Maternal exposure to DDT, DDE, and pyrethroid insecticides for malaria vector control and hypospadias in the VHEMBE birth cohort study, Limpopo, South Africa

The adverse role of endocrine disrupting chemicals in the reproductive system

Reproductive system diseases pose prominent threats to human physical and mental well-being. Besides being influenced by genetic material regulation and changes in lifestyle, the occurrence of these diseases is closely connected to exposure to harmful substances in the environment. Endocrine disrupting chemicals (EDCs), characterized by hormone-like effects, have a wide range of influences on the reproductive system. EDCs are ubiquitous in the natural environment and are present in a wide range of industrial and everyday products. Currently, thousands of chemicals have been reported to exhibit endocrine effects, and this number is likely to increase as the testing for potential EDCs has not been consistently required, and obtaining data has been limited, partly due to the long latency of many diseases. The ability to avoid exposure to EDCs, especially those of artificially synthesized origin, is increasingly challenging. While EDCs can be divided into persistent and non-persistent depending on their degree of degradation, due to the recent uptick in research studies in this area, we have chosen to focus on the research pertaining to the detrimental effects on reproductive health of exposure to several EDCs that are widely encountered in daily life over the past six years, specifically bisphenol A (BPA), phthalates (PAEs), polychlorinated biphenyls (PCBs), parabens, pesticides, heavy metals, and so on. By focusing on the impact of EDCs on the hypothalamic-pituitary-gonadal (HPG) axis, which leads to the occurrence and development of reproductive system diseases, this review aims to provide new insights into the molecular mechanisms of EDCs' damage to human health and to encourage further in-depth research to clarify the potentially harmful effects of EDC exposure through various other mechanisms. Ultimately, it offers a scientific basis to enhance EDCs risk management, an endeavor of significant scientific and societal importance for safeguarding reproductive health.

Comparative in vitro and in silico study on the estrogenic effects of 2,2-bis(4-chlorophenyl)ethanol, 4,4'-dichlorobenzophenone and DDT analogs

DDT and its transformation products (DDTs) are frequently detected in environmental and biological media. Research suggests that DDT and its primary metabolites (DDD and DDE) could induce estrogenic effects by disturbing estrogen receptor (ER) pathways. However, the estrogenic effects of DDT high-order transformation products, and the exact mechanisms underlying the differences of responses in DDT and its metabolites (or transformation products) still remain unknown. Here, besides DDT, DDD and DDE, we selected two DDT high-order transformation products, 2,2-bis(4-chlorophenyl) ethanol (p,p'-DDOH) and 4,4'-dichlorobenzophenone (p,p'-DCBP). We aim to explore and reveal the relation between DDTs activity and their estrogenic effects by receptor binding, transcriptional activity, and ER-mediated pathways. Fluorescence assays showed that the tested 8 DDTs bound to the two isoforms (ERα and ERβ) of ER directly. Among them, p,p'-DDOH exhibited the highest binding affinity, with IC₅₀ values of 0.43 μM and 0.97 μM to ERα and ERβ, respectively. Eight DDTs showed different agonistic activity toward ER pathways, with p,p'-DDOH exhibiting the strongest potency. In silico studies revealed that the eight DDTs bound to either ERα or ERβ in a similar manner to 17β-estradiol, in which specific polar and non-polar interactions and water-mediated hydrogen bonds were involved. Furthermore, we found that 8 DDTs (0.0008-5 μM) showed distinct pro-proliferative effects on MCF-7 cells in an ER-dependent manner. Overall, our results revealed not only for the first time the estrogenic effects of two DDT high-order transformation products by acting on ER-mediated pathways, but also the molecular basis for differential activity of 8 DDTs.

A narrative review of converging evidence addressing developmental toxicity of pyrethroid insecticides

Pyrethroid insecticides are broadly used in agriculture and household products throughout the world. Exposure to this class of insecticides is widespread, and while generally believed to be safe for use, there is increasing concern regarding their effects on neurodevelopment. Due to the critical roles that molecular targets of pyrethroids play in the regulation of neurodevelopment, particular focus has been placed on evaluating the effects of in utero and childhood pyrethroid exposure on child cognition and behavior. As such, this narrative review synthesizes an assessment of converging study types; we review reports of neonatal pyrethroid levels together with current epidemiological literature that convergently address the risk for developmental toxicity linked to exposure to pyrethroid insecticides. We first address studies that assess the degree of direct fetal exposure to pyrethroids in utero through measurements in cord blood, meconium, and amniotic fluid. We then focus on the links between prenatal exposure to these insecticides and child neurodevelopment, fetal growth, and other adverse birth outcomes. Furthermore, we assess the effects of postnatal exposure on child neurodevelopment through a review of the data on pediatric exposures and child cognitive and behavioral outcomes. Study quality was evaluated individually, and the weight of evidence was assessed broadly to characterize these effects. Overall, while definitive conclusions cannot be reached from the currently available literature, the available data suggest that the potential links between pyrethroid exposure and child neurodevelopmental effects deserve further investigation.