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The article examines the impact of the Food Quality Protection Act (FQPA) of 1996 on safety standards used in determining pre- and post-natal toxicity exposure for infants and children in the U.S., based on a review of the toxicology and exposure database on chlorpyrifos conducted by Dow AgroSciences scientists and independent experts. The neurotoxicity of organophosphate-induced delayed neuropathy (OPIDN) and neuropsychological effects are considered. Aggregate exposure to chlorpyrifos by Monte Carlo probabilities and biomonitoring is also performed.

Microbiological degradation of the racemic mixture, the enantiopure R- and S-fipronil was examined under both aerobic and flooded conditions in three Chinese paddy soils. The degradation kinectics and enantiomer fraction (EF) were determined by means of high-performance liquid chromatography (HPLC) with chiral Chiralcel OD-H column, while desulfinyl, sulfone and sulfide derivatives were monitored by reversed phase HPLC with diode array detection (DAD). The degradation/transformation of enantiomers of fipronil in the three live soils under aerobic and flooded conditions generally complied with the first-order kinetics (R 2 ≥0.94). The calculated t1/2 values of the enantiomers of fipronil ranged between 21 and 34 days for aerobic incubation experiments and between 8 and 19 days under flooded conditions incubation, respectively. The calculated EF values of fipronil during the incubation time were all close to 0.5, indicating that the degradation/transformation of fipronil was almost nonenantioselective. The main metabolites of fipronil formed in the incubation experiments were sulfone and sulfide derivatives by oxidative and reductive processes, respectively. The oxidative pathway seemed more active. Under flooded conditions, S-fipronil was preferentially degraded in the three soil samples used. The main metabolite was determined as fipronil sulfide. In control experiments, almost no removal of enantiomers of fipronil was observed indicating that the degradation of fipronil in the paddy soil used was attributed to microbial mediated processes under both aerobic and flooded conditions. In addition, no enantiomerization of fipronil was observed in the soil samples examined under both aerobic and flooded conditions. These results for major differences in the degradation of the enantiomers as well as the formation of toxic metabolites may have some implications for better environmental and ecological risks assessment for chiral pesticides. [Copyright &y& Elsevier]

Grb2-associated binder 1 (Gab1) is known to play an important role in hepatocyte growth factor (HGF) signaling, which rapidly becomes tyrosine-phosphorylated upon HGF stimulation. In this study, we found that the tyrosine phosphorylation of Gab1 in the cells derived from Src/Yes/Fyn null mouse embryos was ∼40% lower than that in their wild type counterparts upon HGF stimulation. Increased expression of wild-type Src enhanced HGF-induced phosphorylation of Gab1, and, in contrast, expression of the Src kinase-deficient mutant or treatment of the specific Src inhibitor PPI suppressed it. Expression of a constitutively active Src mutant (Y527F) or oncogenic v-Src led to a prominent increase in Gab1 phosphorylation independent of HGF stimulation. Moreover, Src interacted with Gab1 via both its Src homology 2 and 3 domains and was capable of phosphorylating purified Gab1 in vitro. Finally, the increased phosphorylation of Gab1 by Src selectively potentiated HGF-induced activation of ERK and AKT. Taken together, our results establish a new role for Src in HGF-induced Gab1 phosphorylation. [ABSTRACT FROM AUTHOR]