Tin [Sn, 50]
333
(Reilly 2002). Its compounds in the liver were estimated within the ranges, as
follows (in mg/kg fresh weight [FW]): MBT, 0.0003–0.018; DBT, 0.0008–0.066;
and TBT, <0.0003–<0.0020 (ATSDR 2005b).
Most natural foods contain Sn in trace amounts, but its concentrations are
increased due to the use of organotin pesticides and the storage of liquids in cans.
In most unprocessed foods, inorganic and total Sn levels are generally <1  mg/kg
(Table 50.2).
The primary sources of Sn are canned goods (Table 50.2). Elevated Sn concentrations can be, as Sn 2+ , in canned foods due to dissolution of the Sn coating or plate. Tin
levels are usually below 25 mg/kg in lacquered food cans, but may exceed 100 mg/kg
in unlacquered cans. Its contents in canned foods increase with storage time and
temperature, and depend largely on the type and acidity of the food. Acidic foods are
more aggressive to the Sn coating in metal cans, and therefore canned acidic foods
have its higher contents. Oxidizing agents (nitrates, Fe salts, Cu salts, S) accelerate
detinning, whereas Sn salts, sugars, and gelatin reduce the dissolution rate.
According to the World Health Organization (WHO), the maximum limit of Sn in
canned food is 250 mg/kg; the Joint FAO/WHO Expert Committee on Food Additives
established a provisional tolerable weekly intake (PTWI) for Sn as 14 mg/kg bw
TABLE 50.2

Tin in Foodstuffs (mg/kg FW)

a
Product
Content
b
c
Food of Plant Origin
Bread and miscellaneous cereals
0.02, 0.03
<0.02
–
Green vegetables
0.02
0.003
–
Other vegetables
0.02
0.012
–
Potatoes
0.02
0.007
–
Canned vegetables
44
36.1
<2–11
Fruit products
17
11.1
41–148
Food of Animal Origin
Carcass meat
0.02
<0.01
–
Canned meat
–
–
<2
Fish
0.44
0.021
–
Canned fish
–
–
<2
Tuna flakes in water
–
–
0.70
Dairy products
–
0.03
<2 (canned)
Canned baby foods
–
–
<2
a
Sources: Ysart, G. et al., Food Addit. Contam., 16, 391–403, 1999;
b Rose, M. et al., Food Addit. Contam., 27, 1380–1404, 2010;
c Boutakhrit, K. et al., Food Addit. Contam., 28, 173–179, 2011.
FW, fresh weight.