Chronic neurologic sequelae to cholinesterase inhibition among agricultural pesticide applicators.

To test the hypothesis that chronic neurologic sequelae are associated with cholinesterase depression short of frank organophosphate poisoning, we compared 45 male subjects who had a history of moderate cholinesterase inhibition with 90 male subjects who had neither past cholinesterase inhibition nor current pesticide exposure. Cholinesterase-inhibited subjects were defined as having had a history of (a) red blood cell cholinesterase at 70% or less of baseline or (b) plasma cholinesterase at 60% or less of baseline absent symptoms of frank poisoning. In the subject comparison evaluation, only 1 of 27 neurologic tests (i.e., serial digit performance) was significant statistically, but it was opposite of the direction hypothesized. In a companion study for which the same battery of neurologic tests and the same subjects were used, neurologic sequelae were related to high exposures among subjects who sought treatment for organophosphate poisoning. The data in the current study, in which the subjects experienced lower exposures short of frank poisoning, provide some evidence that preventing acute organophosphate poisoning also prevents neurologic sequelae.

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.

Irritative and systemic symptoms following exposure to Microban disinfectant through a school ventilation system.

Microban, a pesticide not registered in California, was sprayed into an operating heating/ventilation/air conditioning (HVAC) unit at an elementary school in San Francisco, California. This incident occurred on Monday, September 28, 1992, while 396 students and 67 staff members were in the school. The Microban formulation used contains ortho-phenylphenol (0.21%), a quaternary ammonium complex (di-isobutylphenoxy-ethoxy-ethyldimethylbenzyl-ammonium chloride, 0.69%), and bromine (0.04%). This study of the health effects of Microban mist exposure on the school staff was conducted as a result of legal and toxicological concerns. California registration for this formulation had been denied because of inadequate data and because there were concerns about inhalation toxicity in test animals. Predicted health effects from short-duration exposure to Microban are primarily skin and mucous membrane irritation. A self-administered health symptom questionnaire that covered the work week following the evacuation was used to determine a pattern of higher symptom risks for those who were at work on Monday and who reported that they felt they were exposed to a chemical. Symptoms, which were generally consistent with exposure to an irritating chemical, were elevated on Monday and Tuesday; the symptoms normalized by the end of the work week. No additional health effects were detected following application of chlorpyrifos to cracks and crevices for ant control 2 d following the Microban incident. Strict supervision and coordination of pesticide use in public schools are recommended to prevent adverse health effects and emotional trauma in students and staff.

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.

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.

Community exposure to a paraquat drift.

A mixture of paraquat and water was applied, by helicopter, to agricultural fields near a residential community and near an associated commercial complex. Drift from the application passed directly over the community, which resulted in resident complaints to the local county agricultural department. A community survey was undertaken to determine what health consequences, if any, resulted from the drift. A comparison of 2-wk self-reported symptom rates between the exposed community and three historical control communities indicated that 10 symptoms were elevated significantly at p < .05: cough, diarrhea, eye irritation, headache, nausea, rhinitis, throat irritation, trouble breathing, unusual tiredness, and wheezing. An internal comparison, which predicted symptom rates by an index of paraquat exposure (smelling an unusual odor in the prior 2-wk period), indicated fever (relative risk [RR] = 11.97) and nausea (RR = 3.75) to have elevated relative risks. Odor perception also predicted the report of a greater than the average number of symptoms. Based upon these findings, it was concluded that these residents probably did experience an increase in health symptoms from the drift. It is recommended that paraquat not be sprayed near residential communities.

Acute health effects from community exposure to N-propyl mercaptan from an ethoprop (Mocap)-treated potato field in Siskiyou County, California.

A 145-acre potato field adjacent to Dorris, California, was treated with ethoprop (Mocap) to control nematodes. Ethoprop releases n-propyl mercaptan, a highly odorous and volatile gas, as a degradation product of the pesticide. An epidemiological investigation was undertaken by the California Department of Health Services because community residents sought medical attention for odor-related illness. Elevated health effects were found among those who reported smelling a strong odor (n-propyl mercaptan has a characteristic onion-like odor). In a logistic regression analysis, the most highly elevated 6-wk health effect incidence risks, expressed as odds ratios (ORs) adjusted for age, sex, and current cigarette smoking status, were for headache (OR = 5.08), diarrhea (OR = 3.80), runny nose (OR = 5.31), sore throat (OR = 3.58), burning/itching eyes (OR = 5.64), fever (OR = 3.59), hay fever attacks (OR = 3.50), and asthma attacks (OR = 6.0). Based upon these elevated health effects, it is recommended that human exposures to n-propyl mercaptan be minimized to the extent practicable.

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.

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.

Acute health effects of community exposure to cotton defoliants.

In September and October of 1987, the California Department of Health Services responded to community complaints by investigating the relationship between health symptoms and community exposure to cotton defoliants. Symptoms experienced during the 1987 cotton defoliation season by 232 residents of cotton-growing communities were compared with symptoms of 175 residents of non-cotton-growing agricultural communities. Fatigue, eye irritation, rhinitis, throat irritation, nausea, and diarrhea were statistically elevated in rates adjusted for age, sex, and race and were reported 60-100% more frequently by respondents living or working near sprayed cotton fields than by the comparison group. These symptom rate elevations were substantially unchanged even after adjustment by a model of potentially confounding factors that included cigarette smoking, chronic illness, and some additional demographic variables.

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.

Occupational illnesses from cholinesterase-inhibiting pesticides among agricultural applicators in California, 1982-1985.

California pesticide illness investigation reports involving toxicity category I or II organophosphate and carbamate pesticide exposures among agricultural pesticide applicators were reviewed for the years 1982-1985. The pesticides associated with each illness were recorded, and the exposures were classified as chronic, short-term, or accidental. Illnesses were associated with a range of pesticides, including both organophosphates and carbamates in both toxicity categories I and II. Approximately 19% of the illnesses were due to accidents. Overall, the analysis identified a need for improving occupational health surveillance and the regulations governing worker health and safety.

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.

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.

Effect of chlorine dioxide water disinfection on hematologic and serum parameters of renal dialysis patients.

A study of the blood chemistry parameters of 20 renal dialysis patients was undertaken when a local water district introduced chlorine dioxide (CIO2) as a disinfectant at the filtration plant headworks for 12 months without informing the renal dialysis clinic in the area of this potentially adverse change. Due to data limitations, including changes in clinical laboratories and lack of pre-exposure data for some patients, the analysis was focused on 17 patients for whom data was produced by the same clinical laboratory, for 3 months of pre-exposure and 1 month of exposure. Least-squares means of each parameter by CIO2 levels of 0.0 and 1.0 mg/L at the treatment plant were adjusted for age, sex, and creatinine. Water purification at the clinic included passing the water through granular activated carbon, filtration by 5-mu filters, and the use of reverse osmosis. Chlorination products measured at the clinic after this purification and prior to preparation of the dialysate consisted only of chlorite at the 0.02-0.08 mg/L level. No evidence of CIO2-induced anemia was found, nor were any other biologically significant responses observed. Study limitations include several potentially important hematologic parameters which were not measured, the small sample size, and three clinical laboratory changes.

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.

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.