摘要:

The Arctic is still relatively pristine in nature, but it is also vulnerable to pollution because contaminants originating from midlatitudes are transported to the Arctic by atmospheric processes, ocean currents, and rivers (Muir et al., 1992). Recognition of this fact of Arctic vulnerability has resulted in a Declaration on the Protection of the Arctic Environment by eight Arctic countries. A manifest aim of this declaration is to develop an Arctic Monitoring and Assessment Program. We report here on the presence of measurable levels of polycyclic aromatic hydrocarbon-DNA adducts, including relatively high levels in Arctic beluga (Delphinapterus leucas). These results lend support to the value of developing biological assessment programs for Arctic wildlife.

ISSN:0098-4108    

DOI:10.1080/00984109708984006

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

High levels of cadmium in the liver and kidneys of caribous and sea mammals of the Canadian Arctic have led to recommendations to remove such offal from the traditional diet. Blood cadmium levels have been found to be very high in samples of Inuit volunteers, hence the hypothesis that the Inuit might be exposed to cadmium through their diet. This survey of a population-based random sample of Nunavik residents (n = 518) confirms that blood cadmium of Inuit is indeed very high by comparison to published reports. Blood cadmium levels are closely associated with the current smoking status and are independent of dietary patterns among nonsmokers. Plasma omega-3 fatty acids concentrations have been used to assess the reliability of the dietary information collected by questionnaires and to test for any association of blood cadmium with the consumption of sea mammals. Blood cadmium levels are not related to the reported consumption of sea mammals. Blood cadmium levels are very high among smokers and are associated with levels of exposure to tobacco. Among nonsmoking Inuit, blood cadmium levels are comparable with those reported in nonsmokers elsewhere in the world. In reference to international standards, blood cadmium concentrations are high enough among the Inuit to warrant energetic public health interventions.

ISSN:0098-4108    

DOI:10.1080/00984109708984007

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The transfer of Cd to eggs of white Leghorn laying hens has been shown to be restricted. After Cd was injected ip into laying hens, the Cd concentrations in the blood, livers, ovaries, and eggs were measured. Although the Cd concentrations in the maternal blood and livers increased remarkably at certain levels of administrations, the Cd concentration in the yolks of eggs was not significantly increased, and was less than 0.04 μg/g wet weight. After egg production stopped in the highest injected group (7.5 mg Cd/kg), Cd in the yolks of eggs had an accumulated range of 0.02-0.03 μg/g wet weight. This was despite the high Cd accumulation in the liver. Furthermore, the Cd concentration in the follicle walls of the ovary increased and was 13- to 52-fold higher than in the follicle yolks. An additional experiment was conducted in order to estimate whether hatching success is affected by the Cd in the laid eggs of Cd-injected laying hens. The ratio of hatching success in the 0.3 or 1.2 μg Cd/egg-injected groups was similar to that in the saline-injected group, indicating that a small amount of Cd in the eggs might exert no marked influence on the hatching success. In conclusion, Cd transfer from laying hen to eggs was restricted after the maternal bird was exposed to Cd. Furthermore, Cd accumulates in the follicle walls of ovary. These results suggest that the follicle walls might play a role in protecting the follicle yolks against Cd toxicity.

ISSN:0098-4108    

DOI:10.1080/00984109708984008

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The elimination offi-hexachlorocyclohexane ($-HCH) in humans was investigated in a group of 40 former workers of a lindane-producing plant by analyzing at least 2 blood specimens (3 specimens in 3 workers) from different time points. Assuming a first-order kinetic model for excretion, the median half-life of$-HCH is 7.2 yr calculated by concentrations in whole blood and 7.6 yr calculated by concentrations in extractable lipids. In univariate analyses an influence of age, percent body fat, and liver disease (additionally in whole blood an influence of contents of extractable lipids) on clearance was observed. All factors show a positive correlation with half-life. According to a multiple regression model, influence of percent body fat calculated according to Deurenberg et al. (1991) is an important covariate in the description of the variations of the clearance rate (calculated on the basis of extractable lipids) of$-HCH. The data support the assumption of first-order kinetics.

ISSN:0098-4108    

DOI:10.1080/00984109708984009

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The extensive international use oforganophosphorus compounds (OP) results in numerous acute intoxications each year. OPs inhibit acetylcholinesterase, the enzyme responsible for breaking down the neurotransmitter acetylcholine. The World Health Organization recognizes cholinesterase (ChE) biomonitoring as a preventive measure against OP overexposure. The aim of this study was to determine if dermal OP contamination could interfere with current field ChE biomonitoring assays, which use a fingerstick blood sample. In this study we also sought to determine if high levels of a plasma enzyme, A-esterase, could protect ChE from inhibition by hydrolyzing environmentally generated oxons potentially present in a fingerstick sample. A heparinized venous blood sample was collected from a volunteer. Erythrocyte acetylcholinesterase (AChE) and plasma butyrylcholinesterase (PChE) activities were measured using a field-based colorimetric cholinesterase kit. ChE dose-response curves were constructed by allowing 10-ul blood samples to contact environmentally realistic levels of OP thioate and oxon for 10 s. An inhibition threshold could not be established for PChE when exposed to oxon within the time necessary to perform a fingerstick analysis. AChE was also inhibited by trace amounts of oxon consistent with previously reported environmental levels. These findings suggest that the reliability of field-based biomonitoring results is limited if OP residues remain on a skin surface at the time of sample collection. A-esterase's role in protecting ChE activity was investigated using capillary and venous blood from 30 unexposed individuals. Baseline ChE activities were measured, as were individual A-esterase activities using paraoxon, diazoxon, and phenyl-acetate as substrates. Results were then compared to ChE activities measured after 10 s of contact with an environmentally realistic amount of Of, containing 1 % oxon. Both ChE activities were significantly inhibited, with capillary values being significantly more inhibited than their venous counterparts. ,However, no protective effect could be associated between the degree of A-esterase activity and the subsequent level of ChE inhibition observed in an individual's blood. These results suggest that ( I ) if there is any uncertainty about O f skin contamination, venous blood would be a more appropriate specimen to employ when using field ChE biomonitoring kits-it is collected in larger volumes and has essentially no direct contact to dermal surfaces; and (2) A-esterase activity demonstrates no protective effect against ChE inhibition upon a blood droplet's brief contact with an O f residue containing traces of oxon.

ISSN:0098-4108    

DOI:10.1080/00984109708984010

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Polychlorinated biphenyls (PCBs) and related halogenated hydrocarbons bioaccumulate to high concentrations in top predators, such as raptorial birds, yet little is known of PCB toxicity to such species. This study explored several aspects of both the acute and chronic response of American kestrels (Falco sparverius) to three purified PCB congeners and a commercial mixture, Aroclor 1254, and compared the response to that of the Japanese quail (Coturnix c. japonica), a more studied species known to be PCB sensitive. In one experiment, adult female birds were given single oral doses of either Aroclor 1254, 3,3' ,4,4' -TCB (PCB 77, IUF'AC nomenclature), 3,3' ,4,4' ,5-PCB (PCB 126) or 2,2' ,4,4' ,5,5' -HCB (PCB 153) and sacrificed after 5 d. In kestrels, neither the pure compounds nor the mixture affected hepatic or renal porphyrin levels. There was slight but significant hepatic and renal ethoxyresorufin O-deethylase (EROD) induction in birds dosed with PCBs 77 and 126. A cytochrome P-4501A (CYP1A) cross-reactive protein was detected in liver and kidney of kestrels given PCBs 77 and 126, but not in Aroclor 1254-dosed birds. In quail, an acute dose of Aroclor 1254 caused significant liver weight increases, hepatic and renal EROD and aminopyrine n-demethylase (APND) induction, and dose-related hepatic and renal porphyria. Quail treated with PCB 126 developed hepatic and renal porphyria; EROD and APND were also induced. Administration of PCB 77 caused only slight induction of hepatic EROD activity. PCB 153 caused some hepatic and renal porphyria and induced EROD to the same degree as PCB 126. A hepatic CYP1A cross-reactive protein was induced about 200-fold in all individual quail that exhibited significant EROD induction and was also induced in kidney of 1 quail given Aroclor 1254. A second experiment examined chronic exposure to Aroclor 1254 by feeding adult females of both species a daily dose of 7 mg/kg/d for 4-, 8-, and 12-wk periods. There were no effects on hepatic porphyrins in kestrels. APND and aldrin epoxidase (AE) were induced; EROD was not induced, although a hepatic CYP1A-like protein was detected in 1 kestrel dosed for 12 wk. Chronic exposure of quail to Aroclor 1254 caused highly significant increases in mean hepatic porphyrin levels and in activity of EROD, APND, and 4-chlorobiphenyl hydroxylase; a CYP1A-like protein was also induced about 200-fold. In both studies, Aroclor 1254 residues accumulated in tissues of both species, but there was no significant relationship between residue levels and effects. In conclusion, adult American kestrels were relatively insensitive to the effects of PCBs, from both acute and chronic exposure, on hepatic and renal porphyrin levels. Although concentrations of a CYPIA-like protein were increased in some kestrels given PCBs, EROD activity was only marginally increased, suggesting that catalytic activity of this protein differed among the two species.

ISSN:0098-4108    

DOI:10.1080/00984109708984011

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The effect of prior ozone (03) exposure on airway hyperresponsiveness and inflammation induced by trimellitic anhydride (IMA) has been investigated in TMA-sensitized guinea pigs. Airway responsiveness was measured as the concentration of acetylcholine needed to increase baseline lung resistance (RL) by 300% (PC300). Ozone (3 ppm for 3 h) caused an increase in -log PC300 at 1 h after exposure, with return of-log PC300 to control levels at 8 h. Ozone also increased baseline RL at 8 h. TMA challenge increase -log PC300 in TMA-sensitized guinea pigs at8h after challenge from 3.85 ± 0.09 to 4.11 ± 0.09. Ozone exposure prior to TMA challenge prevented the induction of airway hyperresponsiveness with a mean -log PC300 of 3.51 ± 0.20, which was not different from that of control TMA-sensitized group. Baseline RL was significantly higher in ozone-pretreated animals after TMA challenge when compared to those of either control or challenged with TMA alone. Ozone had no effect on TMA challenge-induced BAL eosinophilia and neutrophilia. We conclude that a single exposure to ozone inhibits the increase in airway responsiveness but increases the bronchoconstrictor response induced by TMA in TMA-sensitized guinea pigs; however, the inflammatory airway response to TMA is unchanged by preexposure to ozone.

ISSN:0098-4108    

DOI:10.1080/00984109708984012

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Furazolidone is an antimicrobial compound used in human and veterinary medicine. The aim of this investigation was to determine its genotoxic capacity in vitro and in vivo. We used the human lymphocyte culture system to detect the effect of 2.0, 4.0, 6.0, 8.0, or 10.0 pg/ml, and the mouse bone marrow assay to determine the effect of 8.6, 30.0, or 75.0 mg/kg furazolidone. In both systems we determined the frequency of sister-chromatid exchanges (SCE), the cell proliferation kinetics (CPK), and the mitotic index (Ml). The in vitro results showed a significant SCE increase starting from the second dose tested and a CPK and Ml decrease starting from the third dose. The in vivo results showed a SCE increase with the two high doses tested, but no significant modification was found in the CPK and Ml with the three doses tested in the experiment.

ISSN:0098-4108    

DOI:10.1080/00984109708984013

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor