Some evidence of effects of environmental chemicals on the endocrine system in children

Effects of Organochlorine Pesticide Residues in Maternal Body on Infants

There are many organochlorine pollutants in the environment, which can be directly or indirectly exposed to by mothers, and as estrogen endocrine disruptors can cause damage to the lactation capacity of the mammary gland. In addition, because breast milk contains a lot of nutrients, it is the most important food source for new-born babies. If mothers are exposed to organochlorine pesticides (OCPs), the lipophilic organochlorine contaminants can accumulate in breast milk fat and be passed to the infant through breast milk. Therefore, it is necessary to investigate organochlorine contaminants in human milk to estimate the health risks of these contaminants to breastfed infants. In addition, toxic substances in the mother can also be passed to the fetus through the placenta, which is also something we need to pay attention to. This article introduces several types of OCPs, such as dichlorodiphenyltrichloroethane (DDT), methoxychlor (MXC), hexachlorocyclohexane (HCH), endosulfan, chlordane, heptachlorand and hexachlorobenzene (HCB), mainly expounds their effects on women's lactation ability and infant health, and provides reference for maternal and infant health. In addition, some measures and methods for the control of organochlorine pollutants are also described here.

Organochlorine pesticides residue in placenta and their influence on anthropometric measures of infants

The objective of this study is to evaluate the influence of placental concentrations of some organochlorine pesticides on newborn's anthropometric measurements (height, weight, head circumference & ponderal index). For this study, we have collected 90 placental tissue samples for the measurement of Dichlorodiphenyltrichloroethane (DDT) & Hexachlocyclohexane (HCH) by Gas Chromatography equipped with Electron Capture Detector (GC-ECD). Regression analysis were performed between outcome variables such as birth weight, birth height, head circumference, ponderal index and independent variable i.e., organochlorine pesticide concentrations. In case of birth weight, there was a substantial decrease of 5.81, 1.94, 4.71, and 2.64 g for 1 ppb (μg/L) increase in placental α-HCH, β-HCH, γ-HCH, and total HCH concentrations respectively. Significant decrease of 2.02 and 0.43 kg/m³ in ponderal index was found with 1 μg/L increase of total-HCH and total DDT concentrations in placenta. The results of this study support an association between environmental exposure to organochlorine pesticides and anthropometric development of the fetus leading to a significant reduction in its birth weight and ponderal index, slight and non-significant reduction in birth height and head circumference. Efforts should be made to reduce exposure of women of reproductive age in relation to long-term impact on health.

Polychlorinated Dibenzo-p-Dioxins, Polychlorinated Dibenzofurans, and Dioxin-Like Polychlorinated Biphenyls in Umbilical Cord Serum from Pregnant Women Living Near a Chemical Plant in Tianjin, China

Polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans (PCDD/Fs), and dioxin-like polychlorinated biphenyls (dl-PCBs) are bioaccumulative compounds that may affect fetal growth and infant development. The aim of this study was to determine whether the pregnant women living near a chemical plant in Tianjin had a risk of exposure to dioxins. Concentrations of PCDD/Fs and dl-PCBs in 24 umbilical cord serum samples collected from pregnant women were measured using a high-resolution gas chromatograph with a high-resolution mass spectrometer (HRGC-HRMS) and an isotopic dilution method. The levels of ∑(PCDD/Fs + dl-PCBs) were in the range 476-8307 pg·g^-1 lipid, with a mean of 3037 pg·g^-1. The mean World Health Organization toxicity equivalent (WHO-TEQ) for PCDD/Fs and dl-PCBs was 14.0 and 2.14 pg·g^-1 lipid, respectively. The PCDD/Fs and dl-PCBs contributed 86.7% and 13.3%, respectively, to the total TEQ. The octa-CDFs and penta-CBs were predominant for the PCDD/Fs and dl-PCBs, accounting for 57.6% and 74.3%, respectively. Several PCDD/F and dl-PCB congeners were highly correlated, such as PCB 105 and PCB 118 (r = 0.982, p < 0.001). Although the results hint at decreasing trends for PCDD/F and dl-PCBs by comparison with a similar study in Tianjin, a total TEQ of 41.7% of study participants had a body burden that exceeded the biomonitoring equivalents for dioxins. It was shown that pregnant women and infants had a health risk of exposure to dioxins.

