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Biomedical subjects

R G Ames

Publications and source records attributed to R G Ames.

At least 19 recordsLinked to original sources
PubMed1995

Mortality following cotton defoliation: San Joaquin Valley, California, 1970-1990.

A proportional mortality study comparing the cotton-growing areas of the San Joaquin Valley with the rest of the State of California was performed by the Office of Environmental Health Hazard Assessment as a continuation of earlier studies related to mercaptan-releasing pesticides. This mortality study found a pattern of increased proportion of "respiratory causes" mortality (ICD codes 460-519), statistically significant at less than the .05 probability level, for 15 of 21 years between 1970 and 1990, for the time period during and immediately following cotton defoliation. Defoliants which have the potential to produce acute symptoms include DEF and Folex, both of which release odorous butyl mercaptan gas as a degradation product. This paper tests the hypothesis that exposure to cotton defoliant breakdown products may be associated with a disproportionate increase in mortality. Prediction of the mortality proportions by pounds of DEF and Folex used was not statistically significant in the unadjusted models or in models adjusted for air pollution variables. One air pollution adjustment factor, total suspended particulates, was a statistically significant independent mortality proportion predictor. This finding suggests that total suspended particulates, not defoliants, may be related to mortality differentials during defoliation season. Possible confounding by demographic variation of the counties was not controlled in the analysis.

Air Pollutants↗
PubMed1994

Carpal tunnel syndrome among grocery store workers.

The California Department of Health Services evaluated carpal tunnel syndrome (CTS), a median nerve entrapment condition associated with forceful and repetitive wrist motion, among grocery store workers at a large California supermarket where a CTS cluster had been reported. Forceful and repetitive wrist motion was measured, in three exposure levels, through a job classification scheme based upon type of work tasks and average time per week spent performing these tasks. A medical questionnaire and measurements of median sensory nerve conduction were used to measure CTS. CTS prevalence was 23% based upon a sample of 56 participants drawn from a workforce of 69 employees. A relative risk of 8.3 (95% confidence interval 2.6-26.4) for a history of CTS-like symptoms between the high and low exposure level groups held up after adjustment for the potential confounders of age, sex, alcohol consumption, and high-risk medical history. It was concluded that the basic principles of good ergonomic design should be used to prevent or diminish the risk of musculoskeletal injury in the workplace.

Adult↗
PubMed1994

Chronic neurological sequelae to organophosphate pesticide poisoning.

OBJECTIVES: This work was undertaken to determine whether there are any chronic neurological sequelae to acute organophosphate pesticide poisoning. METHODS: California surveillance data were used in a study of neurological function among 128 men poisoned by organophosphate pesticides in California from 1982 to 1990 and 90 referents. Tests included a neurological physical examination, 5 nerve conduction tests, 2 vibrotactile sensitivity tests, 10 neurobehavioral tests, and 1 postural sway test. RESULTS: After correcting for confounding, the poisoned group performed significantly worse than the referent group on two neurobehavioral tests (sustained visual attention and mood scales). When the data were restricted to men with documented cholinesterase inhibition (n = 83) or to men who had been hospitalized (n = 36), the poisoned subjects also showed significantly worse vibrotactile sensitivity of finger and toe. Significant trends of increased impairment were found with increased days of disability on a wide spectrum of tests of both central and peripheral nerve function. CONCLUSIONS: While these findings are limited by low response rates and by small sample sizes for specific pesticides, this study was based on a large surveillance database and is the largest study to date of the chronic effects of organophosphate pesticide poisoning. The evidence of some long-term effects of poisoning is consistent with two prior studies.

Adolescent↗
PubMed1991

Investigation of a fatality among parathion applicators in California.

Staff of the California Department of Health Services investigated the death of a parathion applicator in California that was thought to be pesticide-related. A crew of eleven workers (including six sprayers, three mixer/loaders, one mixer/sprayer and one foreman) had been applying 0.125% parathion spray to almond orchards for approximately three weeks. On the day of the fatality, a sprayer rapidly developed symptoms of salivation, sweating, and convulsions after a half-day of work. Despite aggressive medical treatment, the worker died within one hour of his initial symptoms. Significant laboratory results for the decreased case included: parathion residue on the inner and outer garments worn by the worker, parathion in the post-mortem gastric contents, and elevated urinary metabolites consistent with acute parathion intoxication. Interviews with the work crew revealed that three of the 10 workers had complaints of headaches, vomiting, and/or sore throat; yet, subsequent plasma and red cell cholinesterase tests of the co-workers did not show any significant depressions in comparison with pre-season baseline values. This worker death is consistent with prior reports of parathion-related sprayer/applicator intoxications and is the first worker-related parathion death in California since 1972. Substitution of pesticides with less toxic active ingredients or the elimination of parathion is recommended.

Adult↗
PubMed1991

Multiple-episode conjunctivitis outbreak among workers at a nut-processing facility.

Workers in a Kern County almond and pistachio nut-packing facility sought medical care for eye irritation (conjunctivitis) on three separate occasions in 1987 and 1988. These incidents were investigated by the California Department of Health Services to identify the agent responsible for the eye irritation outbreak and to suggest possible remediation. The eye irritation incidents involved only the 30 to 35 workers in the preprocessor shed. Each of the three eye irritation incidents followed phosphine (Gastoxin) fumigation. Four plausible hypotheses were tested as explanations of the outbreaks of eye irritation: phosphine gas exposure, ammonia gas exposure, aluminum hydroxide dust exposure, and almond cleaning and hulling dust exposure, with or without contamination by propargite residues (Omite 6-E). None of these hypotheses received enough consistent support to be viewed as a probable cause for the illness outbreaks.

Adult↗
PubMed1989

Cholinesterase activity depression among California agricultural pesticide applicators.

Cholinesterase activity measurements for 542 California agricultural pesticide applicators under medical supervision during the first 9 months of 1985 were analyzed. Twenty-six workers, 4.8% of the sample, had cholinesterase values at or below the California threshold values for removal from continued exposure to cholinesterase-inhibiting pesticides (60% of baseline for red blood cell cholinesterase and 50% of baseline for plasma cholinesterase activity). Eight of these 26 workers, 31.5%, had pesticide-related illnesses. Pesticides most frequently associated with cholinesterase depressions exceeding California threshold values included mevinphos (Phosdrin), oxydemeton methyl (Metasystox-R), methomyl (Lannate), and acephate (Orthene); these pesticides included organophosphates in toxicity categories I and II and one carbamate in toxicity category I.

Agricultural Workers' Diseases↗
PubMed1989

Health symptoms and occupational exposure to flea control products among California pet handlers.

A statewide telephone survey of health symptoms associated with occupational exposure to flea control products among California pet handlers was conducted in 1987 following several reports of ill workers. The 696 employees interviewed worked at veterinary clinics, pet stores, pet boarding kennels, pet grooming shops, and animal control facilities. Symptom incidence and frequency and flea control product use were reported for the 3 months prior to interview. Eye and skin symptoms and unusual tiredness were elevated among workers who applied flea control products to animals or facilities. After adjustment for potential confounders, these symptoms were elevated 64% to 258% among applicators as compared to nonapplicators who worked in the same facilities. Workers who used protective clothing and equipment and followed some protective work practices were not at increased symptom risk. Some specific flea control active ingredients and application procedures were associated with respiratory effects and with symptoms suggesting systemic pesticide poisoning.

Animals↗
PubMed1989

Protecting agricultural applicators from over-exposure to cholinesterase-inhibiting pesticides: perspectives from the California programme.

California's requirement for medical supervision of applicators regularly handling Toxicity Category I and II organophosphate and carbamate cholinesterase-inhibiting pesticides is examined from a policy perspective by the California Department of Health Services (CDHS). Changes to increase the effectiveness of medical supervision and solutions to a number of practical implementation problems are discussed, including the pesticides which should be monitored, the use of individual cholinesterase baselines, the enzymes to be measured, and the frequency of cholinesterase testing.

Agricultural Workers' Diseases↗
PubMed1987

Respiratory health as a predictor of questionnaire return in a sample of United States underground coalminers.

A logistic model was used to analyse questionnaire return in a postal survey of 311 coalminers who had left their place of employment between 1977 and 1982. Three measures of respiratory health, obstruction, restriction, and presence of chronic bronchitis symptoms, were included in the model as predictors together with the possibly confounding factors of age, education, and marital and smoking status. Age was positively associated with questionnaire return (p less than 0.001). Speed of return, and whether the return was in response to a prompt, were not predicted by either the respiratory health measures or any of the other possibly confounding variables.

Adult↗
PubMed1987

Outbreak of Omite-CR-induced dermatitis among orange pickers in Tulare County, California.

