Herman J. Gibb

Lung cancer among workers in chromium chemical production

BACKGROUND An elevated risk of lung cancer among workers in chromate production facilities has previously been reported. This excess risk is believed to be the result of exposure to hexavalent chromium. There have been mixed reports about whether trivalent chromium exposure is also associated with an excess lung cancer risk. Previous studies of measured hexavalent chromium exposure and lung cancer risk have not examined cigarette smoking as a risk factor. METHODS A cohort of 2,357 workers first employed between 1950 and 1974 at a chromate production plant was identified. Vital status of the workers was followed until December 31, 1992. Work histories of cohort members were compiled from the beginning of employment through 1985, the year the plant closed. Annual average exposure estimates, based on historical exposure measurements, were made for each job title in the plant for the years 1950-1985. These exposure estimates were used to calculate the cumulative hexavalent chromium exposure of each member of the study population. Following closure of the plant, settled dust samples were collected and analyzed for hexavalent and trivalent chromium. The trivalent/hexavalent concentration ratios in each plant area were combined with historic air-sampling data to estimate cumulative trivalent chromium exposure for each individual in the study cohort. Smoking status (yes/no) as of the beginning of employment and clinical signs of potential chromium irritation were identified from company records. RESULTS Cumulative hexavalent chromium exposure showed a strong dose-response relationship for lung cancer. Clinical signs of irritation, cumulative trivalent chromium exposure, and duration of work were not found to be associated with a risk of lung cancer when included in a proportional hazards model with cumulative hexavalent chromium exposure and smoking. Age-specific data on cumulative hexavalent chromium exposure, observed and expected numbers of lung cancer cases, and person-years of observation are provided. CONCLUSIONS Cumulative hexavalent chromium exposure was associated with an increased lung cancer risk; cumulative trivalent chromium exposure was not. The excess risk of lung cancer associated with cumulative hexavalent chromium exposure was not confounded by smoking status. The current study offers the best quantitative evidence to date of the relationship between hexavalent chromium exposure and lung cancer. Am. J. Ind. Med. 38:115-126, 2000. Published 2000 Wiley-Liss, Inc.

World Health Organization Global Estimates and Regional Comparisons of the Burden of Foodborne Disease in 2010

Illness and death from diseases caused by contaminated food are a constant threat to public health and a significant impediment to socio-economic development worldwide. To measure the global and regional burden of foodborne disease (FBD), the World Health Organization (WHO) established the Foodborne Disease Burden Epidemiology Reference Group (FERG), which here reports their first estimates of the incidence, mortality, and disease burden due to 31 foodborne hazards. We find that the global burden of FBD is comparable to those of the major infectious diseases, HIV/AIDS, malaria and tuberculosis. The most frequent causes of foodborne illness were diarrheal disease agents, particularly norovirus and Campylobacter spp. Diarrheal disease agents, especially non-typhoidal Salmonella enterica, were also responsible for the majority of deaths due to FBD. Other major causes of FBD deaths were Salmonella Typhi, Taenia solium and hepatitis A virus. The global burden of FBD caused by the 31 hazards in 2010 was 33 million Disability Adjusted Life Years (DALYs); children under five years old bore 40% of this burden. The 14 subregions, defined on the basis of child and adult mortality, had considerably different burdens of FBD, with the greatest falling on the subregions in Africa, followed by the subregions in South-East Asia and the Eastern Mediterranean D subregion. Some hazards, such as non-typhoidal S. enterica, were important causes of FBD in all regions of the world, whereas others, such as certain parasitic helminths, were highly localised. Thus, the burden of FBD is borne particularly by children under five years old–although they represent only 9% of the global population–and people living in low-income regions of the world. These estimates are conservative, i.e., underestimates rather than overestimates; further studies are needed to address the data gaps and limitations of the study. Nevertheless, all stakeholders can contribute to improvements in food safety throughout the food chain by incorporating these estimates into policy development at national and international levels.

Arsenic exposure from drinking water and birth weight

Background: Arsenic exposures from drinking water increase the risk of various cancers and noncancer health endpoints. Limited evidence suggests that arsenic may have adverse human reproductive effects. We investigated the association between drinking water arsenic exposure and fetal growth, as manifest in birth weight. Methods: We conducted a prospective cohort study in two Chilean cities with contrasting drinking water arsenic levels: Antofagasta (40 &mgr;g/L) and Valparaíso (<1 &mgr;g/L). Study subjects completed in-depth interviews and provided urine samples for exposure analysis. We obtained pregnancy and birth information from medical records. The birth weight analysis was restricted to liveborn, singleton infants born between December 1998 and February 2000. Results: The final study group consisted of 424 infants from Antofagasta and 420 from Valparaíso. After controlling for confounders, results of the multivariable analysis indicated that Antofagasta infants had lower mean birth weight (–57 g; 95% confidence interval = –123 to 9). Conclusion: This study suggests that moderate arsenic exposures from drinking water (<50 &mgr;g/L) during pregnancy are associated with reduction in birth weight, similar in magnitude to that resulting from other environmental exposures such as environmental tobacco smoke and benzene.

Mercury Exposure and Health Impacts among Individuals in the Artisanal and Small-Scale Gold Mining Community: A Comprehensive Review

Background: Mercury (Hg) is used in gold mining to extract gold from ore by forming “amalgam”—a mixture composed of approximately equal parts mercury and gold. Approximately 15 million people, including approximately 3 million women and children, participate in artisanal small-scale gold mining (ASGM) in developing countries. Thirty-seven percent of global air emissions of Hg are produced by ASGM. The recently adopted Minamata Convention calls for nations to gather health data, train health-care workers, and raise awareness in regard to ASGM activity. Objective: The purpose of our review was to evaluate the current literature regarding the health effects of Hg among those working and/or living in or near ASGM communities. Methods: We searched PubMed, ScienceDirect, and Google Scholar for studies relating to health effects and biomarkers of Hg exposure in ASGM communities. Articles published from 1990 through December 2012 were evaluated for relevance. Discussion: Studies reporting health assessments, kidney dysfunction, neurological disorders and symptoms, and immunotoxicity/autoimmune dysfunction in individuals living in or near an ASGM community were identified. More than 60 studies that measured biomarkers of Hg exposure in individuals living in or near ASGM communities were also identified. These studies, conducted in 19 different countries in South America, Asia, and Africa, demonstrated that hair and urine concentrations are well above World Health Organization health guidance values in ASGM communities. Conclusions: ASGM workers and their families are exposed to Hg vapor, and workers, workers’ families, and residents of nearby and downstream communities are consuming fish heavily contaminated with methylmercury. Citation: Gibb H, O’Leary KG. 2014. Mercury exposure and health impacts among individuals in the artisanal and small-scale gold mining community: a comprehensive review. Environ Health Perspect 122:667–672; http://dx.doi.org/10.1289/ehp.1307864

WHO Initiative to Estimate the Global Burden of Foodborne Diseases

Abstract Background The public health impact of foodborne diseases globally is unknown. The WHO Initiative to Estimate the Global Burden of Foodborne Diseases was launched out of the need to fill this data gap. It is anticipated that this effort will enable policy makers and other stakeholders to set appropriate, evidence-informed priorities in the area of food safety. Methods The Initiative aims to provide estimates on the global burden of foodborne diseases by age, sex, and region; strengthen country capacity for conducting burden of foodborne disease assessments in parallel with food safety policy analyses; increase awareness and commitment among Member States for the implementation of food safety policy and standards; and encourage countries to use burden of foodborne disease estimates for cost-effectiveness analyses of prevention, intervention, and control measures. To estimate the global burden (expressed in disability-adjusted life-years), the Foodborne Disease Burden Epidemiology Reference Group (FERG) focused on the contamination of food with enteric and parasitic pathogens, chemicals, and toxins. Findings Study findings will provide the technical background and challenges of assessing the burden of foodborne diseases, based on national and international studies. Systematic reviews to support estimates of the incidence and mortality of food-related diseases are being completed. Results will be used to update and refine global burden estimates for relevant food-related hazards, in the context of other international burden of disease studies. It is recognised that exposure to such hazards may also occur through other pathways including the environment (eg, water, air) and by direct transmission (eg, human-to-human and animal-to-human). Structured expert elicitation will be used to provide the basis for attribution of incidence and burden to food, and estimation of the most important food sources. Interpretation Estimating the global burden of foodborne diseases is highly complex because of the diversity of hazards that can be transmitted by food, the multitude of health outcomes they cause, and complex transmission pathways. WHO is planning to present a global estimate for the first time in 2014. Funding WHO.

World Health Organization Estimates of the Relative Contributions of Food to the Burden of Disease Due to Selected Foodborne Hazards: A Structured Expert Elicitation

Background The Foodborne Disease Burden Epidemiology Reference Group (FERG) was established in 2007 by the World Health Organization (WHO) to estimate the global burden of foodborne diseases (FBDs). This estimation is complicated because most of the hazards causing FBD are not transmitted solely by food; most have several potential exposure routes consisting of transmission from animals, by humans, and via environmental routes including water. This paper describes an expert elicitation study conducted by the FERG Source Attribution Task Force to estimate the relative contribution of food to the global burden of diseases commonly transmitted through the consumption of food. Methods and Findings We applied structured expert judgment using Cooke’s Classical Model to obtain estimates for 14 subregions for the relative contributions of different transmission pathways for eleven diarrheal diseases, seven other infectious diseases and one chemical (lead). Experts were identified through international networks followed by social network sampling. Final selection of experts was based on their experience including international working experience. Enrolled experts were scored on their ability to judge uncertainty accurately and informatively using a series of subject-matter specific ‘seed’ questions whose answers are unknown to the experts at the time they are interviewed. Trained facilitators elicited the 5th, and 50th and 95th percentile responses to seed questions through telephone interviews. Cooke’s Classical Model uses responses to the seed questions to weigh and aggregate expert responses. After this interview, the experts were asked to provide 5th, 50th, and 95th percentile estimates for the ‘target’ questions regarding disease transmission routes. A total of 72 experts were enrolled in the study. Ten panels were global, meaning that the experts should provide estimates for all 14 subregions, whereas the nine panels were subregional, with experts providing estimates for one or more subregions, depending on their experience in the region. The size of the 19 hazard-specific panels ranged from 6 to 15 persons with several experts serving on more than one panel. Pathogens with animal reservoirs (e.g. non-typhoidal Salmonella spp. and Toxoplasma gondii) were in general assessed by the experts to have a higher proportion of illnesses attributable to food than pathogens with mainly a human reservoir, where human-to-human transmission (e.g. Shigella spp. and Norovirus) or waterborne transmission (e.g. Salmonella Typhi and Vibrio cholerae) were judged to dominate. For many pathogens, the foodborne route was assessed relatively more important in developed subregions than in developing subregions. The main exposure routes for lead varied across subregions, with the foodborne route being assessed most important only in two subregions of the European region. Conclusions For the first time, we present worldwide estimates of the proportion of specific diseases attributable to food and other major transmission routes. These findings are essential for global burden of FBD estimates. While gaps exist, we believe the estimates presented here are the best current source of guidance to support decision makers when allocating resources for control and intervention, and for future research initiatives.

Utility of Recent Studies to Assess the National Research Council 2001 Estimates of Cancer Risk from Ingested Arsenic

Objective The purpose of this review is to evaluate the impact of recent epidemiologic literature on the National Research Council (NRC) assessment of the lung and bladder cancer risks from ingesting low concentrations (< 100 μg/L) of arsenic-contaminated water. Data sources, extraction, and synthesis PubMed was searched for epidemiologic studies pertinent to the lung and bladder cancer risk estimates from low-dose arsenic exposure. Articles published from 2001, the date of the NRC assessment, through September 2010 were included. Fourteen epidemiologic studies on lung and bladder cancer risk were identified as potentially useful for the analysis. Conclusions Recent epidemiologic studies that have investigated the risk of lung and bladder cancer from low arsenic exposure are limited in their ability to detect the NRC estimates of excess risk because of sample size and less than lifetime exposure. Although the ecologic nature of the Taiwanese studies on which the NRC estimates are based present certain limitations, the data from these studies have particular strengths in that they describe lung and bladder cancer risks resulting from lifetime exposure in a large population and remain the best data on which to conduct quantitative risk assessment. Continued follow-up of a population in northeastern Taiwan, however, offers the best opportunity to improve the cancer risk assessment for arsenic in drinking water. Future studies of arsenic < 100 μg/L in drinking water and lung and bladder cancer should consider adequacy of the sample size, the synergistic relationship of arsenic and smoking, duration of arsenic exposure, age when exposure began and ended, and histologic subtype.

Clinical findings of irritation among chromium chemical production workers

BACKGROUND Several reports of workers in chromate production and chromeplating have indicated that exposure to hexavalent chromium is associated with skin and nasal irritation. METHODS A cohort of 2, 357 workers first employed between 1950 and 1974 at a chromate production plant was identified. Clinical findings of irritation were identified by a physician as a result of routine examinations or visits to the medical clinic by members of the cohort. Percentages of the cohort with various clinical findings, the time from hire to occurrence of the first finding, and the mean and median annual hexavalent chromium (measured as CrO(3)) concentration for the job title where the clinical finding first occurred were determined. A proportional hazards model was used to evaluate the relationship between hexavalent chromium exposure and first occurrence of each of the clinical findings. RESULTS Nasal irritation and nasal ulceration were the most common clinical findings reported, occurring in more than 60% of the cohort. The average time to first occurrence of these findings was less than 3 months, whereas the time to first occurrence of the other findings ranged from 10 to 22 months. Median exposure to hexavalent chromium at the time of occurrence for most of the findings was about 20 microg/m(3). The proportional hazards model indicated that ulcerated nasal septum, irritated skin, and perforated eardrum were significantly associated with ambient hexavalent chromium exposure; all clinical findings with the exception of conjunctivitis and irritated skin were associated with the calendar year of hire, with the risk being lower as the calendar year of hire became more recent. Annual average ambient hexavalent chromium concentrations generally dropped in the plant over the period of the study. CONCLUSIONS Workers in the chromate production plant in this study experienced a variety of nasal and skin irritations. Irritated and ulcerated nasal septa, in particular, were quite common clinical findings, occurring in over 60% of the cohort, and they occurred in relatively short periods of time-less than 3 months from date of hire. Annual average concentrations of chromium may not be a good predictor of clinical findings of irritation. Am. J. Ind. Med. 38:127-131, 2000. Published 2000 Wiley-Liss, Inc.

Evaluation of issues relating to the carcinogen risk assessment of chromium

Important issues in the carcinogenic risk assessment of chromium compounds are whether both trivalent and hexavalent chromium compounds are carcinogenic, the role of solubility in the carcinogenic response, and the carcinogenicity of ingested chromium. Hexavalent chromium compounds are carcinogenic to animals via several routes of exposure, while trivalent chromium compounds, although they demonstrate evidence of genotoxicity, have not been shown in animal studies to be carcinogenic. Workers in chromate production plants, where the risk of lung cancer is elevated, are exposed to both trivalent and hexavalent chromium compounds. A cancer unit risk estimate for Wistar rats exposed to a hexavalent chromium aerosol (sodium dichromate) is less than the risk estimate for workers in chromate production. If this difference is biologically real, a possible explanation may be that trivalent compounds also have a carcinogenic effect. For hexavalent chromium compounds, it is contended that only sparingly soluble hexavalent chromium compounds are carcinogenic. Recent evidence, however, indicates that highly soluble hexavalent chromium compounds are also carcinogenic. Animal ingestion studies have not found trivalent chromium compounds to be carcinogenic by ingestion; hexavalent compounds have not been studied. Research by EPA to address the issue of valence state and solubility with respect to carcinogenicity is currently being conducted.

Analyses of Radiation and Mesothelioma in the US Transuranium and Uranium Registries

OBJECTIVES We examined the relationship between radiation and excess deaths from mesothelioma among deceased nuclear workers who were part of the US Transuranium and Uranium Registries. METHODS We performed univariate analysis with SAS Version 9.1 software. We conducted proportionate mortality ratio (PMR) and proportionate cancer mortality ratio (PCMR) analyses using the National Institute for Occupational Safety and Health Life Table Analysis System with the referent group being all deaths in the United States. RESULTS We found a PMR of 62.40 (P < .05) and a PCMR of 46.92 (P < .05) for mesothelioma. PMRs for the 4 cumulative external radiation dose quartiles were 61.83, 57.43, 74.46, and 83.31. PCMRs were 36.16, 47.07, 51.35, and 67.73. The PMR and PCMR for trachea, bronchus, and lung cancer were not significantly elevated. CONCLUSIONS The relationship between cumulative external radiation dose and the PMR and PCMR for mesothelioma suggests that external radiation at nuclear facilities is associated with an increased risk of mesothelioma. The lack of a significantly elevated PMR and PCMR for trachea, bronchus, and lung cancer suggests that asbestos did not confound this relationship.