The presence of hundreds of potentially toxic chemical substances in the environment, generally caused by human activity, is the cause of chemical pollution. These pollutants contaminate the water, soil, air and food.
A general classification of chemical pollutants based on their chemical structure includes:
Organic chemical pollutants – are those chemicals of organic origin or that could be produced by living organisms or are based on matter formed by living organisms. Common organic chemical pollutants include:
- Crude oil and petroleum refined products (e.g., gasoline, diesel fuel, kerosene, mineral spirit, motor oil, lubricating oil);
- Solvents (e.g., acetone, MEK, toluene, benzene, xylene) used in industry as well as in many household products;
- Chlorinated solvents (e.g., PCE, TCE, 1,1,1-TCA, 1,2-DCA, 1,1,2-TCA) used in industrial degreasing processes, as well as in dry cleaning, and in various household products;
- PAHs (polyaromatic hydrocarbons) are found in petroleum products, crude oil, but are also a result of burning activities (e.g., from coal power plants as well as historical manufacturing gas plants);
- PCBs (polychlorinated biphenyl ethers) which are now banned but were used in transformers and are already present in large amounts in environment
- Alcohols (e.g., ethanol, methanol, isopropanol) are used in a large variety of applications and household products;
- Trihalomethanes (e.g., chloroform, dibromochloromethane, chlorobromomethane, bromoform) which are common products of water chlorination
- Phenols are usually an indication of waste water and a result of industrial processes;
- Plastics are a result of industrial processes as well as our daily activities involving using and disposing of a large variety of plastics (e.g., bags, bottles, containers);
- Pesticides / Insecticides / Herbicides are commonly used in agriculture and may contain toxic organic chemicals and metals (such as mercury and arsenic);
- Detergents (e.g., nonylphenol ethoxylate) include a variety of chemical compounds with surface activity;
- Organo-metallic compounds (e.g., organo-arsenicals, organo-mercurials) are usually pesticides / insecticides / herbicides.
Inorganic chemical pollutants – are those chemicals of mineral origin in (not produced by living organisms). Common inorganic chemical pollutants include:
- Metals and their salts – usually from mining and smelting activities, as well as disposal of mining wastes;
- Inorganic fertilizers (e.g., nitrates, phosphates) used largely in agriculture and gardening. If present in large amounts in water they can be harmful to human health and usually trigger algae blooming events;
- Sulfides (such as pyrite) are usually mined minerals and once disposed of in the environment, they may generate sulfuric acid in the presence of precipitation water and microorganisms
- Ammonia is a poisonous gas if released in higher amounts and may cause blindness followed by death;
- The oxides of nitrogen and sulfur are very common air pollutants resulting from vehicle emissions, industrial processes, and other human activities
- Acids and bases are used in a variety of industrial applications as well as in chemical laboratories. These are less problematic chemicals because their effect can be easily neutralized in the environment, but if spread in large amounts they may still pose a threat to environment and human health;
- Perchlorate includes the perchloric acids and its various salts. Perchlorate is used in a variety of applications including rocket fuel, explosives, military operations, fireworks, road flares, inflation bags, etc. Perchlorate is problematic because it is persistent and may damage thyroid function in humans.