Journal of environmental pathology and toxicology最新文献

The toxicity of the mixture NIAX-ESN which contains 95% dimethylaminopropionitrile was evaluated in male rats. Large doses (2.0 ml/kg ip) rapidly produced CNS excitation followed by depression and death. The mixture (given orally as two doses of 0.31 or 0.62 ml/kg respectively) induced acute urinary bladder lesions in 3 days. The changes consisted of massive transmural edema, acute ulcers and inflammation and, occassionally hemorrhagic necrosis of the bladder wall.

The effect of varying the dietary intake of Na, K, Ca, Mg, Cd and Pb on blood pressure in 16 groups of rats (10 rats each group) weighing 200 g initially was studied. The animals received Na, K, Ca, and Mg in amounts calculated to be 20% above or 20% below the normal intake of these elements. Lead was given as PbCl2 (300 mg/l) in the drinking water and Cd was given in the drinking water in a concentration of 5 mg Cd/l. The animals were on the diets for 16 weeks. The diets were sufficient for growth and maintenance as indicated by weight increases of 35-45% during the 16-week period. Eight Cd-ingesting groups exhibited increases in blood pressure of from 2 to 12%. The blood pressure of 8 groups of rats which received high levels of Ca and Mg but no Cd exhibited decreases in blood pressure of from 4 to 11%. The other elements modified these responses. The level to which blood pressure would rise or fall could not be predicted on the presence or absence of one mineral alone. These data support the concept that alterations in dietary mineral intake affect the blood pressure.

Dahl hypertension-resistant (R) and hypertension-sensitive (S) lines of rats were used to determine whether cadmium plays an etiological role in hypertension. In Study I, weanling (3-week-old) R and S rats of both sexes were given a low-salt (0.4% NaCl) diet and were divided into two groups. Rats in the cadmium group were injected with cadmium (2 mg/kg body weight, ip), whereas the controls received identical volumes of saline. Three weeks after the first injection, no elevations of systolic blood pressure were detected. A second dose of cadmium (1 mg/kg) produced hypertension in S females but not in S males or in R rats of either sex. Also, female S cadmium rats manifested significant (p less than 0.01) mild to moderate renal vascular changes. The concentrations of cadmium in hepatic and renal tissues of S cadmium rats were significantly higher (p less than 0.001) than in R rats. In Study II, weanling (3-week-old) female S rats on a high-salt (4% NaCl) diet were given cadmium (2 mg/kg body weight, ip) at week 3 followed by second and third injections of cadmium (1 mg/kg) at weeks 6 and 23. S controls received the same volumes of saline. Cadmium enhanced the rate and the degree of salt-induced hypertension development. Pathological lesions of periarteritis nodosa in the mesenteric arteries and renal vascular lesions occurred to the same extent in the cadmium and control groups. These data indicate that differences in genetic background influence the development of cadmium-induced hypertension in weanling rats, and that cadmium exacerbates the severity of salt-induced hypertension.

Chlorite, a by-product of chlorine dioxide disinfection of water, is a strong oxidant compound that produces markedly exaggerated effects in vitro on red cells of G6PD deficient humans when compared to normal human cells. Levels of methemoglobin are significantly greater and GSH levels significantly lower in the G6PD deficient cells than in normal cells after chlorite exposure. Persons with G6PD deficiency may be 3 to 4 times more likely to develop hemolytic anemia from chlorite exposure as persons with normal activity levels when GSH levels are used as a measure of susceptibility. The proposed use of chlorine dioxide as an alternate disinfectant for drinking water supplies should consider this potential high risk group.

This study was designed to further investigate the association(s) of cardiovascular diseases and drinking water constituents. A sample of 4200 adults were randomly selected from 35 geographic areas to represent the civilian noninstitutionalized population of the contiguous United States. Each participant was interviewed and given a thorough physical examination. A tap water grab sample was collected from each participant's residence and analyzed for 80 inorganic chemical constituents. This paper is limited to measures of association between mortality rates and mean inorganic chemical constituent levels for the 35 study areas. Limited statistical analyses of associations among some of the chemical constituent levels are also included. Hardness and calcium appear to follow the normal trend of negative associations with the mortality rates for most groups of cardiovascular diseases, whereas the area means for copper and lead are positively associated. Zinc and cadmium associations were examined, but the range of constituent levels in the sampled drinking waters is too small for meaningful interpretation of the results. Unexpectedly, the area sodium means were negatively related to the male and female cardiovascular mortality rates; the associations were statistically significant (P less than 0.05) for both the male and female total cardiovascular-renal and ischemic heart disease mortality rates.

The Regional Heart Study aims at determining the factors responsible for the marked regional variations in coronary heart disease and stroke in Great Britain. This report is concerned with mortality (1969-1973) from cardiovascular disease in 253 towns in England, Wales and Scotland with particular reference to water quality (hardness), climate, air pollution, socio-economic and genetic (blood group) factors. The preliminary results reaffirm an association between water hardness and cardiovascular (CV) mortality, with towns with soft water tending to have hgiher CV death rates than towns with hard water. Multiple regression analysis shows that this relationship is somewhat weakened after allowing for rainfall, temperature and socio-economic factors but that it remains statistically significant for both coronary heart disease and stroke. A study of 13 towns with artificially softened water supplies indicates that their CV mortality is no higher than in neighbouring towns without softened water. A study of the prevalence of risk factors for cardiovascular disease is being carried out in 25 British towns selected to represent all the variations in CV mortality and water hardness and representing all major geographic regions of Britain. The incidence of CV disease in the 7,500 men aged 40-59 years in this study will be related to personal and environmental risk factors. Preliminary data show an association between mean blood pressure levels and CVD mortality rates.