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

BACKGROUND: Half the world's population is at risk for malaria. Indoor residual spraying (IRS) with insecticides has been effective in controlling malaria, yet the potential neurotoxicity of these insecticides is of concern, particularly for infants exposed in utero. OBJECTIVES: To determine the association of prenatal exposure to DDT/DDE and pyrethroid insecticides and behavioral/emotional problems in two-year-old children. METHODS: The Venda Health Examination of Mothers, Babies and their Environment (VHEMBE) birth cohort in South Africa, measured concentrations of p,p'-DDT and p,p'-DDE in maternal serum and pyrethroid metabolites (cis-DBCA, cis-DCCA, trans-DCCA, and 3-PBA) in maternal urine collected during pregnancy. At 2 years, 683 mothers were interviewed about their children's behavior and emotional development, using the Child Behavior Checklist (CBCL). We examined associations between behavioral or emotional problems and biomarkers of prenatal insecticide exposure. RESULTS: Maternal serum p,p'-DDT concentrations were associated with heightened withdrawn behavior in 2-year olds, with a 0.24 increase in raw scores (95%CI = 0.00, 0.49) and a 12% increase (95%CI = 1.01, 1.23) in risk of being at or above the borderline-clinical level, per 10-fold increase in concentrations. Ten-fold increases in p,p'-DDT and p,p'-DDE were related to 30% (RR = 1.30; 95%CI = 1.01, 1.67) and 39% (RR = 1.39; 95%CI =1.01, 1.91) higher risks, respectively, for increased oppositional-defiant behavior. p,p'-DDE concentrations were also related to increased risk of ADHD-related problems (RR = 1.30; 95%CI = 0.98, 1.72). Maternal urinary concentrations of cis-DBCA and 3-PBA were associated with increased risk of externalizing behaviors (RR = 1.30; 95%CI = 1.05, 1.62; RR = 1.35, 95%CI = 1.03, 1.78 per 10-fold increase, respectively), with some evidence of an association between cis-DBCA and affective disorders (RR = 1.25; 95%CI = 0.99, 1.56). Some associations with maternal pyrethroid concentrations were stronger in girls than boys. CONCLUSIONS: Prenatal exposure to DDT and pyrethroid insecticides may be associated with maternally-reported behavioral problems in two-year-old children. Given their long history and continued use, further investigation is warranted.

Sex, menopause, and age differences in the associations of persistent organic pollutants with thyroid hormones, thyroxine-binding globulin, and peripheral deiodinase activity: A cross-sectional study of the general Korean adult population.

Persistent organic pollutants (POPs) can disrupt the thyroid hormone system in humans. We assessed the associations of several POPs with serum thyroid hormones (T3 and T4) and thyroid-stimulating hormone, and investigated the modulating effects of sex, menopausal status, and age on these associations, in a subgroup of the adult population (n = 1250) from the Korean National Environmental Health Survey. PCB105 and PCB118 were negatively associated with total T4 in premenopausal females and males aged <50, whereas the associations were insignificant in other groups. PCB180, p,p'-DDE, and p,p'-DDT showed positive associations with total T3 in postmenopausal females; however, among males aged ≥50, PCB118, PCB138, and p,p'-DDE showed negative associations with total T3. The effects of exposure to multiple POPs were examined in multi-factor analyses. Factor 2 comprised PCB52, hexachlorobenzene, and BDE-47 was associated with an increase in free T4 in premenopausal females (ß = 0.015, p = 0.024), while Factor 1, which contained most POPs, was associated with a change in total T3 in postmenopausal females (ß = 0.032, p = 0.040) and males aged ≥50 (ß = -0.039, p = 0.023). Changes in total T4 or total T3 could be explained by differences in thyroxine-binding globulin (TBG) and peripheral deiodinase activity (GD). Negative associations of TBG with PCB105 in premenopausal females and PCB153 in males aged <50 may mediate the effect of decreasing total T4. PCB180, p,p'-DDE, p,p'-DDT, and Factor 1 were positively associated with GD, which is consistent with an increased total T3 in postmenopausal females. PCB118 was negatively associated with GD and total T3 in males aged ≥50. BDE-47 and ß-hexachlorocyclohexane were associated with thyroid autoantibodies in premenopausal females and males aged <50. Our observations suggest that the thyroid-disrupting effects of POPs may differ by sex, sex hormonal status, and age, and may be mediated by TBG and GD.

