摘要:

This study was intended to characterize more fully the distribution of serum concentrations of 16 pesticide residues with regard to key demographic and seasonal variables in a subsample of persons from the Second National Health and Nutrition Examination Survey between the ages of 12 and 74 yr old. Blood sera in 2‐ml aliquots were analyzed, and the results were confirmed for 5994 persons. Almost all participants (99.5%) hadp,p‘‐dichlorodiphenyldichloroethylene (p,p‘‐DDE) concentrations ≥1 ppb, ranging as high as 378.6 ppb. For the other pesticide residues, only β‐benzene hexachloride (β‐BHC) (quantified in 17.2% of the sera), dieldrin (10.6%), and another DDT‐related residue,p,p‘‐dichlorodiphenyltrichloroethane (p,p’‐DDT) (35.7%) were found at quantifiable levels in more than 10% of the serum specimens. Of the remaining analytes, hexachlorobenzene (HCB), trans‐nonachlor (TNC), and heptachlor epoxide (HE) were found at quantifiable concentrations in 1–10% of the specimens, whereaso,p’‐DDT,o,p‘‐DDE,p,p’‐DDD, mirex, α‐BHC, γ‐BHC, heptachlor, δ‐BHC, and aldrin were found in <1% of the serum specimens. Results showed that increasing age, residing on a farm, or being a male conferred increased risks of exposure to most of the pesticide residues, independent of all other demographic and seasonal factors. In a pattern less consistent across the different pesticide residues and for fewer of the pesticides, persons who lived below the national poverty level, were nonwhite, resided in the South or West, or were examined in the spring or winter also seemed to have an increased likelihood of having quantifiable serum levels.

ISSN:0098-4108    

DOI:10.1080/15287398909531312

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

An examination was made of the relative efficacies of 2,3‐dimercapto‐1‐propanol (BAL) and three diesters {[CH(SH)COOR]2; DMDMS, R=CH3; DEDMS, R=C2H5; and Di‐PDMS, R=CH(CH3)2} of meso‐2,3‐dimercaptosuccinic acid (DMSA) in mobilizing freshly injected lead from mice. These diesters, like BAL, reduced the lead levels resulting from freshly injected lead in both the soft tissues (liver, kidneys, spleen, and brain) and the bone (tibia). After treatment with the dimethyl (DMDMS), the diethyl (DEDMS), and the diisopropyl (Di‐PDMS) esters the lead content of each of the organs was significantly less than that present in the untreated controls. Each of the diesters reduced lead levels in the kidneys, liver, and spleen significantly below those levels found after BAL treatment. The action of the diesters in reducing brain lead levels was comparable to that of BAL. Di‐PDMS was the most effective of these compounds and was significantly superior to BAL. Each of the esters was also significantly more effective than BAL in reducing the whole body level of lead.

ISSN:0098-4108    

DOI:10.1080/15287398909531313

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Although silicosis has been studied extensively, the mechanism is still not fully understood. Experiments do provide evidence that the actions of unique properties of silica surface on the cell membrane are the starting point of silicotic processes. This paper summarizes literature on chemical properties of silica surface, and the effect of particle size on silica toxicity. This paper also discusses the ways in which silica dusts are thought to interact with the cell membrane, with emphasis on freshness, hydrogen bonding, and free‐radical interactions.

ISSN:0098-4108    

DOI:10.1080/15287398909531314

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Groups of adult male rats (5 rats per group), either normotensive (WKY) or spontaneously hypertensive (SHR), were exposed by inhalation to 0, 821, and 3018 ppm styrene, 5 h per day for 3 consecutive days. After the exposure, the urines were collected for 24 h and the animals were then sacrificed. The various biochemical parameters of hepatorenal toxicity due to styrene as well as its urinary metabolites were measured. Hepatotoxicity due to styrene was not further increased at any exposure level due to hypertension. However, repeated exposure of SHR rats to 3018 ppm styrene showed significant increases in the urinary excretion of γ‐glutamyl transpeptidase, proteins, and volume of urine, compared to WKY treated rats, whereas no such changes were observed due to repeated exposure to 821 ppm styrene. Studies of in vivo metabolism of styrene at higher exposure level showed significant decrease in the urinary excretion of mandelic, phenylglyoxylic, and hippuric acids in SHR rats compared to WKY‐treated rats, suggesting an inhibition of deactivation of styrene reactive intermediate involving the epoxide hydrase pathway due to hypertension. At the same time, a significant increase in the urinary excretion of a potential nephrotoxic metabolite of styrene (e.g., mercapturates or thioethers) was observed in SHR‐treated rats when compared to WKY‐treated rats. These results demonstrate that spontaneous hypertension has the potential to further increase the nephrotoxicity due to repeated exposure to styrene, and the metabolism of styrene plays an important role in modifying such toxicity in the hypertensive state.

ISSN:0098-4108    

DOI:10.1080/15287398909531315

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The influence of the anticarcinogen dehydroepiandrosterone (DHEA) on the metabolism and macromolecular interactions of the potent hepatocarcinogen dimethylnitrosamine (NDMA) was investigated. Male Sprague‐Dawley rats (2–3 mo old) were fed DHEA for 14 d at a dietary level of 0.8%. Compared with pair‐fed controls, the liver weights of the DHEA‐treated animals increased significantly (11.7 vs. 7.1 g) with increases, per total liver, in proteins including those of cytosol and microsomes as well as cytochromes P‐450 andb5. DNA content of the liver, however, remained constant. Five hours after a single ip dose of [14C]NDMA (30 mg/kg body wt, 42 μCi/rat) DNA methylation was reduced in the DHEA‐fed animals as measured by 7‐methyl‐ andO6‐methylguanine per mole of guanine, by 39 and 31%, respectively. The rate of NDMA metabolism was slightly higher in the DHEA‐fed rats as determined in vivo by the exhalation of14CO2and by the declining concentrations of NDMA in the blood. The incorporation of radioactivity from [14C]NDMA into hepatic proteins in vivo was greater (2.1‐fold) in the DHEA‐fed rats.

ISSN:0098-4108    

DOI:10.1080/15287398909531316

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

This report describes studies designed to assess the immunomodulatory effects associated with the consumption of coho salmon containing halogenated aromatic hydrocarbons (HAHs) and other compounds naturally bioaccumulated from Lake Ontario. Diets containing 33% coho salmon from Lake Ontario or the Pacific Ocean were fed to juvenile C57BI/6 mice for 2–4 mo. Following 60 d, the mice that consumed Lake Ontario salmon had reduced IgM, IgG, and IgA plaque‐forming cell responses to sheep erythrocytes. No changes were observed in total numbers of spleen lymphocytes, total T‐lymphocytes or T‐lymphocyte subsets as determined by flow cytometry. Cellular immunity, assessed by the cytotoxic T‐lymphocyte response to allogeneic tumor target cells, was not altered following dietary exposure to Lake Ontario coho salmon for 4 mo. The observed humoral immunomodulation correlated with elevated PCB levels in the Lake Ontario salmon diets. The levels of pollutants such as mercury, tin compounds and other metals, PCDDs, and PCDFs were not examined.

ISSN:0098-4108    

DOI:10.1080/15287398909531317

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Inhaled fly ash may be leached by lung fluids, making potentially toxic trace elements in the fly ash bioavailable. We studied the composition and morphology of fly ash particles recovered from lungs of rats exposed to fly ash from a power plant burning pulverized eastern coal. Animals were sacrificed 1, 3, 6, and 12 mo after the commencement of the 4‐wk exposures. Particles isolated from lungs of exposed animals, control fly ash samples, and samples recovered from control lungs spiked with fly ash were characterized by computer‐controlled scanning electron microscopy (CCSEM) and thin window energy dispersive X‐ray spectroscopy (EDS). EDS spectra of fly ash and ashed lung residues were distinct. Thus, fly ash particles could be distinguished from ashed lung residues. A majority of the fly ash particles recovered from lungs of exposed animals had similar morphology and composition to the exposure material. However, the number of silicon‐rich particles decreased with time. After 6 mo, about 1% by number of the particles had been transformed, producing numerous “needles” associated with residues of fly ash particles. Particles that looked like diatoms were observed. This demonstrated that the sample preparation procedures used did not destroy delicate structures. Fly ash particles from a spiked control lung subjected to the same separation procedures did not have these structures. The structures may be the result of leaching of particles by lung fluids, which suggests that the glassy matrix components of fly ash particles may be bioavailable.

ISSN:0098-4108    

DOI:10.1080/15287398909531318

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

A simple, flexible, low‐cost image analyzer system is presented for determination of the total number of cells and the number of viable cells in monolayers of nonconfluent cells. Viable cells were identified and counted using an immunofluorescence method using fluorescein diacetate. Alveolar macrophages from rabbits were used. The different possible counting procedures that could be performed are analyzed. The precision of the method of estimating the cell numbers is indicated by a coefficient of variation of 5%. The experimental procedure is given for a short‐term toxicological in vitro test in which the semiautomatic counting procedures can be performed within 1.5 h.

ISSN:0098-4108    

DOI:10.1080/15287398909531319

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

By using an image‐analyzer system, toxicological effects of different substances on nonconfluent cells in monolayers can be assessed. The total number of cells and the number of viable cells are semiautomatically counted. Fluorescein diacetate is used as the viability marker. The method was tested by using monolayers of alveolar macrophages from rabbits exposed to manganese dioxide particles. A dose‐response curve was obtained from a series of experiments in which the response at a certain dose level can be obtained from cell‐counting procedures of the duration of 1 h. The method can be used as a short‐term test, testing potentially toxic substances including cytostatic drugs where the viability should be determined. Another example is further given of the use of this technique. The results obtained from it are compared with estimates of the percentage of viable cells assessed by extracellular lactate dehydrogenase from nonexposed and manganese dioxide particle‐exposed monolayers of rabbit alveolar macrophages. The two methods both account well for the theoretical relation when the lactate dehydrogenase activity values are corrected for an inactivation of this enzyme with time.

ISSN:0098-4108    

DOI:10.1080/15287398909531320

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The image‐analyzing system described in the companion paper (Thorén and Lanke, 1989) is considered from a statistical point of view. Special attention is given to the following applications: simple cell counts, viability estimation, and toxicity estimation. Different estimators are considered, their variances are discussed, and it is shown how to compute standard errors in different situations.

ISSN:0098-4108    

DOI:10.1080/15287398909531321

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor