Levels and patterns of DDTs in maternal colostrum from an island population and exposure of neonates

Organochlorine pesticide residues and urinary arsenic and fluoride levels in mothers and their newborns who are residents of rural areas in Durango State, Mexico

Maternal and prenatal exposure to organochlorine pesticides (OCP), arsenic (As), and fluoride (F-) is a critical public health concern. The present study assessed serum OCP residues and urinary As and F- levels in mother and newborn pairs who are residents of rural areas of Durango State, Mexico, from August 2018 to February 2019. Levels of OCP, As, and F- were measured in serum and urine samples by Gas chromatography - Tandem mass spectrometry (GC - MS/MS), Hydride generation - Atomic fluorescent spectrometry (HG-AFS, and ion-selective electron analysis (ISE), respectively, in 60 binomial mothers - newborns. Dieldrin, endrin aldehyde, and endosulfan-II were significantly higher in newborns than in mothers (p ˂0.05). Meanwhile, no significant differences were observed for As and F- concentrations between mother - newborn pairs. Differences were observed in ∑Dienes and ∑DDTs comparing newborns with normal and low birth weights and a positive relationship in ƩDienes, ƩChlordanes, and ƩDDTs between mother and newborn pairs (p ˂ 0.05). These findings highlight the importance of extensive research regarding the influence of pollution.

A review on the enantioselective distribution and toxicity of chiral pesticides in aquatic environment

Chiral pesticides account for about 40% of the total pesticides. In the process of using pesticides, it will inevitably flow into the surface water and even penetrate into the groundwater through surface runoff and other means, as a consequence, it affects the water environment. Although the enantiomers of chiral pesticides have the same physical and chemical properties, their distribution, ratio, metabolism, toxicity, etc. in the organism are often different, and sometimes even show completely opposite biological activities. In this article, the selective fate of different types of chiral pesticides such as organochlorine, organophosphorus, triazole, pyrethroid and other chiral pesticides in natural water bodies and sediments, acute toxicity to aquatic organisms, chronic toxicity and other aspects are summarized to further reflect the risks between the enantiomers of chiral pesticides to non-target organisms in the water environment. In this review, we hope to further explore its harm to human society through the study of the toxicity of chiral pesticide enantiomers, so as to provide data support and theoretical basis for the development and production of biochemical pesticides.

Exposure patterns, chemical structural signatures, and health risks of pesticides in breast milk: A multicenter study in China

China is the world's largest pesticide user. These chemicals are bioaccumulative in the human body, and eventually could be transferred from the mother to the fetus/infant via placental and breastfeeding transport, which might pose developmental deficiency risks. In this study, human biomonitoring of legacy pesticides was conducted in three Chinese cities using 60 breast milk samples. The patterns, chemical structural signatures, and the estimated daily intake of pesticides were assessed. The median concentration of HCB (57.8 ng g^-1 lw, Interquartile range: 28.5-76.9 ng g^-1 lw) was the highest among all pesticides, whereas the HCHs, DDXs, TCVP, and heptachlor were also detected. A significantly different pattern of pesticides was found among three sampling cities: the Mianyang cases were mostly DDXs oriented while the Wuhan and Hangzhou cases were under HCB, HCHs, TCVP, and heptachlor influences. Maternal age and pre-pregnancy BMI were found to be the influencing factors for the pesticides in the breast milk, and dietary preferences were an important factor in the exposure scenario. Chemical structural signatures indicated that for HCHs and DDXs the exposure was mostly historical, while the lindane and dicofol exposure may exist among the volunteering mothers. The EF for chiral pesticides did not deviate significantly from the racemic value. The risk from breastfeeding was negligible according to the Chinese and UN standard, while some cases from Hangzhou and Wuhan exceeded the Canadian restrictions. Thus, the adverse health effects of chemical exposure by dietary intake for infants need to be closely monitored in future studies.

Cardiotoxicity of some pesticides and their amelioration

Pesticides are used to control pests that harm plants, animals, and humans. Their application results in the contamination of the food and water systems. Pesticides may cause harm to the human body via occupational exposure or the ingestion of contaminated food and water. Once a pesticide enters the human body, it may create health consequences such as cardiotoxicity. There is not enough information about pesticides that cause cardiotoxicity in the literature. Currently, there are few reports that summarized the cardiotoxicity due to some pesticide groups. This necessitates reviewing the current literature regarding pesticides and cardiotoxicity and to summarize them in a concrete review. The objectives of this review article were to summarize the advances in research related to pesticides and cardiotoxicity, to classify pesticides into certain groups according to cardiotoxicity, to discuss the possible mechanisms of cardiotoxicity, and to present the agents that ameliorate cardiotoxicity. Approximately 60 pesticides were involved in cardiotoxicity: 30, 13, and 17 were insecticides, herbicides, and fungicides, respectively. The interesting outcome of this study is that 30 and 13 pesticides from toxicity classes II and III, respectively, are involved in cardiotoxicity. The use of standard antidotes for pesticide poisoning shows health consequences among users. Alternative safe medical management is the use of cardiotoxicity-ameliorating agents. This review identifies 24 ameliorating agents that were successfully used to manage 60 cases. The most effective agents were vitamin C, curcumin, vitamin E, quercetin, selenium, chrysin, and garlic extract. Vitamin C showed ameliorating effects in a wide range of toxicities. The exposure mode to pesticide residues, where 1, 2, 3, and 4 are aerial exposure to pesticide drift, home and/or office exposure, exposure due to drinking contaminated water, and consumption of contaminated food, respectively. General cardiotoxicity is represented by 5, whereas 6, 7, 8 and 9 are electrocardiogram (ECG) of hypotension due to exposure to OP residues, ECG of myocardial infraction due to exposure to OPs, ECG of hypertension due to exposure to OC and/or PY, and normal ECG respectively.

Dietary exposure and cancer risk assessment of the Pakistani population exposed to polycyclic aromatic hydrocarbons

The sixteen-priority polycyclic aromatic hydrocarbons (PAHs) were determined in twenty-one groceries from six food groups consumed by the Pakistani population. The highest concentration of the total PAHs was found in fish (243 ng g^-1), while the lowest concentration was determined in rice (53 ng g^-1). The total B[a]P_eq dietary exposure for the male group followed an increasing order of children (865.5 ng day^-1) < adolescents (2301 ng day^-1) < seniors (2864 ng day^-1) < adults (3004 ng day^-1), whereas the similar order was also observed for the female group. The male group showed 1-8.5% (mean 5.5%) of higher exposure amount compared to the female group. Among all food categories, wheat (43%) and milk (34%) contributed the greatest while rice (1%) and egg (1%) contributed the smallest to the total dietary exposure of PAHs. The incremental lifetime cancer risk (ILCR) values for the adults and children revealed a potential cancer risk to the both male and female groups. Whereas at the 95th percentiles, the ILCR values for all age and gender groups exceeded the limit (>10^-5), demonstrating a high potential cancer risk in the Pakistani population. The sensitivity analysis found that the daily dietary intake, exposure duration and the cancer slope factor were the most influential variables contributed to the total variance of risk.

Levels and profiles of persistent organic pollutants in breast milk in China and their potential health risks to breastfed infants: A review

Although some persistent organic pollutants (POPs) were prohibited or limited in use several decades ago, they are still frequently detected in the human body. The purpose of this study was to understand the levels and profiles of POPs in breast milk in China and assess their potential health risks among breastfed infants under six months of age. A literature review focused on China was performed for studies published from 2001 to 2020. The POP levels in breast milk along with other important variables were extracted, and then the average individual POP levels in breast milk were estimated. This review summarises the distribution of traditional and new POPs, including polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), legacy brominated flame retardants (BFRs), perfluorinated compounds (PFCs), and chlorinated paraffins (CPs) and reported notably high levels of short-chain chlorinated paraffins and 1,1-dichloro-2,2-bis (p-chlorophenyl) ethylene (p,p'-DDE) in breast milk. Although the levels of traditional POPs generally declined over time, especially p,p'-DDE and beta-hexachlorocyclohexane (β-HCH), women living in coastal areas, urban areas, and southern China still have a high body burden of certain POPs. In the present study, the estimated daily intake (EDI) of POPs through breastfeeding was used to evaluate the health risk for infants by comparing with acceptable levels. The findings suggested that infants born in coastal areas most likely suffered potential health risk from exposure to DDT, and the health risk of hexachlorobenzene (HCB) in infants in most nationwide regions remains a concern. More importantly, the EDI of PCBs for infants exceeds the safe limit on a national scale. Continuous surveillance of PCBs in breast milk is critical to evaluate the potential health effects on humans.

Are we underestimating the sources of microplastic pollution in terrestrial environment?

Microplastics (MPs, plastic particles < 5 mm) are an ever-increasing global issue due to their widespread occurrence in the environment and negative effects on organisms. Currently, more than 96 % of MPs studies are related to marine systems. However, the majority of marine MPs pollution has been confirmed to originate from land-based sources, evidence of MPs in the terrestrial system cannot be overlooked. In this manuscript, up-to-date knowledge regarding the sources and occurrence of MPs from the terrestrial system is comprehensively reviewed. According to the different studies both in China and abroad, microfibers derived from textile washing attributed approximately 35 % of the MPs identified in the aquatic system. Additionally, personal care and cosmetic products, tires, agricultural plastic films, artificial turfs and road paints, landfill, littering, packaging and construction industry can also release MPs to the environment. The aquatic system plays an important role in MPs transport. By using a one-way ANOVA test, polypropylene (PP) and polyethylene (PE) accounted for significantly higher percentages than other polymer compositions in surface water. Polyamide (PA) and PP accounted for the majority of polymers in soils. PP, PE, and polystyrene (PS) presented an overwhelming proportion in sediment. Atmospheric deposition presents a new vehicle for entering into the wider environment. More research is urgently required on the topic of exposure risk of atmospheric MPs via inhalation. Morphological characteristics including shapes, sizes, and colors have been discussed among waters, soils, sediments and airborne. These source-occurrence implications continuum summaries can bring us new insights that we cannot underestimate the severity of MPs from land-based sources and should pay more attention to MPs contamination in the terrestrial ecosystem.

Pesticides in human milk collected from Jinhua, China: Levels, influencing factors and health risk assessment

In China, many studies have been carried out on pesticide residues in human milk, yet all of them are on organochlorine pesticides (OCPs) and mostly focused on large, economically developed cities. In this study, 27 pesticides including OCPs, pyrethroid pesticides (PYRs) and organophosphate pesticides (OPPs) in human milk were investigated in Jinhua, an inland and medium sized city in China. Method based on QuEChERS extraction and gas chromatography-mass spectrometer (GC-MS) determination was adopted to analyze the above pesticide residues. The influencing factors as well as the health risks were also evaluated. Results show that PYRs and OPPs in human milk samples were both undetectable. Regarding OCPs, the detection rate of hexachlorobenzene (HCB), β-hexachlorocyclohexane (β-HCH) and p,p'-dichlorodiphenyl-dichloroethylene (p,p'-DDE) were 83.6%, 36.4% and 58.2%, respectively, and their mean value were 29.4, 32.0 and 85.2 ng/g lipid, respectively. p,p'-DDE levels in human milk was significantly (p < 0.05) related to maternal age, but no association was detected between OCPs residues and other factors (living environment, dietary habit, living style, etc.), suggesting that OCPs in human milk in Jinhua were originated from nonspecific source. All estimated daily intake of pesticides (EDI_pesticides) by infants were under the guideline suggested by Food and Agriculture Organization (FAO) and China Ministry of Health (CMH). Yet 9% of EDIs_HCB and 16% of EDIs_HCHs exceeded the guideline recommended by Health Canada. The associations between DDE residues and the delivery way as well as HCBs residues and the birth weight were seemly significant, yet the significance disappeared when consider age or gestational age as a cofounder, indicating that OCPs residue in mother's body in Jinhua has no obvious influence on fetus development and the delivery way.

