摘要:

Blood lead (PbB) levels were determined in children living in Campania (in Naples and in a rural zone in the district of Caserta). Atmospheric lead (PbA) concentration in these considered areas was monitored for 1 yr (1993-1994). The children tested were questioned about comm on sources of lead, other than atmospheric, relating to their living and dietary habits. The PbB levels in children living in Naples were, at the 50th percentile, 13.8 mu g/dl in males and 13.7 mu g/dl in females; in children living in the rural area the median PbB levels were 8.9 mu g/dl in males and 8.8 mu g/dl in females. The annual mean values of atm ospheric lead were 1.15 +/- 0.24 mu g/m3 in Naples and 0.23 +/- 0.07 mu g/m3 in the rural area. Significant and congruent mean differences between urban and rural sites were found in children's blood and concurrent air lead. Considering the PbB level of 10 mu g/dl as the maximum level that is not associated any known adverse effect in children, the Neapolitan group can be considered at risk of chronic intoxication by lead.

ISSN:0098-4108    

DOI:10.1080/009841096161663

出版商:Informa UK Ltd    

年代:1996

数据来源: Taylor

摘要:

Health and exposure criteria have not been established for lewisite [dichloro(2-chlorovinyl) arsine], a potent toxic vesicant that reacts with the sulfhydryl groups of proteins through its arsenic group. Sixty Sprague-Dawley rats of each sex, 6-7 wk old, were divided into 6 groups (10/group/sex) and gavaged with either 0, 0.01, 0.1, 0.5, 1.0, or 2.0 m g/kg of lewisite in sesame oil 5 d/wk for 13 wk. No significant dose-related change in body weight was observed. At the high dose, serum protein, creatinine, SGOT, and SGPT were decreased in males; lymphocytes and platelets were increased in females. A treatment related lesion was detected in the forestomach of both sexes at 2.0 m g/kg. These lesions were characterized by necrosis of the stratified squamous epithelium accompanied by infiltration of neutrophils and macrophages, proliferation of neocapillaries, hemorrhage, edema, and fibroblast proliferation. Mild acute inflammation of the glandular stomach was also observed in some cases at 1.0 and 2.0 mg/kg. Early deaths were attributed to severe inflammation of the upper and/or lower respiratory tract, possibly from deposition or reflux of test material into the pharynx. Estimated dose range for NOEL appears to be >0.5 and <1.0 m g/kg when administered orally.

ISSN:0098-4108    

DOI:10.1080/009841096161672

出版商:Informa UK Ltd    

年代:1996

数据来源: Taylor

摘要:

The herbicide 2,4-dichlorophenoxyacetic acid (2,4-D), used for control of weeds in agriculture, forestry, and rights of way, can accumulate as a residual chemical in soil. The objective was to determ ine percutaneous absorption of 2,4-D from soil, with emphasis on soil load and skin contact time. With control acetone vehicle, in vivo absorption of 2,4-D in the rhesus monkey was 8.6 +/- 2.1% of the dose, which compared closely to published human absorption of 6.0 +/- 2.4%. Percutaneous absorption from soil loads of 1 and 40 mg/cm2 were 9.8 +/- 4.0 and 15.9 +/- 4.7%, respectively, values similar to acetone vehicle. In vitro absorption in human skin calculated from skin content accumulation over 24 h was 1.8 +/1.7, 1.7 +/- 1.3, and 1.4 +/- 1.2% for soil loads of 5, 10, and 40 mg/cm2, respectively. Thus, soil load did not affect 24-h percutaneous absorption. Current Environmental Protection Agency (EPA) recommended calculated reductions due to soil load are not supported by these results with 2,4-D. Percutaneous absorption of 2,4-D from acetone vehicle for 8 h dosing period was 3.2 +/- 1.0%, one-third the value of 8.6 +/- 2.1% over 24 h. With soil vehicle, absorption for 8 h was only 0.03 +/- 0.02% for 40 mg/cm2 soil load and 0.05 +/- 0.004% for 1 mg/cm2 soil load. Absorption for 16 h was 2.2 +/- 1.2%. Absorption over time was linear for acetone vehicle, where total dose is deposited on skin, but not linear for soil vehicle, which had an 8-h delay (lag time). This equates with a normal 8-h work day where most of the contaminated soil can be washed off the skin. The apparent partition coefficient of 2,4-D between soil and water changed over time. This suggests there is a "mobility" phase for 2,4-D in soil that will change with time. For soil vehicle, percutaneous absorption of 2,4-D was not linear in respect to soil load or to skin contact time. Calculation based on assumed linearity can falsely estimate potential human health hazard. Clearly, the dermatokinetics with soil and skin represent complex interactive forces that require detailed evaluation before overgeneralizing rules for interpretation in terms of risk assessment.