Exposure to organochlorine pesticides as a predictor to breast cancer: A case-control study among Ethiopian women.

Breast cancer (BC) is becoming one of the most prevalent non-infectious disease in low and middle income countries. The steady rise of BC incidence may be related to the different risk factors. Among many, rampant presence of environmental pollutants might be one of the risk factors. Therefore, the aim of this study is to investigate exposure to organochlorine pesticides as a risk factor to breast cancer. A case-control study design was employed among breast cancer patients and non-breast cancer individuals (controls). Blood samples were collected from 100 study participants (50 cases and 50 controls) followed by serum separation, extraction and cleanup using standard analytical procdures. The findings revealed that ten organochlorine pesticides were detected in the serum of the study participants. From the detected organochlorine pesticides, heptachlor was observed at higher concentration for breast cancer patients (6.90±4.37 µg/L) and controls (9.15±3.84 µg/L). Mean serum level of p,p'-DDE, p,p'-DDT, heptachlor, gamma-chlordane, endosulfan, and dibutyl-chlorendate were significantly higher in the serum of breast cancer patients than the controls. From the studied pesticides, p,p'-DDT and gamma-chlordane are significant predictors for BC, while, others are equivocal. A unit increment of the concentration of p,p'-DDT (AOR; 2.03, 95% CI: 1.041-3.969) increased the odds of developing breast cancer by two, while for gamma-chlordane (AOR;3.12, 95% CI; 1.186-8.203) by three. Our study results suggesting that, organochlorines are a risk factors for breast cancer in Ethiopia. Decreasing exposure to such organochlorines might have a significant public health relevance in reducing non-communicable chronic illnesses. Besides, continues monitoring of persistent organic pollutants using body biomarkers is important for disease prevention and device mitigation measures.

Influence of o,p'-DDT on MUC5AC expression via regulation of NF-κB/AP-1 activation in human lung epithelial cells.

o,p'-Dichlorodiphenyltrichloroethane (o,p'-DDT) is a representative endocrine disruptor, and exposure to o,p'-DDT may produce immune disorders and inflammation, leading to various diseases such as cancer. Chronic airway inflammation is characterized by excessive mucus secretion resulting in chronic obstructive pulmonary disease (COPD). Mucin 5AC  (MUC5AC), one of the mucus genes, plays an important role in mucus secretion and inflammation in the airways. The aim of this study was to examine the effects of o,p'-DDT on the regulation of MUC5AC expression in human lung epithelial A549 cell line. o,p'-DDT increased mRNA levels and the promoter activity of MUC5AC. Transient transfection with mutation promoter constructs of MUC5AC demonstrated that nuclear factor kappa-b (NF-κB) and activator protein 1(AP-1) response elements were essential for the consequences of o,p'-DDT on MUC5AC expression. In addition, o,p'-DDT induced phosphorylation of ERK, JNK, p38, and Akt, which are involved in the regulation of MUC5AC expression. It is noteworthy that inhibitors of NF-κB, AP-1, Akt, and MAPKs blocked enhanced o,p'-DDT-induced MUC5AC mRNA expression. Data indicate that o,p'-DDT increase in NF-κB, and AP-1 transcriptional activation-dependent MUC5AC expression is associated with stimulation of Akt and MAPK signaling pathways in A549 cells.

The associations between p,p'-DDE levels and plasma levels of lipoproteins and their subclasses in an elderly population determined by analysis of lipoprotein content.

BACKGROUND: Lipoproteins at aberrant levels are known to play a role in cardiovascular disease. The metabolite of the insecticide dichlorodiphenyltrichloroethane (DDT), p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE), physically associates with lipids and accumulates in adipose tissue. Little is known about which lipoproteins associate with p,p'-DDE. An association between p,p'-DDE exposure and altered levels of circulating lipids was assessed in a large human cohort using a detailed analysis of lipoprotein content. METHODS: Plasma samples were collected from the subset of 75-year old Swedes in the Prospective Investigation of the Vasculature of Uppsala Seniors (PIVUS) cohort who were not prescribed lipid lowering medication (n = 571). p,p'-DDE concentrations in plasma were measured using high-throughput solid phase extraction and gas chromatography-high resolution mass spectrometry. Analysis of plasma lipoprotein content was performed with nuclear magnetic resonance spectroscopy. RESULTS: Detectable levels of p,p'-DDE were found in the plasma samples of all subjects. Elevated p,p'-DDE levels were associated with increased concentrations of lipoproteins of all diameters, with the exception of high density lipoprotein (HDL) of diameters between 14.3 nm-10.9 nm. Of the lipoprotein constituents, triglycerides were most uniformly associated with elevated p,p'-DDE across lipoproteins. p,p'-DDE was furthermore associated with apolipoprotein B, but not apolipoprotein A1. CONCLUSIONS: The positive associations observed between each lipoprotein class and elevated p,p'-DDE support previous data suggesting that p,p'-DDE interacts with lipoproteins within plasma. It is speculated that both physio-chemical and biological mechanisms may explain why p,p'-DDE does not uniformly associate with lipids across lipoproteins.

Insecticide use and risk of non-Hodgkin lymphoma subtypes: A subset meta-analysis of the North American Pooled Project.

Insecticide use has been linked to increased risk of non-Hodgkin lymphoma (NHL), however, findings of epidemiologic studies have been inconsistent, particularly for NHL subtypes. We analyzed 1690 NHL cases and 5131 controls in the North American Pooled Project (NAPP) to investigate self-reported insecticide use and risk of NHL overall and by subtypes: follicular lymphoma (FL), diffuse large B-cell lymphoma (DLBCL) and small lymphocytic lymphoma (SLL). Odds ratios (OR) and 95% confidence intervals for each insecticide were estimated using logistic regression. Subtype-specific associations were evaluated using ASSET (Association analysis for SubSETs). Increased risks of multiple NHL subtypes were observed for lindane (OR = 1.60, 1.20-2.10: FL, DLCBL, SLL), chlordane (OR = 1.59, 1.17-2.16: FL, SLL) and DDT (OR = 1.36, 1.06-1.73: DLBCL, SLL). Positive trends were observed, within the subsets with identified associations, for increasing categories of exposure duration for lindane (Ptrend = 1.7 × 10-4 ), chlordane (Ptrend = 1.0 × 10-3 ) and DDT (Ptrend = 4.2 × 10-3 ), however, the exposure-response relationship was nonlinear. Ever use of pyrethrum was associated with an increased risk of FL (OR = 3.65, 1.45-9.15), and the relationship with duration of use appeared monotonic (OR for >10 years: OR = 5.38, 1.75-16.53; Ptrend = 3.6 × 10-3 ). Our analysis identified several novel associations between insecticide use and specific NHL subtypes, suggesting possible etiologic heterogeneity in the context of pesticide exposure.

Association between maternal exposure to the pesticide dichlorodiphenyltrichloroethane (DDT) and risk of obesity in middle age.

BACKGROUND: Obesity is a malnourishment epidemic worldwide. A meta-analysis of prospective human studies across the world demonstrated a consistent positive association between maternal exposure to the pesticide dichlorodiphenyltrichloroethane (DDT) and its metabolite dichlorodiphenyldichloroethylene (DDE) and children with obesity. The present study evaluates the association of maternal exposure to DDT and DDE with the risk of obesity in daughters during their mid-life in a prospective birth cohort with up to 53 years of follow-up. METHODS: Gravidas' blood was collected during their 1959-1967 enrollment into the prospective Child Health and Development Studies birth cohort in California. Their daughters aged 44-53 years had their height, weight, and waist circumference measured during a home visit to evaluate associations of daughters' adiposity and relative risk of overweight and obesity with their mothers' prenatal serum levels of DDT and DDE quantified by gas chromatograph-tandem mass spectrometer (n = 511). RESULTS: Maternal o,p'-DDT was positively associated with body mass index (ß = 0.59 kg/m2 per ln ng/ml (95th percentile confidence interval, 95% CI: 0.17, 1.00)) and waist circumference (ß = 1.19 cm per ln ng/ml (95% CI: 0.26, 2.13)) in multivariable models. Maternal o,p'-DDT was positively associated with a 26% (95% CI: 6-49) to 31% (95% CI: 6-62) higher risk of overweight and the same magnitude of additional risk for obesity, based on waist circumference and BMI definitions respectively, in multivariable models. CONCLUSIONS: These data indicate maternal DDT exposure is significantly associated with increased obesity risk among middle-aged women independent of the obesity definition, confounding, and obesity risk factors. Our findings suggest that policies supporting the use of DDT for malaria vector abatement need to consider the obesity risk as a health cost when weighing the benefits of using DDT in malaria vector control.