Pesticide residues in breast milk and the associated risk assessment: A review focused on China

This review aims to provide an overview of studies on pesticide residues in breast milk in China and the related health risk to mother and infants. Results showed that the investigations of breast milk covered 22 provincial administrative regions of China. Beijing and some densely populated and economically developed areas have most publications. The study frequency was followed the order of DDTs>HCHs>HCB > ∑Drins,∑Chlordane. While the residue levels were ranked as DDTs, HCHs > ∑Drins>HCB > ∑Chlordane. The highest residue levels of DDTs and HCHs in breast milk were found in 1980s (~10,000 ng/g lipid), then experienced a sharp decrease in 1990s (~1000-2000 ng/g lipid). In 2000s and 2010s, DDTs, and HCHs residue still showed a decreasing trend. Spatially, people located in urban area, coastal areas and southern China tend to have higher pesticide residues as compared to rural area, inland area and northern China, respectively. Other factors such as dietary habit, living environment, the maternal age, the parity, body mass index, lactation period, menstruation characteristics as well as hormonal drug intake and infertility treatment will also affect the pesticide residues in breast milk of Chinese people. According to the estimated daily ingestion (EDI) of breast milk, the average health risk for infants were generally exceeded the acceptable level before 2006, while after that, most EDI values were within the standard. Body burden of pesticides in mother can also be evaluated by using the residue data in breast milk, but no relevant guidelines were available. Other knowledge gap included 1) for some provinces with large consumption of pesticides or located in remote and plateau areas, there are few/no studies available; 2) current study on pesticide residues in breast milk in China were only focused on organochlorine pesticides, research on current used pesticides (such as pyrethroids, organophosphorus, carbamate) were necessary in the future.

Transplacental transfer mechanism of organochlorine pesticides: An in vitro transcellular transport study

Recent studies show that, even after being banned for agricultural applications for over 30 years, organochlorine pesticides (OCPs), including hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethane (DDT) and its metabolites (DDXs), can still be found in various biological matrices and pose a potential hazard to the fetus in the womb. This study aimed to investigate the possible transplacental transfer mechanism of OCPs using an in vitro placental model. The results showed that for HCHs and DDXs, the placenta had a potential protection mechanism for the fetus by having higher efflux than intake active transport efficiency to transfer the xenobiotic out of the fetal circulation. No enantiomer-specific transport was observed for the chiral OCPs in vitro, hints simple diffusion played the major role in the transplacental transfer. Metabolic and transporter inhibitors were applied in the transepithelial transport experiment to evaluate the role that major transporting protein played in the active efflux process. The ATP production inhibitors were observed to have significant inhibition on transfer, proving the hypothesis that active transport participates in the transplacental transport of OCPs in humans. Multiple transporters contributed simultaneously in the active transport for the OCPs. In this study, we could confirm that the transplacental transfer of OCPs is a combination of simple diffusion and active transport. ATP-binding cassette (ABC) superfamily transporters on the placenta contribute in the active transport. These findings could improve the understanding of the mechanisms of transplacental transfer of the OCPs.

Multicenter biomonitoring of polybrominated diphenyl ethers (PBDEs) in colostrum from China: Body burden profile and risk assessment

Polybrominated diphenyl ethers (PBDEs) were listed in the Stockholm Convention due to their persistent and toxic nature. In utero exposure to PBDEs might affect fetal development as it is sensitive when exposed to even low dose of xenobiotic substances during the pregnancy. In this study, a multi-centre human biomonitoring study of tri-to hexa-BDEs was conducted in three Chinese cities using 60 colostrum samples from local residents. The patterns and influencing factors, correlation with the birth outcome, and potential health risks during the breastfeeding of tri-to hexa-BDEs in the colostrum samples were assessed. The median concentration of tri-to hexa-BDEs was 9.1 (Interquartile range: 3.1-19.5) ng g^-1 lipid weight, and BDE-153 contributed 68% of the detected PBDEs. The PBDE levels were mostly associated with maternal age and drinking water sources, while correlations with other factors including weight gain, BMI, parity and the number of aborted pregnancies was not significant. The level of BDE-28 was positively correlated with the birth weight, while the BDE-99 was positively correlated with the head circumference, using multilinear regression. For the total hazard quotients, 60% of the infants have an estimated value higher than 1, showed potential chronic hazard for future development and possible adverse health effects to the babies from the exposure to PBDE congeners. Alternative food source seems to have a lower risk for neonates than the colostrum, but the advantages of breastfeeding undoubtedly outweigh the risks and potential adverse health effects caused by environmental PBDEs and other xenobiotic chemical exposure.

