摘要:

The Kehoe Pb balance experiments were carried out from 1937 to 1972 and involved over 21,000 d of measured exposure of Pb in humans. Pb balance and Pb in the diet, feces, urine, and blood were measured under normal conditions and during periods of oral and airborne Pb supplementation. Considerable natural variability was seen throughout the experimental periods, due primarily to variations in dietary Pb. The overall mean blood Pb concentration for all subjects was 25 μg per 100 g, with individual control means ranging from 18 to 40 μg per 100 g. Urinary Pb averaged 29 μg/l overall, with individual control means ranging from 19 to 45 μg/l. The overall average diet contained 181 μg/d (159 μg/d based on median data); however, the mean dietary Pb for the individual control periods decreased from approximately 300 μg/d in 1937 to 100 μg/d in 1970. Fecal Pb had an overall mean of 225 μg/d (212 μg/d based on median data) on a per‐sample basis, which exceeded the dietary Pb average because most subjects did not defecate daily. Averaged over the entire control period, fecal Pb was 196 μg/d, still in excess of the overall average diet. Pb balance was calculated as dietary Pb minus Pb in the feces and urine and did not include an estimate of inhaled Pb. Although three subjects were in positive balance during their control periods, the overall average balance was —32 μg/d, ranging from —106 to +25 μg/d for individual control periods. The balance data indicate that an appreciable amount of Pb absorbed from the air was excreted.

ISSN:0098-4108    

DOI:10.1080/15287398109530075

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

The Scientific Committee of the Food Safety Council recently recommended use of the gamma multihit model for risk assessment. Some practical problems arising from the use of this model are presented. In some instances the model produces what appear to be unreasonably high “safe dose” estimates. In other instances the estimates appear unreal‐istically low. Neither the original “standard” nor the “conservative” confidence limits seem adequate for practical application. The assumptions leading to the use of Abbott's correction are difficult to verify, but have a great effect on safe dose estimates. Indeed, the introduction of as little as 1% additive background into the gamma multihit model leads to safe dose estimates closer to those produced by the Armitage‐Doll model than to those of the pure gamma multihit model.

ISSN:0098-4108    

DOI:10.1080/15287398109530076

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

The interaction of sodium selenite (Na2SeO3) and aflatoxin B1(AFB1) was studied in 6‐wk‐old male Mongolian gerbils. Each of four groups of gerblls were fed one of the following diets during a 12‐wk experimental period: control (commercial Chow), 5.0 ppm Na2SeO3, 12.8 ppm AFB1, or 5.0 ppm Na2SeO3+ 12.8 ppm AFB1Animals receiving Na2SeO3in the diet, alone and with AFB1, had a significantly lower mean total weight gain during the experiment than did control animals. Animals receiving both compounds together displayed a very high level of physical activity compared to the three other groups. Blood analysis showed no change in total leukocytes, but the relative percentage of lymphocytes increased and the percentage of neutrophils decreased concurrently in the order: control <AFB1< Na2SeO3+ AFB, < Na2SeO3. A significant reduction in organ weight relative to body weight was observed in the liver, kidney, and lung of the animals fed AFB1alone but only in the liver of those fed both Na2SeO3and AFBlNo similar alterations were observed in the Na2SeO3group. Histopathological examination revealed considerably less hepatic damage in animals fed Na2SeO3with AFB1than in those receiving either compound alone. Renal and intestinal damage, however, was most severe in this double‐treatment group. Hepatic protein analysis revealed two protein peaks in the Na2SeO3+ AFB1group that were absent in all other groups. It was concluded that these proteins may be selenoproteins directly or indirectly involved in the lower incidence of histopathological damage in this group.

ISSN:0098-4108    

DOI:10.1080/15287398109530077

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

The pharmacokinetic profile of the herbicide 2,4,5‐T PGBE ester (propylene glycol butyl ether esters of 2,4,5‐trichlorophenoxyacetic acid)14C‐labeled in the ring was examined in rats given a single dermal application of 5 mg/kg. The rate of absorption of the ester through the skin was lower than the rate of hydrolysis to 2,4,5‐T acid and the rate of excretion of 2,4,5‐T in the urine. Urinary excretion of radioactivity was apparently first order with a half‐life of approximately 24 h. Clearance of radioactivity from blood plasma, liver, kidneys, and the remaining carcass was also apparently first order with half‐life values ranging from 25 to 37 h. Six days (144 h) after application of the dose, an average of 98.7 ± 5.1% of the applied radioactivity was recovered in the urine, and approximately 97% of the urinary radioactivity was identified as 2,4,5‐T acid. The tissue‐to‐plasma ratios of14C activity in liver and kidney were similar to those observed previously in rats given a single iv dose of 5 mg/kg 2,4,5‐Tacid.

ISSN:0098-4108    

DOI:10.1080/15287398109530078

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Radioimmunoassays for abrin and ricin are described. There is little cross‐reactivity between the two toxins. The procedures described are capable of determining blood concentrations down to 50–100 pg/ml, permitting identification of abrin and ricin poisoning and monitoring of the blood concentrations in cancer patients treated with these agents.

ISSN:0098-4108    

DOI:10.1080/15287398109530079

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

In vivo experiments with48V and59Fe radiotracers were performed to study the association of V with Fe proteins. Each male rat was injected ip with 10 μg48VO2+and then with 1 μg59Fe3+to label Fe‐containing proteins. The radioactivities incorporated were measured in plasma transferrin, red blood cell hemoglobin, liver ferritin, partially purified heart myoglobin, and liver mitochondrial and microsomal cytochromes b and c and ferriporphyrin.

ISSN:0098-4108    

DOI:10.1080/15287398109530080

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

The effects of fly ash from a coal‐fired power plant on tracheal epithelium of CrRGH (SYR) Syrian golden hamsters were studied in organ cultures and after in vivo exposures. The trachéal epithelium of animals receiving 5–9 daily (5 d/wk) 3‐h exposures to 2 mg fly ash per cubic meter showed large areas of basal cell hyperplasia and stratification. Surface alterations characteristic of stratified metaplasia were observed. Exposure to 1 mg/m3produced diffuse basal cell hyperplasia. Hamster tracheal ring cultures exposed in vitro to 50 μg/ml fly ash for 1 h/d or to 10 μg/ml for 3 h/d showed epithelial changes similar to those observed in vivo. Whole suckling hamster tracheas in organ culture exposed to fly ash at concentrations of 10 and 50 μg/ml for 1 or 3 h/d exhibited cornifying epidermoid metaplasia after 7 exposures. The most characteristic findings in surface cells were broad metaplastic areas with keratin formation.

ISSN:0098-4108    

DOI:10.1080/15287398109530081

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

The effect of vanadium chloride on rat brain synaptosomal adenosinetriphosphatase (A TPase) activities was determined in vitro and in rats treated at 1 mg/kg‐d ip and 10 mg/kg‐d po for 10 d. Additional experiments were conducted to determine the effect of vanadium chloride on binding of [3H]ouabain and45Ca to rat brain synaptosomes. Na++ K+‐ and Ca2+‐A TPase activities were inhibited significantly in a concentration‐dependent manner by V in vitro. Mg2+‐ATPase inhibition was neither dose‐dependent nor significant except at 10−5M. Na++ K+‐A TPase inhibition by V was more pronounced than that of other A TPases studied. Vanadium inhibited [3H]ouabain binding to synaptosomes by 90% at 10−3M; the inhibition was concentration‐dependent. Binding of45Co was inhibited 50% at 10−4M; but concentration‐dependent inhibition was not evident.

ISSN:0098-4108    

DOI:10.1080/15287398109530082

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

The autoradiographic unscheduled DNA synthesis measured in the hepatocyte primary culture/DNA repair test after exposure to chemical carcinogens was characterized, in order to document that this synthesis was occurring in nonreplicated DNA, density‐labeled, replicated DNA was separated from nonreplicated DNA by cesium chloride gradient centrifugation. Incorporation of [3H]thymidine into nonreplicated DNA was detected after exposure of hepatocytes to methyl methanesulfonate, an activation‐independent carcinogen, or N‐2‐acetylaminofluorene, an activation‐dependent carcinogen, but not with fluorene, a noncarcinogen. N‐4‐Acetylaminofluorene, a mutagenic compound of uncertain carcinogenicity, also caused DNA repair. Both the autoradiographic assay and density gradient centrifugation detected incorporation of [3H]thymi‐dine into DNA from the same hepatocyte preparation.

ISSN:0098-4108    

DOI:10.1080/15287398109530083

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

The urinary excretion of Cd, Cu, and Zn was measured in rats injected with 0.5 mg/kg Cd, sc, 6 d/wk for up to 25 wk. Gel Chromatographic analyses for these urinary metals were also carried out.

ISSN:0098-4108    

DOI:10.1080/15287398109530084

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor