Different effects of pretreatment with 2-diethylaminoethyl-2,2-diphenylvalerate on the mouse liver polysomal disaggregation by dimethylnitrosamine and lasiocarpine.
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Biomedical subjects
Publications and source records attributed to V F Garry.
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Because tool and die workers are exposed to a number of potentially genotoxic agents, including mutagenic metals, polyaromatic hydrocarbons, and nitrosamines, and may be at increased cancer risk, the present study was undertaken to test whether chromosomal damage in peripheral blood cells is associated with work in the tool and die industry. Lymphocyte cultures were established from 27 tool and die fabrication workers from one manufacturing plant who had worked in the trade for more than 15 years. 15 of these workers also had some form of malignancy at the time of the study, but had not been treated with radiation or chemotherapies that could themselves induce chromosomal damage. The frequencies of chromosomal aberrations and sister-chromatid exchanges (SCEs) were measured in workers and the data compared with those of a control group consisting of 7 non-fabrication workers from the same plant and 8 age-matched community controls. In addition, the relative rates of lymphocyte proliferation were estimated for each group by analyzing the percentages of first-, second- and third-division mitotic cells after 72 h of culture. The results of the chromosomal studies show that tool and die workers have significantly increased frequencies of aberrations whether engaged in fabrication work or not, compared to control subjects. The frequency of SCEs and the frequencies of 1st, 2nd and 3rd division figures are not different among the study groups. Among workers who are engaged in fabrication, including those who are cancer patients, the frequency of more complex aberrations (i.e., interstitial deletions and small acentric fragments) is increased. In a five-year follow-up of these workers, 2 of the 13 workers with these aberrations developed some form of colon cancer. Whether the presence of interstitial deletions and small acentric fragments is related to the occupation of these workers, or is tangentially related to the development of cancer, is presently under consideration.
Sister chromatid exchanges (SCE) were studied in peripheral lymphocyte cultures of 13 adult male patients with epilepsy treated chronically with valproate (VPA) and in their matched controls. No statistically significant differences in SCE level were found between the patient and control groups, indicating a lack of mutagenic potential of VPA within the therapeutic dose range.
We surveyed 1,000 randomly selected state-licensed pesticide appliers to improve our understanding of pesticide use and its potential health effects. Participants were stratified by pesticide class (herbicides, insecticides, fungicides, fumigants) to determine potential differences in health characteristics among different pesticide groups. A subset of 60 applicators, divided by pesticide class used, were studied for exposure-related cholinesterase (ChE) depression. ChE depression in excess of 20% was most frequent in fumigant applicators who did enclosed-space application, in addition to other pesticide application procedures (p < .05). Survey data demonstrated that the prevalence of all common chronic diseases considered together was significantly increased (p = .015) in fumigant appliers, compared with all other pesticide use groups. The frequency of chronic lung disease was also significantly increased in the fumigant applier group (p = .027). Curiously, two cases of a rare hematopoietic neoplasm--hairy cell leukemia--were identified in our study group (annual incidence 0.67/100,000 in Minnesota). Whether there is an association between this unique tumor and agricultural work is uncertain, and further study is needed in this regard.
Phenytoin (PHT) has been suspected of having a mutagenic effect with chronic administration, but the existing evidence is equivocal. Contradictory results have been obtained using different testing systems. Sister chromatid exchange (SCE), a sensitive indicator of genotoxic environmental influences, has been used in only a few limited studies of PHT users, with varying results. The present study was designed to evaluate the potential mutagenicity of PHT in a more objective and reliable way than has been done previously. Following careful screening procedures, 16 adult male patients with epilepsy receiving long-term PHT monotherapy and 16 healthy controls were selected for a study of SCE frequencies in peripheral lymphocytes. The patients and controls were matched for sex, age, and smoking habits. Strict exclusionary criteria were observed, including all factors known to affect or suspected of affecting the SCE frequencies. Statistical analyses did not reveal any significant differences between the SCE rates of PHT-treated patients and controls, indicating a lack of PHT mutagenicity as expressed by induction of SCE in adults.
The present report examines the in vitro genotoxicity (micronucleus assay) of herbicides and adjuvants and reports on an in vivo human study on potential endocrine effects of pesticides, including herbicides. Adjuvants are used in conjunction with 2,4-dichlorophenoxy acetic acid (2,4-D) and other herbicides. Earlier pesticide applier survey results (n = 709) show that 59% of the applicators used adjuvants, and the majority of this group used paraffinic oils and/or surfactant mixtures. As a beginning effort to explore the role of adjuvants and herbicides in hormonally based reproductive effects, a prospective, controlled study was performed to analyze blood specimens from three different exposure groups (applicators using herbicides only; applicators using both herbicides and insecticides; and applicators using fumigants in addition to herbicides and insecticides; and a control group composed of other agricultural workers including organic farmers). The applicators and controls were age- and smoking-matched. Study subjects (n = 78) were tested before, during, and after completion of pesticide application season for the effects of pesticide products on hormone levels in the bloodstream. Of the applicator exposure groups examined, only the herbicide group showed significant endocrinologic differences from controls. Free testosterone levels were significantly elevated in post-season measurements (p = 0.032), and follicle-stimulating hormone (FSH) was significantly decreased at the height of the season (p = 0.016) and in the post-season (p = 0.010) as compared to controls. These endocrinologic findings are discussed in terms of their possible relationship to potential endocrine effects of herbicides, herbicide contaminants, and adjuvants. In vitro genotoxicity examination compared four different commercially available surfactant mixtures with 12 different commercial herbicide products, including six different chlorophenoxy herbicides. Only one herbicide yielded a significant dose-response curve. All four adjuvants showed positive dose-response effects. These preliminary data suggest that adjuvants are not inert but are toxicologically active components added to herbicide mixtures. Whether adjuvant toxicant effects are additive or are independent of herbicide effects is poorly understood.
Appliers of pesticides (n = 18) who are exposed to the fumigant phosphine or who have a mixed exposure to other pesticides and phosphine demonstrate a significant increase in chromosome rearrangements in G-banded chromosomes from peripheral blood compared to control subjects (n = 26). Appliers who had discontinued using phosphine for at least 8 months prior to specimen collection (n = 5) do not demonstrate significant increases in chromosome rearrangements compared to controls. Breakpoint analysis of 6,138 metaphases from all subjects demonstrates 196 breaks per 3605 metaphases in exposed subjects and 102 breaks per 2,533 metaphases in control subjects. Bands with significantly more breaks than expected based on band length in all study subjects were 1q32, 3p14, 7p15, and 14q11. Three of these four bands had significantly more breaks than expected in the exposed group, and all four bands had a significant excess of breaks in the control group. There are four bands with a significant excess of breaks in the exposed group and no breaks in the control group; each of these occurs in a known protooncogene region. These are 1p13 (NRAS), 2p23 (NMYC), 14q32 (ELK2), and 21q12 (ETS-2). Most breaks at bands 1p13, 14q32, and 21q22 are associated with chromosome rearrangements and occurred in appliers who have a mixed exposure to phosphine and other pesticides. Cytogenetic abnormalities, i.e., rearrangements and/or deletions involving bands 1p13, 2p23, and 14q32, are associated with non-Hodgkin's lymphoma. We speculate that these findings could relate to the risk of evolution of a neoplastic clone in these workers. Epidemiological studies of similarly exposed workers indicate an excess of non-Hodgkin's lymphoma.