Dennis J. Darcey

Occupational exposure to pesticides increases the risk of incident AD The Cache County Study

Background: Commonly used organophosphate and organochlorine pesticides inhibit acetylcholinesterase at synapses in the somatic, autonomic, and central nervous systems and may therefore have lasting effects on the nervous system. Few studies have examined the relationship of pesticide exposure and risk of dementia or Alzheimer disease (AD). We sought to examine the association of occupational pesticide exposure and the risk of incident dementia and AD in later life. Methods: Residents of the agricultural community of Cache County, UT, who were aged 65 years and older as of January 1995, were invited to participate in the study. At baseline, participants completed detailed occupational history questionnaires that included information about exposures to various types of pesticides. Cognitive status was assessed at baseline and after 3, 7, and 10 years. Standardized methods were used for detection and diagnosis of dementia and AD. Cox proportional hazards survival analyses were used to evaluate the risk of incident dementia and AD associated with pesticide exposure. Results: Among 3,084 enrollees without dementia, more men than women reported pesticide exposure (p < 0.0001). Exposed individuals (n = 572) had more years of education (p < 0.01) but did not differ from others in age. Some 500 individuals developed incident dementia, 344 with AD. After adjustment for baseline age, sex, education, APOE ε4 status, and baseline Modified Mini-Mental State Examination scores, Cox proportional hazards models showed increased risks among pesticide-exposed individuals for all-cause dementia, with hazard ratio (HR) 1.38 and 95% confidence interval (CI) 1.09–1.76, and for AD (HR 1.42, 95% CI 1.06–1.91). The risk of AD associated with organophosphate exposure (HR 1.53, 95% CI 1.05–2.23) was slightly higher than the risk associated with organochlorines (HR 1.49, 95% CI 0.99–2.24), which was nearly significant. Conclusions: Pesticide exposure may increase the risk of dementia and Alzheimer disease in late life.

Clinical findings for residents near a polyurethane foam manufacturing plant.

Abstract Clinical findings for 38 community residents who complained of symptoms they attributed to exposure to air emissions from nearby fiber processing and polyurethane foam manufacturing facilities are reported. Common complaints included headache, mucosal irritation, shortness of breath, chest tightness, and wheezing. Airway hyperreactivity, measured by methacholine challenge, was observed in 8 individuals (22% of those tested), who also reported temporal relationships between exposure to visible emissions or odors and symptoms consistent with environmentally induced asthma. Six individuals (18.2%) had antibodies to at least 1 of the 3 common industrial diisocyanates. The number of individuals with antibodies to diisocyanates, coupled with the absence of other diisocyanate exposure, was highly suggestive of environmental exposure. The findings raised concern that some residents may have become sensitized to toluene diisocyanate.

Hexabromonaphthalene contaminants of polybrominated biphenyls: chemical composition and disposition in the rat

Hexabromonaphthalene (HBN) has been identified as a toxic contaminant of Firemaster BP-6, a mixture of polybrominated biphenyls (PBBs) that is used commercially as a fire retardant and that was responsible for a major public health emergency in Michigan in 1974. Previously reported to be a single compound, the hexabrominated naphthalene derived from direct bromination of naphthalene was here shown by high-field nuclear magnetic resonance (NMR) to be a mixture of two closely related isomers, 1,2,3,4,6,7-HBN and 2,3,4,5,6,7-HBN, in a ratio of 60:40. The absorption, distribution, metabolism, and excretion of the HBN mixture was studied in the male Fischer-344 rat. [14C] HBN was incompletely absorbed after oral doses of 0.4 and 4.0 mumol/kg body weight. After iv treatment, fecal excretion accounted for 24% of the total dose by the end of d 1, 44% by d 3, and 62% by d 35. Urinary excretion was negligible. The excreted radioactivity was in the form of metabolite(s). Biliary excretion studies confirmed the nature of the excreted dose. The tissue distribution pattern showed accumulation and redistribution during early time points (0.5-3 h). By the end of the first day, 30.7% and 12.3% of the total dose remained in the liver and fat, respectively. All other tissues accounted for less than 5% of the total dose by d 1. The major tissue depots remained liver and adipose tissue, which contained 26% and 4.6% of the total dose, respectively, by d 35. This residual radioactivity was found to be unmetabolized HBN. Thus, over 60% of the dose of HBN is readily metabolized and excreted and was tentatively identified with the toxic isomer 1,2,3,4,6,7-HBN. The remainder, probably 2,3,4,5,6,7-HBN, was relatively nontoxic and extremely persistent, with the liver being the primary site of long-term accumulation.

Prevention of laboratory animal allergy in the United States: a national survey.

Objective: Respiratory allergy to laboratory animals is a common and preventable occupational health problem. This study documents current laboratory animal allergy (LAA) prevention programs in the United States. Methods: An online survey was e-mailed to designated institutional officials at laboratory animal facilities identified by the National Institutes of Health Office of Laboratory Animal Welfare. Results: A total of 198 organizations responded and more than 80% required the use of uniforms and gloves to control exposure. Respirators were required by 25% of organizations. Medical surveillance was mandated by 58% of organizations (70% for organizations with at least 100 employees working with animals). Work restriction practices varied. Only 25% of organizations reported knowing the prevalence (range: 0% to 75%) and 29% reported knowing the incidence of LAA (range: 0% to 18%). Conclusions: There is broad variation in policy and practice to prevent LAA. An evidence-based consensus would ensure greater protection of workers.

Occupational and Environmental Exposure to Asbestos

The usefulness of asbestos as an industrial material must be considered to understand the breadth of its public health impact. Since its discovery as an indestructible material centuries ago, it has found countless applications. Few substances rival its engineering and commercial performance.

Association Between Exercise Frequency and Health Care Costs Among Employees at a Large University and Academic Medical Center.

Objective: The aim of this study was to evaluate the relationship between exercise frequency and health care costs associated with medical and pharmacy claims among a 10-year employee cohort. Methods: The relationship between self-reported exercise (days/week) and health care costs was analyzed with negative binomial regression, using an integrated database involving 32,044 person-years and linking employee demographics, health risk appraisal information, and health insurance claims. Results: An association demonstrating exercise frequency lowering health care costs was present in most medical and prescription drug categories and was strongest among employees reporting 2 to 3 and 4 to 5 days/week of exercise. Increased exercise was associated with statistically significant reductions in endocrine disease costs and gastrointestinal prescription drug costs. Conclusions: This cohort demonstrates lower health care costs in employee populations when exercise frequency is increased. Employers may lower modifiable risk factors for chronic disease and reduce health care costs by promoting exercise among their employee population.