In-utero exposure to DDT and pyrethroids and child behavioral and emotional problems at 2 years of age in the VHEMBE cohort, South Africa

Effect of Indoor Residual Spraying on Malaria in Pregnancy and Pregnancy Outcomes: A Systematic Review

Malaria in pregnancy increases maternal and perinatal morbidity and mortality. Indoor residual spraying (IRS) is a core vector control strategy used to reduce transmission in endemic areas; however, its efficacy in reducing the sequelae of malaria in pregnancy is not well described. PubMed, Embase, Cochrane, and Web of Science were searched for all studies assessing IRS exposure during pregnancy. Abstracts and full texts were reviewed independently by two researchers, with discrepancies adjudicated by a third. Of 3,319 studies that met the search criteria, 17 met the inclusion criteria. Thirteen studies reported on the effect of IRS on malaria endpoints during pregnancy, five on birth outcomes, and one on a fetal anomaly. Twelve of the 13 studies exploring maternal malaria and 3 of 3 studies reporting on placental malaria demonstrated a reduction among those exposed to IRS during pregnancy. Results were more mixed for obstetric outcomes. Two of the best-quality studies showed reductions in preterm birth, low birthweight, and fetal/neonatal mortality; a third high-quality study did not demonstrate a reduction in perinatal mortality but did not evaluate preterm birth. One study found a significantly increased risk of preterm birth in those exposed to IRS, although the study was of lower quality. A final study demonstrated a small, although statistically significant, association between IRS and male urogenital birth defects. In malaria-endemic areas, the published literature suggests that IRS during pregnancy reduces the incidence of malaria parasitemia. However, without high-quality prospective studies directly examining IRS in pregnancy, the impact on birth outcomes is less clear.

A preliminary estimate of the environmental burden of disease associated with exposure to pyrethroid insecticides and ADHD in Europe based on human biomonitoring

Human biomonitoring (HBM) data indicate that exposure to pyrethroids is widespread in Europe, with significantly higher exposure observed in children compared to adults. Epidemiological, toxicological, and mechanistic studies raise concerns for potential human health effects, particularly, behavioral effects such as attention deficit hyperactivity disorder (ADHD) in children at low levels of exposure. Based on an exposure-response function from a single European study and on available quality-assured and harmonized HBM data collected in France, Germany, Iceland, Switzerland, and Israel, a preliminary estimate of the environmental burden of disease for ADHD associated with pyrethroid exposure was made for individuals aged 0-19 years. The estimated annual number of prevalence-based disability-adjusted life years (DALYs) per million inhabitants were 27 DALYs for Israel, 21 DALYs for France, 12 DALYs for both Switzerland and Iceland, and 3 DALYs for Germany; while the annual ADHD cases per million inhabitants attributable to pyrethroids were 2189 for Israel, 1710 for France, 969 for Iceland, 944 for Switzerland, and 209 for Germany. Direct health costs related to ADHD ranged between 0.3 and 2.5 million EUR yearly per million inhabitants for the five countries. Additionally, a substantial number of ADHD cases, on average 18%, were associated with pyrethroid exposure. Yet, these figures should be interpreted with caution given the uncertainty of the estimation. A sensitivity analysis showed that by applying a different exposure-response function from outside the EU, the population attributable fraction decreased from an average of 18 to 7%. To ensure more robust disease burden estimates and adequate follow-up of policy measures, more HBM studies are needed, along with increased efforts to harmonize the design of epidemiological studies upfront to guarantee meta-analysis of exposure-response functions. This is particularly important for pyrethroids as evidence of potential adverse health effects is continuously emerging.

Effects of DDT and DDE on placental cholinergic receptors

The placental cholinergic system; known as an important factor in intracellular metabolic activities, regulation of placental vascular tone, placental development, and neurotransmission; can be affected by persistent organic pesticides, particularly organochlorine pesticides(OCPs), which can influence various epigenetic regulations and molecular pathways. Although OCPs are legally prohibited, trace amounts of the persistent dichlorodiphenyltrichloroethane(DDT) are still found in the environment, making prenatal exposure inevitable. In this study, the effects of 2,4'-DDT and 4,4'-DDT; and its breakdown product 4,4'-DDE in the environment on placental cholinergic system were evaluated with regards to cholinergic genes. 40 human placentas were screened, where 42,50% (17 samples) were found to be positive for the tested compounds. Average concentrations were 10.44 μg/kg; 15.07 μg/kg and 189,42 μg/kg for 4,4'-DDE; 2,4'-DDT and 4,4'-DDT respectively. RNA-Seq results revealed 2396 differentially expressed genes in positive samples; while an increase in CHRM1,CHRNA1,CHRNG and CHRNA2 genes at 1.28, 1.49, 1.59 and 0.4 fold change were found(p<0028). The increase for CHRM1 was also confirmed in tissue samples with immunohistochemistry. In vitro assays using HTR8/SVneo cells; revealed an increase in mRNA expression of CHRM1, CHRM3 and CHRN1 in DDT and DDE treated groups; which was also confirmed through western blot assays. An increase in the expression of CHRM1,CHRNA1, CHRNG(p<0001) and CHRNA2(p<0,05) were found from the OCPs exposed and non exposed groups.The present study reveals that intrauterine exposure to DDT affects the placental cholinergic system mainly through increased expression of muscarinic receptors. This increase in receptor expression is expected to enhance the sensitivity of the placental cholinergic system to acetylcholine.

Prenatal current-use pesticide exposure and children's neurodevelopment at one year of age in the Infants' Environmental Health (ISA) birth cohort, Costa Rica

BACKGROUND

Pesticide exposure may affect young children's neurodevelopment, but only few cohort studies have addressed possible effects of non-organophosphate pesticides.

OBJECTIVE

We evaluated associations between prenatal current-use pesticide exposure and neurodevelopmental outcomes among 1-year-old children from the Infants' Environmental Health (ISA) birth cohort.

METHODS

To determine prenatal pesticide exposure, we measured biomarkers of pyrimethanil, chlorpyrifos, synthetic pyrethroids, and 2,4-D in urine samples among 355 women, 1-3 times during pregnancy. One-year post-partum, we evaluated children's neurodevelopment with the Bayley Scales of Infant and Toddler Development 3rd edition (BSID-III). We assessed associations between exposures and neurodevelopmental outcomes (composite and z-scores) using single-chemical linear regression models adjusted for possible confounders (maternal education, parity, sex, gestational age at birth, child age, HOME-score, location of assessment, biomarkers of mancozeb), and studied effect-modification by sex. We evaluated non-linear associations of multiple pesticide exposures with Bayesian kernel machine regression (BKMR).

RESULTS

We found higher prenatal urinary 2,4-D concentrations were associated with lower language (βper ten-fold increase = -2.0, 95 % confidence interval (CI) = -3.5, -0.5) and motor (βper ten-fold increase = -2.2, 95 %CI = -4.2, -0.1) composite scores among all children. Also, higher chlorpyrifos exposure [measured as urinary 3,5,6-trichloro-2-pyridinol (TCPy)] was associated with lower cognitive composite scores (βper ten-fold increase = -1.9, 95 %CI = -4.7, 0.8), and lower motor composite scores among boys (βper ten-fold increase = -3.8, 95 % CI = -7.7, 0.1) but not girls (βper ten-fold increase = 2.3, 95 %CI = -1.6, 6.3, pINT = 0.11). Finally, higher pyrimethanil was associated with lower language abilities among girls, but not boys. Pyrethroid metabolite concentrations did not explain variability in BSID-III composite scores. Associations were similar for BSID-III z-scores, and we found no evidence for non-linear associations or mixture effects.

DISCUSSION

Prenatal exposure to common-use pesticides may affect children's neurodevelopment at 1-year of age, some effects may be sex-specific.

Exposure to chlorpyrifos and pyrethroid insecticides and symptoms of Attention Deficit Hyperactivity Disorder (ADHD) in preschool children from the Odense Child Cohort

BACKGROUND

Attention Deficit Hyperactivity Disorder (ADHD) is a common childhood psychiatric disorder with severe and lifelong impact on mental health and socioeconomic achievements. Environmental factors may play a role in the increasing incidens rates. Previous studies on associations between prenatal and childhood exposure to organophosphate and pyrethroid insecticides and ADHD symptoms have yielded mixed findings.

OBJECTIVES

To investigate associations between prenatal and childhood exposure to chlorpyrifos and pyrethroids and ADHD symptoms in 5-year-old children from the Odense Child Cohort.

