ABSTRACT
The air quality of large-and medium-sized cities is poor worldwide. Air pollution affects many countries but is the worst in the developing world. Soil is commonly contaminated with solvents, hydrocarbons derived from petrochemicals, heavy metals and pesticides. Organic pollutants are a major problem affecting water quality. Eutrophication occurs naturally as bodies of water age, but the process is accelerated by pollution. Many lakes in China are in the intermediate or advanced stages of eutrophication. Pollution from industry, agriculture and domestic life damages the ecosystem and is a major hazard to human health. Air pollution increases excess mortality rates especially in the developing countries. The incidence of gastrointestinal tract tumors is increased with consumption of contaminated water. Many environmental contaminants, pollutants and toxins interfere with immune defense, immune signal transduction, and induce hypoimmunity and do harm to population health.
