Tin - Toxicology of Metals - page 825

exposure to tin dust or fumes results in accumulation
of the particles of tin compounds in the lung tissues,
because it is poorly absorbed. Inorganic tin deposits in
the lung because of its insolubility and lack of absorp-
tion (Browning, 1969; Krigman and Silverman, 1984).
Thus, lungs are the main target organs for tin dust.
Inhalation of SnO 2 dust is a hazard in the deep mining
of tin, and a chronic industrial exposure to tin dust also
causes benign pneumoconiosis called stannosis (Pend-
ergrass and Pryde, 1948; Sluis-Cremer et al ., 1989). Inha-
lation of tin oxides in molten metal refi ning can lead to
the same condition. Silicosis and pulmonary heart dis-
eases were reported as common causes of death among
Chinese workers in tin mines in the late 1980s (Chen et
al ., 1992). There was nearly a sixfold increase in deaths
from pulmonary heart disease and approximately 50%
increase in mortality from nonmalignant respiratory
diseases. However, the risk from pulmonary heart dis-
eases among tin miners may be due to respirable silica
dust in hard rock tin mines (Chen et al ., 2005). It has also
been found that the risk of lung cancer was increased
among the tin miners and that silicosis seems not to be
related to the increased risk of cancer (Chen and Chen,
2002; Fu et al ., 1994). Later study analyzed mortality
among the UK tin miners and revealed an increased
risk of death from gastric cancer, especially among
underground workers (Raj et al ., 2003). The incidence
of gastric cancer was increased by 40% from 1941 to
1986. However, such an increase can be associated with
high concentration of radon in the UK tin mines and
exposure to arsenic, a by-product of certain tin mines.
Exposure of workers to a stannous chloride solution in
a bottle factory has caused wheezing, exertional short-
ness of breath, cough, and thoracic pain. However, it
has been shown that the causal agent was the hydro-
chloric acid released by the action of heat on the aque-
ous stannous chloride solution.

et al ., 1970). The toxic effects of tin depend on the con-
centration of tin in the foodstuff ingested (WHO, 2001).
There are several case reports of gastric irritation and
vomiting in humans consuming canned foods, espe-
cially acidic fruit products packed in unlacquered or
partially lacquered tinplate cans. Fifteen students were
poisoned after the consumption of canned orange bev-
erages in 1963, and a further 81 cases were reported
elsewhere. The symptoms observed were vomiting,
diarrhea, fatigue, and headache. Tin content of ran-
dom samples of cans from the same manufacturers
ranged from approximately 75-500 mg/kg; 113 cases
were reported in Washington and Oregon in 1969 after
ingestion of canned tomato juice (Barker and Runte,
1972). Analysis of tin from the juice consumed has
shown a tin content of 477 mg inorganic tin per liter
juice. In general, the levels of tin in foods, which are
responsible for these symptoms, are between 250 and
2000 mg/L. In the fruit juice, tin mostly exists in the
ionic form as complexes with acids (WHO, 2001).
Gastrointestinal irritation has been seen in cats, but
not dogs, given 5 or 10 mL/kg of orange juice contain-
ing >400 mg/kg of tin (Benoy et al ., 1971; Omori et al .,
1973).

5.1.1.3 Skin Contact
Tin tetrachloride, stannous chloride, and stannous
sulfate are strong acids, whereas sodium stannate and
potassium stannate are strong alkalies. Therefore, such
inorganic tin compounds can cause irritation of the
skin or the eyes because of acid or alkaline reactions
produced with water. Tin salts are irritants to the skin,
especially dusts or mists of acidic and basic tin salts.
However, despite widespread use of tin salts, only
occasional cases of allergic dermatitis in human have
been reported.

5.1.2 Distribution

5.1.1.2 Ingestion
In fact, inorganic tin compounds are comparatively
harmless because of their poor absorption, relative
insolubility, and low retention in tissue (Johnson and
Greger, 1982; Krigman and Silverman, 1984; Winship,
1988). Studies on animals and on human subjects show
that the absorption of ingested inorganic tin is approxi-
mately 5% in mice, rats, dogs, and monkeys, whereas
apparent absorption in humans is approximately 3%
from a diet supplemented with 50 mg tin/day (John-
son and Greger, 1982). Stannous compounds are more
readily absorbed from the gastrointestinal tract than
stannic compounds (WHO, 1980). Results of a study
on distribution of tin in green beans from cans and in
tin-free green bean puree indicated that stannous ions
are strongly bound to insoluble bean constituents, and
such complex prevents liberation of free tin ions (Horio

Tin is present in small amounts in all human and
animal organs, with approximately 352 mg total in an
adult man. Animals fed on tin-containing food may
accumulate tin in the body, and it is retained in the liver,
kidneys, heart, bones, and least in the brain (Brown-
ing, 1969). Tin is widely distributed after parenteral
injection, especially in the liver and spleen, where it
deposits in the reticuloendothelial system, and most
of it is excreted eventually in the urine and a little in
the bile (Barnes and Stoner, 1959). In mice, it has been
shown that intraperitoneally injected stannous chloride
is accumulated in all organs except the testis (Chiba
et al ., 1990). A 1% solution of SnCl 2 , when applied for 18
hours to dermal scratches in rabbits, produced a reac-
tion with intraepidermal pustules but none on intact
skin (Stone and Willis, 1968). It is generally accepted