Hazardous environments: Local and global

Abstract

The environmental health research agenda has now widened to encompass local, regional, and global hazards. Concerns about localised ambient environmental health hazards such as electricity power-lines, radiation leaks from nuclear installations, and traffic exhaust persist. Since many environmental exposures impinge on whole communities, it can be difficult to find and compare contrasting subgroups; and since exposures may not be high, an increase in risk (even if widespread) may be diffcult to detect. Some progress has been made. Pope reports that longterm exposure to airborne respirable particulates increases cardiopulmonary mortality, although there are uncertainties about interactive contributions of other air pollutants (Epidemiology 1995; 6: 471). These epidemiological findings have special implications for urban traffic policy. Diesel engines, which are becoming more prevalent, produce less carbon dioxide but more particulates. Meanwhile, car ownership is proliferating, especially in the ex-communist countries and bustling Asian economies (figure). The volume and speed of traffic have been confirmed as the main urban risk factors for childhood pedestrian injury (Epidemiology 1995; 6: 169). In cities everywhere but particularly in the third world, as shown by Stephens, differential exposure to traffic is part of a wider constellation of physical and socioeconomic deprivations causing a pronounced mortality gradient between rich and poor. A substantial review of environment and health in the central-eastern European region by Hertzman has documented widespread hazardous exposures to air pollutants, lead, groundwater nitrates, and chemical contaminants in food. Concerns about regional environmental hazards were heightened by French resumption of nuclear tests in the South Pacific--50 years after atomic bombs were dropped on Japan, and 100 years after Wilhelm Roentgen discovered X-rays. Follow-up of the Japanese bomb survivors continues to provide insights into the biology of risk gradients of radiation-related cancer (JAMA 1995; 274 402) and suggests that a small subgroup of women are especially susceptible to radiation. Also at the regional level, various vector-borne diseases (eg, dengue in central America, South America, and South Pacific; malaria in southern Russia; and schistosomiasis in southern Africa) have increased their range. This seems to reflect the combined impact of land clearance, demographic shifts, poverty, impaired public health services, and regional climatic changes, as reviewed by Patz. At the global level, there is clearer perception of