Human Health Effects of Agriculture: Physical Diseases and Illnesses

Agriculture has experienced major bio-technological advances and economic and socio-cultural disruptions since the publication of the white paper "Agriculture at Risk" in 1988. At that time it was recognized that there were acute needs in the prevention of musculoskeletal conditions, agricultural respiratory disease, noise-induced hearing loss, and pesticide-related illnesses, and the excesses of cancers noted in epidemiological studies of farmers. In this paper, we will discuss the progress made in identification of new respiratory syndromes related to confined animal feeding operations, pesticide-related illnesses, cancers implicated with agricultural exposures, and ergonomics in agriculture. The focus will be upon the current state of knowledge in these areas, recommendations for further improvement in research techniques, and the potential application of this information to improve human health in production agriculture nation wide. Human Health Effects of Agriculture The agricultural sector has undergone immense change since the publication of Agriculture at Risk in 1988. In some respects there has been improvement in the health and safety of those working in agriculture due to improved technology, personal protection, and awareness of hazards. The establishment of the NIOSH Agricultural Health and Safety Centers as a result of that effort has provided a network for the collaboration of academic health center researchers, agricultural safety educators, and agricultural engineers to institute a multi-disciplinary approach to research, outreach, and education in agricultural health and safety. The regional centers appropriately reflect the geographic variation in farming conditions and practices. Regulatory approaches to improving occupational and environmental health in agricultural practices have included the passage of the Worker Protection Standard in 1992 and the Food Quality Protection Act in 1996, both dealing exclusively with pesticides. There is still much to be done, however, to prevent injuries and improve the health status of those working in agriculture. Even with the consolidation of agricultural operations and the increased complexity and size of farms and other agricultural operations, there is a lack of knowledge of how many people are adversely affected by their exposures, particularly long-term, low level exposures. The majority of production operations are exempted from direct OSHA regulation and as a result the medical surveillance that occurs in other industries often does not or at best, occurs sporadically in agriculture. The reporting system for occupational illnesses is still woefully inadequate which makes it almost impossible to accurately track trends, determine accurate numbers of those with illnesses that are consequences of agricultural occupational exposures, and determine long-term adverse health effects from agricultural exposures. Farmers have an increased prevalence of many acute and chronic health conditions including cardiovascular and respiratory disease, arthritis, skin cancer, hearing loss, and amputations. Other health outcomes have been little studies in the agricultural workplace, such as stress and adverse reproductive outcomes. (Brackbill, Cameron, Behrens, 1994). Three prospective cohort studies have been launched that will help answer some of the questions: The Agricultural Health Study in North Carolina and Iowa, the Keokuk Study in Iowa, and the California Farmer Cohort Study (Alvanja, Sandler, McMaster, Zahm, McDonnell, Lynch, Pennybacker, Rothman, Dosemeci, Bond, & Blair 1996). In this paper we describe the progress that has been made since 1988 in addressing respiratory exposures and illnesses, cancers related to agricultural chemical exposures, pesticide-related illnesses, and ergonomic issues. As other papers will address agricultural injuries, mental health, and environmental issues, the focus will be upon occupational exposures that have the potential to cause physical illnesses from occupational exposures. We will also recommend future courses of action to improve the health of those who work in agriculture, with a focus upon production agriculture. Space limitations preclude a full discussion of the topics covered. Health studies must consider several modifying factors in agricultural exposures resulting in physical illnesses including work force age and ethnicity, type of commodity, work practices, engineering controls, and use of personal protective equipment. The work force has significantly changed and varies greatly by region. Principle operators tend to be Caucasian and older. There has been a slight increase in women principle operators. There has also been an increase in principle operators that work off the farm, which adds additional exposure issues (US Census of Agriculture, 1997). Hired farm workers are increasingly foreign born, younger males. It is thought that agriculture is now at a low point in agricultural labor and as the number of farms decrease, there will be an increase in the size of the agricultural labor force. According to the 1997 USDA Agricultural census the average age of principle operators is 54.3 years. Aging of the farm population may lead to increased susceptibility to the adverse effects of occupational exposures, on chronic diseases including respiratory and musculoskeletal illnesses. Many hired farm workers no longer have an agricultural background and use employment in the agricultural sector as an entry-level job. A language barrier exists which can impede following safety information on labels and training in proper work practices. Farm labor contractors instead of farm owners now hire large numbers of farm workers, raising new health and safety concerns. All of these changes may increase health and safety hazards in the agricultural workplace. Perhaps the hallmark of agricultural exposures is their enormous diversity in type, as well as in dose and duration. The ethnic variation in the agricultural workforce compounds the potential health hazards. Respiratory Illnesses and Exposures This topic has recently been reviewed in detail (Schenker, 1998). Agriculture involves potential exposure to a wide range of respiratory toxins, many in concentrations higher than in other industries. Despite low rates of cigarette smoking, farmers have an increased prevalence of several acute and chronic respiratory diseases.