo reproductive and developmental endpoints examined suggest that no TCF reproductive toxicity occurs at exposures less than 10 mg/kg/d.

Protective effects of garlic extract and vitamin C against in vivo cypermethrin-induced teratogenic effects in rat offspring

Exposure of male (55.1 mg/kg b.wt. orally for 60 days) and/or pregnant female Wistar rats (55.1 mg/kg b.wt. orally at days 6-15 of gestation), to the insecticide cypermethrin (CYP); resulted in the development of a lot of external morphological deformities and visceral malformations in their offspring pubs, which signify the potential of such insecticide to induce reproductive toxicity and teratogenesis. Data cleared that CYP treatment induced significant increase in the percentages of post-implantation deaths, dwarf foeti and subcutaneous oedema beside significant decrease in percentages of live borne foeti and uterine implants. CYP also caused many visceral malformations among different treated groups including nasal, ophthalmic, cerebral, pulmonary, cardiac and renal malformations. Concomitant oral administration of garlic extract or vitamin C (5 days/week) to treated fathers and/or pregnant mothers with CYP provided significant reduction in the percentage of the foetal malformations induced by the insecticide, when compared with the control. The current study proves that garlic and ascorbic acid dampen the reproductive toxicity and/or teratogenicity of cypermethrin toxicity in rats; therefore might prove to be effective dietary supplements in developing countries where pesticide pollution is high.

Acute toxicity to zebrafish of two organophosphates and four pyrethroids and their binary mixtures

BACKGROUND

Environmental pollutants, including metals, pesticides and other organics, pose serious risks to many aquatic organisms. The acute toxicities to zebrafish (Brachydanio rerio Hamilton & Buchanan) were determined for two organophosphorus insecticides, four pyrethroid insecticides and 50:50 binary mixtures.

RESULTS

At 24, 48, 72 and 96 h after treatment, LC(50) of permethrin, tetramethrin, bifenthrin, etofenprox, dichlorvos and phoxim to zebrafish were 0.0052-0.0025, 0.0782-0.0460, 0.0065-0.0032, 0.0969-0.0791, 51.3-13.0 and 1.28-0.469 mg L(-1) respectively. LC(50) of permethrin + dichlorvos, permethrin + phoxim, tetramethrin + dichlorvos, tetramethrin + phoxim, bifenthrin + dichlorvos, bifenthrin + phoxim, etofenprox + dichlorvos and etofenprox + phoxim were 0.0082-0.0046, 0.0078-0.0042, 0.264-0.124, 0.141-0.121, 0.0251-0.0154, 0.0154-0.0087, 0.396-0.217 and 0.213-0.0391 mg L(-1).

CONCLUSION

Toxicity levels of all pyrethroid insecticides to the zebrafish were high or very high. The organophosphate dichlorvos showed low toxicity, but phoxim showed high or intermediate toxicities to zebrafish, and the toxicities of binary mixtures of permethrin and dichlorvos or phoxim, bifenthrin and dichlorvos or phoxim and etofenprox and phoxim (48, 72 and 96 h exposure) were very high. The toxicities of binary mixtures of tetramethrin and dichlorvos or phoxim, etofenprox and dichlorvos and etofenprox and phoxim (24 h exposure) were high.

Investigation of the genotoxicity of malathion to freshwater teleost fish Channa punctatus (Bloch) using the micronucleus test and comet assay

Malathion [S-(1,2-dicarboethoxyethyl) O, O-dimethyl phosphorodithioate] is a widely used organophosphorus insecticide throughout the world. However, limited efforts have made to study its genotoxic effect in different fish tissues. The present investigation was aimed to assess the genotoxic potential of the pesticide to the freshwater teleost fish Channa punctatus at sublethal concentrations using the micronucleus test and comet assay. Initially, the 96-h LC50 value of commercial-grade malathion (50% EC) was determined as 5.93 ppm in a semistatic system. Based on LC50, three test concentrations (viz. sublethal I, sublethal II, and sublethal III) were determined to be 1.48, 0.74, and 0.59 ppm, respectively, and the fish specimens were exposed to these concentrations. Tissue samplings were done on days 0, 1, 3, 7, 15, 22 and 29 of malathion exposure for assessment of the induction of micronuclei (MN) frequency and DNA damage. The MN formation in the peripheral blood cells was found to be significantly higher (p < 0.05) in the treated specimens at all sampling intervals compared to the control. The MN frequency reached maximum on days 3 and 7 at sublethal I and II concentrations, respectively, followed by a nonlinear decline with the progression of the experiment. Similarly, significant effects (p < 0.05) of both concentration and time of exposure were observed on DNA damage in the gill, kidney, and lymphocytes. All of the tissues exhibited a concentration-dependent increase in DNA damage up to day 3, followed by a nonlinear decrease with the duration of exposure. A comparison of the extent of DNA damage among the tissues showed the sensitivity of gill tissue to malathion.

Employment in the Ecuadorian cut-flower industry and the risk of spontaneous abortion

BACKGROUND

Research on the potentially adverse effects of occupational pesticide exposure on risk of spontaneous abortion (SAB) is limited, particularly among female agricultural workers residing in developing countries.

METHODS

Reproductive histories were obtained from 217 Ecuadorian mothers participating in a study focusing on occupational pesticide exposure and children's neurobehavioral development. Only women with 2+ pregnancies were included in this study (n = 153). Gravidity, parity and frequency of SAB were compared between women with and without a history of working in the cut-flower industry in the previous 6 years. Logistic regression analysis was conducted to assess the relation between SAB and employment in the flower industry adjusting for maternal age.

RESULTS

In comparison to women not working in the flower industry, women working in the flower industry were significantly younger (27 versus 32 years) and of lower gravidity (3.3 versus 4.5) and reported more pregnancy losses. A 2.6 (95% CI: 1.03-6.7) fold increase in the odds of pregnancy loss among exposed women was observed after adjusting for age. Odds of reporting an SAB increased with duration of flower employment, increasing to 3.4 (95% CI: 1.3, 8.8) among women working 4 to 6 years in the flower industry compared to women who did not work in the flower industry.

CONCLUSION

This exploratory analysis suggests a potential adverse association between employment in the cut-flower industry and SAB. Study limitations include the absence of a temporal relation between exposure and SAB, no quantification of specific pesticides, and residual confounding such as physical stressors (i.e., standing). Considering that approximately half of the Ecuadorian flower laborers are women, our results emphasize the need for an evaluating the reproductive health effects of employment in the flower industry on reproductive health in this population.

The effects of trichlorfon on maternal reproduction and mouse embryo development during organogenesis

The organophosphate pesticide trichlorfon is a widely used agricultural broad spectrum insecticide. The health effects on a developing fetus of low level exposure to trichlorofon ingested by the mother in contaminated foods are unclear. We assessed reproductive and developmental toxicity in pregnant female mice following gavage-administered exposure to distilled water or to low levels (12.5, 25, or 50 mg/kg body weight/d) of trichlorofon during organogenesis (gestation days 6-15). Following sacrifice on day 17, reproductive outcomes and teratogenesis were assessed. Trichlorfon exposure did not affect maternal weight gain, organ weights, corpora lutea, implantation sites, or reproductive success, nor where external or skeletal abnormalities evident. The lack of effects of trichlorfon on any in vivo reproductive and fetuses endpoints above suggested that for trichlorfon, a hazard of reproductive toxicity below 50 mg/kg body weight/d maybe not expected. However, a well-designed epidemiological study is necessary for further risk assessment of human developing fetus exposed to trichlorfon at a lower level.

Oral exposure of mice to formulations of organophosphorous pesticides: gestational and litter outcomes

The purpose of this study was to examine gestational and litter outcomes in mice models from oral exposure to a mixture of formulations of organophosphorous pesticides used in local vegetable production. Male and female mice were exposed to premating and preconception, respectively, to a mixture of organophosphorous pesticide formulations for a period of 7 weeks. The pregnant dams were monitored during gestation and delivered by Caesarean section pre-partum. The percentages of resorptions and the resorptions/implantations ratios, in all the exposed groups, were significantly higher than the reference and the control groups. Percentages of litters with one or more lost embryos were observed in all the exposed groups and were significantly higher than the comparison groups. Fetal weights were significantly lower and the maternal weight gains per live fetus were significantly higher in the medium-dose-exposed groups than the control group. Percentages of fetuses with intra-uterine growth retardation at one standard deviation were significantly higher in all the exposed groups than the comparison groups.

DNA damage in workers occupationally exposed to pesticide mixtures

Pesticides are used in agriculture to protect crops but represent at the same time a potential risk to farmers and environment. The aim of this work is the evaluation of 54 subjects occupationally exposed to pesticides and 30 subjects as a control group using the quantification of DNA damage level by means of the alkaline Comet assay and the evaluation of repair processes. Damage index Comet assay (DICA) and damage index repair assay (DIRA) were studied in 27 pesticide applicator workers, 27 non-pesticide applicators and controls. Our results show that both exposed groups revealed significant increase in DICA when compared with controls (P < 0.0001), as well as in DIRA (P < 0.0001). However, the spraying group exhibited a marginally significant difference in DICA (P = 0.05) when years of exposure are considered and a significant difference (P < 0.05) when the personal protective equipment used by individuals was taken as a comparison factor. The influence of confounding factors on the genotoxic effects of occupational exposure to pesticides was investigated and no significant differences were observed considering age, gender, smoking and alcohol consumption in relation to DICA and DIRA. Since DNA damage is an important step in events leading from carcinogen exposure to cancer disease, our study highlights the potential health risk associated with agrochemical exposure in developing countries with vast cultivated areas, such as Argentina.

Epidemiologic evidence of relationships between reproductive and child health outcomes and environmental chemical contaminants

This review summarizes the level of epidemiologic evidence for relationships between prenatal and/or early life exposure to environmental chemical contaminants and fetal, child, and adult health. Discussion focuses on fetal loss, intrauterine growth restriction, preterm birth, birth defects, respiratory and other childhood diseases, neuropsychological deficits, premature or delayed sexual maturation, and certain adult cancers linked to fetal or childhood exposures. Environmental exposures considered here include chemical toxicants in air, water, soil/house dust and foods (including human breast milk), and consumer products. Reports reviewed here included original epidemiologic studies (with at least basic descriptions of methods and results), literature reviews, expert group reports, meta-analyses, and pooled analyses. Levels of evidence for causal relationships were categorized as sufficient, limited, or inadequate according to predefined criteria. There was sufficient epidemiological evidence for causal relationships between several adverse pregnancy or child health outcomes and prenatal or childhood exposure to environmental chemical contaminants. These included prenatal high-level methylmercury (CH(3)Hg) exposure (delayed developmental milestones and cognitive, motor, auditory, and visual deficits), high-level prenatal exposure to polychlorinated biphenyls (PCBs), polychlorinated dibenzofurans (PCDFs), and related toxicants (neonatal tooth abnormalities, cognitive and motor deficits), maternal active smoking (delayed conception, preterm birth, fetal growth deficit [FGD] and sudden infant death syndrome [SIDS]) and prenatal environmental tobacco smoke (ETS) exposure (preterm birth), low-level childhood lead exposure (cognitive deficits and renal tubular damage), high-level childhood CH(3)Hg exposure (visual deficits), high-level childhood exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) (chloracne), childhood ETS exposure (SIDS, new-onset asthma, increased asthma severity, lung and middle ear infections, and adult breast and lung cancer), childhood exposure to biomass smoke (lung infections), and childhood exposure to outdoor air pollutants (increased asthma severity). Evidence for some proven relationships came from investigation of relatively small numbers of children with high-dose prenatal or early childhood exposures, e.g., CH(3)Hg poisoning episodes in Japan and Iraq. In contrast, consensus on a causal relationship between incident asthma and ETS exposure came only recently after many studies and prolonged debate. There were many relationships supported by limited epidemiologic evidence, ranging from several studies with fairly consistent findings and evidence of dose-response relationships to those where 20 or more studies provided inconsistent or otherwise less than convincing evidence of an association. The latter included childhood cancer and parental or childhood exposures to pesticides. In most cases, relationships supported by inadequate epidemiologic evidence reflect scarcity of evidence as opposed to strong evidence of no effect. This summary points to three main needs: (1) Where relationships between child health and environmental exposures are supported by sufficient evidence of causal relationships, there is a need for (a) policies and programs to minimize population exposures and (b) population-based biomonitoring to track exposure levels, i.e., through ongoing or periodic surveys with measurements of contaminant levels in blood, urine and other samples. (2) For relationships supported by limited evidence, there is a need for targeted research and policy options ranging from ongoing evaluation of evidence to proactive actions. (3) There is a great need for population-based, multidisciplinary and collaborative research on the many relationships supported by inadequate evidence, as these represent major knowledge gaps. Expert groups faced with evaluating epidemiologic evidence of potential causal relationships repeatedly encounter problems in summarizing the available data. A major driver for undertaking such summaries is the need to compensate for the limited sample sizes of individual epidemiologic studies. Sample size limitations are major obstacles to exploration of prenatal, paternal, and childhood exposures during specific time windows, exposure intensity, exposure-exposure or exposure-gene interactions, and relatively rare health outcomes such as childhood cancer. Such research needs call for investments in research infrastructure, including human resources and methods development (standardized protocols, biomarker research, validated exposure metrics, reference analytic laboratories). These are needed to generate research findings that can be compared and subjected to pooled analyses aimed at knowledge synthesis.

The influence of the environment and other exogenous agents on spontaneous abortion risk

It is estimated that close to 30% of all pregnancies end in spontaneous abortion. Although about 60% of spontaneous abortions are thought to be due to genetic, infectious, hormonal, and immunological factors, the role of the environment remains poorly understood. Pregnancy involves a delicate balance of hormonal and immunological functions, which may be affected by environmental substances. Many toxic substances that are persistent in the environment and accumulate in the fatty tissues may disrupt this equilibrium. This overview addresses known risk factors for spontaneous abortions and examines the role, if any, that environmental factors (chemical and physical) may play in the etiology of this adverse health outcome.

Oral exposure of male and female mice to formulations of organophosphorous pesticides: congenital malformations

Birth outcome was studied in pre-partum litters of mice exposed to oral doses of organophosphorous pesticides at low and high concentrations before mating. Exposed and unexposed pregnant dams were delivered by Caesarean section 1 day before partum, the fetuses were collected, counted and weighed, and the numbers of resorptions were recorded. Live litter sizes were non-significantly higher in all the exposed groups compared with the control group. The numbers of resorptions were significantly higher in all the exposed groups than in the comparison groups. The incidence of intra-uterine growth retardation was significantly higher in all the exposed groups than in the comparison groups. The incidences of congenital malformations were significantly higher in the exposed groups than in one or more of the comparison groups for the defects of the ears, eyes, jaws, brain, and tongue in all the exposed groups. Low set microtia, cataract or open eyelids, microcephaly or anencephaly, maxillary or mandibular hypoplasia, and protruding tongue were observed in all groups, but the numbers were significantly higher in the exposed groups compared with one or more of the comparison groups. Curled or missing tail and intra-auricular septal or intra-ventricular septal defects were observed in higher numbers in the groups in which both the males and the females were exposed than in the comparison groups. Male:female sex ratios were significantly higher in the groups in which males only and females only were exposed.

Genotoxic biomonitoring study of population residing in pesticide contaminated regions in Göksu Delta: micronucleus, chromosomal aberrations and sister chromatid exchanges

Pesticides are widely used throughout the world in agriculture to protect crops and in public health to control diseases. Nevertheless, exposure to pesticides represents a potential risk to humans. This paper describes a study of possible genetic damage in the people living in regions contaminated with complex mixture of pesticides in Göksu Delta. In this study, used methods were chromosomal aberration (CA), sister chromatid exchange analysis (SCE) in the peripheral blood lymphocytes, and micronucleus (MN) assay in the buccal epithelial cells. In the present investigation, 32 affected subjects consist of 16 smoking and 16 non-smokings and an equal number of control subjects were assessed for genome damage. Micronucleus (MN), Broken egg (BE), Karyorrhexis (KR), Karyolysis (KL) and Binucleus (BN) frequencies were higher in affected subjects than in controls. Smoking had a statistically significant effect on the Micronucleus, Karyorrhexis and Binucleus frequencies for both the control and the exposed group. Also smoking and exposure affected the frequency of sister chromatid exchange and chromosomal aberrations compared with control groups.

Fetal deaths and proximity to hazardous waste sites in Washington State

BACKGROUND

The in utero period is one of increased susceptibility to environmental effects. The effects of prenatal exposure to environmental toxicants on various adverse pregnancy outcomes, including fetal death, are not well understood.

OBJECTIVE

We examined the risk of fetal death in relation to maternal residential proximity to hazardous waste sites.

METHODS

We conducted a population-based case-control study using Washington State vital records for 1987-2001. Cases were women with fetal deaths at > or = 20 weeks (n = 7,054). Ten controls per case were randomly selected from live births. Locations of 939 hazardous waste sites were identified from the Department of Ecology registry. We measured distance from maternal residence at delivery to the nearest hazardous waste site, and calculated odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

The risk of fetal death for women residing < or = 0.5 miles, relative to > 5 miles, from a hazardous waste site was not increased (adjusted OR = 1.06; 95% CI, 0.90-1.25). No associations were observed for any proximity categories < or = 5 miles from sites with contaminated air, soil, water, solvents, or metals; however, fetal death risk increased among women residing < or = 1 mile from pesticide-containing sites (OR = 1.28; 95% CI, 1.13-1.46).

CONCLUSION

These results do not suggest that fetal death is associated with residential proximity to hazardous waste sites overall; however, close proximity to pesticide-containing sites may increase the risk of fetal death.

Environmental hazards: evidence for effects on child health

The human fetus, child, and adult may experience adverse health outcomes from parental or childhood exposures to environmental toxicants. The fetus and infant are especially vulnerable to toxicants that disrupt developmental processes during relatively narrow time windows. This review summarizes knowledge of associations between child health and development outcomes and environmental exposures, including lead, methylmercury, polychlorinated biphenyls (PCBs), dioxins and related polyhalogenated aromatic hydrocarbons (PHAHs), certain pesticides, environmental tobacco smoke (ETS), aeroallergens, ambient air toxicants (especially particulate matter [PM] and ozone), chlorination disinfection by-products (DBPs), sunlight, power-frequency magnetic fields, radiofrequency (RF) radiation, residential proximity to hazardous waste disposal sites, and solvents. The adverse health effects linked to such exposures include fetal death, birth defects, being small for gestational age (SGA), preterm birth, clinically overt cognitive, neurologic, and behavioral abnormalities, subtle neuropsychologic deficits, childhood cancer, asthma, other respiratory diseases, and acute poisoning. Some environmental toxicants, notably lead, ionizing radiation, ETS, and certain ambient air toxicants, produce adverse health effects at relatively low exposure levels during fetal or child developmental time windows. For the many associations supported by limited or inadequate epidemiologic evidence, major sources of uncertainty include the limited number of studies conducted on specific exposure-outcome relationships and methodologic limitations. The latter include (1) crude exposure indices, (2) limited range of exposure levels, (3) small sample sizes, and (4) limited knowledge and control of potential confounders. Important knowledge gaps include the role of preconceptual paternal exposures, a topic much less studied than maternal or childhood exposures. Large longitudinal studies beginning before or during early pregnancy are urgently needed to accurately measure and assess the relative importance of parental and childhood exposures and evaluate relatively subtle health outcomes such as neuropsychologic and other functional deficits. Large case-control studies are also needed to assess the role of environmental exposures and their interactions with genetic factors in relatively uncommon outcomes such as specific types of birth defects and childhood cancers. There is also an urgent need to accelerate development and use of biomarkers of exposure and genetic susceptibility in epidemiologic studies. This review supports the priority assigned by international agencies to relationships between child health and air quality (indoor and outdoor), lead, pesticides, water contaminants, and ETS. To adequately address such priorities, governments and agencies must strengthen environmental health research capacities and adopt policies to reduce parental and childhood exposures to proven and emerging environmental threats.

Pesticide exposures and developmental outcomes: the epidemiological evidence

Since the advent of DDT as an insecticide in the late 1930s, billions of kilograms of pesticide active ingredient have been sold in North America and around the world. In recent years, there has been a heightened public awareness of pesticides and child health and a number of epidemiologic studies linked pre- and postnatal exposures to pesticides to a number of adverse developmental outcomes, including fetal death, intrauterine growth restriction, preterm birth, and birth defects. Given this, it was felt prudent to critically appraise the evidence for periconceptual pesticide exposures and developmental outcomes. The epidemiological evidence for specific pesticide classes, families, and active ingredients were examined and summarized and recommendations were made for how to improve future studies in order to address the current pitfalls and gaps in the studies in this area. Many of the studies suffered from poor exposure estimation, relying on job title only and/or the exposure category "any pesticide" as a measure of exposure, and there was limited or inadequate evidence to support causality for all associations examined.

Addressing the linkage between exposure to pesticides and human health effects--research trends and priorities for research

In recent years, there has been escalating concern over the possible association between exposure to pesticides and adverse human health effects by a number of non-governmental organizations, professional and public interest groups. Recognizing the need to document the scientific basis of these concerns as a foundation for initiating a research theme devoted to linkages between exposures to pesticides and human health effects, the Canadian Institutes of Health Research (CIHR) requested a summary of recent research trends that address these linkages. Experts across Canada in the field of pesticide regulation and research were invited to participate in the review. The review summarizes the limitations of past and current studies related to pesticides and human health effects research and makes suggestions for future research priorities and proposed study designs that will improve the assessment of pesticide exposure, the associated health risks, and improved methodology for regulatory decision making.

Pesticide exposure: the hormonal function of the female reproductive system disrupted?

Some pesticides may interfere with the female hormonal function, which may lead to negative effects on the reproductive system through disruption of the hormonal balance necessary for proper functioning. Previous studies primarily focused on interference with the estrogen and/or androgen receptor, but the hormonal function may be disrupted in many more ways through pesticide exposure. The aim of this review is to give an overview of the various ways in which pesticides may disrupt the hormonal function of the female reproductive system and in particular the ovarian cycle. Disruption can occur in all stages of hormonal regulation: 1. hormone synthesis; 2. hormone release and storage; 3. hormone transport and clearance; 4. hormone receptor recognition and binding; 5. hormone postreceptor activation; 6. the thyroid function; and 7. the central nervous system. These mechanisms are described for effects of pesticide exposure in vitro and on experimental animals in vivo. For the latter, potential effects of endocrine disrupting pesticides on the female reproductive system, i.e. modulation of hormone concentrations, ovarian cycle irregularities, and impaired fertility, are also reviewed. In epidemiological studies, exposure to pesticides has been associated with menstrual cycle disturbances, reduced fertility, prolonged time-to-pregnancy, spontaneous abortion, stillbirths, and developmental defects, which may or may not be due to disruption of the female hormonal function. Because pesticides comprise a large number of distinct substances with dissimilar structures and diverse toxicity, it is most likely that several of the above-mentioned mechanisms are involved in the pathophysiological pathways explaining the role of pesticide exposure in ovarian cycle disturbances, ultimately leading to fertility problems and other reproductive effects. In future research, information on the ways in which pesticides may disrupt the hormonal function as described in this review, can be used to generate specific hypotheses for studies on the effects of pesticides on the ovarian cycle, both in toxicological and epidemiological settings.

Occupational Exposure to Pesticides and Pregnancy Outcomes in Gardeners and Farmers: A Study Within the Danish National Birth Cohort

OBJECTIVE

We conducted a follow-up study to examine whether exposure to pesticides during pregnancy had an adverse effect on pregnancy outcomes among Danish gardeners and farmers.

METHODS

Using data from the National Birth Cohort in Denmark, we identified 226 pregnancies of gardeners and 214 pregnancies of farmers during 1997 through 2003. Work activities and exposure to pesticides were reported in an interview (around 16 weeks of gestation). Totally, 62,164 other workers in the cohort served as a reference group. Pregnancy outcomes were obtained by linkage to the national registers. Cox regression was applied to analyze late fetal loss and congenital malformations, and logistic regression was used to analyze preterm birth and small for gestational age.

RESULTS

There were no significant differences in the studied pregnancy outcomes between gardeners or farmers and all other workers, except for an increased risk of very preterm birth for gardeners and a favorable birth weight for farmers. With the exception of biologic approach used in gardening, neither work activities nor exposure to pesticides showed a significant increased risk of adverse birth outcomes among gardeners or farmers.

CONCLUSIONS

Our data suggest little effect of occupational exposures to pesticides on pregnancy outcomes among gardeners or farmers in Denmark. The results may not apply to other countries.

Disrupted sex differentiation and feminization of man and domestic animals

Genital malformations constitute the most common birth defects in man and domestic animals and occur frequently in males since the participation of many genes is required for sex differentiation to proceed in the male direction. The precise dose, timing, and coordination needed for their expression add to the proneness of various stages in male sex differentiation to external influences. The emerging insight, through the identification of genes involved in the sex differentiation cascade, is that over 85% of sex anomalies in human and domestic animal populations are not attributable to chromosome aberrations or to mutations in a known gene. Since a majority of severely malformed individuals are incapable of reproduction, the high rates of these defects have to be results either of new mutations or of collaboration of environmental factors with genes. Increase in specific malformations in domestic animals often indicates increased concentration of liability genes brought together in the conceptus by inbreeding. However, in human populations where inbreeding is not the norm such increases may reflect environment-induced new mutations or interaction of environmental agents with hormone-sensitive genes. This review summarizes the information currently available on the genetics of major events in male sex differentiation and briefly discusses the collaborative role that environment may play in disrupting different components of this process.

Cytotoxicant-induced trophoblast dysfunction and abnormal pregnancy outcomes: role of zinc and metallothionein

Normal trophoblast function, including implantation, hormone production, and formation of the selectively permeable maternofetal barrier, is essential for the establishment and maintenance of the fetoplacental unit and proper fetal development. Maternal cytotoxicant exposure causes the destruction of these cells, especially the terminally differentiated syncytiotrophoblasts, and results in a myriad of poor pregnancy outcomes. These outcomes range from intrauterine growth retardation and malformation to spontaneous abortion or stillbirth. There is recent evidence that the metal-binding protein, metallothionein, is involved in the protection of human trophoblastic cells from heavy metal-induced and severe oxidative stress-induced apoptosis. Metallothionein, with its unique biochemical structure, can both bind essential metal ions, such as the transcription modulator zinc, and yet allow their ready displacement by toxic nonessential metal ions or damaging free radicals. These properties suggest that metallothionein may be responsible not only for sequestering the cytotoxic agents, but also for altering signal transduction in the affected cells. Here, we review several identified causes of adverse pregnancy outcomes (specifically, prenatal exposure to cigarette smoke and alcohol, gestational infection, and exposure to environmental contaminants), discuss the role of zinc in modulating the cellular response to these toxic insults, and then propose how metallothionein may function to mediate this protective response.

Evaluation of cytogenetic effects of lambda-cyhalothrin on Wistar rat bone marrow by gavage administration

In this study, a synthetic pyrethroid insecticide, lambda-cyhalothrin (LCT), was administered to adult female albino rats (Wistar rats) by gavage dose of 6.12, 3.06, 0.8 mg/kg b.w. repeated for 13 days at 48 h intervals. The cytotoxic and genotoxic effects of LCT were investigated in bone marrow cells, using the structural chromosomal aberration (SCA) and micronucleus (MN) test systems. Mitomycin C (MMC) was also used as positive control (2mg/kg b.w.). All the doses of LCT increased the number of SCAs and the frequency of micronucleated erythrocytes, with respect to the control group. Only the highest dose of LCT significantly increased the MN frequency compared with control (P < 0.01). It was also observed that LCT caused a significant decrease in the number of polychromatic erythrocytes compared with controls (p < 0.001). These observations indicate the in vivo suspectibility of mammals to the genetic toxicity and cytotoxicity potential of LCT.

Acute toxicity bioassays of mercuric chloride and malathion on air-breathing fish Channa punctatus (Bloch)

Acute toxicity tests (96 h) were conducted in flow-through systems to determine the lethal toxicity of a heavy metal compound, mercuric chloride, and an organophosphorus pesticide, malathion, to air-breathing teleost fish, Channa punctatus (Bloch) and to study their behavior. The 96-h LC50 values were determined, as well as safe levels. The results indicate that mercuric chloride is more toxic than malathion to the fish species under study. Dose- and dose-time-dependent increases in mortality rate were also observed in response to both test chemicals.

Perfluorinated organic compounds in human blood serum and seminal plasma: a study of urban and rural tea worker populations in Sri Lanka

Concentrations and accumulation of 13 fluorinated organic compounds (FOCs) in human sera and seminal plasma were measured in an Asian developing country, Sri Lanka. Six of the FOCs, PFOS (perfluorooctanesulfonate), PFHS (perfluorohexanesulfonate), PFUnA (perfluoroundecanoic acid), PFDA (perfluorodecanoic acid), PFNA (perfluorononanoic acid) and PFOA (perfluorooctanoic acid), were detected in all of the sera samples. Measurable quantities of two main perfluorosulfonates, PFOS and PFHS, were found in all seminal plasma samples. The detection frequency of the predominant perfluoroalkylcarboxylate, PFOA, in seminal plasma was >70%. Accumulation of PFOS in sera was significantly positively correlated with PFOA, PFHS and PFNA. Positive linear regressions were also found between PFNA and PFUnA and PFNA and PFDA suggesting that these compounds may have a similar origin of exposure and accumulation. Significantly positive associations were observed for partitioning of both PFOS and PFNA between sera and seminal plasma. The accumulation of FOCs was not significantly different in sera from Colombo (urban population) and Talawakele (rural conventional tea workers). However, the Haldummulla population (rural organic tea workers) had relatively lower exposure to FOCs compared to the other two groups, urban and rural conventional tea workers. Concentrations of FOCs in Sri Lanka were similar to those reported for industrialized countries suggesting that human exposure to such chemicals is widespread even in developing countries. The novel finding of FOCs in human seminal plasma implies that further studies are needed to determine whether long-term exposure in humans can result in reproductive impairments.

Environmental and occupational factors affecting fertility and IVF success

Reproductive function has been shown to be sensitive to changes in the physical, psychosocial and chemical environments. Although reproductive effects of occupational exposure to hazardous chemicals have been well documented in the literature, the potential effects of chemical contaminants at levels representative of contemporary exposures in the general population are much less certain. Evidence for adverse effects of exposure to environmental contaminants is more conclusive among the lower animals than for humans where considerable controversy remains. In addition to potential reproductive hazards of exposure to environmental contaminants, there is also evidence for adverse reproductive effects of the physical and psychosocial environments. In this review we focus on the difficulties involved in linking exposure to putative hazardous substances in environmental and occupational settings to adverse reproductive outcomes, especially success of IVF procedures. We highlight the plausibility of adverse events through animal and cell studies and the application of these results to the interpretation of human data. We consider both the male and female partners since it is essentially their combined contributions of gametes which may be affected by chemicals, which lead to successful outcomes.

Placental morphology of rats prenatally exposed to methyl parathion

Although prenatal exposure to pesticides has been associated with numerous adverse reproductive effects, data on the effects of such toxics in the placenta is limited. Thus, the present study was carried out to determine the morphology of the rat placenta exposed to the organophosphate pesticide methyl parathion (MP) in ad libitum fed and restricted diet animals. The pregnant females were randomly divided into control groups and experimental groups, the latter of which received MP at the doses of 0.0, 1.0, 1.5 and 2.0 mg/kg. Most cells in the maternal-fetal interface showed significant alterations in the presence of MP. Trophoblast giant cells exhibited either prominent characteristics of degeneration or normal morphology with many phagosome vacuoles, apparently containing cell debris. Vascular congestion was also more frequent in the labyrinth of the treated animals. Areas of fibrosis and hemorrhage were found in the decidua, as well as decidual cells presenting pyknotic nuclei and acidophilic cytoplasm. In the placentas of females treated with both restricted diet and MP, such changes were much more severe. Together, these alterations suggest a direct, toxic effect of MP on the placental cells. The phagocytic activity exhibited by trophoblast cells, may be playing a role in the removal of death cells from the maternal-placental interface and/or in a compensatory mechanism to maintain the uptake of maternal nutrients, following decreased metabolic exchange functions of the labyrinth due to the toxic effect of the MP.

Genotoxic effects of malathion: an organophosphorus insecticide, using three mammalian bioassays in vivo

The genotoxic effects of malathion was evaluated using chromosome aberration, sister chromatid exchange (SCE) and sperm abnormality assays in mice. All the three acute doses (2.5, 5 and 10mg/kg) of malathion tested in the present study, induced significant dose-dependent increase in the frequency of chromosome aberrations and sperm abnormalities, but did not affect the total sperm count. The highest acute dose induced a >12-fold increase in the frequency of chromosome aberrations, two-fold increase in the frequency of SCEs and four-fold increase in the frequency of sperms with abnormal head morphology following intraperitoneal (i.p.) exposure. Further, a significant increase in the frequency of SCEs was observed, but the increase was not dose-dependent. At higher doses, malathion induced a moderate delay in cell cycle as evident from the increase in average generation time (AGT). The present findings suggest that technical grade malathion is a potent genotoxic agent and may be regarded as a potential germ cell mutagen also.

Occupational exposure to pesticides and cytogenetic damage: results of a Hungarian population study using the micronucleus assay in lymphocytes and buccal cells

The frequency of micronuclei (MN) in peripheral blood lymphocytes and in buccal epithelial cells was used as a biomarker of genotoxic effects resulting from occupational exposure to pesticides. In addition, the cytokinesis-block proliferation index (CBPI) was calculated to detect possible variations in the proliferative kinetics of lymphocytes due to pesticide exposure. This study was performed on 84 pesticide-exposed workers and 65 unexposed controls from Hungary. The pesticide-exposed workers, classified as moderately and highly exposed, were also evaluated separately. Statistical evaluation of the cytogenetic biomarkers indicated that there were no significant differences between pesticide-exposed workers and controls, nor between moderately and highly exposed workers. Nevertheless, the statistical analysis revealed that additional factors such as age, sex, ingestion of raw vegetables, and working as a pesticide applicator affected lymphocyte MN frequency. In addition, age, sex, and smoking affected the frequency of MN in buccal cells. Results from the CBPI analysis showed that the proliferation index decreased with pesticide exposure and that this parameter was also affected by smoking and by the gender of individuals. The results of this study indicate no significant increase in MN in this group of Hungarian workers; however, the reduced CBPI in the highly exposed population suggests a possible genotoxic effect of pesticide exposure.

National farmworker database: establishing a farmworker cohort for epidemiologic research

BACKGROUND

There is little research into the long-term health effects of pesticides and other agricultural exposures among seasonal and migrant farmworkers in the United States. We present results of a feasibility study that established a cohort of farmworkers for use in epidemiologic research.

METHODS

Subjects consisted of migrant and seasonal farmworkers who joined the cohort while seeking social services through members of the Association of Farmworker Opportunity Programs (AFOP) and were entered in the National Farmworker Database (NFD) between the end of 1997 and March 1999. We designed an add-on interview with information that enhanced the utility of the database for epidemiologic research.

RESULTS

We recruited and obtained basic demographic and employment information on 5,597 farmworkers at very modest cost and effort. Subjects were mostly seasonal (61.5%), female (56.7%), and Hispanic (67.4%), with a median age of 27. Most (62.6%) had not completed high school; almost all (99.1%) reported being U.S. citizens or permanent residents, an eligibility requirement for some of the services provided by AFOP. The majority (62.5%) had engaged in farmwork for less than 10 years, but had performed a wide variety of tasks on different crops, including row crops and tree fruits. Picking was the most common task reported. Most subjects had performed farmwork in Florida, North Carolina, Texas, Michigan, or Georgia. For usual source of health care, 63.7% reported use of U.S. hospitals or emergency rooms/clinics, 42.0% U.S. private physicians, and 29.7% migrant health clinics. Among subjects reporting a prior diagnosis of cancer, primary sources of health care for treatment of that cancer included U.S. private physicians (61.9%), U.S. hospitals or emergency rooms/clinics (23.8%), and migrant health clinics (10.5%).

CONCLUSIONS

Results suggest that by adding a brief interview to the existing NFD data collection process, which was designed for other purposes, it is feasible to create an efficient tool for conducting longitudinal epidemiologic research among farmworkers.

Analysis of cytogenetic and developmental effects on pre-implantation, mid-gestation and near-term mouse embryos after treatment with trichlorfon during zygote stage

Trichlorfon has been widely used in agriculture as a broad spectrum insecticide. We examined cytogenetic and developmental effects on early mouse zygotes exposed to trichlorfon in vivo. Pregnant female mice were intraperitoneally administered a single dose of trichlorfon (100 or 200mg/kg) at 6h post presumed conception and either sacrificed on day of gestation (dg) 3, 9 or 17 to assess the developmental toxicity and mutagenic effects on embryos. Mean cell number (dg 3) and somite number (dg 9) of embryos in the two trichlorfon-treated groups were significantly fewer than in the control group and the mean micronucleus (MN) number (dg 3) and the frequency of mosaic aneuploidies including monosomic or trisomic cell lines (dg 9) was significantly increased in both trichlorfon-treated groups compared with the control group. However, there was no difference in fetal body weight (dg 17) between the control and trichlorfon-treated groups and no increased incidence of external malformations was observed in the trichlorfon-treated groups. These findings suggest that acute exposure of trichlorfon around fertilization induces a high frequency of MN, mosaic aneuploidies and developmental retardation in pre-implantation and mid-gestation embryos, and thereafter these embryos with MN or chromosome damage appear to develop past mid-gestation and catch up with normal embryos by near-term.

2,4-Dichlorophenoxyacetic acid residues in semen of Ontario farmers

Although paternal exposures to environmental toxicants probably play a role in adverse pregnancy outcomes, few data are available on the extent of this exposure. One semen and two 24-h urine samples were collected from 97 Ontario farmers who had recently used the phenoxy herbicides 2,4-D (2.4-dichlorophenoxyacetic acid) and/or MCPA ([4-chloro-2-methylphenoxyl acetic acid). Both samples were analyzed for 2,4-D using an immunoassay-based technique. Approximately 50% of the semen samples had detectable levels of 2, 4-D (> or =5.0 pph (ng/mL)). Semen levels of 2.4-D were correlated more closely with the second of the two urine samples. Although several studies have measured 2.4-D in the urine of applicators, this study is the first to attempt to measure 2,4-D levels in semen. As these pesticides can be excreted in the semen, they could be toxic to sperm cells and be transported to the woman and developing embryo/fetus. Further research is needed to understand how pesticide handling practices can affect semen pesticide residues and the relationship between the levels observed and reproductive health.