Hexachlorocyclohexane exposure alters the microbiome of colostrum in Chinese breastfeeding mothers

Breast milk, especially colostrum, is not just a source of nutrients and immune factors for the newborn, but also accumulates environmental persistent pollutants and its diverse microbes affect the early colonization of the newborn's gut. Little is known about associations between environmental pollutants and the microbial composition of human colostrum. We assessed the influence of hexachlorocyclohexane (HCH), a persistent organic pollutant (POP), in colostrums on the microbial composition of human colostrum samples. HCH concentrations in 89 colostrum samples collected from a population living on the easternmost island of China were measured via gas chromatography equipped with mass spectrometer (GC-MS), HCH exposure risks for infants via dietary intake of breast milk were assessed, and for 29 colostrum samples the microbiota were profiled using 16S rRNA gene pyrosequencing to assess the association with HCH exposure levels. Our study confirmed high colostrum exposure levels of total HCHs (12.19 ± 13.68 μg L^-1) in this Chinese population. We predominantly identified Proteobacteria (67.6%) and Firmicutes (25.1%) in colostrum and microbial diversity at the genus level differed between samples with different HCH levels; e.g., Pseudomonas which contains several HCH degrading strains was found in significantly higher abundance in γ-HCH rich samples. Also, microbes that were statistically significantly associated with HCH levels were also highly correlated with each other (false discovery rate (FDR)＜0.01) and clustered in network analysis. Microbial diversity is associated with HCH levels in human colostrum and these associations might be attributable to their HCH degrading ability. These finding provide first insights into the role that environmental persistent pollutants may play in the microbial composition of human colostrum and the colonization of the infant gut.

Transplacental transfer of organochlorine pesticides: Concentration ratio and chiral properties

Currently, there is limited information about the mechanism of the human transplacental transfer for organochlorine pesticides (OCPs). This study aimed to evaluate the transplacental transfer of OCPs to better understand the influencing factors of exposure and transplacental efficiency. The study involved quantitative determination of OCPs and the enantiomer fraction (EF) of chiral OCPs in pregnant women from Wuhan, China. The results indicate that the exposure levels of OCPs varied in the order: maternal serum > cord serum > placenta. Chiral contaminants, such as α-HCH, o,p'-DDD and o,p'-DDT, were non-racemic in the three biological matrices, wherein EF_α-HCH < 0.5, EF_o,p'-DDD < 0.5, EF_o,p'-DDT > 0.5. For HCHs, the concentration ratio between cord serum and maternal serum (R_cm) <1, while for DDXs, the R_cm ≈ 1, indicating that the transport efficiency of different pollutants is related to the physicochemical properties. These results showed that placenta seems to be a more efficient barrier for β-HCH than for p,p'-DDE. The concentration ratios across placenta significantly lower than 1 and the enantiomeric selective transfer imply that some OCPs may have more complicated maternal-fetus transfer mechanisms, involving both simple diffusion and active transport. To the best of our knowledge, this is the first study to investigate the transfer of OCPs and their enantiomer fractions across placenta. These findings could expand the database of chemical exposure in biological matrices and improve the understanding of the mechanisms of transplacental transfer of OCPs.

Enantioselectivity in biotransformation and bioaccumulation processes of typical chiral contaminants

Chirality is a critical topic in the medicinal and agrochemical fields. One quarter of all agrochemicals was chiral in 1996, and this proportion has increased remarkably with the introduction of new compounds over time. Despite scientists have made great efforts to probe the enantiomeric selectivity of chiral chemicals in the environment since early 1990s, the different behaviours of individual enantiomers in biologically mediated processes are still unclear. In the present review, we highlight state-of-the-knowledge on the stereoselective biotransformation and accumulation of chiral contaminants in organisms ranging from invertebrates to humans. Chiral insecticides, fungicides, and herbicides, polychlorinated biphenyls (PCBs), pharmaceuticals, flame retardants hexabromocyclododecane (HBCD), and perfluorooctane sulfonate (PFOS) are all included in the target compounds. Key findings included: a) Changes in the enantiomeric fractions in vitro and in vivo models revealed that enantioselectivity commonly occurs in biotransformation and bioaccumulation. b) Emerging contaminants have become more important in the field of enantioselectivity together with their metabolites in biological transformation process. c) Chiral signatures have also been regarded as powerful tools for tracking pollution sources when the contribution of precursor is unknown. Future studies are needed in order to understand not only preliminary enrichment results but also detailed molecular mechanisms in diverse models to comprehensively understand the behaviours of chiral compounds.

