Tin

Tin is a soft, white, silvery metal found in the earth's crust. Tin combines with other chemicals to form compounds. It is used in brass, bronze, pewter, and some soldering materials. It also combines with chemicals like chlorine, sulfur, or oxygen to form inorganic tin compounds. Tin can also combine with carbon to make organotin compounds.

Uses
Tin is used to line cans for food, beverages, and aerosols. Inorganic tin compounds are also used in toothpaste, perfumes, soaps, food additives, and dyes. Organotin compounds are used in plastics, food packaging, plastic pipes, pesticides, paints, and pest repellents.

In the Environment
Tin metal as well as both organic and inorganic tin compounds are found in air, water, and soil near places where they are naturally present in rocks or where they are mined, manufactured, or used. In is released into the environment by natural processed and human activities like mining, coal and oil combustion, and the production or use of tin compounds. When metallic tin is released into the environment, it will quickly form inorganic compounds. Organic tin compounds can be degraded into inorganic tin compounds by sunlight and bacteria.

"In the atmosphere, tin exists as gases and fumes, and attaches to dust particles. Particles in the air containing tin may be transported by wind or washed out of the air by rain or snow." Both inorganic and organic tin binds to soil and to sediments in the water, but some inorganic tin compounds can dissolve in water. Organic tin compounds can bioaccumulate in fish, plants, and other organisms.

In Sewage Sludge
Tin is one of many metals found in sewage sludge, and it can enter the environment when sewage sludge is applied to land. In the Targeted National Sewage Sludge Survey, a 2009 test of 84 samples of sewage sludge from around the U.S., the EPA found tin in 78 samples (93%) in concentrations ranging from 7.50 to 522 parts per million.

Human Exposure
Humans are exposed to tin by eating or drinking liquids from tin-lined cans. However, today 90% of tin-lined cans used for food are coated with lacquer. Humans are also exposed to tin by breathing air or touching dusts containing tin, either in the workplace or near hazardous waste sites. Additionally, humans can be exposed to organotin compounds by eating seafood or from contact with household products containing organotin compounds.

Health Effects
"Metallic tin is not very toxic due to its poor gastrointestinal absorption. Human and animal studies show that ingestion of large amounts of inorganic tin compounds can cause stomachache, anemia, and liver and kidney problems."

"Breathing or swallowing, or skin contact with some organotins, such as trimethyltin and triethyltin compounds, can interfere with the way the brain and nervous system work. In severe cases, it can cause death."

"Some organotin compounds, such as dibutyltins and tributyltins, have been shown to affect the immune system in animals, but this has not been examined in people. Studies in animals also have shown that some organotins, such as dibutyltins, tributyltins, and triphenyltins can affect the reproductive system. This, also, has not been examined in people."

"Inorganic or organic tin compounds placed on the skin or in the eyes can produce skin and eye irritation."

Last, the organotin triphenyltin hydroxide cause cancer in mice and rats after long-term oral administration in studies.

Related SourceWatch articles

 * Biosolids
 * Sewage sludge
 * Food Rights Network

External resources

 * Agency for Toxic Substances & Disease Registry, ToxFAQs for Tin

External articles

 * Voulvoulis N, Scrimshaw MD, Lester JN., "Removal of organotins during sewage treatment: a case study", Environmental Technology, June 2004.