Pyridine is a flammable colorless liquid with an unpleasant smell. It can be made from crude coal tar or from other chemicals. Pyridine is used as a solvent and to make many different products such as medicines, vitamins, food flavorings, pesticides, paints, dyes, rubber products, adhesives, and waterproofing for fabrics. Pyridine can also be formed from the breakdown of many natural materials in the environment. Many of the foods that you eat have flavors that are the result of complex compounds that contain pyridine.
Liquid pyridine evaporates into the air very easily. If pyridine is released to the air, it may take several months to years until it breaks down into other compounds. Pyridine also mixes very easily with water. If it is released to water or soil, it may break down in a few days to few months.
Pyridine and pyridine-containing compounds are present throughout the environment at very low levels. Pyridine has been found in the air inside and around factories that produce it or use it to make other products. You could be exposed to pyridine if you work in one of these factories or if you live or work near a hazardous waste site that releases it to the surrounding air. Pyridine is also released into the air from burning cigarettes and from hot coffee.
Pyridine is not usually found in rivers or other natural waters. It has been found in wells in an industrial area in Wyoming. The levels of pyridine in the well water were as high as 53 parts of pyridine in 1 billion parts of water (53 ppb). Pyridine is not usually found in the soil near hazardous waste sites or in industrial areas. Pyridine has been found in drinking water samples taken around hazardous waste sites and industrial areas. However, we do not know the levels. It is also found in certain foods such as fried chicken, cheese, and fried bacon. Although the levels in these foods are not known, they are probably very low and are not expected to result in any health effects. The level of pyridine in some frozen mango (a tropical fruit) was reported to be 1 part of pyridine per million parts of mango (1 ppm). You could be exposed to small amounts of pyridine if you eat these foods or drink water containing pyridine.
Pathways in the body
Pyridine can enter your body when you breathe in air, drink water, or eat food that contains this chemical, or by skin contact with the chemical. When it enters your body by mouth, more than half of it is absorbed. Within 1 day, most of what was absorbed leaves your body in urine as pyridine itself or its breakdown products. We do not know what happens to the rest of it. There is also no information about what happens to pyridine that is breathed in or gets on your skin.
Very few studies have been conducted to determine the possible effects of pyridine exposure on human health. From case reports on humans and studies in animals, we think the most important health concern for humans exposed to pyridine will be damage to the liver. Other health concerns for humans may be neurological effects, renal effects, and irritation of the skin and eye. We do not know whether pyridine can cause cancer, birth defects, or problems with reproduction.
Tests can be used to find out whether you have been recently exposed to pyridine. These tests measure levels of pyridine in urine and blood. They use special equipment and are done in special laboratories, so they are not usually available in a doctor's office. The levels of pyridine in urine or blood cannot be used, however, to find out how much pyridine you were exposed to or whether specific harmful effects will occur.
Disclaimer: This article is taken wholly from, or contains information that was originally published by, the Agency for Toxic Substances and Disease Registry. Topic editors and authors for the Encyclopedia of Earth may have edited its content or added new information. The use of information from the Agency for Toxic Substances and Disease Registry should not be construed as support for or endorsement by that organization for any new information added by EoE personnel, or for any editing of the original content.