An outbreak of dermatitis cases among 198 orange pickers employed by a Tulare County, California, packinghouse was investigated. Dermatitis was contracted by 114 (58%) of the 198 workers exposed when Omite-CR-treated fields were harvested. The dermatitis occurred predominantly in the exposed areas of the neck and chest. A dose-response association with dermatitis was suggested for Omite-CR exposure, but not for Carzol, Omite-CR + Carzol, or other pesticides. Because no violations of pesticide preharvest intervals or application rates were found, it appears that residue degradation was not given adequate consideration in the registration of Omite-CR, thus compromising the safety of the worker.

Agricultural Workers' Diseases↗
PubMed1985

Respiratory predictors of disability days: a five year prospective study of U.S. coal miners.

A 5-year prospective analysis tests the hypothesis that coal miners who have impaired respiratory health also experience greater numbers of disability days due to occupational injury. Occupational and respiratory health information collected for the period 1977 through 1981 by the National Institute for Occupational Safety and Health (NIOSH) on 1,118 U.S. underground coal miners was linked to coal miner injury records collected under a mandatory reporting system by the Mine Safety and Health Administration (MSHA). Respiratory impairment, based on spirometric measures, and a questionnaire measure of chronic bronchitis symptoms, after adjustment for cigarette smoking and total years of underground mining, did not provide statistically significant prediction of average disability days. In addition, respiratory impairment did not predict the number of episodes of occupational injuries resulting in days lost from work.

Absenteeism↗
PubMed1985

Smoking cessation among coal miners as predicted by baseline respiratory function and symptoms: a 5-year prospective study.

A prospective analysis was used to test whether respiratory impairment or the presence of respiratory symptoms predicts 5-year cigarette smoking cessation in a sample of 1,118 U.S. white, male, underground coal miners. Miners were examined in 1977 and re-examined in 1982 by NIOSH, and all miners with test abnormalities were so informed by letter. Respiratory impairment was measured by an index of airways obstruction combining the spirometric measures of Forced Vital Capacity (FVC) and Forced Expiratory Volume in 1 sec (FEV1). Bronchitis symptoms were measured by an index that combined chronic cough (3+ months/year) and chronic phlegm (3 + months/year). Among these coal miners, the presence of chronic respiratory symptoms initially was inversely associated with cigarette smoking cessation. Respiratory impairment, however, was positively associated with cigarette smoking cessation but did not reach statistical significance.

Bronchitis↗
PubMed1985

Leukemia risk among U.S. white male coal miners. A case-control study.

The relevance of occupational exposure to electrical and magnetic fields (EMF) in the etiology of leukemia has been raised in several studies. Underground coal miners represent an occupational group with situationally determined EMF exposure, as high-voltage power distribution lines are strung overhead in the mines and converters and step-down transformers provide power to mining equipment. Risk in occupational exposure to EMF was examined in a case-control study of 40 leukemia decedents and 160 control subjects who died of causes other than cancer or accident and who were matched on age at death. The control subjects were selected from a group of 6,066 persons whose deaths were reported in four National Institute for Occupational Safety and Health cohort mortality follow-up studies. Based on these data, 25 or more years of underground mining, a surrogate of EMF exposure, was found to pose a statistically significant risk for leukemia (International Classification of Diseases [ICD] codes 204 through 207, eighth revision), myelogenous leukemia (ICD 205), and chronic lymphocytic leukemia (CLL) (ICD 204.1). Accumulative exposure to chemical agents probably poses a risk for acute myelogenous leukemia, although this relationship fell short of being statistically significant. Although CLL has not previously been attributed to environmental agents, these data suggest a possible CLL risk from prolonged exposure to EMF.

Adult↗
PubMed1984

Mutagenicity of tobacco snuff: possible health implications for coal miners.

Mutagenicity of tobacco snuff extracts was studied using the Ames Salmonella/microsome assay system. No mutagenic activity was found for tobacco snuff extracts without S9 activation. However, mutagenic substances were formed from tobacco snuff extracts in an acidic environment. The mutagenic substances induced predominantly frameshift mutations and were direct-acting mutagens. Mutagenic activity of tobacco snuff extracts was enhanced in the presence of coal-dust extracts at low pH. Since tobacco snuff has been used by some coal miners to substitute for cigarettes, a possible risk for gastric cancer induction among coal miners is proposed.

Animals↗