Differential occurrence, profiles and uptake of dust contaminants in the Barcelona urban area

Dust is a complex but increasingly used matrix to assess human exposure to organic contaminants both in indoor and outdoor environments. Knowledge concerning the effects of organic pollution towards health outcome is crucial. This study is aimed to determine the presence of legacy compounds (DDTs and polychlorinated biphenyls, PCBs), compounds used in recent times (organophosphorous flame retardants, organophosphorous pesticides, BPA, phthalates and alkylphenols) and compounds originated from combustion processes (polycyclic aromatic hydrocarbons, PAHs) as well as nicotine in indoor environments along the metropolitan area of Barcelona. Monitored sites include public areas with high turnout (high schools, museums samples) and libraries and private spaces (houses and cars). Almost all compounds (57 over the 59 targeted) were found in each dust sample and libraries and schools were the most contaminated, with concentrations of ∑phthalates and ∑OPFRs up to 15 and 10 mg g^-1, respectively. One-way ANOVA tests, Tukey contrasts and principal component analysis (PCA) revealed that sampling place influenced the observed contamination profiles and public and private environments were clearly differentiated. Finally, based on the concentrations detected, a deterministic calculation was performed to estimate the total daily intakes of each compound via dust. This information was used to evaluate the human exposure for toddlers, teenagers and adult workers. Consistently, the highest concentrations coming from plasticisers and flame retardants gave the major exposure rates. As expected, toddlers were the most affected group followed by museum and library workers, although the levels were below the reference doses.

Exposure to persistent organic pollutants: impact on women's health

This literature review focuses on the causal relationship between persistent organic pollutants (POPs) exposure and women's health disorders, particularly cancer, cardio-metabolic events and reproductive health. Progressive industrialization has resulted in the production of a multitude of chemicals that are released into the environment on a daily basis. Environmental chemicals or pollutants are not only hazardous to our ecosystem but also lead to various health problems that affect the human population worldwide irrespective of gender, race or age. However, most environmental health studies that have been conducted, until recently, were exclusively biased with regard to sex and gender, beginning with exposure studies that were reported mostly in male, occupational workers and animal studies being carried out mostly in male rodent models. Health-related issues pertaining to women of all age groups have not been studied thoroughly and rather disregarded in most aspects of basic health science research and it is therefore pertinent that we address these limitations in environmental health. The review also addresses studies looking at the associations between health outcomes and exposures to POPs, particularly, polychlorinated biphenyls (PCBs), dioxins and pesticides, reported in cohort studies while accounting for gender differences. Considering that current levels of POPs in women can also impact future generations, informative guidelines related to dietary patterns and exposure history are needed for women of reproductive age. Additionally, occupational cohorts of highly exposed women worldwide, such as women working in manufacturing plants and female pesticide applicators are required to gather more information on population susceptibility and disease pathology.

Association of Bisphenol A Exposure with Breastfeeding and Perceived Insufficient Milk Supply in Mexican Women

Introduction Estrogen inhibits lactation and bisphenol A (BPA) is a high production environmental estrogen. We hypothesize an inhibitory effect of BPA on lactation and aim to analyze the association between third trimester pregnancy urinary BPA and breastfeeding rates 1 month postpartum. Methods Odds ratios (OR) and 95 % confidence intervals (95 % CI) of breastfeeding and perceived insufficient milk supply (PIM) in relation to maternal peripartum urinary BPA concentrations were calculated in 216 mothers. Results 97.2 % of mothers in the lowest BPA tertile were breastfeeding at 1 month postpartum, compared to 89.9 % in highest (p = 0.01). Adjusted ORs (95 % CI) for not breastfeeding at 1 month were 1.9 (0.3, 10.7) and 4.3 (0.8, 21.6) for second and third BPA tertiles, respectively, compared to the lowest (p = 0.06, trend). 4.2 % reported PIM in the lowest BPA tertile, compared to 8.7 % in the highest (p = 0.03). Adjusted ORs (95 % CI) for PIM were 1.8 (0.4, 7.7) and 2.2 (0.5, 9.5), for the second and third BPA tertiles, respectively, compared to the lowest (p = 0.29, trend). Discussion These results suggest an association between maternal BPA exposure and decreased breastfeeding.

State of the evidence 2017: an update on the connection between breast cancer and the environment

BACKGROUND

In this review, we examine the continually expanding and increasingly compelling data linking radiation and various chemicals in our environment to the current high incidence of breast cancer. Singly and in combination, these toxicants may have contributed significantly to the increasing rates of breast cancer observed over the past several decades. Exposures early in development from gestation through adolescence and early adulthood are particularly of concern as they re-shape the program of genetic, epigenetic and physiological processes in the developing mammary system, leading to an increased risk for developing breast cancer. In the 8 years since we last published a comprehensive review of the relevant literature, hundreds of new papers have appeared supporting this link, and in this update, the evidence on this topic is more extensive and of better quality than that previously available.

CONCLUSION

Increasing evidence from epidemiological studies, as well as a better understanding of mechanisms linking toxicants with development of breast cancer, all reinforce the conclusion that exposures to these substances - many of which are found in common, everyday products and byproducts - may lead to increased risk of developing breast cancer. Moving forward, attention to methodological limitations, especially in relevant epidemiological and animal models, will need to be addressed to allow clearer and more direct connections to be evaluated.

Effects of 17β-estradiol (E2) on aqueous organisms and its treatment problem: a review

Natural estrogens, estrone (E1), 17β-estradiol (E2) and estriol (E3) are endocrine disrupting chemicals (EDCs) that are discharged consistently and directly into surface waters with wastewater treatment plants (WWPTs) effluents, disposal sludges and in storm-water runoff. The most common and highest potential natural estrogen that causes estrogen activity in wastewater influent is E2. This review describes and attempts to summarize the main problems involved in the removal of E2 from WWTP by traditional processes, which fundamentally rely on activated sludge and provide an insufficient treatment for E2, as well as advanced oxidation processes (AOPs) that are applied in tertiary section treatment works. Biological processes affect and play an important role in the degradation of E2. However, some investigations have reported that operations that rely on high retention times have low efficiencies. Although advanced treatment technologies are available, their cost and operational considerations do not make them sustainable solutions. Therefore, E2 is still being released into aqueous areas, as shown in this study that investigates results from different countries. E2 is present on the watch list of substances in the Water Framework Directive (WFD) of the European Union since 2013 and the minimum acceptable concentration of it is 0.4 ng/L.

Low birth weight of Vietnamese infants is related to their mother's dioxin and glucocorticoid levels

We aimed to determine the relationship between dioxin congeners in maternal breast milk and maternal glucocorticoid levels with newborn birth weight after nearly 45 years of use of herbicides in the Vietnam War. The study subjects comprised 58 mother-infant pairs in a region with high dioxin levels in the soil (hotspot) and 62 pairs from a control region. Dioxin levels in maternal breast milk were measured by HRGC-HRMS. Salivary glucocorticoid levels were determined by LC-MS/MS. Dioxin congener levels in mothers from the hotspot were found to be two to fivefold higher than those in mothers from the control region. Birth weight was inversely correlated with 2,3,7,8-TeCDD and 2,3,4,7,8-PeCDF congener levels. The rate of newborns whose birth weight was less than 2500 g was threefold higher in the hotspot (12 %) than in the control region (4 %). Salivary glucocorticoid levels in mothers with low birth weight infants were significantly higher than those in the normal birth weight group. Low birth weight of Vietnamese newborns in a hotspot for dioxin levels is related to some dioxin congener levels and high glucocorticoid levels in mothers. This finding in mother-infant pairs suggests that excess maternal glucocorticoid levels are related to dioxin burden and they result in low birth weight.

Prenatal exposure to DDE and PCB 153 and respiratory health in early childhood: a meta-analysis

BACKGROUND

Persistent organic pollutants may affect the immune and respiratory systems, but available evidence is based on small study populations. We studied the association between prenatal exposure to dichlorodiphenyldichloroethylene (DDE) and polychlorinated biphenyl 153 (PCB 153) and children's respiratory health in European birth cohorts.

METHODS

We included 4608 mothers and children enrolled in 10 birth cohort studies from 7 European countries. Outcomes were parent-reported bronchitis and wheeze in the first 4 years of life. For each cohort, we performed Poisson regression analyses, modeling occurrences of the outcomes on the estimates of cord-serum concentrations of PCB 153 and DDE as continuous variables (per doubling exposure) and as cohort-specific tertiles. Summary estimates were obtained through random-effects meta-analyses.

RESULTS

The risk of bronchitis or wheeze (combined variable) assessed before 18 months of age increased with increasing DDE exposure (relative risk [RR] per doubling exposure = 1.03 [95% confidence interval = 1.00-1.07]). When these outcomes were analyzed separately, associations appeared stronger for bronchitis. We also found an association between increasing PCB 153 exposure and bronchitis in this period (RR per doubling exposure = 1.06 [1.01-1.12]) but not between PCB 153 and wheeze. No associations were found between either DDE or PCB 153 and ever-wheeze assessed after 18 months. Inclusion of both compounds in the models attenuated risk estimates for PCB 153 tertiles of exposure, whereas DDE associations were more robust.

CONCLUSION

This large meta-analysis suggests that prenatal DDE exposure may be associated with respiratory health symptoms in young children (below 18 months), whereas prenatal PCB 153 levels were not associated with such symptoms.

Hormone changes in peripubertal girls

CONTEXT

Studies of hormone changes in the peripubertal period note increases in adrenal hormones prior to increases in sex steroids. It is unclear how these processes are related to each other, except through this temporal relationship.

OBJECTIVE

Examine relationships in adrenal and sex hormones in 252 peripubertal girls.

SETTING AND DESIGN

Longitudinal observation study. School districts, at the Cincinnati site of the Breast Cancer and the Environment Research Centers, between 2004-2010. Participants were recruited between ages 6 and 7 years of age and were seen every 6 months. Main outcome measures included height, weight, maturation status, and fasting blood specimen. Serum was analyzed for selected hormones every six months, beginning 30 months prior to, and extending to 6 months after, breast development. Androstenedione, estradiol, estrone, and T were measured by high-performance liquid chromatography (HPLC) with tandem mass spectrometry. Dehydroepiandrosterone-sulfate (DHEA-S) and SHBG also were measured.

RESULTS

DHEA-S concentrations increased 24 months before breast development; androstenedione and estrone between 12 to 18 months before breast development; whereas estradiol and T increased, and SHBG fell between 6 and 12 months before breast development. Girls with greater body mass index had lower estradiol concentrations at onset of breast development as well as 6 months after pubertal onset.

CONCLUSIONS

Serum estrone and DHEA-S increased prior to estradiol concentrations, and the increase in estradiol occurred prior to breast development. Heavier peripubertal girls have lower estradiol levels at puberty, suggesting peripheral conversion of adrenal androgens to estrone.

Testosterone sorption and desorption: effects of soil particle size

Soils contain a wide range of particles of different diameters with different mobility during rainfall events. Effects of soil particles on sorption and desorption behaviors of steroid hormones have not been investigated. In this study, wet sieve washing and repeated sedimentation methods were used to fractionate the soils into five ranges. The sorption and desorption properties and related mechanisms of testosterone in batch reactors filled with fractionated soil particles were evaluated. Results of sorption and desorption kinetics indicate that small soil particles have higher sorption and lower desorption rates than that of big ones. Thermodynamic results show the sorption processes are spontaneous and exothermal. The sorption capacity ranks as clay>silt>sand, depending mainly on specific surface area and surface functional groups. The urea control test shows that hydrogen bonding contributes to testosterone sorption onto clay and silt but not on sand. Desorption tests indicate sorption is 36-65% irreversible from clay to sand. Clays have highest desorption hysteresis among these five soil fractions, indicating small particles like clays have less potential for desorption. The results provide indirect evidence on the colloid (clay)-facilitated transport of hormones (micro-pollutants) in soil environments.

Puberty dysregulation and increased risk of disease in adult life: possible modes of action

Puberty is the developmental window when the final maturation of body systems is orchestrated by hormones; lifelong sex-related differences and capacity to interact with the environment are defined during this life stage. Increased incidence in a number of chronic, multifactorial diseases could be related to environmental exposures during puberty: however, insight on the susceptibility of the peripubertal period is still limited. The estrogen/androgen balance is a crucial axis in harmonizing the whole pubertal development, pointing out the significance of exposures to endocrine disruptors. Besides the reproductive system, endocrine-related perturbations may affect the maturation of skeleton, adipose tissues, brain, immune system, as well as cancer predisposition. Thus, risk assessment of environmental stressors should duly consider specific aspects of the pubertal window. Besides endocrine-related mechanisms, suggested research priorities include signaling molecules (e.g., kisspeptins, dopamine) as xenobiotic targets and disturbances of specific pubertal methylation processes potentially involved in neurobehavioral disorders and cancer risk in adulthood.