Prenatal exposure to polychlorinated biphenyl and umbilical cord hormones and birth outcomes in an island population

Prenatal exposure to polychlorinated biphenyl (PCB) is suspected to interfere with fetal development including reproductive and thyroid function and birth outcomes, but published evidence are still sparse. We designed a cross-sectional study to analyze the associations between PCB levels in umbilical cord sera and hormones and birth outcomes of mothers and newborns who are residents from an island. Seven indicator-PCB (PCB-28, 52, 101, 118, 138, 153, 180), and five reproductive hormones including luteotropic hormones (LH), estradiol (E2), testosterone (T), follicle-stimulating hormones (FSH) and anti-Mullerian hormones (AMH), and three thyroid hormones including tri-iodothyronine (T3), tetra-iodothyronine (T4) and thyroid stimulating hormones (TSH) were measured in 106 cord sera specimens. Birth outcomes include birth weight, length, head circumference, and gestational age. Multiple linear regression and quartile regression were used to analyze the associations between PCB and each of the hormones and birth outcomes, adjusting for selected potential confounders. The median value of total PCB in umbilical cord sera was 2.02 μg L^-1 (IQR, 1.13-4.64). Several negative associations between PCB exposure and reproductive hormones were found. Among them, the β value of PCB-101 for FSH reached -0.38 (95%CI, -0.69, -0.07; p = 0.02). Moreover, we also found some sex-specific associations i.e. PCB-28 was negatively correlated with LH and T and PCB-118 was negatively correlated with T in male newborns but not in female newborns. The associations between PCB and birth outcomes seem to differ by molecular weight of the PCB congeners i.e. the low-chlorinated PCB congeners were negatively associated with gestational age and head circumference while high-chlorinated PCB congeners were positively associated birth weight and gestational age. In this study, we found that PCB congeners with different molecular weight has different associations with hormones and birth outcomes, and future studies are recommended to investigate underlying mechanisms of these associations.

Risk assessment of the endocrine-disrupting effects of nine chiral pesticides

The increased release of chiral pesticides into the environment has generated interest in the role of enantioselectivity in the environmental fate and ecotoxicological effects of these compounds. However, the information on the endocrine disrupting effects (EDEs) of chiral pesticides is still limited and discrepancies are also usually observed among different assays. In this study, we investigated the enantioselectivity of EDEs via estrogen and thyroid hormone receptors for nine chiral pesticides using in vitro and in silico approaches. The results of the luciferase reporter gene assays showed 7 chiral pesticides possessed enantioselective estrogenic activities and 2 chiral pesticides exerted thyroid hormone antagonistic effects. Proliferation assays in MCF-7 and GH3 cells were also used to verify the results of the dual-luciferase reporter gene assays. At last, the molecular docking results indicated that the enantioselective EDEs of chiral pesticides were partially due to enantiospecific binding affinities with receptors. Our data not only show enantioselective EDEs of nine chiral pesticides, but also would be helpful to better understanding the molecular biological mechanisms of enantioselectivity in EDEs of chiral pesticides.

Environmental exposure to polycyclic aromatic hydrocarbons (PAHs): The correlation with and impact on reproductive hormones in umbilical cord serum

Polycyclic aromatic hydrocarbons (PAHs) are a type of ubiquitous pollutant with the potential ability to cause endocrine disruption that would have an adverse health impact on the general population. To assess the maternal exposure to PAHs in neonates and evaluate the possible impact of PAHs on reproductive hormone levels, the concentration of PAHs and reproductive hormone levels in the umbilical cord serum of 98 mother-infant pairs in the Shengsi Islands were investigated. The median concentration of total PAHs was determined to be 164 (Inter-Quartile Range, IQR 93.6-267) ng g^-1 lipid, and 68% of the PAHs were lower-molecule congeners. The highest level was found for pyrene (PYR) and naphthalene (NAP), which contributed 54.6% of all the PAHs present in the samples. The exposure to PAHs negatively affected estradiol (E2) and Anti-Mullerian hormones (AMH) and positively affected FSH in the umbilical cord serum. The result expanded the database of the human burden of PAHs and suggested that PAHs can act as a type of Endocrine-Disrupting Chemical (EDC). These results may help to understand the complex pathways involved in disorders of human reproductive health associated with prenatal exposure to PAHs.