Adipocyte epigenetic alterations and potential therapeutic targets in transgenerationally inherited lean and obese phenotypes following ancestral exposures.

The incidence of obesity has increased dramatically over the past two decades with a prevalence of approximately 40% of the adult population within the United States. The current study examines the potential for transgenerational adipocyte (fat cell) epigenetic alterations. Adipocytes were isolated from the gonadal fat pad of the great-grand offspring F3 generation 1-year old rats ancestrally exposed to DDT (dichlorodiphenyltrichloroethane), atrazine, or vehicle control in order to obtain adipocytes for DNA methylation analysis. Observations indicate that there were differential DNA methylated regions (DMRs) in the adipocytes with the lean or obese phenotypes compared to control normal (non-obese or lean) populations. The comparison of epigenetic alterations indicated that there were substantial overlaps between the different treatment lineage groups for both the lean and obese phenotypes. Novel correlated genes and gene pathways associated with DNA methylation were identified, and may aid in the discovery of potential therapeutic targets for metabolic diseases such as obesity. Observations indicate that ancestral exposures during critical windows of development can induce the epigenetic transgenerational inheritance of DNA methylation changes in adipocytes that ultimately may contribute to an altered metabolic phenotype.

Population recovery of peregrine falcons in central Norway in the 4 decades since the DDT-ban.

The breeding population of peregrine falcons (Falco peregrinus) in Norway was almost exterminated by the early 1970's. Long-term monitoring of breeding pairs has been conducted since 1976 up to present. Peregrine falcons were first established at breeding sites in coastal habitats, where they remained at stable low numbers until the early 1990's. Starting around 2000, numbers began to increase steadily, and current numbers have now reached historical population levels from the pre-DDT era. We documented a range expansion with increasing numbers of peregrines nesting in the fjords and inland valleys. We found that once a territory was colonized, the probability that a territory remained occupied was high (S > 0.958). During early stages of population recovery, the transitional probabilities of becoming or remaining a breeding territory were high (ψN-B > 0.40, ψB-B > 0.65) but declined over time, especially in coastal habitats. Moreover, the productivity per nest has also decreased over time at sites in coastal habitats in the former stronghold of the population. The levels of environmental pollutants in eggs of the peregrines have dropped sharply over the last few decades, and contaminant levels now seem to be below critical levels. Eggshells were relatively thin throughout the 1970s, 1980s, and 1990s, but have increased to almost normal levels during the last 2 decades. Reductions in levels of organochlorine pollutants, especially DDT, appear to have been the main factor in explaining the population recovery. The territory dynamics are consistent with density-dependence and the low breeding success of the coastal-breeding peregrines is believed to be caused by declining numbers of colonial seabirds and other prey species.

Dietary risk factors for inflammatory bowel diseases in a high-risk population: Results from the Faroese IBD study.

Background: The Faroe Islands currently have the highest recorded inflammatory bowel disease (IBD) incidence in the world. Objective: This study investigated environmental risk factors for IBD in the Faroese population. Methods: Environmental exposure data including lifestyle risk factors and neurotoxicants collected for over 30 years were retrieved from the Children's Health and the Environment in the Faroes (CHEF) cohorts including mainly mother-child pairs, with exposure data collected from pregnant mothers. For lifestyle risk factors, the incidence of IBD and ulcerative colitis (UC) was calculated as the rate ratio (RR) with 95% confidence intervals (CI) in exposed versus non-exposed persons. For neurotoxicants RR was calculated for persons with high versus low exposure. Results: Six cohorts included 5698 persons with complete follow-up data and at least one exposure, and 37 were diagnosed with IBD. For pilot whale/blubber, the RR was 1.02 (95% CI, 0.48-2.18); RR of 1.01 for fish (95% CI, 0.35-2.91); and of the pollutants studied, a statistical significantly increased risk was found for 1,1,1,-trichloro-2,2-bis-(p-chlorophenyl) ethane (p,p'-DDT); RR 3.04 (95% CI, 1.12-8.30). RRs were 1.96 (95% CI, 1.03-3.73) for smoking and 1.10 (95% CI, 0.55-2.19) for alcohol intake. Conclusion: The high IBD incidence is unlikely to be caused by special dietary habits or by environmental pollutants.

Epigenetic modifications associated with in utero exposure to endocrine disrupting chemicals BPA, DDT and Pb.

Endocrine disrupting chemicals (EDCs) are xenobiotics which adversely modify the hormone system. The endocrine system is most vulnerable to assaults by endocrine disruptors during the prenatal and early development window, and effects may persist into adulthood and across generations. The prenatal stage is a period of vulnerability to environmental chemicals because the epigenome is usually reprogrammed during this period. Bisphenol A (BPA), lead (Pb), and dichlorodiphenyltrichloroethane (DDT) were chosen for critical review because they have become serious public health concerns globally, especially in Africa where they are widely used without any regulation. In this review, we introduce EDCs and describe the various modes of action of EDCs and the importance of the prenatal and developmental windows to EDC exposure. We give a brief overview of epigenetics and describe the various epigenetic mechanisms: DNA methylation, histone modifications and non-coding RNAs, and how each of them affects gene expression. We then summarize findings from previous studies on the effects of prenatal exposure to the endocrine disruptors BPA, Pb and DDT on each of the previously described epigenetic mechanisms. We also discuss how the epigenetic alterations caused by these EDCs may be related to disease processes.

Assessing predator-prey interactions in a chemically altered aquatic environment: the effects of DDT on Xenopus laevis and Culex sp. larvae interactions and behaviour.

Behavioural assays are used as a tool to understand ecotoxicological effects on organisms, but are often not applied in an ecologically relevant context. Assessment of the effect of chemical contaminants on behaviours relating to fitness and trophic interactions for example, requires incorporating predator-prey interactions to create impact assessments. Dichlorodiphenyltrichloroethane (DDT) is a controlled substance but is still regularly used as a form of mosquito control. There is little explicit information on the effect of DDT on animal behaviour and the consequent effects upon trophic interactions. This study uses a 3 × 2 factorial design to assess the feeding behaviour of Xenopus laevis toward Culex sp. larvae when supplied with different prey cues. We also assess the behavioural responses of mosquito larvae when supplied with no threat cue and predator threat cues when exposed to 0 µg/L, 2 µg/L and 20 µg/L DDT. There was a significant "DDT exposure" x "prey cue" interaction whereby DDT significantly decreased the foraging behaviour of X. laevis towards live prey cues, however there was no effect of DDT on X. laevis response to olfactory prey cues. Dichlorodiphenyltrichloroethane exposure caused mosquito larvae to appear hyperactive regardless of DDT concentration. Mosquito larvae anti-predator response was significantly dampened when exposed to 2 µg/L DDT, however when exposed to 20 µg/L the anti-predator responses were not impaired. Our results indicate a complex interplay in trophic interactions under DDT exposure, wherein effects are mediated depending on species and concentration. There are possible implications regarding reduced anti-predator behaviour in the prey species but also reduced foraging capacity in the predator, which could drive changes in ecosystem energy pathways. We demonstrate that in order to quantify effects of pesticides upon trophic interactions it is necessary to consider ecologically relevant behaviours of both predator and prey species.

Elevated atmospheric CO2 might increase the health risk of long-term ingestion of leafy vegetables cultivated in residual DDT polluted soil.

Residual dichlorodiphenyltrichloroethane (DDT) in the environment and a continuously increasing atmospheric carbon dioxide (CO2) concentration are two issues that have received a lot of attention. This study was conducted using a pot experiment to investigate the interactive effects of elevated CO2 and DDT on the uptake of DDT, the physiological responses and the resulting health risks in three vegetables. These vegetables included Brassica juncea var. foliosa Bailey (B. Bailey), Brassica campestris L. var. communis Tsen et Lee Suzhou Qing (B. Lee) and Brassica campestris L. ssp. pekinensis (Lour.) Olsson Chun Dawang (B. Olsson). Two levels of CO2 and four DDT treatment levels were set up. Results showed 5 mg kg-1 DDT significantly reduced the shoot biomass of B. Bailey when compared to 0 mg kg-1 DDT treatment under ambient CO2 condition. Elevated CO2 concentration stimulated the growth of B. Bailey and B. Lee, increased the DDT uptake in the shoots of both vegetables and the values of some photosynthesis indices, and triggered the activity of peroxidase and catalase in the shoots when compared to the related ambient CO2 treatment. Elevated CO2 concentration increased the values of hazard indexes for non-carcinogenic and cancer risks of all vegetables when compared to the individual ambient CO2 treatment (each of vegetable has an ambient CO2 treatment), especially for B. Bailey (increase amplitude of 123.81%-127.78% at 5 mg kg-1 DDT). Long-term ingestion with these DDT-polluted vegetables might result in an elevated carcinogenic risk and elevated atmospheric CO2 may enhance the non-carcinogenic and carcinogenic risks.

Prediagnostic serum organochlorine insecticide concentrations and primary liver cancer: A case-control study nested within two prospective cohorts.

Although experimental evidence indicates that certain organochlorine insecticides are hepatocarcinogens, epidemiologic evidence for most of these chemicals is very limited. We estimated associations, using prospectively collected sera, between organochlorine insecticide concentrations and cancer registry-identified primary liver cancer in two cohorts, one from the United States and one from Norway. In nested case-control studies, we used sera collected in the 1960s-1980s from 136 cases and 408 matched controls from the Kaiser Permanente Northern California Multiphasic Health Checkup (MHC) cohort and 84 cases and 252 matched controls from the population-based Norwegian Janus cohort. We measured concentrations of nine organochlorine insecticides/metabolites and markers of hepatitis B and C in sera. Adjusted odds ratios (OR) and 95% confidence intervals (CI) for tertiles of lipid-corrected organochlorines were calculated for each cohort using conditional logistic regression. Among MHC participants with sera from the 1960s, there was a suggestive exposure-response trend for trans-nonachlor (second and third tertile of analyte ORs = 1.63 and 1.95, respectively; p-trend = 0.08) and a nonsignificantly elevated risk for the highest tertile of oxychlordane (OR = 1.87). Among Janus participants with sera from the 1970s, we observed an apparent trend for p,p'-DDT (second and third tertile ORs = 1.70 and 2.14, respectively; p-trend = 0.15). We observed little consistency in patterns of association between the cohorts. We found limited evidence that exposure to p,p'-DDT and chlordane-related oxychlordane and trans-nonachlor may be associated with increased risk of primary liver cancer. However, the modest strength of these associations and their lack of concordance between cohorts necessitate caution in their interpretation.

Associations of Maternal Exposure to Dichlorodiphenyltrichloroethane and Pyrethroids With Birth Outcomes Among Participants in the Venda Health Examination of Mothers, Babies and Their Environment Residing in an Area Sprayed for Malaria Control.

Although effective in controlling malaria, indoor residual spraying results in elevated exposure to insecticides such as dichlorodiphenyltrichloroethane (DDT) and pyrethroids. These chemicals cross the placenta, but no studies have examined their associations with birth outcomes in populations residing in indoor residual spraying areas. We investigated this question in the Venda Health Examination of Mothers, Babies and Their Environment (VHEMBE), a birth cohort study of 751 South African children born between 2012 and 2013. We measured maternal peripartum serum DDT and urine pyrethroid metabolite concentrations and collected data on birth weight, length, head circumference, and duration of gestation. We analyzed the data using marginal structural models with inverse-probability-of-treatment weights, generalized propensity scores, and standard conditional linear regression. Using all 3 analytical methods, p,p'-DDT, o,p'-DDT, and to a lesser extent p,p'-dichlorodiphenyldichloroethylene were related to elevated birth weight, birth length, and head circumference among girls. Changes in gestational duration did not mediate this relationship, suggesting that these exposures accelerate fetal growth, which is consistent with the known estrogenic properties of o,p'-DDT and p,p'-DDT. No associations with pyrethroid metabolites were found. Results suggest that prenatal exposure to DDT is related to elevated birth size. Further studies are needed to elucidate the implications of these findings.

DDT exposure in early childhood and female breast cancer: Evidence from an ecological study in Taiwan.

Researchers still lack consensus on the association between exposure to DDT and the risk of breast cancer. One reason could be that the measurements of DDT obtained during or near the time of diagnosis may not reflect exposure during the etiologically relevant time period in a woman's life. This study undertook an ecological analysis to investigate whether exposure to DDT among cohort born between 1951 and 1959 (i.e. age 0-5 years) and who reached the age 50-54 years during 2001-2013 had an increased risk of breast cancer in adulthood. To do this, we used the number of DDT sprays in each township during the anti-malaria campaign in Taiwan in the 1950s as a proxy for direct DDT exposure. The DDT sprays were then linked to the township female breast cancer incidence rate in the 2000s when the birth cohorts had reached age 50-54 years. Insurance claims data were used to identify breast cancer cases during 1996-2013. Zero-Inflated Poisson regression was performed to estimate the effect of DDT sprays on the breast cancer incidence rate. The analysis was based on a total of 9 birth cohorts (1951-1959) in 349 townships who had lived at least up to age 50. On average, one DDT spray experienced during age 0-5 years was associated with an increase of 8 more female breast cancer cases per 100,000 during age 50-54. The effect appears to increase with the number of sprays. Our finding suggests that DDT exposure in early childhood could raise the risk of breast cancer in adulthood.

Expression of the miR-190 family is increased under DDT exposure in vivo and in vitro.

A non-genotoxic insecticide dichlorodiphenyltrichloroethane (DDT), can affect mRNA and microRNA levels, however, its precise mechanism of action remains poorly understood. Using in silico methods we found that the rat miR-190 family is potentially regulated by CAR and ER receptors activated by DDT. We showed that exposure to DDT results in a dose- and organ-dependent increase in the expression of miR-190a, -190b in the liver, uterus, ovaries and mammary gland of female Wistar rats. Additionally, we demonstrate a decrease in protein product level of Tp53inp1, the target gene of these microRNAs, in the rat uterus. It is known that miR-190 is probably regulated by ER in humans, thus we measured the level of miR-190a, -190b in primary cultures of malignant and normal human endometrial cells treated with different doses of DDT. We detected an increase in miR-190b level in normal endometrial cells under DDT exposure. Thus, our results indicate that DDT exposure lead to change in the expression of oncogenic miR-190 family and its target gene Tp53inp1 which may be due to activation of CAR and ER.

Investigation of mRNA expression changes associated with field exposure to DDTs in chickens from KwaZulu-Natal, South Africa.

The objective of this study was to identify potential mRNA expression changes in chicken livers associated with environmental exposure to dichloro-diphenyl-trichloroethane (DDT) and its metabolites (DDTs). In particular, we focused on genes relating to the immune system and metabolism. We analyzed liver samples from free-ranging chickens in KwaZulu-Natal, South Africa, for contamination by DDTs. This area predominantly uses DDT in its malaria control program, and homes are sprayed annually with the pesticide. Genes relating to the immune system and metabolism were selected as potential genetic biomarkers that could be linked to higher contamination with DDTs. RT-qPCR analysis on 39 samples showed strong correlations between DDTs contamination and mRNA expression for the following genes: AvBD1, AvBD2, AvBD6 and AvBD7 (down-regulated), and CYP17, ELOVL2 and SQLE (up-regulated). This study shows for the first time interesting and significant correlations between genetic material collected from environmentally-exposed chickens and mRNA expression of several genes involved in immunity and metabolism. These findings show the usefulness of analysis on field samples from a region with high levels of environmental contamination in detecting potential biomarkers of exposure. In particular, we observed clear effects from DDT contamination on mRNA expression of genes involved in immune suppression, endocrine-disrupting effects, and lipid dysregulation. These results are of interest in guiding future studies to further elucidate the pathways involved in and clinical importance of toxicity associated with DDT exposure from contaminated environments, to ascertain the health risk to livestock and any subsequent risks to food security for people.

Maternal Peripartum Serum DDT/E and Urinary Pyrethroid Metabolite Concentrations and Child Infections at 2 Years in the VHEMBE Birth Cohort.

BACKGROUND: Indoor residual spraying (IRS) of insecticides, conducted in low- and middle-income countries to control malaria, may result in high exposure to dichlorodiphenyltrichloroethane (DDT), its breakdown product dichlorodiphenyldichloroethylene (DDE), or pyrethroids. Animal studies suggest in utero exposure to these chemicals may increase childhood infection frequency. OBJECTIVES: We investigated associations between maternal DDT/E and pyrethroid metabolite concentration and child infection associations in an IRS setting in which susceptibility factors are common and infections are leading causes of child morbidity and mortality. METHODS: Using gas chromatography-mass spectrometry, we measured serum DDT/E and urinary pyrethroid metabolite concentrations in peripartum samples from 674 women participating in the Venda Health Examination of Mother, Babies and their Environment (VHEMBE) study. Counts of persistent child fevers, otitis media, and severe sore throat between 1 and 2 y of age were ascertained from maternal interviews. Associations between DDT/E and pyrethroid metabolite concentrations and infections were estimated using zero-inflated Poisson regression. We estimated relative excess risks due to interaction (RERI) with poverty, maternal energy intake, and maternal HIV status. RESULTS: Concentrations of DDT/E, particularly p,p'-DDE, were associated with higher rates of persistent fevers [IRR=1.21 (95% CI: 1.01, 1.46)], for a 10-fold increase in p,p'-DDE). This association was stronger among children from households below versus above the South African food poverty line [IRR=1.31 (95% CI: 1.08, 1.59) vs. IRR=0.93 (95% CI: 0.69, 1.25), respectively] and for children whose mothers had insufficient versus sufficient caloric intake during pregnancy [IRR=1.30 (95% CI: 1.07, 1.58) vs. IRR=0.96 (95% CI: 0.72, 1.28), respectively]. CONCLUSIONS: In utero IRS insecticide exposure may increase childhood infection rates. This was particularly apparent among children from poorer households or whose mothers had low energy intake during pregnancy. https://doi.org/10.1289/EHP2657.

Prenatal Exposure to DDT and Pyrethroids for Malaria Control and Child Neurodevelopment: The VHEMBE Cohort, South Africa.

BACKGROUND: Although indoor residual spraying (IRS) with dichlorodiphenyltrichloroethane (DDT) and pyrethroids effectively controls malaria, it potentially increases human exposure to these insecticides. Previous studies suggest that prenatal exposure to these insecticides may impact human neurodevelopment. OBJECTIVES: We aimed to estimate the effects of maternal insecticide exposure and neurodevelopment of toddlers living in a malaria-endemic region currently using IRS. METHODS: The Venda Health Examination of Mothers, Babies and their Environment (VHEMBE) is a birth cohort of 752 mother-child pairs in Limpopo, South Africa. We measured maternal exposure to DDT and its breakdown product, dichlorodiphenyldichloroethylene (DDE), in maternal serum, and measured pyrethroid metabolites in maternal urine. We assessed children's neurodevelopment at 1 and 2 y of age using the Bayley Scales of Infant Development, third edition (BSID-III), and examined associations with maternal exposure. RESULTS: DDT and DDE were not associated with significantly lower scores for any BSID-III scale. In contrast, each 10-fold increase in cis-DCCA, trans-DCCA, and 3-phenoxybenzoic acid were associated, respectively, with a -0.63 (95% CI: -1.14, -0.12), -0.48 (95% CI: -0.92, -0.05), and -0.58 (-1.11, -0.06) decrement in Social-Emotional scores at 1 y of age. In addition, each 10-fold increase in maternal cis-DBCA levels was associated with significant decrements at 2 y of age in Language Composite scores and Expressive Communication scores [ß=-1.74 (95% CI: -3.34, -0.13) and ß=-0.40 (95% CI: -0.77, -0.04), respectively, for a 10-fold increase]. Significant differences by sex were estimated for pyrethroid metabolites and motor function scores at 2 y of age, with higher scores for boys and lower scores for girls. CONCLUSIONS: Prenatal exposure to pyrethroids may be associated at 1 y of age with poorer social-emotional development. At 2 y of age, poorer language development was observed with higher prenatal pyrethroid levels. Considering the widespread use of pyrethroids, these findings deserve further investigation. https://doi.org/10.1289/EHP2129.