摘要:

Because of the wide use of pesticides for domestic and industrial purposes, the evaluation of their immunotoxic effects is of major concern for public health. Despite the large amount of experimental data describing pesticide-induced immunosuppression, evidence that pesticides may severely impair immune functions in humans is lacking or scarce. Contact hypersensitivity is a well-identified immunotoxic effect of pesticides but remains a rare complaint in pesticide-exposed workers. By contrast, immunologically mediated systemic reactions have been described only as debatable case reports. The association between autoimmune diseases and pesticide exposure has more recently been suggested. Despite the lack of convincing human data, a potential risk for the immune system should not be excluded, especially during chronic exposure to pesticides or in otherwise (immuno) compromised patients (malnutrition, children, old patients). Epidemiological studies including markers of exposure and the assessment of immune competence in exposed individuals, or registries of sentinel diseases related to immunosuppression (e.g., non-Hodgkin's lymphoma, opportunistic infections) or autoimmunity (e.g., lupus erythematosus, rheumatoid arthritis), are warranted.

ISSN:0098-4108    

DOI:10.1080/009841096161294

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

It has been established in the literature that constraints on the designs of experiments used to estimate carcinogenic potencies cause overestimation of true biological interspecies correlations of such potencies. This article explores the potential for appreciable underestimation of interspecies correlations, due to the experimental error that occurs in the estimation of carcinogenic potencies.

ISSN:0098-4108    

DOI:10.1080/009841096161302

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Concentrations of selenium in plasma and urine and activity of glutathione peroxidase in erythrocytes were determined in workers exposed to selenium and in a control group. Plasma selenium concentrations were significantly lower in exposed workers compared to the controls. Erythrocyte glutathione peroxidase activity in selenium workers was significantly higher than in the control subjects. Urine selenium concentrations were not statistically different between the two groups. There was a significant positive correlation between plasma selenium concentrations and urine selenium concentrations in workers exposed to selenium. A weak significant positive correlation was found between plasma selenium concentrations and erythrocyte glutathione peroxidase activity in exposed workers. Our results suggest that the lower plasma selenium concentrations in selenium workers may be attributed to an increase of urinary selenium excretion.

ISSN:0098-4108    

DOI:10.1080/009841096161311

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Arsenic has been recognized as a human toxicant for over 2000 years. More recently it has been readily accepted as a human carcinogen. Animal research has demonstrated arsenic's ability to have profound detrimental effects on the developing embryo in avian and mammalian species. This article comprehensively reviews the human and animal literature on the subject of the reproductive toxicity of arsenic. A variety of endpoints are considered, including spontaneous abortion, cardiovascular defects, and arsenic's role in the causation of neural tube defects (NTDs). A summary of the literature that has examined the various postulated mechanisms by which arsenic may produce NTDs is also considered. In addition, a discussion of literature relative to the presence of arsenic in the general environment and in the workplace is presented. This article reaches the conclusion that while further research is clearly needed, particularly on the potential toxicity of organic arsenical compounds, the current literature suggests it may be prudent and appropriate to treat inorganic arsenic as a probable human reproductive toxin.

ISSN:0098-4108    

DOI:10.1080/009841096161320

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The purpose of this study was to investigate the toxicity of styrene and styrene oxide in the lung in comparison to the toxicity in the liver. Pneumotoxicity caused by styrene or styrene oxide was measured by elevations in the release of gamma-glutamyltranspeptidase (GGT) and lactate dehydrogenase (LDH) into bronchoalveolar lavage fluid (BALF), while hepatotoxicity was measured by increases in serum sorbitol dehydrogenase (SDH) in non-Swiss Albino (Hsd:NSA) mice. Intraperitoneal administration of styrene at doses of 500–1000 mg/kg caused consistent dose-dependent increases in both sets of biomarkers with the hepatic effect appearing earlier than the pulmonary effect. Pyridine, phenobarbital, and β-naphthoflavone, inducers of CYP2E1, CYP2B, and CYP1A, respectively, increased the toxicity of styrene. Pyridine and phenobarbital treatments increased mortality due to styrene. Styrene oxide exists in two enantiomeric forms: (R)- and (S)-styrene oxide, and the differential toxicities of the two enantiomers and racemic styrene oxide were compared. In all studies, (R)-styrene oxide caused greater toxicity than the (S) enantiomer, especially in the liver. Trichloropropene oxide, an epoxide hydrolase inhibitor, was used to inhibit styrene oxide detoxification and increased its hepatotoxicity, while buthionine sulfoxamine, a glutathione depletor, did not. These results demonstrated the greater role of epoxide hydrolase in styrene oxide detoxification.

ISSN:0098-4108    

DOI:10.1080/009841096161339

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Objective measures of upper respiratory function are needed to understand the effects of inhaled toxicants on the nasal passages. Acoustic rhinometry (AR) is a simple new technique that determines nasal volume by measuring the cross-sectional area of the upper airway as a function of the distance along the nasal passage. This study compares acoustic rhinometry with the more traditional posterior rhinomanometry (NAR) and correlates these objective measures with the symptom of nasal congestion. Healthy young adults (n= 29) were studied on 4 days, each separated by at least 1 wk, in a climate-controlled environmental chamber for 6 h, with exposure to clean air or sidestream tobacco smoke (SS) (2 h, 1, 5, and 15 ppm CO). The coefficient of variation for single measurements was 8–15% (AR) and 4% (NAR); for across-day measurements it was 15–25% (AR) and 13–15% (NAR); and for between days it was 19–27% AR and 17–21% (NAR). These coefficients were similar in subjects with a history of environmental tobacco smoke sensitivity (ETS-S) and those with no history of ETS sensitivity (ETS-NS). At baseline, the perception of unilateral nasal congestion was significantly correlated with unilateral nasal dimensions or nasal resistance; the symptom of baseline bilateral nasal congestion (estimated for both nasal passages simultaneously) correlated less well with objective measures of nasal patency. Under challenge conditions (SS at 1–15 ppm CO), there were typically significant correlations between changes in unilateral congestion and both unilateral rhinomanometry and acoustic rhinometry, but correlations of bilateral congestion and measurable dimensions were much lower. ETS-S and ETS-NS subjects differed in correlations between bilateral subjective and objective measures: ETS-S subjects showed significant correlation between baseline congestion and NAR; in contrast, ETS-NS subjects showed significant correlation between baseline congestion and acoustic rhinometry. These results indicate that NAR and AR are complementary tests for use in inhalation challenge studies and have different correlations with nasal congestion under baseline and challenge conditions.

ISSN:0098-4108    

DOI:10.1080/009841096161348

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Okadaic acid, a diarrhetic shellfish toxin, is a potent promoter of tumors in mouse skin and a specific inhibitor of protein phosphatases 1 and 2A. In the present study, we investigated its effects on protein synthesis in Vero cells and rabbit reticulocyte lysate. Protein synthesis was inhibited by okadaic acid in Vero cells in a concentration-dependent manner (IC50 = 3.3 × 108M−1). DNA synthesis was also inhibited by okadaic acid in Vero cells in a concentration-dependent manner (IC50 = 5.3 × 108M−1). DNA synthesis inhibition in Vero cells occurred only after 8 h or longer. RNA synthesis was inhibited with an IC50 of 8.2 × 108M−1. The time lag before DNA and RNA synthesis inhibition occurred was longer than the time lag before protein synthesis inhibition occurred in the same cells (4 h), indicating that protein synthesis is probably the main target and the first of okadaic acid's cytotoxic effects. Moreover, the inhibition of DNA and RNA synthesis is probably a consequence of the inhibition of protein synthesis. Since okadaic acid does not impair the uptake of the precursor of protein synthesis, it is assumed that the inhibition is due to a direct effect on one of the components of the protein synthesis machinery. We then used a cell-free system of rabbit reticulocyte lysate in which specific mRNA is translated into globin to ensure that protein synthesis is a direct target of okadaic acid in vitro. In rabbit reticulocyte lysate, okadaic acid inhibited protein synthesis in a concentration-dependent manner (IC50 = 6.3 × 1012M−1) with a correlation coefficient for percent inhibition values ofr= .918. The molecular target of okadaic acid inside the cell whereby protein synthesis is inhibited remains to be discovered.

ISSN:0098-4108    

DOI:10.1080/009841096161357

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor