The Significance of Health Risks Caused by Chemical Compounds

Assessing health risks induced by exposure to chemical compounds is differ­ent in different societies. Typically, in industrialized societies, traffic exhausts, ex­
hausts of power plants, and indoor and outdoor emissions of the chemical industry are the greatest concerns. In the occupational environment, one deals with relatively high exposure levels, whereas among the general public, one deals with very low exposure concentrations but large exposed populations, which complicates the assessment of the additional risks caused by the exposure. Also, the magnitude of risks may vary widely The excess risks of the general population due to air pollution (nitric and sulfur dioxide, ozone, small particles) in Europe and the United States are between one and five percent in terms of excess mortality. In Europe this corresponds, however, to between 50 000 and 100 000 extra deaths. In occupational environments, the exposure levels may be several fold as compared to environmental risks, perhaps even orders of magnitude higher, but usually the exposure levels are relatively low when compared with the situation 20 or 30 years ago. Also, in occupational environments, the exposed populations can be clearly defined, and appropriate measures can be undertaken to avoid excessive exposure. In industrialized countries, the exposures are nowa­days much better regulated than before. This does not imply that toxicity and risk assessment are any less important for guaranteeing chemical safety for workers
and the general population. It simply means that the nature of exposures and their consequences have changed; rather than causing acute poisonings, exposures in these societies cause long-term effects such as allergies, cancers, and other chronic diseases such as cardiovascular diseases and asthma. The risk assessment of long­term effects of chemical exposures is much more demanding than assessing the risks of deterministic effects due to high exposures.49’180’201-204

In developing countries, exposure to chemicals, e. g., pesticides, is respon­sible for millions of acute poisoning cases and hundreds of thousands of fatal­ities every year.203 This is due to the low standard of living, poor education, failure to appreciate the significance of hygienic measures and the effects of the compounds, and general attitudes. Furthermore, most developing coun­tries are situated in subtropical or tropical areas where the use of a number of chemicals, such as pesticides, is a necessity. Thus, inadequate safety measures, regulations, and education easily lead to careless use of highly toxic com­pounds. Much can be done to alleviate this situation, e. g., experts can visit to highlight problems in these countries, but ultimately the situation can only be improved by measures in each country. These measures will include improved education and increased awareness of the toxicity of the compounds and ap­propriate safety measures.

A good example is the accident that took place in Bhopal, India, in 1984. An explosion in a pesticide plant producing carbaryl, a highly toxic insecti­cide, caused a release of the raw material of the pesticide, methyl isocyanate, into the environment. In all, 10-25 tons of this highly toxic and reactive com­pound were released into the densely populated area surrounding the plant. The LC50 value (concentration that kills 50% of the exposed experimental animals) of the gas is 10-30 ppm. In the Bhopal region, the exposure resulted in 5000 deaths and 100 000 less severe poisonings, with 5000 persons suffer­ing permanent damage to their respiratory systems.41