Despite the fact that the biological processes of chiral compounds are enantioselective, the endocrine disruption activity and uptake of chiral contaminants with respect to enantioselectivity has so far received limited research. In this study, the estrogenic potential and uptake of the enantiomers of a newer pyrethroid insecticide, bifenthrin (BF), were investigated. Significant differences in estrogenic potential were observed between the two enantiomers in the in vitro human breast carcinoma MCF-7 cell proliferation assay (i.e., the E-SCREEN assay) and the in vivo aquatic vertebrate vitellogenin enzyme-linked immunosorbent assay (ELISA). In the E-SCREEN assay, the relative proliferative effect ratios of 1S-cis-BF and 1R-cis-BF were 74.2% and 20.9%, respectively, and the relative proliferative potency ratios were 10% and 1%, respectively. The cell proliferation induced by the two BF enantiomers may be through the classical estrogen response pathway via the estrogen receptor (ER), as the proliferation induced by the enantiomers could be completely blocked when combined with 10-6 mol/L of the ER antagonist ICI 182,780. Measurement of vitellogenin induction in Japanese medaka (Oryzias latipes) showed that, at an exposure level of 10 ng/mL, the response to 1S-cis-BF was about 123 times greater than thattothe Renantiomer. Significant selectivity also occurred in the uptake of BF enantiomers in the liver and other tissues of J. medaka. These results together suggest that assessment of the environmental safety of chiral insecticides should consider enantioselectivity in acute and chronic ecotoxicities such as endocrine disruption.

No abstract

No abstract

The enantioselective environmental toxic effect of chiral pesticides is becoming more important. As the industry develops, increasing numbers of chiral insecticides and herbicides will be introduced into use, potentially posing toxic effects on nontarget living beings. Chiral pesticides, including herbicides such as acylanilides, phenoxypropanoic acids, and imidazolinones, and insecticides such as synthetic pyrethroids, organophosphates, and DDT often behave enantioselectively during agricultural use. These compounds also pose unpredictable enantioselective ecological threats to nontarget living beings and/or humans, affecting the food chain and entire ecosystems. Thus, to investigate the enantioselective toxic effects of chiral insecticides and herbicides is necessary during environmental protection. The environmental toxicology of chiral pesticides, especially the findings obtained from studies conducted in our laboratory during the past 10 years, is reviewed.

No abstract

As the substitute of polybrominated diphenyl ethers (PBDEs), further assessments about the potential ecological safety and health risks of phosphorus-containing flame retardants (PFRs) are required because the worldwide demand for PFRs has been increasing every year. In this study, we examined the agonistic/antagonistic activity of a group of PFRs by three in vitro models (luciferase reporter gene assay, yeast two-hybrid assay, and E-screen assay). Molecule docking was used to further explain the interactions between ERα and PFRs. Data from luciferase reporter gene analysis showed three members of the nine tested PFRs significantly induced estrogenic effects, with the order of TPP > TCP > TDCPP, while TCEP and TEHP have remarkable antiestrogenic properties with calculated REC20 and RIC20 values of 10–6 M or lower. Results from the luciferase reporter gene method are generally consistent with results obtained from the yeast two-hybrid assay and E-screen, except for the positive estrogenic activity of TBP in E-screen testing. Docking results showed that binding between ligands and ERα was stabilized by hydrophobic interactions. As a proposed alternative for brominated flame retardant, PFRs may have anti/estrogenic activity via ERα at the low dose typical of residue in environmental matrix or animals. PFRs with a short chain, halogen, and benzene ring in the substituent group tend to be estrogenic. Our research suggests that comprehensive evaluations, including health and ecological assessments, are required in determining whether PFRs are preferable as an emerging industrial substitute.

Neonicotinoids have become the most widely used insecticides in the world since introduced in the mid 1990s, yet the extent of human exposure and health impacts is not fully understood. In this study, the residues were analyzed of seven neonicotinoids in fruit and vegetable samples collected from two cross-sectional studies: the U.S. Congressional Cafeteria study (USCC) and the Hangzhou China (HZC) study. We then employed a relative potency factor method to integrate all neonicotinoids in each food sample using the respective reference dose values as the basis for summation. The findings were compared with data published by the U.S. Department of Agriculture Pesticide Data Program (USDA/PDP). Imidacloprid and thiamethoxam were the most commonly detected neonicotinoids in fruits and vegetables with 66 and 51% detection in the HZC study and 52 and 53% detection in the USCC study, respectively. The overall frequency of detection for neonicotinoids in the USDA/PDP samples was much lower than those reported here for the USCC or HZC studies, with imidacloprid being the most frequently detected neonicotinoid at 7.3%. The high frequencies of neonicotinoid detection in fruits and vegetables in the USCC and HZC studies give us a snapshot of the ubiquity of neonicotinoid use in global agriculture and make it clear that neonicotinoids have become part of the dietary staple, with possible health implications for individuals.

The combination of levonorgestrel and quinestrol (EP-1) has been shown to have anti-fertility effects on several wild rodents, but the mechanism underlying these effects is poorly understood. We investigated the effects of EP-1 and each of its components, levonorgestrel (P) and quinestrol (E), on the fertility of Brandt's voles (Lasiopodomys brandtii) by using a gastric gavage method. The doses for EP-1, E and P were 1, 0.34 and 0.66 mg/kg body weight, respectively. Male voles (n = 98) were treated daily for 5 or 14 days, then the testes and epididymides were collected, weighed and examined histologically at 30 (D30), 60 (D60) or 90 (D90) days after the end of treatment. Four males were allowed to mate with normal females at D90. Female voles (n = 75) were treated for 3 days and a further 3 days after a 7-day interval. The uteri and ovaries were weighed and examined histologically at 15 (D15), 30 (D30) or 75 (D75) days after the end of treatment. Each of three females were mated with fertile males at D30 and D75, respectively. Our results indicated that quinestrol (E) significantly decreased the sperm numbers in the testes as well as the weight of the testes and epididymides, with both of these tissues showing obvious structural abnormalities, and significantly reduced the litter size and the pup weight for females mated with males of the E treatment group. For female voles, treatment with E, P or EP-1 resulted in no marked influence on the fertility status. These data indicate that quinestrol (E) alone has a significant anti-fertility effect on male Brandt's voles, but is ineffective in combination with levonorgestrel (P).