Cheryl A. Fields

Mortality Disparities in Appalachia Reassessment of Major Risk Factors

Objective: To determine the predictive value of coal mining and other risk factors for explaining disproportionately high mortality rates across Appalachia. Method: Mortality and covariate data were obtained from publicly available databases for 2000 to 2004. Analysis employed ordinary least square multiple linear regression with age-adjusted mortality as the dependent variable. Results: Age-adjusted all-cause mortality was independently related to Poverty Rate, Median Household Income, Percent High School Graduates, Rural–Urban Location, Obesity, Sex, and Race/Ethnicity, but not Unemployment Rate, Percent Uninsured, Percent College Graduates, Physician Supply, Smoking, Diabetes, or Coal Mining. Conclusions: Coal mining is not per se an independent risk factor for increased mortality in Appalachia. Nevertheless, our results underscore the substantial economic and cultural disadvantages that adversely impact health in Appalachia, especially in the coal-mining areas of Central Appalachia.

Use of Beryllium Lymphocyte Proliferation Testing for Screening of Asymptomatic Individuals: An Evidence-based Assessment

Objective: We reviewed published data describing use of beryllium lymphocyte proliferation testing (BeLPT) to determine the appropriateness of BeLPT for screening asymptomatic individuals. Methods: Published studies were identified by computerized literature searches and hand searches of relevant bibliographies and cited references. Critical assessment of evidence focused on five elements essential to judging effectiveness of preventive services: 1) burden of suffering, 2) accuracy and reliability of screening tests, 3) effectiveness of early detection, 4) harms of screening, and 5) benefits outweighing harms. Results: Important gaps and deficiencies in the evidence were found. The prevalence of beryllium sensitization and chronic beryllium disease in asymptomatic individuals are unknown. The accuracy and reliability of BeLPT are uncertain. Marked intra- and interlaboratory variability has been reported. The clinical benefits of early intervention have not been confirmed or quantified in asymptomatic individuals. Conclusions: There is currently insufficient scientific evidence to support the use of BeLPT for routine screening of asymptomatic individuals.

Methyl methacrylate and respiratory sensitization: A Critical review

Methyl methacrylate (MMA) is a respiratory irritant and dermal sensitizer that has been associated with occupational asthma in a small number of case reports. Those reports have raised concern that it might be a respiratory sensitizer. To better understand that possibility, we reviewed the in silico, in chemico, in vitro, and in vivo toxicology literature, and also epidemiologic and occupational medicine reports related to the respiratory effects of MMA. Numerous in silico and in chemico studies indicate that MMA is unlikely to be a respiratory sensitizer. The few in vitro studies suggest that MMA has generally weak effects. In vivo studies have documented contact skin sensitization, nonspecific cytotoxicity, and weakly positive responses on local lymph node assay; guinea pig and mouse inhalation sensitization tests have not been performed. Cohort and cross-sectional worker studies reported irritation of eyes, nose, and upper respiratory tract associated with short-term peaks exposures, but little evidence for respiratory sensitization or asthma. Nineteen case reports described asthma, laryngitis, or hypersensitivity pneumonitis in MMA-exposed workers; however, exposures were either not well described or involved mixtures containing more reactive respiratory sensitizers and irritants. The weight of evidence, both experimental and observational, argues that MMA is not a respiratory sensitizer.