METHODS

Spot urine samples from pregnant women in gestational week 28 (n = 614) and offspring at 5 years of age (n = 814) were collected and analyzed for the specific metabolite of chlorpyrifos, TCPY (3,5,6-trichloro-2-pyridinol), as well as the generic pyrethroid metabolite, 3-PBA (3-phenoxybenzoic acid). Offspring ADHD symptoms were assessed at age 5 years using the parent reported "ADHD scale" from the "Child Behavior Checklist 1½-5" (n = 1114). Associations between insecticide exposure variables and an ADHD score ≥90th percentile were analyzed using logistic regression for all children and stratified by sex.

RESULTS

Most pregnant women had detectable concentrations of 3-PBA (93%) and TCPY (91%) with median concentrations of 0.20 μg/L and 1.62 μg/L, respectively. In children, 3-PBA and TCPY concentrations were detectable in 88% and 82% of the samples, and the median concentrations were 0.17 and 1.16 μg/L. No statistically significant associations were observed between insecticide metabolites and an ADHD score ≥90th percentile at age 5.

CONCLUSION

In this relatively large Danish birth cohort study with mainly low dietary insecticide exposure, we found no statistically significant associations between prenatal or childhood exposure to chlorpyrifos or pyrethroids, and excess ADHD-symptom load, in 5-year-old children. Prospective studies with multiple urine samples across vulnerable windows of neurodevelopment is warranted to improve assessment of safe exposure levels, which is particularly relevant for pyrethroids, since their use is increasing.

Maternal exposure to pesticides and autism or attention-deficit/hyperactivity disorders in offspring: A meta-analysis

OBJECTIVE

To analyze the association between maternal pesticide exposure and autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorders (ADHD) in offspring.

METHOD

Five databases including PubMed, Embase, Web of Science, Medline, as well as PsycINFO were systematically retrieved for the records related to pesticide exposure during pregnancy and ASD and ADHD in offspring before August 30, 2022. The pesticide category, maternal age and window of exposure as the main subgroups were presented.

RESULTS

949 studies were initially identified, and 19 studies were eventually included. Eleven were on ASD, seven were on ADHD, and one was on both disorders. Maternal pesticide exposure was positively related to ASD (pooled OR = 1.19 (95%CI: 1.04 to 1.36)) and ADHD (pooled OR = 1.20 (95%CI: 1.04 to 1.38)) in offspring. In the subgroup analysis, organophosphorus pesticides (OPs) (pooled OR = 1.14 (95%CI: 1.04 to 1.24)), pyrethroid (pooled OR = 1.40 (95%CI: 1.09 to 1.80)), and maternal age ≥30 years old (pooled OR = 1.24 (95%CI: 1.10 to 1.40)) increased the risk of ASD in offspring. Maternal organochlorine pesticides (OCPs) exposure was a risk factor for ADHD in offspring (pooled OR = 1.22 (95%CI: 1.03 to 1.45)).

CONCLUSION

Maternal pesticide exposure increased the risk of ASD and ADHD in offspring. Moreover, OPs, pyrethroid, and maternal age ≥30 years old were found to be risk factors affecting children's ASD. Maternal exposure to OCPs increased the risk of ADHD in offspring. Our findings contribute to our understanding of health risks related to maternal pesticide exposure and indicate that the in utero developmental period is a vulnerable window-of-susceptibility for ASD and ADHD risk in offspring. These findings should guide policies that limit maternal exposure to pesticides, especially for pregnant women living in agricultural areas.

Expression levels and network analysis of inflammamiRs in peripheral blood mononuclear cells exposed to DDE "in vitro"

Recent studies have demonstrated that dichlorodiphenyldichloroethylene (DDE) induced a pro-inflammatory condition in peripheral blood mononuclear cells (PBMC). However, the molecular mechanisms implicated in this condition are poorly understood. Therefore, this study aimed to evaluate miR-155, miR-126, and miR-21 expression levels in PBMC exposed "in vitro" to DDE. PBMC were dosed with increasing concentrations of DDE (10-80 µg mL^-1) at different treatment times (0-24 h). The results showed an up-regulation in the expression levels of assessed miRNAs (miR-155, miR-146, and miR-21) after PBMCs were exposed to DDE. Besides, bioinformatic analysis was performed to understand the biological roles of assessed miRNAs. The bioinformatic analysis shows that assessed miRNAs are associated with regulating signaling pathways involved in cancer, apoptosis, cell cycle, inflammation, metabolism, etc. These findings offer new insights into the molecular mechanisms related to the inflammatory processes and their regulation induced by DDE in PBMC exposed "in vitro".