ISSN:0098-4108    

DOI:10.1080/009841096161681

出版商:Informa UK Ltd    

年代:1996

数据来源: Taylor

摘要:

Previous studies have indicated that human exposure to perchloroethylene (PCE) produces subtle behavioral changes and other neurological effects at concentrations at or below the current occupational exposure limit. Since comparable effects in anim als may be reflected by changes in schedule-controlled operant behavior, the ability of orally administered PCE to alter fixed-ratio (FR) responding for a food reward was investigated in m ale SpragueDawley rats. Furthermore, since behavioral effects of solvents are likely to be more closely related to blood or target tissue (i.e., brain) concentrations than administered dose, the relationship between the pharm acokinetic distribution of PCE and its effects on operant responding was also evaluated. Rats trained to lever-press for evaporated milk on an FR-40 reinforcement schedule were gavaged with 160 or 480 mg/kg PCE and im mediately placed in an operant test cage for 90 min. Separate animals gavaged with equivalent doses of PCE were used to determine profiles of blood and brain concentrations versus time. Perchloroethylene produced changes in responding that varied not only with dose but also among animals receiving the same dose. Changes in the response rates of rats receiving 160 mg/kg PCE were either not readily apparent, restricted to the first 5 m in of the operant session, or attributable to gavage stress and the dosing vehicle. However, 480 mg/kg produced either an imm ediate suppression of responding for 15-30 m in before a rapid recovery to control rates or a complete elimination of lever-pressing for the majority of the operant session. Although the two doses of PCE produced m arkedly different effects on operant behavior during the first 30 min of exposure, differences in brain concentrations of PCE were minimal. Furthermore, the majority of animals receiving 480 mg/kg PCE fully recovered from response suppression while blood and brain levels of the solvent continued to rise. Thus,

ISSN:0098-4108    

DOI:10.1080/009841096161690

出版商:Informa UK Ltd    

年代:1996

数据来源: Taylor

摘要:

The elimination of 2,3,7,8-substituted polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) was investigated in a group of n=43 exposed workers with 2 blood measurements and n=5 workers with 3 measurements. Under the assumption of a one-compartment, first-order kinetic m odel the median half-life for 2,3,7,8-TCDD was 7.2 yr, while for the other dioxins the estimates were between 3.7 yr for 1,2,3,4,6,7,8-HpCDD (hepta-chlorinated) and 15.7 yr for 1,2,3,7,8-PCDD (penta-chlorinated). For the furans median half-lives between 3.0 yr for 1,2,3,4,6,7,8-HpCDF and 19.6 yr for 2,3,4,7,8-PCDF were observed. There was no indication for a deviation from a first-order kinetic. Increasing age and percent body fat were associated with increasing half-life for most of the congeners. Smokers in general had a faster decay than non-and ex-smokers. In summary, the higher chlorinated PCDD/F like TCDD appear to be highly persistent in humans with half-lives ranging between 4 and 12 yr.

ISSN:0098-4108    

DOI:10.1080/009841096161708

出版商:Informa UK Ltd    

年代:1996

数据来源: Taylor

摘要:

Induction of CYP1A1 is one of the best characterized responses to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). EROD activity has been used as an enzymatic marker for CYP1A1 following TCDD treatm ent. Enzymatic markers for the induction of CYP1A2 by TCDD are not as well characterized. The present study examines the relationship between CYP1A1 and CYP1A2 protein and the corresponding enzymatic markers. Induction of hepatic ethoxyresorufin O-deethylase (EROD) activity and methoxyresorufin O -demethylase (MEROD) and acetanilide 4-hydroxylase (ACOH) activity (both markers for CYP1A2)

ISSN:0098-4108    

DOI:10.1080/009841096161717

出版商:Informa UK Ltd    

年代:1996

数据来源: Taylor

摘要:

Multidrug resistance (MDR) to chem ically unrelated therapeutic anticancer agents in mammalian cells is m ediated by the overexpression of an ATP-dependent 150- to 180-kD membrane glycoprotein, P-glycoprotein (P-gp). Although the complete physiological role of P-gp is unknown, it is proposed to function in cellular detoxification of xenobiotics. In this study, we investigated whether the organophosphorus insecticide chlorpyrifos (O, Odiethyl O-3,5,6-trichloro-2-pyridinyl phosphorothioate) or its metabolites interact with Pgp. Immunohistochemical analysis of tissues from male Fischer 344 rats adm inistered chlorpyrifos (7.6 m g/kg gavage) showed increased P-gp expression in the kidney, adrenal, liver, jejunum, and stomach (tissues associated with elimination of xenobiotics), compared to control tissues. The most prominent increase was detected in the large bile ducts of the liver and the proximal tubule region of the kidney. P-gp expression was increased throughout the adrenal medulla and cortex, while a moderate increase was detected in the epithelial layers of the stomach and jejunum. To exam ine further the interaction between chlorpyrifos and P-gp, we evaluated whether chlorpyrifos or its active metabolite, chlorpyrifos oxon, could inhibit [3H]azidopine labeling of P-gp in M DR1 baculovirus-infected insect Sf9 cells. A concentration-dependent inhibition of [3H]azidopine labeling of P-gp was detected with chlorpyrifos oxon, while significant inhibition was not detected with chlorpyrifos. To correlate the binding of chlorpyrifos oxon to P-gp with a biochemical effect, we examined its ability to stim ulate P-gp-mediated ATPase activity in these Sf9 cells. Chlorpyrifos oxon stimulated P-gp ATPase activity 1.75 times that of the positive control (10 mu M verapamil). Taken together, these results suggest that chlorpyrifos oxon interacts with P-gp, and support the hypothesis that P-gp may play a role in the cellular detoxification of insecticides in mammalian tissues. To our knowledge this is the first report of an organophosphorus insecticide interacting with and increasing the expression of P-gp.

ISSN:0098-4108    

DOI:10.1080/009841096161726

出版商:Informa UK Ltd    

年代:1996

数据来源: Taylor