7091

• UCREFRP Catalog Number: 7091
• Author: Eisler, R.
• Title: Tin Hazards to Fish, Wildlife, and Invertebrates
• USFW Year: 1989.
• USFW - Doc Type: A Synoptic Review.
• Copyright Material: NO

concentration producing outbreaks was about 250 mg Sn per liter in canned
orange and apple juice. Ingestion of 50 mg of tin through eating canned
peaches that contained Sn concentrations of about 450 mg/kg caused acute
symptoms in 2 of 7 human volunteers (WHO 1980). Inhalation of SnO dust is a
hazard in the deep-mining of tin; deposits in lungs are easily det9ctable as
"stannosis" (Krigman and Silverman 1984).
Inorganic tin and its salts are not highly toxic due to their poor
absorption, relative insolubility of their oxides, and rapid tissue turnover
(WHO 1980; Hassett et al. 1984; Krigman and Silverman 1984; Blunden and
Chapman 1986). The absorption of ingested inorganic tin is usually less than
5%, although up to 20% has been reported. Stannous compounds are more readily
absorbed from the gastrointestinal tract than stannic compounds, but absorbed
tin leaves the vascular system rapidly. Bone is the main site of tin
deposition, followed by lung, liver, and kidney. Penetration of the
blood-brain and placental barriers by inorganic tin seems to be very slight.
Except for lung, inorganic tin does not accumulate in organs with increasing
age. Absorbed inorganic tin is excreted mainly in the urine, although
excretion through the bile may account for up to 15% of the total. Tin and
its inorganic compounds do not produce significant dermatitis or allergic
reactions to skin epithelium, and results of all long-term studies of
carcinogenicity, teratogenicity, and mutagenicity have been negative to date
(WHO 1980).
The half-time (Tbi) of inorganic tins in animals was reviewed by WHO
(1980). Studies with Sn+? in mouse, rat, monkey, and dog show that in all
species elimination is a four-compartment process regardless of the route of
administration (i.e., intraperitoneal or intravenous). The Tb- for the
longest-lived Sn component was >3 months. In studies with rats, for exfmple,
radiotin-113 in skeleton following intramuscular administration had a Tb2 of
3 to 4 months, but for oral administration of Sn+2 and Sn+4 it was only 28 to
40 days in bone and 10 to 20 days in liver and kidney.
Inorganic tin can be biomethylated by microorganisms in the aquatic
environment and subsequently mobilized in the ecosystem (Tugrul et al. 1983;
Yemenicioglu et al. 1987). The process is slow and usually does not proceed
beyond the monomethyltin stage (Zuckerman et al. 1978), although dimethyltin
formation by Pseudomonas bacteria has been reported (Smith 1978b).
Tin is an essential nutrient for growth in the rat, and a tin-deficient
diet leads to reduced growth (WHO 1980; Krigman and Silverman 1984). The
mechanism of action is unclear, but involves increasing metabolic activity of
liver lysosomes and liver hydrolytic enzymes during regeneration (Dwivedi et
al. 1985a,b).
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