Pesticide exposure in children

Pesticides are a collective term for a wide array of chemicals intended to kill unwanted insects, plants, molds, and rodents. Food, water, and treatment in the home, yard, and school are all potential sources of children's exposure. Exposures to pesticides may be overt or subacute, and effects range from acute to chronic toxicity. In 2008, pesticides were the ninth most common substance reported to poison control centers, and approximately 45% of all reports of pesticide poisoning were for children. Organophosphate and carbamate poisoning are perhaps the most widely known acute poisoning syndromes, can be diagnosed by depressed red blood cell cholinesterase levels, and have available antidotal therapy. However, numerous other pesticides that may cause acute toxicity, such as pyrethroid and neonicotinoid insecticides, herbicides, fungicides, and rodenticides, also have specific toxic effects; recognition of these effects may help identify acute exposures. Evidence is increasingly emerging about chronic health implications from both acute and chronic exposure. A growing body of epidemiological evidence demonstrates associations between parental use of pesticides, particularly insecticides, with acute lymphocytic leukemia and brain tumors. Prenatal, household, and occupational exposures (maternal and paternal) appear to be the largest risks. Prospective cohort studies link early-life exposure to organophosphates and organochlorine pesticides (primarily DDT) with adverse effects on neurodevelopment and behavior. Among the findings associated with increased pesticide levels are poorer mental development by using the Bayley index and increased scores on measures assessing pervasive developmental disorder, inattention, and attention-deficit/hyperactivity disorder. Related animal toxicology studies provide supportive biological plausibility for these findings. Additional data suggest that there may also be an association between parental pesticide use and adverse birth outcomes including physical birth defects, low birth weight, and fetal death, although the data are less robust than for cancer and neurodevelopmental effects. Children's exposures to pesticides should be limited as much as possible.

Levels of DDT and its metabolites in placenta, maternal and cord blood and their potential influence on neonatal anthropometric measures

Previous studies of in utero exposure to dichlorodiphenyltrichloroethane (DDT) have shown mixed results for the harmful effects on fetal growth and development. This cross-sectional study was designed to: (1) examine the extent of DDT exposure in 1578 women, aged 28.5±6.0 who delivered between June 2005 and 2006 in the area of Al-Kharj, Saudi Arabia; and (2) assess its influence on neonatal anthropometric measurement of newly born babies. DDT and its metabolites, namely 1,1-dichloro-2,2-bis (p-chlorophenyl) ethylene (p,p'-DDE), 1,1-dichloro-2,2-bis (p-chlorophenyl) ethane (p,p'-DDD) and 1,1,1-trichloro-2,2' bis (p-chlorophenyl) ethane (p,p'-DDT) were measured in cord and maternal serum as well as placenta by Gas Chromatography coupled with an Electron Capture Detector (GC/ECD). p,p'-DDE was detected in 28.3% of cord and 54.4% of maternal serum, reflecting past exposure, whereas the p,p'-DDT was only found in 0.46% cord and 1.2% maternal samples. As expected the p,p'-DDE cord levels (0.197±0.961μg/L) were 2.8 times lower than the maternal levels (0.551±1.778μg/L), and both were significantly correlated (r=0.517) suggesting its transplacental transfer. The picture was different in placental tissues. p,p'-DDE and p,p'-DDT were detected in 84% and 99% of placental tissues, with the highest p,p'-DDT in placental tissues (29.62±158.282µg/kg dry wt.) compare to p,p'-DDE (10.167±18.851μg/kg dry wt.). In general, the presence of DDT metabolites in our participants indicates that these chemicals are still relevant despite the fact that they have been banned or restricted in the study area for many years. Our results support the view for an association between low in utero exposure to DDT and the anthropometric development of the fetus leading to a reduction in its head circumference, crown-heel length, birth weight and birth height. Since the reduction in these measures was independent of gestational age and/or preterm births, our findings suggest a detrimental effect of the DDT exposure on fetal growth. Neonatal anthropometric measures are considered as an important tool to detect newborns at higher risk of morbidity and impairment of growth. Efforts should be made to decrease exposure of women of reproductive age and to examine maternal DDT exposure in relation to long-term impact on health.

Peripheral precocious puberty in a 4-month-old girl: role of pesticides?

