Tin (whole blood)

Tin is present in the air, water, soil, and landfills and is a normal part of many plants and animals that live on land and in water. Tin is also present in the tissues of your body. There is no evidence that tin is an essential element for humans.

Since tin is naturally found in soils, it will be found in small amounts in foods. Tin concentrations of vegetables, fruits and fruit juices, nuts, dairy products, meat, fish, poultry, eggs, beverages, and other foods not packaged in metal cans are generally less than 2 parts per million (ppm) (1 ppm = 1 part of tin in a million parts of food by weight).

Tin concentrations in pastas and breads have been reported to range from less than 0.003 to 0.03 ppm. You can be exposed to tin when you eat food or drink juice or other liquids from tin-lined cans. Canned food from lacquered tin-lined cans contains less than 25 ppm of tin since the lacquer prevents the food from reacting with the tin. Food from unlacquered tin-lined cans contains up to 100 ppm of tin since the reaction of the food with the can causes some of the tin to dissolve in the contents of the can. Greater than 90% of tin-lined cans used for food today are lacquered. Only light colored fruit and fruit juices are packed in unlacquered tin-lined cans, since tin helps maintain the color of the fruit. Tin concentrations in food also increase if food is stored in opened cans. Stannous fluoride, a tin-containing compound, is added to toothpaste.

You can also be exposed to higher-than-normal levels of tin if you work in a factory that makes or uses tin. Because tin compounds have many uses, you can be exposed by breathing in tin dusts or fumes or getting tin compounds on your skin. Tin compounds can also be spilled accidentally. If you live near a hazardous waste site, you could be exposed by breathing dusts, touching materials, or drinking water contaminated with tin.

Humans are usually exposed to tin at far less than 1 ppm from air and water. The amounts in air and water near hazardous waste sites could be higher.

Young children sometimes eat soil during play. While most soil contains about 1 ppm tin, some soils may contain as much as 200 ppm tin. Assuming that children eat 200 mg of soil per day, exposure to tin from eating soil would be low.

You may be exposed to organic tin compounds (mainly butyltin compounds) by eating seafood from coastal waters or from contact with household products that contain organotin compounds, (polyurethane, plastic polymers, and silicon-coated baking parchment paper). Organic tin compounds have been detected in drinking water in Canada where pipes made of polyvinyl chloride (PVC), which contain organic tin compounds, are used in the distribution of drinking water.

Scientists use many tests to protect the public from harmful effects of toxic chemicals and to find ways for treating persons who have been harmed.

One way to learn whether a chemical will harm people is to determine how the body absorbs, uses, and releases the chemical. For some chemicals, animal testing may be necessary. Animal testing may also help identify health effects such as cancer or birth defects. Without laboratory animals, scientists would lose a basic method for getting information needed to make wise decisions that protect public health. Scientists have the responsibility to treat research animals with care and compassion. Scientists must comply with strict animal care guidelines because laws today protect the welfare of research animals.

Because inorganic tin compounds usually enter and leave your body rapidly after you breathe or eat them, they do not usually cause harmful effects. However, humans who swallowed large amounts of inorganic tin in research studies suffered stomachaches, anemia, and liver and kidney problems. Studies with inorganic tin in animals have shown similar effects to those observed in humans. There is no evidence that inorganic tin compounds affect reproductive functions, produce birth defects, or cause genetic changes. Inorganic tin compounds are not known to cause cancer.

Inhalation (breathing in), oral (eating or drinking), or dermal exposure (skin contact) to some organotin compounds has been shown to cause harmful effects in humans, but the main effect will depend on the particular organotin compound. There have been reports of skin and eye irritation, respiratory irritation, gastrointestinal effects, and neurological problems in humans exposed for a short period of time to high amounts of certain organotin compounds. Some neurological problems have persisted for years after the poisoning occurred. Lethal cases have been reported following ingestion of very high amounts. Studies in animals have shown that certain organotins mainly affect the immune system, but a different type primarily affects the nervous system. Yet, there are some organotins that exhibit very low toxicity. Exposure of pregnant rats and mice to some organotin compounds has reduced fertility and caused stillbirth, but scientists still are not sure whether this occurs only with doses that are also toxic to the mother. Some animal studies also suggested that reproductive organs of males may be affected. There are no studies of cancer in humans exposed to organotin compounds. Studies of a few organotins in animals suggest that some organotin compounds can produce cancer. On the basis of no data in humans and questionable data from a study in rats, EPA has determined that one specific organotin, tributyltin oxide, is not classifiable as to human carcinogenicity; that is, it is not known whether or not it causes cancer in humans.

References:

Toxicological Profile for Tin [L]