A REVIEW OF THE TOXICOLOGY OF AIR-POLLUTANTS - TOXICOLOGY OF CHEMICAL-MIXTURES

On a temporal basis, air has immense capacity for moving a large mass of pollutants. Mammals and birds are exposed to pollutants in air by t he inhalation (nose and mouth), cutaneous or ocular routes. Most labor atory studies on air pollutants have been limited to single air pollut ants and very little research has been done on the complex mixture of compounds that exist in ambient air. Complex mixtures are further comp licated by dynamic chemical reactions that occur after the emissions l eave point sources. Exposure parameters are also important in the toxi city of air pollutants, Intermittent exposure of monkeys to ozone incr eased the adverse pulmonary effects. Superimposing spikes of 0.8 ppm n itrogen dioxide on a baseline of 0.2 ppm, as occurs on a calm winter d ay, increased the susceptibility of mice to bacteria-induced pneumonia . Sulfur dioxide at concentrations of 5 ppm increased pulmonary resist ance by 39% Sulfuric acid is the predominate acid particle in the atmo sphere. Exposure for 1 h to >200 mu g sulfuric acid/m(3) depressed bro nchomucociliary clearance. Concentrations of 100 mu g/m(3) of photoche mical products caused headaches and 510 mu g/m(3) produced cough and c hest pain. For chemical interactions in dose response, nitrogen dioxid e is synergistic with ozone and ammonium sulfate. When all 3 chemicals are used in mixture, the response was 340%. atmospheric conditions, s uch as fog, can alter the toxicity of air pollutants. The dose respons e to a single chemical can be altered by chemical mixtures and pre-exi sting disease conditions. Understanding these relationships is importa nt for establishing no observable adverse effect levels. Mechanisms fo r multiple chemical interactions are multifaceted. One chemical may in terfere with the metabolism or detoxification of another. Others may i nteract at cell receptors. To understand the effects of multiple chemi cal interactions of air pollutants, there Is a need for a blend of epi demiological, laboratory and field studies. Studies are expensive. In the rural agricultural settings, the economic and environmental health risks are high. Should field observations and chemical problems be us ed as ''red flags'' for action?