Exposure of female August-Copenhagen Irish (ACI) rats for 28 weeks to 3 mg of estradiol (E(2)) contained in cholesterol pellets elevated blood E(2) levels and caused palpable mammary tumors in all animals. Coadministration of phenobarbital (PB) in their drinking water reduced the incidence, number, and size of mammary tumors (MTs) but did not reduce blood E(2) levels. Inhibition of MTs by PB wa...

BACKGROUND Lead (Pb) and cadmium (Cd) are known reproductive toxicants thought to disrupt hormone production throughout sensitive developmental windows, although this has not been previously examined in nationally representative peripubertal children. OBJECTIVES We examined the association between blood Pb and urinary Cd concentrations and the reproductive hormones inhibin B and luteinizing h...

The natural background concentration of lead (Pb) in soils in the United States ranges from 10 to 700 ppm, with an average of 20 ppm (Demayo et al., 1982). However, as a result of anthropogenic activities, soils may be contaminated with elevated levels of Pb. For example, gasoline combustion releases Pb into the atmosphere, and this Pb can be deposited· onto roadside soils. 1,225 ppm Pb ~s note...

The effect of the antioxidant gallic acid (GA) on Pb toxicity in blood, liver and kidney was investigated in the present study. Rats Wistar received Pb nitrate (50 mg/Kg/day, i.p., 5 days) followed by GA (13.5 mg/Kg, p.o., 3 days) or a chelating agent (EDTA, 55 mg/Kg, i.p.). As result, Pb decreased body weight, hematocrit and blood δ-aminolevulinic acid dehydratase (ALA-D) activity. In addition...

Phenobarbital (PB) is a prototypical inducer for studies of xenobiotic responses in animals. In mammals, the nuclear receptors constitutive androstane receptor (CAR) and pregnane X receptor (PXR) have been identified as key transcription factors regulating PB induced transcription of xenobiotic responsive genes. In insects, much less is known about the transcription factors involved in regulati...

Heavy metal contamination of soils resulting from mining and smelting is causing major concern due to the potential risk involved. This study was designed to investigate the heavy metal (Cu, Zn, Pb and Cd) concentrations in soils and food crops and estimate the potential health risks of metals to humans via consumption of polluted food crops grown at four villages around the Dabaoshan mine, Sou...

There is growing evidence that the budget of Pb in mantle peridotites is largely contained in sulfide, and that Pb partitions strongly into sulfide relative to silicate melt. In addition, there is evidence to suggest that diffusion rates of Pb in sulfide (solid or melt) are very fast. Given the possibility that sulfide melt ‘wets’ sub-solidus mantle silicates, and has very low viscosity, the im...

Lead (Pb) is a non-threshold toxin capable of inducing toxic effects at any blood level but availability of soil screening criteria for assessing potential health risks is limited. The oral bioaccessibility of Pb in 163 soil samples was attributed to sources through solubility estimation and domain identification. Samples were extracted following the Unified BARGE Method. Urban, mineralisation,...

The bioavailability and ultimate fate of heavy metals in the environment are controlled by adsorption-desorption process. Batch equilibrium experiments were performed to assess the effects of pH and low molecular weight organic acids (LMWOAs) on competitive adsorption and desorption of cadmium and lead in paddy soils from China. The results indicated that both soils exhibited greater sorption c...