A 4-month-old girl presented with sexual development, including breast enlargement, menstruation, uterine length of 69 mm at ultrasonography, and dramatically high estrogen bioactivity, but no growth acceleration, pubic hair, pelvis masses or adrenal tumors. Gas chromatography with an electron capture detector and mass spectrometry detected pesticides (p,p'-DDD, p,p'-DDT, lindane and endosulfan sulfate) in plasma from the infant, the mother, and the 38-year-old father, who reported a dramatic decrease in libido, and in soil samples from their farm. The precocious sexual development was probably caused by the estrogen activity of the environmental contamination by tons of pesticides stored in the family farm.

US assessment of estrogen-responsive organ growth among healthy term infants: piloting methods for assessing estrogenic activity

BACKGROUND

A mother's circulating estrogen increases over the third trimester, producing physiological effects on her newborn that wane postnatally. Estrogenization might be prolonged in newborns exposed to exogenous estrogens, such as isoflavones in soy formula.

OBJECTIVE

We evaluated ultrasonography for monitoring growth of multiple estrogen-responsive organs in healthy infants and developed organ-growth trajectories.

MATERIALS AND METHODS

We studied 38 boys (61 visits) from birth to age 6 months and 41 girls (96 visits) from birth to age 1 year using a partly cross-sectional, partly longitudinal design. We measured uterus and ovaries in girls, testes and prostate in boys, and kidneys, breasts, thymus, and thyroid in all children. We imaged all organs from the body surface in one session of < 1 h.

RESULTS

Uterine volume decreased from birth (P < 0.0001), whereas ovarian volume increased sharply until age 2 months and then decreased (P < 0.001). Testicular volume increased with age (P < 0.0001), but prostatic volume showed minimal age trend. Breast bud diameter showed no age trend in girls but declined from birth in boys (P = 0.03).

CONCLUSION

US examination of multiple estrogen-responsive organs in infants in a single session is feasible and yields volume estimates useful for assessing potential endocrine disruptor effects on organ growth.

Endocrine disruption and ovarian morphometric responses in rats following exposure to tetradifon

We have investigated whether exposure to tetradifon causes ovary injuries, disrupts folliculogenesis in rat and whether ovary hormones (estrogen and progesterone) to be affected by this endocrine-active agent. Female rats were exposed orally to a dose of 28.9 mg/kg/day for 6 or 12 weeks. After sacrifice, ovary glands were examined for morphometric changes. The serums were used to determine levels of 17beta-estradiol and progesterone. Results showed no sign of toxicity. However, tetradifon promoted a significant increase in the percentage of atretic follicles in the 12-weeks treated rats. Number and the diameter of mature follicles (tertiary and preovulatory) were markedly diminished together with a reduction of the relative weight of ovaries. Compared with controls, the treated rats exhibited significant reduction in serum 17beta-estradiol and progesterone levels. These results suggest an endocrine disruption by tetradifon which may interfere with ovarian follicles development in rat.

Minding the calcium store: Ryanodine receptor activation as a convergent mechanism of PCB toxicity

Chronic low-level polychlorinated biphenyl (PCB) exposures remain a significant public health concern since results from epidemiological studies indicate that PCB burden is associated with immune system dysfunction, cardiovascular disease, and impairment of the developing nervous system. Of these various adverse health effects, developmental neurotoxicity has emerged as a particularly vulnerable endpoint in PCB toxicity. Arguably the most pervasive biological effects of PCBs could be mediated by their ability to alter the spatial and temporal fidelity of Ca2+ signals through one or more receptor-mediated processes. This review will focus on our current knowledge of the structure and function of ryanodine receptors (RyRs) in muscle and nerve cells and how PCBs and related non-coplanar structures alter these functions. The molecular and cellular mechanisms by which non-coplanar PCBs and related structures alter local and global Ca2+ signaling properties and the possible short and long-term consequences of these perturbations on neurodevelopment and neurodegeneration are reviewed.

Effects of mixtures of polychlorinated biphenyls, methylmercury, and organochlorine pesticides on hepatic DNA methylation in prepubertal female Sprague-Dawley rats

DNA methylation is one of the epigenetic mechanisms that regulates gene expression, chromosome structure, and stability. Our objective was to determine whether the DNA methylation system could be a target following in utero and postnatal exposure to human blood contaminants. Pregnant rats were dosed daily from gestation day 1 until postnatal day 21 with 2 dose levels of either organochlorine pesticides (OCP; 0.019 or 1.9 mg/kg/day), methylmercury chloride (MeHg; 0.02 or 2 mg/kg/day), polychlorinated biphenyls (PCBs; 0.011 or 1.1 mg/kg/day), or a mixture (Mix; 0.05, or 5 mg/kg/day) including all 3 groups of chemicals. Livers from 1 female offspring per litter were collected at postnatal day 29. Hepatic analysis revealed that the mRNA abundance for DNA methyltransferase (DNMT)-1, -3a, and -3b were significantly reduced by the high dose of PCB, that the high dose of MeHg also reduced mRNA levels for DNMT-1, and -3b, but that OCP had no significant effects compared with control. The high dose of PCB and Mix reduced the abundance of the universal methyl donor S-adenosylmethionine, and Mix also reduced global genome DNA methylation (5-methyl-deoxycytidine/5-methyl-deoxycytidine + deoxycytidine). The latter is consistent with pyrosequencing methylation analysis, revealing that the high-dose groups (except OCP) generally decreased the methylation of CpG sites (position -63 to -29) in the promoter of the tumor suppressor gene p16(INK4a). Overall, these hepatic results suggest that the DNA methylation system can be affected by exposure to high doses of blood contaminants, and that OCP is the least potent chemical group from the investigated mixtures.

Glyphosate-based herbicides are toxic and endocrine disruptors in human cell lines

Glyphosate-based herbicides are the most widely used across the world; they are commercialized in different formulations. Their residues are frequent pollutants in the environment. In addition, these herbicides are spread on most eaten transgenic plants, modified to tolerate high levels of these compounds in their cells. Up to 400 ppm of their residues are accepted in some feed. We exposed human liver HepG2 cells, a well-known model to study xenobiotic toxicity, to four different formulations and to glyphosate, which is usually tested alone in chronic in vivo regulatory studies. We measured cytotoxicity with three assays (Alamar Blue, MTT, ToxiLight), plus genotoxicity (comet assay), anti-estrogenic (on ERalpha, ERbeta) and anti-androgenic effects (on AR) using gene reporter tests. We also checked androgen to estrogen conversion by aromatase activity and mRNA. All parameters were disrupted at sub-agricultural doses with all formulations within 24h. These effects were more dependent on the formulation than on the glyphosate concentration. First, we observed a human cell endocrine disruption from 0.5 ppm on the androgen receptor in MDA-MB453-kb2 cells for the most active formulation (R400), then from 2 ppm the transcriptional activities on both estrogen receptors were also inhibited on HepG2. Aromatase transcription and activity were disrupted from 10 ppm. Cytotoxic effects started at 10 ppm with Alamar Blue assay (the most sensitive), and DNA damages at 5 ppm. A real cell impact of glyphosate-based herbicides residues in food, feed or in the environment has thus to be considered, and their classifications as carcinogens/mutagens/reprotoxics is discussed.

Endocrine disrupting chemicals in indoor and outdoor air

The past 50 years have seen rapid development of new building materials, furnishings, and consumer products and a corresponding explosion in new chemicals in the built environment. While exposure levels are largely undocumented, they are likely to have increased as a wider variety of chemicals came into use, people began spending more time indoors, and air exchange rates decreased to improve energy efficiency. As a result of weak regulatory requirements for chemical safety testing, only limited toxicity data are available for these chemicals. Over the past 15 years, some chemical classes commonly used in building materials, furnishings, and consumer products have been shown to be endocrine disrupting chemicals-that is they interfere with the action of endogenous hormones. These include PCBs, used in electrical equipment, caulking, paints and surface coatings; chlorinated and brominated flame retardants, used in electronics, furniture, and textiles; pesticides, used to control insects, weeds, and other pests in agriculture, lawn maintenance, and the built environment; phthalates, used in vinyl, plastics, fragrances, and other products; alkylphenols, used in detergents, pesticide formulations, and polystyrene plastics; and parabens, used to preserve products like lotions and sunscreens. This paper summarizes reported indoor and outdoor air concentrations, chemical use and sources, and toxicity data for each of these chemical classes. While industrial and transportation-related pollutants have been shown to migrate indoors from outdoor sources, it is expected that indoor sources predominate for these consumer product chemicals; and some studies have identified indoor sources as the predominant factor influencing outdoor ambient air concentrations in densely populated areas. Mechanisms of action, adverse effects, and dose-response relationships for many of these chemicals are poorly understood and no systematic screening of common chemicals for endocrine disrupting effects is currently underway, so questions remain as to the health impacts of these exposures.