Mercury-induced motor and sensory neurotoxicity: systematic review of workers currently exposed to mercury vapor

Abstract The neurotoxicity of elemental mercury (Hg0) is well-recognized, but it is uncertain whether and for how long neurotoxicity persists; among studies that evaluated previously exposed workers, only one examined workers during and also years after exposure ceased. The aim of this review is to document the type, frequency, and dose-relatedness of objective neurological effects in currently exposed mercury workers and thereby provide first approximations of the effects one would have expected in previously exposed workers evaluated during exposure. We systematically reviewed studies of neurotoxicity in currently exposed mercury workers identified by searching MEDLINE (1950–2015), government reports, textbook chapters, and references cited therein; dental cohorts were not included. Outcomes on physical examination (PE), neurobehavioral (NB) tests, and electrophysiological studies were extracted and evaluated for consistency and dose-relatedness. Forty-five eligible studies were identified, comprising over 3000 workers chronically exposed to a range of Hg0 concentrations (0.002–1.7 mg/m3). Effects that demonstrated consistency across studies and increased frequency across urine mercury levels (<50; 50–99; 100–199; ≥200 μg/L) included tremor, impaired coordination, and abnormal reflexes on PE, and reduced performance on NB tests of tremor, manual dexterity and motor speed. The data suggest response thresholds of UHg ≈275 μg/L for PE findings and ≈20 μg/L for NB outcomes. These results indicate that PE is of particular value for assessing workers with UHg >200 μg/L, while NB testing is more appropriate for those with lower UHg levels. They also provide benchmarks to which findings in workers with historical exposure can be compared.

Persistence of mercury-induced motor and sensory neurotoxicity: systematic review of workers previously exposed to mercury vapor

Abstract Elemental mercury (Hg0) is a well-recognized neurotoxicant, but it is uncertain whether and for how long its neurotoxicity persists. Among studies that evaluated previously-exposed workers, only one examined workers during and also years after exposure had ceased. The objective of this review is to create a series of ‘synthetic’ longitudinal studies to address the question of persistence of Hg0 neurotoxicity in occupationally exposed workers. We systematically reviewed studies describing objective motor and sensory effects in previously-exposed mercury workers. Data from physical examination (PE), neurobehavioral (NB) tests, and electrophysiological studies (EPS) were extracted into structured tables and examined for their consistency and dose-relatedness and then compared with the corresponding results from studies of currently exposed workers. We identified six cohorts that described neurological findings in 1299 workers, examined an average of 4.8–30 years after the cessation of exposure. Historical group mean UHg levels ranged from 23 to >500 μg/L, with UHg levels >6000 μg/L in some individuals. Overall, few findings were significant; most were inconsistent across the previous-exposure studies, and in comparisons between studies of previously and currently exposed workers. The results of this systematic review indicate that Hg0-related neurotoxic effects detectable on PE, NB testing, and EPS are substantially reversed over time. To the extent that such effects do persist, they are reported principally in workers who have had very high-dose exposures. In addition, based on the limited available data, those effects reported to persist have been described as having little or no functional significance.

Iodine Deficiency in Vegetarian and Vegan Diets: Evidence-Based Review of the World's Literature on Iodine Content in Vegetarian Diets

As the iodine content is generally low in most vegetables and fruits, it is biologically plausible that compliance with strict vegetarian diets would increase risks of iodine deficiency. This chapter responds to these concerns by first considering the prevalence, demography and lifestyle characteristics of vegetarians residing mainly in developed countries and finally, by reviewing the nutrition and epidemiological studies that assessed iodine nutrition in vegetarians. The number of people who self-identify as “vegetarian” or “vegan” is significantly larger than the number who adhere to such diets. The iodine content of vegetarian diets may be inadequate. Vegetarians are generally more educated, have higher socioeconomic status, and more likely to adopt healthy and healthful behaviors. Strict vegetarians and vegans are likely to use iodine supplements. On balance, vegetarians and others following restrictive diets should recognize that they may be at increased risk of iodine, as well as other nutritional, deficiencies. Pregnant vegetarians and vegans are a population at particular risk of iodine deficiency and should use iodinecontaining prenatal vitamins. Nutritional studies suggest that the iodine content of vegetarian diets may be inadequate, but adherence to a vegetarian diet need not lead to iodine deficiency. As diets become increasingly restrictive, assurance of adequate iodine intake increasingly depends on the appropriate use of iodized salt and other dietary supplements.