Sex-Specific Neurotoxic Effects of Organophosphate Pesticides Across the Life Course

Association between exposure to organophosphorus pesticide and suicidal ideation among U.S. adults: A population-based study

OBJECTIVE

This study aims to investigate the potential link between exposure to organophosphorus pesticides (OPPs) and suicidal ideation (SI) among adults.

METHODS

This study encompassed four cycles of the National Health and Nutrition Examination Survey (NHANES), involving 5244 participants aged 20 and above. SI was assessed using the Patient Health Questionnaire-9. The levels of exposure to OPPs were estimated by analyzing concentrations of OPP metabolites in urine samples. Multivariate logistic regression models were used to explore the association between exposure to each OPP and SI. Stratified analyses and interaction tests were conducted across various groups, including pairwise combinations of gender and age, as well as body mass index, smoking status, hypertension, and diabetes. Weighted Quantile Sum (WQS) regression and Bayesian Kernel Machine Regression (BKMR) models were applied to assess the cumulative impact of exposure to the four OPPs on SI, along with their respective contributions. Additionally, the potential interactions among these four OPPs were evaluated.

RESULTS

Multivariate logistic regression revealed that only dimethylthiophosphate (DMTP) among OPPs demonstrated a statistically significant positive association with SI [OR: 1.18; 95 % CI: 1.02-1.37]. Stratified analyses indicated that the influence of OPPs on SI was particularly pronounced in young and older men. The WQS regression analysis revealed a statistically significant association between the mixed metabolites of OPPs and SI [OR = 1.10, 95 % CI: 1.04-1.16], with DMTP (weighted 0.63) contributing the most. Furthermore, the BKMR model supported a positive trend in the overall impact of these OPP metabolites on SI, displaying notable individual exposure-response relationships for DMTP (PIP: 0.77).

CONCLUSIONS

Our study suggests an association between exposure to DMTP and an increased risk of SI. Specifically, young adult males and older males appear particularly susceptible to the effects of OPP exposure.

Pesticide-Induced Alterations in Locomotor Activity, Anxiety, and Depression-like Behavior Are Mediated through Oxidative Stress-Related Autophagy: A Persistent Developmental Study in Mice

Chlorpyrifos (CPF), dichlorvos (DDV), and cypermethrin (CP), as commonly used pesticides, have been implicated in inducing neuropsychiatric disorders, such as anxiety, depression-like behaviors, and locomotor activity impairment. However, the exact molecular mechanisms of these adverse effects, particularly in both sexes and their next-generation effects, remain unclear. In this study, we conducted behavioral analysis, along with cellular assays (monodansylcadaverine staining) and molecular investigations (qRT-PCR and western blotting of mTOR, P62, and Beclin-1) to clear the potential role of autophagy in pesticide-induced behavioral alterations. For this purpose, 42 adult female and 21 male inbred ICR mice (F0) were distributed into seven groups. Maternal mice (F0) and 112 F1 offspring were exposed to 0.5 and 1 ppm of CPF, DDV, and CP through drinking water. F1 male and female animals were studied to assess the sex-specific effects of pesticides on brain tissue. Our findings revealed pronounced anxiogenic effects and impaired locomotor activity in mice. F1 males exposed to CPF (1 ppm) exhibited significantly elevated depression-like behaviors compared to other groups. Moreover, pesticide exposure reduced mTOR and P62 levels, while enhancing the Beclin-1 gene and protein expression. These changes in autophagy signaling pathways, coupled with oxidative and neurogenic damage in the cerebral cortex and hippocampus, potentially contribute to heightened locomotor activity, anxiety, and depression-like behaviors following pesticide exposure. This study underscores the substantial impact of pesticides on both physiological and behavioral aspects, emphasizing the necessity for comprehensive assessments and regulatory considerations for pesticide use. Additionally, the identification of sex-specific responses presents a crucial dimension for pharmaceutical sciences, highlighting the need for tailored therapeutic interventions and further research in this field.

Prenatal exposure to pyrethroids and chlorpyrifos and IQ in 7-year-old children from the Odense Child Cohort

BACKGROUND

Organophosphates and pyrethroids are two major groups of insecticides used for crop protection worldwide. They are neurotoxicants and exposure during vulnerable windows of brain development may have long-term impact on human neurodevelopment. Only few longitudinal studies have investigated associations between prenatal exposure to these substances and intelligence quotient (IQ) at school age in populations with low, mainly dietary, exposure.

OBJECTIVE

To investigate associations between maternal urinary concentrations of insecticide metabolites at gestational week 28 and IQ in offspring at 7-years of age.

MATERIALS AND METHODS

Data was derived from the Odense Child Cohort (OCC). Metabolites of chlorpyrifos (TCPy) and pyrethroids (3-PBA, cis- and trans-DCCA, 4-F-3PBA, cis-DBCA) were measured in maternal urine collected at gestational week (GW) 28. An abbreviated version of the Danish Wechsler Intelligence Scale for Children fifth edition (WISC-V) consisting of four subtests to estimate full scale IQ (FSIQ) was administered by trained psychologists. Data were analyzed by use of multiple linear regression and adjusted for confounders.

RESULTS

812 mother/child-pairs were included. Median concentrations were 0.21 μg/L for 3-PBA, 1.67 μg/L for TCPy and the mean IQ for children were 99.4. Null association between maternal 3-PBA and child IQ at 7 years was seen, but with trends suggesting an inverse association. There was a significant association for maternal TCPy and child IQ at mid-level exposure. Trans-DCCA above the level of detection (LOD) was also associated with slightly lower child IQ, but the association was also not statistically significant.

CONCLUSIONS

We found no significant associations between maternal 3-PBA metabolites and child IQ at 7 years, but with trends suggesting an inverse association. A non-significant trend between maternal TCPy exposure and child IQ in 7-year-children was seen even in this low exposed population. Given the widespread exposure and increasing use of insecticides, this should be elaborated in future studies.

Sex comparison of oxidative stress, mitochondrial dysfunction, and apoptosis triggers induced by single-dose Abamectin in albino rats

Abamectin (AB) is widely used in agriculture and has been employed as an insecticide, nematicide, and livestock pest control agent. However, it may also pose a serious threat to mammals. The primary purpose of this research was to compare the sex variations between male and female rats during exposure and to assess the risk of toxicity of abamectin, which are still largely unknown. The twenty albino rats were divided randomly into four groups (n = 5): 1) the male control group; 2) the male treatment group treated with AB (1 mg/kg B.W.); 3) the female control group; and 4) the female treatment group treated with AB (1 mg/kg B.W.). AB administration caused a drop in body weight in females more than males with showing oxidative stress in both sexes of animals, as characterized by an increase in MDA content and a decrease in glutathione (GSH) content and superoxide dismutase (SOD) activity. Reported sex-specific effects suggested that females are more susceptible from males in brain tissues for alteration of antioxidant markers while females' liver and kidney tissues showed more level of lipid peroxidation than males. In addition, mitochondrial dysfunction was associated with a significant decrease in NADH dehydrogenase (Complex I) and a significant decrease in mitochondrial ATPase, which led to apoptosis and histopathological alterations in the targeted tissues, indicating that females are higher sensitive than males to these biological events. In brief, the results of this study led to female rats are generally more sensitive than male rats to neurobehavioral and hepatic complications associated with abamectin treatment. Further evaluation should be performed to determine the adverse outcome pathways involved and to determine the effects of sex on improving the risk assessment of abamectin in both sexes.

Sex-specific neurobehavioral and biochemical effects of developmental exposure to Malathion in offspring mice

Malathion is an organophosphate pesticide (OP) commonly used in agriculture, industry, and veterinary medicine. Sex is a crucial factor in responding to neurotoxicants, yet the sex-specific effects of OP exposure, particularly neurological impairments following chronic low-level exposure remains limited. Our study aims to evaluate the neurobehavioral and biochemical effects of developmental exposure to Malathion across sexes. Pregnant mice were exposed to a low oral dose of Malathion from gestation up to the weaning of the pups, which were individually gavaged with a similar dose regimen until postnatal day 70. Our results show that Malathion decreased body weight and food intake, reduced locomotor activity and recognition memory. Motor coordination and special memory were only altered in females, whereas we found a male-specific effect of Malathion on social behavior and marble burying. These alterations were accompanied by increased malondialdehyde (MDA), decreased brain acetylcholinesterase activity (AChE), and disrupted brain redox homeostasis. Our findings about the effects of Malathion exposure across sexes may, in part, contribute to understanding the dimorphic susceptibilities observed in neurological disorders.

Agricultural activities and risk of Alzheimer's disease: the TRACTOR project, a nationwide retrospective cohort study

Data regarding Alzheimer's disease (AD) occurrence in farming populations is lacking. This study aimed to investigate whether, among the entire French farm manager (FM) workforce, certain agricultural activities are more strongly associated with AD than others, using nationwide data from the TRACTOR (Tracking and monitoring occupational risks in agriculture) project. Administrative health insurance data (digital electronic health/medical records and insurance claims) for the entire French agricultural workforce, over the period 2002-2016, on the entire mainland France were used to estimate the risk of AD for 26 agricultural activities with Cox proportional hazards model. For each analysis (one for each activity), the exposed group included all FMs that performed the activity of interest (e.g. crop farming), while the reference group included all FMs who did not carry out the activity of interest (e.g. FMs that never farmed crops between 2002 and 2016). There were 5067 cases among 1,036,069 FMs who worked at least one year between 2002 and 2016. Analyses showed higher risks of AD for crop farming (hazard ratio (HR) = 3.72 [3.47-3.98]), viticulture (HR = 1.29 [1.18-1.42]), and fruit arboriculture (HR = 1.36 [1.15-1.62]). By contrast, lower risks of AD were found for several animal farming types, in particular for poultry and rabbit farming (HR = 0.29 [0.20-0.44]), ovine and caprine farming (HR = 0.50 [0.41-0.61]), mixed dairy and cow farming (HR = 0.46 [0.37-0.57]), dairy farming (HR = 0.67 [0.61-0.73]), and pig farming (HR = 0.30 [0.18-0.52]). This study shed some light on the association between a wide range of agricultural activities and AD in the entire French FMs population.

Sex Differences in Organophosphate Model of Benzodiazepine-Refractory Status Epilepticus and Neuronal Damage

Sex differences are common in human epilepsy. Although men are more susceptible to seizure than women, the mechanisms underlying sex-specific vulnerabilities to seizure are unclear. The organophosphate (OP) diisopropylfluorophosphate (DFP) is known to cause neurotoxicity and status epilepticus (SE), a serious neurologic condition that causes prolonged seizures and brain damage. Current therapies for OP poisoning and SE do not consider neuronal variations between male and female brains. Therefore, we investigated sex-dependent differences in electrographic seizure activity and neuronal injury using the DFP model of refractory SE in rats. Electroencephalogram recordings were used to monitor DFP-induced SE, and the extent of brain injury was determined using fluoro-jade-B staining to detect cellular necrosis. After DFP exposure, we observed striking sex-dependent differences in SE and seizure activity patterns as well as protective responses to midazolam treatment. Following acute DFP exposure, male animals displayed more severe SE with intense epileptiform spiking and greater mortality than females. In contrast, we observed significantly more injured cells and cellular necrosis in the hippocampus and other brain regions in females than in males. We also observed extensive neuronal injury in the somatosensory cortex of males. The anticonvulsant effect of midazolam against SE was limited in this model and found to be similar in males and females. However, unlike males, females exhibited substantially more protection against neuronal damage after midazolam treatment. Overall, these results demonstrate significant sex-dependent differences in DFP-induced refractory SE and neuronal damage patterns, suggesting that it may be possible to develop sex-specific neuroprotective strategies for OP intoxication and refractory SE. SIGNIFICANCE STATEMENT: Sex-dependent differences in neurotoxicity and status epilepticus (SE) are key biological variables after organophosphate (OP) exposure. Here, we investigated sex-dependent differences in SE and brain injury after acute diisopropylfluorophosphate exposure. Male rats had more severe SE and less survival than females, while females had more neuronal damage. Females had more neuroprotection to midazolam than males, while both sexes had similar but partial anticonvulsant effects. These findings suggest that a sex-specific therapeutic approach may prevent neurological complications of OP-induced SE.

Investigating the relationship between non-occupational pesticide exposure and metabolomic biomarkers

The relationship between pesticide exposures and metabolomics biomarkers is not well understood. We examined the changes in the serum metabolome (early biomarkers) and the metabolic pathways associated with various pesticide exposure scenarios (OPE: overall exposure, PEM: exposure in months, PEY: exposure in years, and PEU: reported specific pesticides use) using data from the Northern Finland Birth Cohort 1966 31-year cross-sectional examination. We utilized questionnaire data on pesticide exposures and serum samples for nuclear magnetic resonance (NMR)-based metabolomics analyses. For exposures and metabolites associations, participants size varied between 2,361 and 5,035. To investigate associations between metabolomics biomarkers and exposure to pesticide scenarios compared to those who reported no exposures multivariable regression analyses stratified by sex and adjustment with covariates (season of pesticide use, socioeconomic position (SEP), alcohol consumption, BMI, and latitude of residence) were performed. Multiple testing by Benjamini-Hochberg false discovery rate (FDR) correction applied. Pesticide exposures differed by sex, season of pesticide use, alcohol, SEP, latitude of residence. Our results showed that all pesticide exposure scenarios were negatively associated with decreased HDL concentrations across all lipoprotein subclasses in women. OPE, PEY, and PEU were associated with decreased branched-chain amino acid concentrations in men and decreased albumin concentrations in women. OPE, PEY and PEU were also associated with changes in glycolysis metabolites and ketone bodies in both sexes. Specific pesticides exposure was negatively associated with sphingolipids and inflammatory biomarkers in men. In women, OPE, PEM, and PEU were associated with decreased apolipoprotein A1 and increased apolipoprotein B/apolipoprotein A1 ratio. Our findings suggest that identification of early biomarkers of disease risk related to pesticide exposures can inform strategies to reduce exposure and investigate causal pathways. Women may be more susceptible to non-occupational pesticide exposures when compared to men, and future sex-specific studies are warranted.

Association of Prenatal Exposure to Organophosphate, Pyrethroid, and Neonicotinoid Insecticides with Child Neurodevelopment at 2 Years of Age: A Prospective Cohort Study

BACKGROUND

Widespread insecticide exposure might be a risk factor for neurodevelopment of our children, but few studies examined the mixture effect of maternal coexposure to organophosphate insecticides (OPPs), pyrethroids (PYRs), and neonicotinoid insecticides (NNIs) during pregnancy on child neurodevelopment, and critical windows of exposure are unknown.

OBJECTIVES

We aimed to evaluate the association of prenatal exposure to multiple insecticides with children's neurodevelopment and to identify critical windows of the exposure.

METHODS

Pregnant women were recruited into a prospective birth cohort study in Wuhan, China, from 2014-2017. Eight metabolites of OPPs (mOPPs), three metabolites of PYRs (mPYRs), and nine metabolites of NNIs (mNNIs) were measured in 3,123 urine samples collected at their first, second, and third trimesters. Children's neurodevelopment [mental development index (MDI) and psychomotor development index (PDI)] was assessed using the Bayley Scales of Infant Development at 2 years of age (N = 1,041 ). Multivariate linear regression models, generalized estimating equation models, and weighted quantile sum (WQS) regression were used to estimate the association between the insecticide metabolites and Bayley scores. Potential sex-specific associations were also examined.

RESULTS

Single chemical analysis suggested higher urinary concentrations of some insecticide metabolites at the first trimester were significantly associated with lower MDI and PDI scores, and the associations were more prominent among boys. Each 1-unit increase in ln-transformed urinary concentrations of two mOPPs, 3,5,6-trichloro-2-pyridinol and 4-nitrophenol, was associated with a decrease of 3.16 points [95% confidence interval (CI): - 5.59 , - 0.74 ] and 3.06 points (95% CI: - 5.45 , - 0.68 ) respectively in boys' MDI scores. Each 1-unit increase in that of trans-3-(2,2-dichloroethenyl)-2,2-dimethylcyclopropanecarboxylic acid (trans-DCCA; an mPYR) was significantly associated with a decrease of 2.24 points (95% CI: - 3.89 , - 0.58 ) in boys' MDI scores and 1.90 points (95% CI: - 3.16 , - 0.64 ) in boys' PDI scores, respectively. Significantly positive associations of maternal urinary biomarker concentrations [e.g., dimethyl phosphate (a nonspecific mOPP) and desmethyl-clothianidin (a relatively specific mNNI)] with child neurodevelopment were also observed. Using repeated holdout validation, a 1-quartile increase in the WQS index of the insecticide mixture (in the negative direction) at the first trimester was significantly associated with a decrease of 3.02 points (95% CI: - 5.47 , - 0.57 ) in MDI scores among the boys, and trans-DCCA contributed the most to the association (18%).

CONCLUSIONS

Prenatal exposure to higher levels of certain insecticides and their mixture were associated with lower Bayley scores in children, particularly in boys. Early pregnancy may be a sensitive window for such an effect. Future studies are needed to confirm our findings. https://doi.org/10.1289/EHP12097.

Succinate prodrugs as treatment for acute metabolic crisis during fluoroacetate intoxication in the rat

Sodium fluoroacetate (FA) is a metabolic poison that systemically inhibits the tricarboxylic acid (TCA) cycle, causing energy deficiency and ultimately multi-organ failure. It poses a significant threat to society because of its high toxicity, potential use as a chemical weapon and lack of effective antidotal therapy. In this study, we investigated cell-permeable succinate prodrugs as potential treatment for acute FA intoxication. We hypothesized that succinate prodrugs would bypass FA-induced mitochondrial dysfunction, provide metabolic support, and prevent metabolic crisis during acute FA intoxication. To test this hypothesis, rats were exposed to FA (0.75 mg/kg) and treated with the succinate prodrug candidate NV354. Treatment efficacy was evaluated based on cardiac and cerebral mitochondrial respiration, mitochondrial content, metabolic profiles and tissue pathology. In the heart, FA increased concentrations of the TCA metabolite citrate (+ 4.2-fold, p < 0.01) and lowered ATP levels (- 1.9-fold, p < 0.001), confirming the inhibition of the TCA cycle by FA. High-resolution respirometry of cardiac mitochondria further revealed an impairment of mitochondrial complex V (CV)-linked metabolism, as evident by a reduced phosphorylation system control ratio (- 41%, p < 0.05). The inhibition of CV-linked metabolism is a novel mechanism of FA cardiac toxicity, which has implications for drug development and which NV354 was unable to counteract at the given dose. In the brain, FA induced the accumulation of β-hydroxybutyrate (+ 1.4-fold, p < 0.05) and the reduction of mitochondrial complex I (CI)-linked oxidative phosphorylation (OXPHOSCI) (- 20%, p < 0.01), the latter of which was successfully alleviated by NV354. This promising effect of NV354 warrants further investigations to determine its potential neuroprotective effects.

Neurologic symptoms among solar greenhouse workers and field workers in China

It has been widely reported that the farmers were at increased risk of neurologic disorders, which probably be related with agricultural risk factors. The intensity of agricultural risk factors was rather high in the solar greenhouse than those in the agricultural farm, while the risk and prevalence of neurologic symptoms among solar greenhouse workers are unclear, which may provide evidence of neurologic dysfunction before clinically measurable signs are evident. This study aimed to evaluate the association among solar greenhouse working, field working, and neurologic symptoms. A cross-sectional study was conducted in China, and 986 Chinese Han population consisting 711 solar greenhouse workers (greenhouse worker group) and 275 field farmers (field worker group) were included. Participants provided information on demographic information, number of solar greenhouses owned (only solar greenhouse workers), working lifetime, and neurologic symptoms through an established questionnaire Q16 to assess the impact of occupational exposure to neurotoxicants, and the total scores were calculated. Multiple linear regression models were used to analyze the association among solar greenhouse working, field working, and neurologic symptoms. The total scales of the neurologic symptoms were higher in the solar greenhouse worker group (20.29 ± 4.79) than those in the field worker group (19.44 ± 4.22) (p < 0.05). Multivariate multiple linear regression showed that solar greenhouse working was positively associated with the scales of the neurologic symptoms (β = 0.248, 95% CI: (0.112, 0.383)). And the age, working lifetime, and current smoking were also positively associated with the scores of the neurologic symptoms, β = 0.007, 0.006 and 0.485 respectively (All p < 0.05). Solar greenhouse workers probably be at an increased risk of neurologic symptoms scores, and the age, working lifetime, and current smoking were also risk factors.

Domain-specific effects of prenatal fluoride exposure on child IQ at 4, 5, and 6-12 years in the ELEMENT cohort

OBJECTIVE

Prenatal exposure to fluoride has been associated with adverse neurodevelopmental outcomes. However, the neuropsychological profile of fluoride's developmental neurotoxicity at low levels and the stability of this relationship across childhood has not been characterized. We investigated the longitudinal and domain specific effect of prenatal fluoride exposure on IQ among children ages 4, 5, and 6-12 years in the Early Life Exposures in Mexico to Environmental Toxicants (ELEMENT) cohort.

METHODS

We measured the average of maternal urinary fluoride at each trimester of pregnancy adjusted for creatinine (MUF_CRE). Children were administered the McCarthy Scales of Children's Abilities at ages 4 (N = 386) and 5 (N = 308), and the Wechsler Abbreviated Scale of Intelligence at age 6-12 (N = 278). We used generalized estimating equation (GEE) models to estimate the population averaged effect of MUF_CRE concentration on longitudinal General Cognitive Index (GCI)/Full-Scale IQ (FSIQ), Verbal IQ (VIQ), and Performance IQ (PIQ) scores (N = 348). We tested for possible interactions between MUF_CRE and child sex as well as for MUF_CRE and time point on children's IQ. All models controlled for relevant available covariates.

RESULTS

The mean/median MUF_CRE concentration was 0.90/0.83 mg/L (SD = 0.39; IQR, 0.64-1.11 mg/L). A 0.5 mg/L increase in MUF_CRE predicted an average 2.12-point decrease in GCI/FSIQ (95% CI: -3.49, -0.75) and 2.63-point decrease in PIQ (95% CI: -3.87, -1.40). MUF_CRE was marginally associated with VIQ across time (B = -1.29, 95% CI: -2.60, 0.01). No interactions between MUF_CRE and child sex or MUF_CRE and time were observed.

CONCLUSION

The negative association between prenatal fluoride exposure and longitudinal IQ was driven by decrements in non-verbal intelligence (i.e. PIQ), suggesting that visual-spatial and perceptual reasoning abilities may be more impacted by prenatal fluoride exposure as compared to verbal abilities.

Sexual dimorphism in neurological function after SCI is associated with disrupted neuroinflammation in both injured spinal cord and brain

Whereas human spinal cord injury (SCI) is more common in men, the prevalence is growing in women. However, little is known about the effect of biological sex on brain dysfunction and injury mechanisms. To model the highest per capita rate of injury (ages between 16 and 30 years old) in humans, in the present study, young adult or a young/middle-aged male and female C57BL/6 mice were subjected to moderate contusion SCI. When mice were injured at 10-12-week-old, transcriptomic analysis of inflammation-related genes and flow cytometry revealed a more aggressive neuroinflammatory profile in male than females following 3 d SCI, ostensibly driven by sex-specific changes myeloid cell function rather than cell number. Female mice were generally more active at baseline, as evidenced by greater distance traveled in the open field. After SCI, female mice had more favorable locomotor function than male animals. At 13 weeks post-injury, male mice showed poor performance in cognitive and depressive-like behavioral tests, while injured female mice showed fewer deficits in these tasks. However, when injured at 6 months old followed by 8 months post-injury, male mice had considerably less inflammatory activation compared with female animals despite having similar or worse outcomes in affective, cognitive, and motor tasks. Collectively, these findings indicate that sex differences in functional outcome after SCI are associated with the age at onset of injury, as well as disrupted neuroinflammation not only at the site of injury but also in remote brain regions. Thus, biological sex should be considered when designing new therapeutic agents.

Sex-specific acute and chronic neurotoxicity of acute diisopropylfluorophosphate (DFP)-intoxication in juvenile Sprague-Dawley rats

Preclinical efforts to improve medical countermeasures against organophosphate (OP) chemical threat agents have largely focused on adult male models. However, age and sex have been shown to influence the neurotoxicity of repeated low-level OP exposure. Therefore, to determine the influence of sex and age on outcomes associated with acute OP intoxication, postnatal day 28 Sprague-Dawley male and female rats were exposed to the OP diisopropylfluorophosphate (DFP; 3.4 mg/kg, s.c.) or an equal volume of vehicle (∼80 µL saline, s.c.) followed by atropine sulfate (0.1 mg/kg, i.m.) and pralidoxime (2-PAM; 25 mg/kg, i.m.). Seizure activity was assessed during the first 4 h post-exposure using behavioral criteria and electroencephalographic (EEG) recordings. At 1 d post-exposure, acetylcholinesterase (AChE) activity was measured in cortical tissue, and at 1, 7, and 28 d post-exposure, brains were collected for neuropathologic analyses. At 1 month post-DFP, animals were analyzed for motor ability, learning and memory, and hippocampal neurogenesis. Acute DFP intoxication triggered more severe seizure behavior in males than females, which was supported by EEG recordings. DFP caused significant neurodegeneration and persistent microglial activation in numerous brain regions of both sexes, but astrogliosis occurred earlier and was more severe in males compared to females. DFP males and females exhibited pronounced memory deficits relative to sex-matched controls. In contrast, acute DFP intoxication altered hippocampal neurogenesis in males, but not females. These findings demonstrate that acute DFP intoxication triggers seizures in juvenile rats of both sexes, but the seizure severity varies by sex. Some, but not all, chronic neurotoxic outcomes also varied by sex. The spatiotemporal patterns of neurological damage suggest that microglial activation may be a more important factor than astrogliosis or altered neurogenesis in the pathogenesis of cognitive deficits in juvenile rats acutely intoxicated with OPs.

Critical windows of fluoride neurotoxicity in Canadian children

BACKGROUND

Fluoride has been associated with IQ deficits during early brain development, but the period in which children are most sensitive is unknown.

OBJECTIVE

We assessed effects of fluoride on IQ scores across prenatal and postnatal exposure windows.

METHODS

We used repeated exposures from 596 mother-child pairs in the Maternal-Infant Research on Environmental Chemicals pregnancy and birth cohort. Fluoride was measured in urine (mg/L) collected from women during pregnancy and in their children between 1.9 and 4.4 years; urinary fluoride was adjusted for specific gravity. We estimated infant fluoride exposure (mg/day) using water fluoride concentration and duration of formula-feeding over the first year of life. Intelligence was assessed at 3-4 years using the Wechsler Preschool and Primary Scale of Intelligence-III. We used generalized estimating equations to examine the associations between fluoride exposures and IQ, adjusting for covariates. We report results based on standardized exposures given their varying units of measurement.

RESULTS

The association between fluoride and performance IQ (PIQ) significantly differed across prenatal, infancy, and childhood exposure windows collapsing across child sex (p = .001). The strongest association between fluoride and PIQ was during the prenatal window, B = -2.36, 95% CI: -3.63, -1.08; the association was also significant during infancy, B = -2.11, 95% CI: -3.45, -0.76, but weaker in childhood, B = -1.51, 95% CI: -2.90, -0.12. Within sex, the association between fluoride and PIQ significantly differed across the three exposure windows (boys: p = .01; girls: p = .01); among boys, the strongest association was during the prenatal window, B = -3.01, 95% CI: -4.60, -1.42, whereas among girls, the strongest association was during infancy, B = -2.71, 95% CI: -4.59, -0.83. Full-scale IQ estimates were weaker than PIQ estimates for every window. Fluoride was not significantly associated with Verbal IQ across any exposure window.

CONCLUSION

Associations between fluoride exposure and PIQ differed based on timing of exposure. The prenatal window may be critical for boys, whereas infancy may be a critical window for girls.

The pesticide chlorpyrifos promotes obesity by inhibiting diet-induced thermogenesis in brown adipose tissue

Obesity results from a caloric imbalance between energy intake, absorption and expenditure. In both rodents and humans, diet-induced thermogenesis contributes to energy expenditure and involves the activation of brown adipose tissue (BAT). We hypothesize that environmental toxicants commonly used as food additives or pesticides might reduce BAT thermogenesis through suppression of uncoupling protein 1 (UCP1) and this may contribute to the development of obesity. Using a step-wise screening approach, we discover that the organophosphate insecticide chlorpyrifos suppresses UCP1 and mitochondrial respiration in BAT at concentrations as low as 1 pM. In mice housed at thermoneutrality and fed a high-fat diet, chlorpyrifos impairs BAT mitochondrial function and diet-induced thermogenesis, promoting greater obesity, non-alcoholic fatty liver disease (NAFLD) and insulin resistance. This is associated with reductions in cAMP; activation of p38MAPK and AMPK; protein kinases critical for maintaining UCP1 and mitophagy, respectively in BAT. These data indicate that the commonly used pesticide chlorpyrifos, suppresses diet-induced thermogenesis and the activation of BAT, suggesting its use may contribute to the obesity epidemic.

Organophosphate pesticide exposure during pregnancy and childhood and onset of juvenile delinquency by age 16 years: The CHAMACOS cohort

BACKGROUND

Though prenatal organophosphate pesticide (OP) exposure has been associated with lower intellectual quotient and behavioral disorders in childhood, factors related to later delinquency, no research has directly evaluated the impact of OPs on delinquency.

OBJECTIVE

To evaluate the association between prenatal and childhood OP exposure and juvenile delinquency in Mexican-American youth in the Center for Health Assessment of Mothers and Children of Salinas (CHAMACOS).

METHODS

We measured dialkyl phosphate (DAPs) urinary metabolites of OPs in two prenatal maternal samples and in five child samples collected between six months and five years of age. Youth completed delinquency questionnaires at 16 years. We examined associations of prenatal and childhood DAPs with several delinquency outcomes (n = 313) using survival and generalized linear models.

RESULTS

Almost 60% of youth reported delinquent acts (mostly minor), and 8% reported a police arrest. We observed largely null results of prenatal or childhood DAP concentrations and delinquency outcomes, with some isolated associations. A ten-fold increase in maternal dimethylphosphate (DM) concentrations measured after 20 weeks gestation was associated with an earlier age of first delinquent act (Hazard Ratio = 1.38, 95% CI: 1.01, 1.88) and an increased Odds Ratio (OR) of having committed 1-3 or ≥4 delinquent acts, compared to the no delinquency reference group (OR = 1.77, 95% CI: 1.01-3.08 and 2.17, 95% CI: 1.13-4.17, respectively). Higher childhood diethylphosphate (DE) concentrations were associated with a later age of first delinquent act (HR: 0.67; 95% CI: 0.46-0.97).

DISCUSSION

We did not find strong evidence of association between prenatal or childhood OP exposure and juvenile delinquency in the present cohort. There is an increasing literature that relates OP exposure to neurobehavioral impairments in childhood, and there is a need to understand long-term potential neurodevelopmental effects of early-life OP exposure.

Prospective association between organic food consumption and the risk of type 2 diabetes: findings from the NutriNet-Santé cohort study

BACKGROUND

Organic food (OF) consumption has substantially increased in high income countries, mostly driven by environmental concerns and health beliefs. Lower exposure to synthetic pesticides has been systematically documented among consumers of organic products compared to non-consumers. While experimental studies suggest that pesticides currently used in food production may be associated with type 2 diabetes (T2D), no well-conducted prospective studies have investigated the potential association between consumption of organic products and the risk of T2D, controlling for potential confounding factors. The objective of this prospective study was to estimate the association between OF consumption and the risk of T2D.

METHODS

A total of 33,256 participants (76% women, mean (SD) age: 53 years (14)) of the French NutriNet-Santé prospective cohort study who completed the organic food frequency questionnaire were included (2014-2019). The proportion of OF in the diet (as weight without drinking water) was computed. The associations between the proportion of OF in the diet (as 5% increment and as quintiles) and the risk of T2D were estimated using multivariable Hazard Ratio (HR) and 95% confidence interval (95% CI) derived from proportional hazards models adjusted for confounders (sociodemographic, anthropometric, lifestyle, medical and nutritional factors).

RESULTS

During follow-up (mean = 4.05 y, SD = 1.03 y, 134,990 person-years), 293 incident cases of T2D were identified. After adjustment for confounders including lifestyle (physical activity, smoking status, alcohol consumption) and nutritional quality of the diet assessed by the adherence to the French food-based dietary guidelines, OF consumption was associated with a lower risk of T2D. Participants with the highest quintile of OF consumption, compared with those with the lowest quintile, had 35% lower risk of T2D (95% CI = 0.43-0.97). Each increment of 5% in the proportion of OF in the diet was associated with 3% lower risk of T2D (HR 0.97, 95% CI = 0.95-0.99).

CONCLUSIONS

In this large prospective cohort study, OF consumption was inversely associated with the risk of T2D. Further experimental and prospective studies should be conducted to confirm these observations.

CLINICAL TRIAL REGISTRY

The study was registered at ClinicalTrials.gov ( NCT03335644 ).

Exposure to organophosphorus insecticides and increased risks of health and cancer in US women

Results of this paper provide evidence that chronic long-term exposure to organophosphorus insecticides poses a significantly higher health risk for US women than for men, based on dialkylphosphate biomarker data from NHANES cycles 2003-2012. The risk of cardiovascular disease for female non-smokers aged 60-85 years in the highest dimethylthiophosphate (DMTP) urinary concentration quartile is 3.0 (odds ratio, OD = 3.0, 95%CI 1.4-6.4) times higher than that in the lowest quartile. Women with higher urinary DMTP concentrations also have significantly higher risk of asthma at the ages 6-39 years and an apparently higher risk of chronic bronchitis at the ages 60-85. Overall cancer risk is significantly higher for female non-smokers aged 60-85 years in the higher urinary DMTP quartiles (OD = 2.7, 95% CI 1.3-5.9). Increasing risks of breast cancer for female smokers and prostate cancer for male smokers aged 60-85 years with higher exposure to organophosphorus insecticides in the US are also significant.

Global trends in pesticides: A looming threat and viable alternatives

Pesticides are widely used chemical compounds in agriculture to destroy insects, pests and weeds. In modern era, they form an indispensable part of agricultural and health practices. Globally, nearly 3 billion kg of pesticides are used every year with a budget of ~40 billion USD. This extensive usage has increased the crop yield as well as led to significant reduction in harvest losses and thereby, enhanced food availability. On the other hand, indiscriminate usage of these chemicals has led to several environmental implications and caused adverse effects on human health. Epidemiological evidences have revealed the harmful effects of pesticides exposure on various organs including liver, brain, lungs and colon. Recent investigations have shown that pesticides can also lead to fatal consequences such as cancer among individuals. These chemicals enter ecosystem, thus hampering the sensitive environmental equilibrium through bio-accumulation. Due to their non-biodegradable nature, they can persist in nature for years and are regarded as potent biohazard. Worldwide, very few surveillance methods have been considered, which can bring awareness among the individuals, therefore the present review is an attempt to delineate consequences induced by various types of pesticide exposure on the environment. Further, the prospective of biopesticides use could facilitate the increase of crop production without compromising human health.

Exposure of pregnant women to organophosphate insecticides and child motor inhibition at the age of 10-12 years evaluated by fMRI

BACKGROUND

Organophosphate pesticides (OP) are widely used for both agricultural and domestic purposes. Epidemiological studies suggest neurotoxicity in children after exposure to organophosphates pesticides (OP) at low levels but possible mechanism is still unclear.

OBJECTIVES

We aimed at investigating the effects of prenatal exposure to OPs on inhibitory control of 10-12 year-old-children assessed by a motor inhibition task during functional magnetic resonance imaging (fMRI).

METHODS

Ninety-five children from the PELAGIE cohort (Brittany-France, from 2002) underwent a fMRI examination during which inhibition was assessed by a Go/No-Go task. Task performance was assessed by average response latency, commission rate and composite performance score (PS). Whole brain activation was estimated by modeling the hemodynamic response related to inhibition demand and successful inhibition. OP exposure was assessed by measuring six dialkylphosphate (DAP) metabolites in the urine of women in early pregnancy (<19 WG). Concentrations were summed to obtain overall levels of diethylphosphate (DE), dimethylphosphate (DM) and total non-specific metabolites (DAP), standardized to homogenize sampling conditions and categorized into levels of exposure: low (reference), moderate or high. Regression models were adjusted for potential cofounders considered by restriction and statistical criteria.

RESULTS

Moderate levels of DAP were associated with a decreased commission rate (β = -6.65%, p = 0.04), indicating improved performance. Increasing levels of DM and DE were associated with decreased brain activity in the left inferior and bilateral superior frontal regions during successful inhibition. We did not observe any differential activation related to inhibitory demands.

DISCUSSION

These results suggest that prenatal OPs may be associated with altered pattern of brain activity in regions related to inhibition among children and need to be confirmed by additional studies.

Organic Diet and Intermittent Fasting are Associated With Improved Erectile Function

OBJECTIVE

To explore associations between dietary habits and erectile dysfunction (ED) in a cohort of patients presenting to a high-volume men's health clinic.

MATERIALS AND METHODS

All patients presenting to a high-volume men's health clinic between July 2018 and May 2019 were evaluated for their dietary habits and screened with the International Index of Erectile Function-5 (IIEF-5) and Androgen Deficiency in Aging Males (ADAM). The primary outcome measure was the impact of dietary habits on ED, defined as IIEF-5 <22. Stepwise logistic regressions were used to control for patient characteristics and relevant comorbidities.

RESULTS

Two hundred seventy-one patients were included. Primary reasons for visit were ED (110, 40.6%), hypogonadism (39, 14.4%), benign prostatic hyperplasia/lower urinary tract symptoms (80, 29.5%), and Peyronie's Disease (30, 11.1%). 176 (64.9%) followed no diet, while 11 (4.1%), 11 (4.1%), 8 (2.9%), and 11 (4.1%) were whole food only, low-carb/keto, vegetarian/pescatarian, and low-fat, respectively. Additionally, 105 (38.7%) reported organic foods consumption, while 51 (18.8%) had no processed food consumption, and 77 (28.4%) performed intermittent fasting. Patients reporting ED were more likely to be over the age of 65, had higher body mass index, more comorbidities, and less likely to report an organic diet or intermittent fasting. There were no correlations between diet and ADAM score. In adjusted analysis, patients reporting organic diet or intermittent fasting were significantly less likely to have ED.

CONCLUSION

This is the first study suggesting organic diet and intermittent fasting to be protective against ED. These results are hypothesis-generating and warrant further exploration.

Sustainable, healthy cities: protocol of a mixed methods evaluation of a cluster randomized controlled trial for Aedes control in Brazil using a community mobilization approach

Background

Dengue is increasing in its global presence with an estimated 4 billion people at-risk of infection in at least 128 countries. Despite the promising results of EcoHealth and community mobilization approaches to Aedes reduction, more evidence of their efficacy on reducing dengue risk is needed. The principal research question is to determine if interventions based upon community mobilization reduce the risk of dengue virus infection among children 3 to 9 years old compared to usual dengue control practice in Fortaleza, Brazil.

Methods

The present study will follow a pragmatic cluster randomized controlled trial (cRCT) design with randomization at the census tract level with equal allocation to the two arms. In each arm, there will be 34 clusters of 86 children between 3 to 9 years old for an expected total of 5848 children enrolled in the study, assuming a risk reduction of 29.5% based upon findings from a previous multi-site cRCT. The primary outcomes are rates of anti-dengue Immunoglobulin G (IgG) seroconversion and adult female Aedes density. The intervention is based upon a participatory health research approach, Socializing Evidence for Participatory Action (SEPA), where the research evidence is used to foster community engagement and ownership of the health issue and solution. Following allocation, intervention communities will develop and implement their own solutions that will likely include a wide variety of collective events and media approaches. Data collection activities over a period of 3 years include household visits for blood collection, household surveys, and entomological surveys; and qualitative activities including focus groups, in-depth interviews, and document analysis to evaluate the process, acceptability, fidelity, and sustainability of the intervention. Study participants will be aware of their assignment and all research staff will be blinded although the intervention assignment will likely be revealed to field staff through interaction with participants.

Discussion

The results of our study will provide evidence on community mobilization as an intervention for dengue control. We anticipate that if community mobilization is effective in Fortaleza, the results of this study will help develop evidence-based vector control programs in Brazil, and also in other countries struggling with Aedes-transmitted diseases.

Trial registration

ISRCTN66131315, registration date: 1 October 2018.

Early prenatal exposure to suspected endocrine disruptor mixtures is associated with lower IQ at age seven

BACKGROUND

Endocrine disrupting chemicals (EDCs) are xenobiotics with the ability to interfere with hormone action, even at low levels. Prior environmental epidemiology studies link numerous suspected EDCs, including phthalates and bisphenol A (BPA), to adverse neurodevelopmental outcomes. However, results for some chemicals were inconsistent and most assessed one chemical at a time.

OBJECTIVES

To evaluate the overall impact of prenatal exposure to an EDC mixture on neurodevelopment in school-aged children, and identify chemicals of concern while accounting for co-exposures.

METHODS

Among 718 mother-child pairs from the Swedish Environmental Longitudinal, Mother and child, Asthma and allergy study (SELMA) study, we used Weighted Quantile Sum (WQS) regression to assess the association between 26 EDCs measured in 1st trimester urine or blood, with Wechsler Intelligence Scale for Children (IV) Intelligence Quotient (IQ) scores at age 7 years. Models were adjusted for child sex, gestational age, mother's education, mother's IQ (RAVEN), weight, and smoking status. To evaluate generalizability, we conducted repeated holdout validation, a machine learning technique.

RESULTS

Using repeated holdout validation, IQ scores were 1.9-points (CI = -3.6, -0.2) lower among boys for an inter-quartile-range (IQR) change in the WQS index. BPF made the largest contribution to the index with a weight of 14%. Other chemicals of concern and their weights included PBA (9%), TCP (9%), MEP (6%), MBzP (4%), PFOA (6%), PFOS (5%), PFHxS (4%), Triclosan (5%), and BPA (4%). While we did observe an inverse association between EDCs and IQ among all children when training and testing the WQS index estimate on the full dataset, these results were not robust to repeated holdout validation.

CONCLUSION

Among boys, early prenatal exposure to EDCs was associated with lower intellectual functioning at age 7. We identified bisphenol F as the primary chemical of concern, suggesting that the BPA replacement compound may not be any safer for children. Future studies are needed to confirm the potential neurotoxicity of replacement analogues.

A Multiomics Study To Unravel the Effects of Developmental Exposure to Endosulfan in Rats: Molecular Explanation for Sex-Dependent Effects

Exposure to low levels of environmental contaminants, including pesticides, induces neurodevelopmental toxicity. Environmental and food contaminants can reach the brain of the fetus, affecting brain development and leading to neurological dysfunction. The pesticide endosulfan is a persistent pollutant, and significant levels still remain detectable in the environment although its use is banned in some countries. In rats, endosulfan exposure during brain development alters motor activity, coordination, learning, and memory, even several months after uptake, and does so in a sex-dependent way. However, the molecular mechanisms driving these effects have not been studied in detail. In this work, we performed a multiomics study in cerebellum from rats exposed to endosulfan during embryonic development. Pregnant rats were orally exposed to a low dose (0.5 mg/kg) of endosulfan, daily, from gestational day 7 to postnatal day 21. The progeny was evaluated for cognitive and motor functions at adulthood. Expression of messenger RNA and microRNA genes, as well as protein and metabolite levels, were measured on cerebellar samples from males and females. An integrative analysis was conducted to identify altered processes under endosulfan effect. Effects between males and females were compared. Pathways significantly altered by endosulfan exposure included the phosphatidylinositol signaling system, calcium signaling, the cGMP-PKG pathway, the inflammatory and immune system, protein processing in the endoplasmic reticulum, and GABA and taurine metabolism. Sex-dependent effects of endosulfan in the omics results that matched sex differences in cognitive and motor tests were found. These results shed light on the molecular basis of impaired neurodevelopment and contribute to the identification of new biomarkers of neurotoxicity.

Effects of prenatal and postnatal exposure to organophosphate pesticides on child neurodevelopment in different age groups: a systematic review

Exposure to pesticides is a major factor in the cause of dysfunction in the nervous system and neurodevelopment disorders in children at critical periods of great vulnerability. The aim of this study was to review scientific evidence published on neurodevelopmental effects of prenatal and postnatal exposure to organophosphate pesticides (OPs) in different stages, including neonates, infants, toddlers, preschool children, and school-age children. Full-text articles published in PubMed, Scopus, and ISI databases between 1973 and 2019 were reviewed and the scientific evidence was evaluated. Results: Fifty studies were eligible for inclusion in this quantitative synthesis. Fifteen of these papers evaluated the effects on neonates and infants, 18 on the effects on toddlers and preschool children, and 24 the effects on school-age children. Considerable evidence suggests that prenatal exposure to OPs contributes to child neurodevelopment disorders in all stages, whereas data about the effects of postnatal exposure are limited. Therefore, the available evidence supports the theory that sensitive time-windows occur prenatally rather than postnatally. Although 45 out of the total 50 selected articles found an association between OP exposure and child neurodevelopment, some of the evidence is controversial. A standardized methodology is needed to enable the comparison of the results in several studies, and further research studies are needed to warrant firmer conclusions. A systematic review of this evidence should be performed continuously to update the state of knowledge regarding neurodevelopmental effects associated with OP exposure.

Fetal growth in environmental epidemiology: mechanisms, limitations, and a review of associations with biomarkers of non-persistent chemical exposures during pregnancy

BACKGROUND

Non-persistent chemicals, such as phthalates, environmental phenols, organophosphate pesticides, and others, are challenging to study because of their ubiquity in the environment, diverse exposure routes, and high temporal variability of biomarkers. Nonetheless, there is interest in understanding how gestational exposure to these chemicals may affect fetal growth, as perturbations to normal fetal growth are related to a plethora of adverse health outcomes in childhood and adulthood.

METHODS

The purpose of this review is to describe the state of the science on this topic. We searched PubMed for studies that included both 1) biomarkers of non-persistent chemicals collected during pregnancy and 2) fetal growth outcomes measured at birth (e.g., birth weight) or by ultrasound in utero (e.g., estimated fetal weight).

RESULTS

The bulk of the literature we found uses biomarkers measured at a single time point in pregnancy and birth weight as the primary measure of fetal growth. There is a small, but growing, body of research that uses ultrasound measures to assess fetal growth during pregnancy. In addition to summarizing the findings of the publications we identified, we describe inconsistencies in methodology, areas for improvement, and gaps in existing knowledge that can be targeted for improvement in future work. This literature is characterized by variability in methodology, likely contributing to the inconsistency of results reported. We further discuss maternal, placental, and fetal pathways by which these classes of chemicals may affect fetal growth.

CONCLUSIONS

To improve understanding of how everyday chemical exposures affect fetal growth, and ultimately lifelong health outcomes, mechanisms of toxicant action should be considered alongside improved study designs for future hypothesis-driven research.

Impaired innate and conditioned social behavior in adult C57Bl6/J mice prenatally exposed to chlorpyrifos

Background

Signs of pervasive developmental disorder and social deficits were reported in toddlers and children whose mothers were exposed to organophosphate pesticides during pregnancy. Deficits in social preference were reported in adult male mice exposed to chlorpyrifos on gestational days 12–15. This study aimed (a) to test the hypothesis that adult female and male mice that were exposed prenatally to subtoxic doses of chlorpyrifos would be impaired in social behavior and (b) to determine if prenatal chlorpyrifos altered the expression of transcripts for oxytocin in the hypothalamus. Pregnant mice were treated by gavage with corn oil vehicle or 2.5 mg/kg or 5 mg/kg of CPF on gestational days 12–15. Social preference, social and non-social conditioned place preference tasks were tested in adults. Expression of oxytocin transcripts in hypothalamus was measured by qPCR.

Results

Chlorpyrifos (5 mg/kg on GD 12–15) reduced the innate preference for a conspecific in a dose and sex dependent manner. Adult males exposed prenatally to 5 mg/kg CPF showed a reduction in social preference. Socially conditioned place preference was impaired in offspring of dams treated with either dose of CPF. Non-social appetitive place conditioning was impaired in offspring of dams exposed to 2.5 mg/kg, but not to 5 mg/kg chlorpyrifos. Prenatal chlorpyrifos treatment did not alter the expression of the oxytocin mRNA in the hypothalamus, although expression was significantly lower in females.

Conclusions

Prenatal chlorpyrifos induced innate and learned social deficits and non-specific conditioning deficits in adult mice in a sex-dependent manner. Males showed specific social deficits following the higher dose whereas both males and females showed a more generalized conditioning deficit following the intermediate dose.

Sex Differences in Neurotoxicogenetics

A major development in biomedical research is the recognition that the sex of an individual plays a key role in susceptibility, treatment, and outcomes of most diseases. In this contribution, we present evidence that sex is also important in the toxicity of many environmental toxicants and contributes to the effect of genetics. Thus, individual differences in response to toxicants includes genetic makeup, the environment and sex; in fact, sex differences may be considered a part of genetic constitution. In this review, we present evidence for sex contribution to susceptibility for a number of toxicants.

Species and Sex Differences in the Morphogenic Response of Primary Rodent Neurons to 3,3'-Dichlorobiphenyl (PCB 11)

PCB 11 is an emerging global pollutant that we recently showed promotes axonal and dendritic growth in primary rat neuronal cell cultures. Here, we address the influence of sex and species on neuronal responses to PCB 11. Neuronal morphology was quantified in sex-specific primary hippocampal and cortical neuron-glia co-cultures derived from neonatal C57BL/6J mice and Sprague Dawley rats exposed for 48 h to vehicle (0.1% DMSO) or PCB 11 at concentrations ranging from 1 fM to 1 nM. Total axonal length was quantified in tau-1 immunoreactive neurons at day in vitro (DIV) 2; dendritic arborization was assessed by Sholl analysis at DIV 9 in neurons transfected with MAP2B-FusRed. In mouse cultures, PCB 11 enhanced dendritic arborization in female, but not male, hippocampal neurons and male, but not female, cortical neurons. In rat cultures, PCB 11 promoted dendritic arborization in male and female hippocampal and cortical neurons. PCB 11 also increased axonal growth in mouse and rat neurons of both sexes and neuronal cell types. These data demonstrate that PCB 11 exerts sex-specific effects on neuronal morphogenesis that vary depending on species, neurite type, and neuronal cell type. These findings have significant implications for risk assessment of this emerging developmental neurotoxicant.