Tiina Folley

Estimated Burden of Disease Attributable to Selected Occupational Exposures in The United Arab Emirates

BACKGROUND As part of an effort to strengthen occupational safety and health programs, the United Arab Emirates (UAE) commissioned a study to estimate the burden of disease attributable to occupational exposure to carcinogens, particulate matter, and noise. METHODS We developed an innovative simulation model to estimate the occupational disease burden and facilitate future assessments as more field-based quantitative data become available. RESULTS We determined that, in 2008, an estimated 46 deaths (95% CI: 27-71) and 17,000 health-care facility visits (95% CI: 16,000-18,000), along with 4,500 cases of noise-induced hearing loss, were attributable to the occupational risk factors covered in this study. Lung cancer and leukemia were associated with the highest number of deaths (38), whereas asthma and chronic obstructive pulmonary disease contributed most to the health-care facility visits (nearly 16,900). The highest estimated occupational disease burden is in construction. CONCLUSION These results will help the UAE to institute new policies for environment, health, and safety management.

Burden of Disease from Indoor Air Pollution

Indoor air pollution has evolved into a high-priority risk across the globe, with various organizations ranking indoor air pollution in the top category of environmental risks. Indoor air pollutant concentrations are a function of indoor source emissions, the infiltration of ambient pollution via building leakage, and the air exchange rate (ventilation) in the building. Health effects range from acute conditions such as sensory irritation to chronic, potentially life-threatening conditions such as cancer and cardiovascular disease. The three primary factors that affect indoor air quality are the nature of indoor pollutant sources, ventilation of the building, and occupant behaviors. This initial modeling effort focuses on the residential environment because people spend the majority of their time indoors in residential dwellings. Deficient air quality can exist in all types of enclosed buildings and structures. In the future, the methods and models developed here could be applied to other indoor environments. The burden of disease due to a particular pollutant was calculated by multiplying the attributable fraction by the observed number of cases of the relevant health outcome in the population. The leading source of indoor air pollution contributing to excess cases of illness is environmental tobacco smoke. Altogether, it appears to cause more than 80% of the health-care facility visits attributed to indoor air pollution. The leading health outcomes attributed to indoor air pollution are cardiovascular disease and lower respiratory tract infections. An estimated 280 deaths result from those diseases, with approximately 88% of those deaths attributed to cardiovascular disease caused by environmental tobacco smoke. Our analyses suggest that indoor air pollution is a considerable risk to public health in the United Arab Emirates (UAE), accounting for at least 77,000 excess visits to health-care facilities in 2008 in addition to the 280 excess deaths. In terms of mortality, indoor air quality ranks second only to outdoor air pollution as a cause of environmentally related diseases in the UAE.

Prioritizing Environmental Risks to Health

This chapter discusses in detail the process we used to engage stakeholders in further refining the scope of issues to consider in this environmental burden of disease assessment. First, we provide background on innate human cognitive biases that affect our perceptions of risk and how these biases pose challenges to rational priority setting. Then, we describe previous international experiences in prioritizing environmental risks to health for policymaking. Next, we describe the systematic approach used here to prioritize environmental risk factors—an approach that compensates for cognitive biases, incorporates scientific information, systematically involves multiple stakeholders, and builds on international experiences. Finally, we describe how we implemented this ranking process and how the results led to the eight environmental risk factor categories that are the subjects of the remaining chapters of this book: outdoor air pollution, indoor air pollution, occupational exposures, climate change, drinking water contamination, coastal water pollution, soil and groundwater contamination, and produce and seafood contamination.

Burden of Disease from Produce and Seafood Contamination

Eating fruits and vegetables is beneficial to human health but exposes people to risk if the produce contains hazardous contaminants. Two potential contaminants are human pathogens (e.g., Salmonella, E. coli) and agricultural pesticides (e.g., organophosphates, carbamates), both of which can be reduced with proper food handling and preparation. Foodborne pathogens can cause and/or contribute to an array of human illnesses, including acute gastroenteritis as well as more complex chronic conditions such as organ failure, arthritis, and heart disease. Agricultural pesticide exposure can result in dizziness, nausea, abdominal cramps, diarrhea, tremors, anxiety, confusion, neurological disorders, developmental/reproductive disorders, and death. Because large percentages of fruit, vegetables, grains, and legumes consumed in the United Arab Emirates are produced abroad, pesticide use and other farm management practices in countries exporting to the UAE will affect contamination levels of food consumed in the UAE. Domestically harvested seafood has historically been a primary staple of the Emirati diet. More than 90% of citizens eat fish during at least one meal every week. Consumption of fish provides numerous documented health benefits, including a reduction in risk of chronic heart disease; however, fish can also serve as a vector for pathogenic microorganisms (e.g., Vibrio spp.), heavy metals (e.g., mercury) and other toxins (e.g., dioxin). Estimates of illness resulting from seafood consumption focus on exposure to mercury. Although numerous metals can result in adverse health effects if consumed in seafood, mercury is generally regarded as of greatest concern. Chronic mercury poisoning results in a host of neurological and psychological symptoms, including tremors, motor/cognitive dysfunction, and memory loss. Exposure in utero can result in serious lifetime illness, including mental retardation, sensory loss, developmental delay, cerebral palsy, and seizures. In lieu of estimating foodborne mortality and morbidity cases, our modeling approach directly calculates the probability of exceeding international guidelines for exposure to specific hazardous chemicals in fruit, vegetables, and seafood in the UAE. For fruits and vegetables, the model estimates the number of daily incidents in which UAE residents are exposed to a particular type of pesticide residue above a prespecified benchmark dose, due to eating a particular type of fruit or vegetable. For seafood, the model estimates the number of daily incidents in which UAE residents are exposed to mercury levels above the reference dose maintained by the U.S. Environmental Protection Agency due to eating fish. Results of daily cases in which a UAE resident may be at risk of overexposure to methylmercury from eating seafood and exceeding the reference dose suggest 2,927 women and 11,882 men—with the gender imbalance an artifact of the male-dominated expatriate workforce—could be at risk for health effects. Of all pesticides and crops, chlorpyrifos on tomato has the highest mean ratio (0.26) of average estimated pesticide exposure (0.000078 mg/kg) to its chronic population adjusted dose (cPAD) value (0.0003 mg/kg), making tomatoes the most suitable candidate for a worst-case hypothetical scenario. Considering an atypical but theoretical UAE resident eating 100% tomatoes, and assuming no reduction in pesticide due to washing, peeling, and/or cooking, the model estimates this person has 20.6% (chlorpyrifos) and 1.0% (vinclozolin) chances of exceeding cPAD values each day. Overall, this model estimates 631,074 worst-case daily incidents (cPAD exceedance) contributing to potential chronic illness. Although these probabilities may seem high, daily cPAD incidents are assumed contributory toward potential cases of annual chronic illness; the model assumes (worst-case) no reduction in pesticide due to washing, peeling, and/or cooking for all incidents; and, only very limited human epidemiologic studies exist to objectively link chronic pesticide exposure with adverse health effects—a major reason for the safety factors already built into the cPAD and other benchmarks.

Burden of Disease from Occupational Exposures

Workers may be exposed to physical, chemical, and biological hazards at work that may lead to occupational illness. Hazardous substance exposure routes include dermal and inhalation exposure and ingestion. Families of workers also can face risks from toxic substances brought home on contaminated work clothes or vehicles. This chapter estimates occupational exposures to harmful chemicals and noise in the United Arab Emirates (UAE) and calculates the burden of disease related to selected occupational hazards. Occupational health studies conducted in the UAE have revealed unsafe work practices and unhealthy working conditions in many industry sectors, but the majority of UAE workers who are potentially exposed to hazardous substances and noise are employed in construction, agriculture, or manufacturing. The exposures covered in this study were selected following the approach by the World Health Organization, covering common occupational carcinogens, occupational airborne particulates, and noise, excluding occupational injuries and ergonomic stressors. The estimated total number of annual deaths due to health outcomes included in this study is 47, and the total number of health-care facility visits is 17,160. In addition, the model estimates that 4,770 cases of noise-induced hearing loss occur due to occupational exposures each year. Of the health outcomes covered in the study, lung cancer and leukemia were responsible for the highest number of deaths (25 and 12, respectively). For health-care facility visits, asthma and chronic obstructive pulmonary disease contributed most to the disease burden with 11,854 and 5,012 visits, respectively. It is likely that the UAE could reduce the amount it spends on medical care by reducing exposure to respiratory irritants, carcinogens, and noise in workplaces. These numbers should not be considered to represent the total disease burden arising from all occupational exposures. Many prevalent occupational hazards, such as injuries and ergonomic stressors, were excluded because this study focuses on health risks due to releases of hazardous physical, chemical, and biological agents into the environment as a result of human activities.

Applying Environmental Burden of Disease Models to Strengthen Public Policy

The methods described in this book can provide a foundation for the next generation of environment and health strategic plans. Our approach provides an empirically validated means for the kinds of cooperative planning by the various levels of government, nongovernmental organizations and local communities needed in order to reduce human impacts on the environment and environmental impacts on human health. The project documented in this book followed three major steps: (1) developing preliminary environmental burden of disease estimates for 14 risk categories, (2) engaging stakeholders in a systematic process to prioritize these 14 risk categories based on the burden of disease information and other factors, and (3) analyzing in detail the burden of disease for eight key risk categories emerging from the priority-setting exercise. This chapter integrates the environmental burden of disease estimates from Chaps. 4, 5, 6, 7, 8, 9, 10, and 11. It provides a big-picture view of the United Arab Emirates’ environmental disease burden across risk categories. It then outlines how the environmental burden of disease model described in these chapters can serve as a foundation for systematically analyzing interventions to improve environmental quality and lessen the associated disease burden. Next, it explains how a process like that in Chap. 2 could provide the foundation for the next generation of environment and health strategic plans, in which stakeholders come together to prioritize environmental interventions from a menu of options. The chapter also explains how ecological impacts of interventions could be incorporated in this priority-setting process. The budget struggles that many nations face as they contend with the continuing global economic crisis underline the need for renewed environment and health strategic planning. The approach outlined in this book paves the way for doing more with less—for increasing the public health gains of environmental interventions without necessarily increasing the economic burden on governments and their citizens.

Burden of Disease from Soil and Groundwater Contamination

Soil and groundwater contamination due to waste disposal may pose an increasing public health threat in the United Arab Emirates (UAE) if measures are not taken to improve waste management practices and prevent exposure to wastes disposed of improperly in the past. The UAE currently has one of the highest rates of solid waste generation per capita of any country in the world. In addition, waste disposal in the UAE historically has been inadequately controlled, with wastes of a wide variety disposed of in open, unlined dump sites in the desert. Chemicals can leach from uncontrolled waste disposal sites and contaminate soil and the underlying groundwater. The soil in much of the UAE is silty and sandy with low cation exchange capacity. This soil type is highly permeable, and thus contaminants that leach from waste sites have the potential to migrate rapidly and contaminate large areas. At the time this project was carried out, no data were available on the nature and amounts of hazardous chemicals found in soil and groundwater in the UAE from waste disposal sites, but the types of chemicals present due to releases from waste disposal sites are likely to be similar to those found in groundwater contaminated from past waste disposal practices in other developed countries. These chemicals are associated with a range of effects, from cancer to neurological and reproductive effects to suppression of the immune system. Current information is not sufficient to assess the burden of disease due to soil and groundwater contamination from waste sites in the UAE. At present, this disease burden is likely to be small because of the small size of the potentially exposed population. However, given the plans to invest in developing the Western Region, it would be prudent for the UAE to begin to collect the information needed to assess risks from these sites to the current population and to future residents. Our primary recommendation is a two-part process that first would provide approximate estimates of the potential burden of disease from individual waste disposal sites and then develop detailed risk assessments for sites showing a significant health risk potential. The information needed for the first part of this process should be relatively easy to obtain, with the primary effort required for additional visual inspections of a selected number of waste sites. Once these basic site inspections and preliminary risk assessments are completed, the UAE government will have greatly improved estimates of which waste sites may be cause for concern, allowing it to focus on sites that have significant risk potential.

Burden of Disease from Climate Change

Expected climate change may be particularly important in the United Arab Emirates (UAE) due to its already hot and arid climate. Compared with other nations, the UAE has a relatively low level of total greenhouse gas (GHG) emissions, with an estimated 0.31–0.42% of global emissions since 1994. However, the UAE has one of the highest levels of GHG emissions per capita, consistently ranking second or third in the world over the past two decades. Climate change is likely to have only limited impacts on infectious and diarrheal diseases in the UAE due to relatively low baseline levels of these climate-sensitive diseases. The major impacts of climate change in the UAE are expected to be increased heat stress and possibly increased water- and vector-borne diseases, as well as decreased water availability and food production. The total burden of disease from climate change is inherently difficult to determine due to the many mechanisms through which climate can affect public health and the high level of uncertainty with future climate scenarios, GHG emission levels, and human adaptation measures. Our model includes only the effect of climate change on cardiovascular disease. The results show that climate change currently has minimal effects on human health relative to the other modeled priority areas. There were approximately 410 additional health-care facility visits and three additional deaths from cardiovascular disease in the UAE in 2008 due to the added risks of climate change.

Burden of Disease from Coastal Water Pollution

Contamination of coastal water with pathogenic microorganisms is generally considered a relatively lesser environmental concern in developed nations such as the United Arab Emirates (UAE) that require treatment of municipal wastewater prior to discharge. In the Arabian Gulf in the 1990s, measurements of coliform bacteria (which indicate possible contamination with fecal matter and hence disease-causing organisms) generally supported this assumption, with reports of low average coliform concentrations along the coast. However, more recent data provided by the Environment Agency–Abu Dhabi indicate that concentrations of enterococci, which are the most important indicators of fecal contamination in coastal waters, at the city’s public beaches occasionally exceed World Health Organization recommended water quality standards. Additional observations of high coliform concentrations in nearby Abu Dhabi shipping channels and news reports of high E. coli concentrations along the Dubai coastline suggest that episodic events involving high concentrations of microorganisms of fecal origin may need to be addressed to preserve coastal water quality. Microorganisms in coastal water can enter the body through ingestion, inhalation, or transport through existing skin lesions or open wounds. Gastroenteritis (including diarrhea, vomiting, and associated symptoms) is the most common type of illness resulting from such exposures in developed countries. The analysis in this chapter focuses on risks due to pathogenic microorganisms of fecal origin because these organisms pose the most important public health risk from short-term exposure to coastal water as occurs during swimming and other coastal recreational activities. Further, at present, industrial effluents appear to be sufficiently regulated with no recorded violations, and a public notification system exists to warn beachgoers of “catastrophic” single incidents such as local oil spills or red tides. Our model estimates that swimming in UAE coastal waters could contribute to 1,300 medical visits for gastroenteritis per year among UAE residents. If the potential total number of illnesses (reported through medical visits and unreported) is considered, the estimate rises to 64,000. In addition to the cases among residents, another 24,000 cases could be expected among tourists. This suggests that virtually immediate reductions in health risks related to recreational waters could be achieved through increased monitoring of fecal indicator bacteria concentrations at local beaches and closure of areas in violation of international recommended standards until adequate reductions in microbial concentrations are achieved. Ideally, to provide consistent public health safeguards throughout the nation, a standardized coastal water monitoring program should be instituted at the federal level by the Ministry of Environment and Water and implemented by relevant emirate-level agencies.