Overview
Blunden and Wallace (ITRI Ltd, UK) review the literature on tin dissolution from tinplate food and beverage cans, surveyed occurrence values in retail canned foods, published acute clinical and human-incident reports of gastrointestinal effects following ingestion of tin-rich canned products, and the chronic-effect and absorption literature for divalent inorganic tin. The review’s central conclusion is that adverse gastrointestinal effects have been clinically documented at tin concentrations of approximately 700 mg/kg and above in canned foods or beverages, but that two human studies at higher concentrations reported no adverse effects, and that no published reports of acute adverse effects attributable to tin contamination in the 100-200 mg/kg range have appeared in the 25 years preceding the review. The authors estimate that approximately 4% of UK plain (unlacquered) tinplate food cans contain over 150 mg/kg tin and infer that the contents of roughly 25 million such cans containing at least 150 mg/kg tin are consumed annually in the UK alone without published acute-effect reports. The review supports the position that tin contamination at concentrations up to about 200 mg/kg in canned products is not associated with reported acute gastrointestinal effects, while noting that controlled clinical studies at these concentrations are absent. ITRI Ltd is the tin-industry research institute and the sponsorship context of the review is relevant when interpreting its overall framing.
Key numbers
Tin can production and use (pp. 1651-1652)
| Quantity | Reported value | Source cited in review |
|---|---|---|
| European food cans produced and filled per annum | ~25,000 million | Review’s own industry data |
| Worldwide food cans per annum | ~80,000 million | Review’s own industry data |
| Proportion of European food cans with plain (unlacquered) internal tin surface | ~20% | Review |
| European beverage cans per annum | >15,000 million tinplate (all internally lacquered) | Review |
| UK plain (unlacquered) tinplate food cans containing ≥150 mg/kg tin | ”almost 4%“ | MPMA, 2000 |
| UK plain (unlacquered) tinplate food cans per annum | ~2,500 million | MPMA, 2000 |
| Implied UK cans containing ≥150 mg/kg tin consumed per annum | ~25 million can contents | Review’s arithmetic |
Regulatory limits cited (p. 1653, Section 2)
| Limit body | Analyte | Matrix | Value | Cite in review |
|---|---|---|---|---|
| JECFA | Total tin | All sources | PTWI 14 mg/kg body weight | JECFA, 1988a, 1988b |
| Codex | Total tin | Solid foods | 250 mg/kg recommended maximum (200 mg/kg UK) | Codex, 1998; MAFF, 1992 |
| Codex | Total tin | Beverages | 150 mg/kg recommended maximum | Codex, 1998 |
| UK statutory | Total tin | Canned fruit and vegetables | 200 mg/kg | MAFF, 1999a, 1999b; FSA, 2002 |
Occurrence in canned foods (Section 4)
Table 1 of the review (p. 1654, citing Ratana-Ohpas et al. 1996) reports concentrations of total tin in conserves of acidic fruit:
Additional occurrence values cited in the review body:
| Population / matrix | Reported tin value | Source cited in review |
|---|---|---|
| French daily dietary tin intake | 2.7 mg/day, or 0.04 mg/kg bw/day | Biégo et al., 1999 |
| Fresh food | 0.03 mg/kg | Biégo et al., 1999 |
| Food in lacquered cans | 3.2 ± 2.3 mg/kg | Biégo et al., 1999 |
| Food in unlacquered cans | 76.6 ± 36.5 mg/kg | Biégo et al., 1999 |
| USA unlacquered (or partially lacquered) cans of grapefruit juice, orange juice, tomato sauce, and pineapple at can-opening | 51-150 mg/kg; mean across unlacquered cans 88 mg/kg | Greger and Baier, 1981 |
| UK canned pineapple survey, Jan-Mar 1999 | 50 mg/kg to 210 mg/kg | MAFF, 1999a |
| UK 2002 FSA repeat survey of canned fruit and vegetables | All but two samples (gooseberries) below 200 mg/kg statutory limit; mean 59 mg/kg across 234 unlacquered-can samples | FSA, 2002 |
| UK 1994 Total Diet Study | Canned vegetables contributed 66%, canned fruit 31% of 2.4 mg/day estimated total tin intake | MAFF, 1997 |
Storage-temperature effect on tin dissolution (Section 3, citing Calloway and McMullen, 1966)
| Matrix | Storage temperature comparison | Reported tin concentration after 20 months |
|---|---|---|
| US military rations, five fruit types, unlacquered cans | 37 °C versus 1 °C | 420 mg/kg vs 34 mg/kg (~12-fold increase) |
| US military rations, seven mixed-dish types, unlacquered cans | 37 °C versus 1 °C | 190 mg/kg vs 32 mg/kg (~6-fold increase) |
Acute clinical studies (Section 6.1.1, Primary reports)
| Study population | Tin concentration | Outcome | Source cited in review |
|---|---|---|---|
| 5 adults, 240 ml orange juice, pH 3.9 (no-nitrate arm) | 0, 498, 540 mg/kg | No overt adverse effects (review describes lower concentrations as “apparently without effect”) | Benoy et al., 1971 |
| 5 adults, 240 ml orange juice, pH 3.9 (nitrate-supplemented arm) | 730 mg/kg tin + 50 mg/kg nitrate | No overt adverse effects | Benoy et al., 1971 |
| 5 adults, 240 ml orange juice, pH 3.9 (no-nitrate arm) | 1,370 mg/kg | Nausea and/or diarrhoea in all 5; on re-administration one month later, nausea in 1 of 5 | Benoy et al., 1971 |
| 9 US Army personnel, 24 days, canned combat rations stored at extreme temperatures | Daily menus 99 (72-125) to 310 (273-356) mg/kg dry solids; average daily intake 162.8 mg (115.8-206.7) | No gastrointestinal effects specifically mentioned in the study report | Calloway and McMullen, 1966 |
| 8 men, 20 or 40 days, dietary tin 49.67 mg/day | ~50 mg/day total intake | No overt gastrointestinal effects | Johnson and Greger, 1982; Johnson et al., 1982 |
Acute clinical studies (Section 6.1.2, Secondary reports)
| Study population | Tin concentration | Outcome | Source cited in review |
|---|---|---|---|
| 4 participants, 6 days canned pumpkin and asparagus | Pumpkin 383-476 mg/kg, asparagus 361 mg/kg | No overt adverse effects | Dack, 1955 |
| 8 subjects, tomato-vegetable juice mixture (unpublished) | 700 mg/kg | Nausea in 2, nausea/diarrhoea in 2 | Cheftel, 1967 |
| Same 8 subjects, pH 4.5 citrate buffer with stannous chloride before meal | 700 mg/kg | Nausea/vomiting in 2, diarrhoea in 1 | Cheftel, 1967 |
| Unspecified number of volunteers | Fruit juice 342 mg | Gastrointestinal irritation symptoms | MAFF, 1983 |
| Same volunteers | Similar juice 125-182 mg | No effect | MAFF, 1983 |
Acute episode reports (Section 6.2)
Reported general dose range associated with episode reports: 250-2,000 mg/kg, predominantly in acidic fruits and fruit juices. Symptom frequency (combined across reports): nausea 97%, abdominal cramps 87%, vomiting 70%, headaches 57%, diarrhoea 33%, fever 13%. Incubation 15-30 minutes, duration 30 minutes to 3 weeks (Piscator, 1979; Schafer and Femfert, 1984; Dewitte et al., 2001; Barker and Runte, 1972).
| Episode | Tin concentration | Affected | Source cited in review |
|---|---|---|---|
| Swedish meeting, canned peaches | Fruit 413-597 mg/kg, juice 398 mg/kg, pH 3.9-4.1 | 76 of 85 respondents (89%) had GI symptoms; 95% of those eating ≥220 g | Svensson, 1975 |
| Washington/Oregon canned tomato juice, 1969 | 327-392 mg/kg (4 banquets, unopened can analyses) and 154-289 mg/kg (family outbreaks); 4 opened cans from family outbreaks 131-405 mg/kg | 113 cases over 3 months: two banquets with 43 and 22 cases respectively (~65% of those consuming juice at banquets affected); 30 family outbreaks (48 of 49 = 98% affected) | Barker and Runte, 1972 |
| Subsequent samples implicated lots | 227-294 mg/kg (partially detinned) to 381-477 mg/kg (completely detinned) | Detinning attributed to elevated nitrate (or sodium chlorate) | Barker and Runte, 1972 |
| Peaches | Fruit 350-600 mg/kg, liquor 220-440 mg/kg | Nausea/vomiting in 91 of unknown total | Nehring, 1972 |
| Canned peaches | ≥100 mg tin total dose | 74 of 78 GI disturbances | Piscator, 1979 |
| Canned peaches | 50 mg tin total dose | 2 of 7 GI disturbances | Piscator, 1979 |
| Repeated ingestion 3 × 24 days, 9 volunteers | 13, 33, 204 mg tin per ingestion from canned foods | No signs of toxicity | Piscator, 1979 |
| Volunteers, fruit juice | 500 mg/l | No signs | Piscator, 1979 |
| Volunteers, fruit juice | 1,370 mg/l | Digestive disturbances | Piscator, 1979 |
| Orange/grapefruit juice | 330-400 mg/kg | GI effects in unspecified consumer number | Anon., FDA Consumer, 1986 |
| Grapefruit juice, visibly corroded cans | 450 mg/kg | GI effects | Anon., The Guardian, 1972 |
| Orange juice | 100-494 mg/kg | At least 15 students with GI symptoms | Horio et al., 1967; JECFA, 1971, 1982 |
| Orange drink, Japan (Omori 1966) | 425-452 mg/kg (figures differ between reports) | 1,838 affected | Omori, 1966 |
| Orange and apple juice, Kuwait | 250-385 mg/kg | ”Large but unspecified” number | Metal Box Co., 1967 |
| Tomato juice (Kojima 1969) | 156-247 mg/kg (cited concentration); samples from same maker 75-500 mg/kg | 8 affected | Kojima, 1969 |
| Tomato juice (Horio 1967) | 156-221 mg/kg | 8 of 10 affected | Horio et al., 1967 |
| Vodka punch with pineapple/grapefruit juice, pH 3, retinned container | 2,000 mg/kg | 32 with severe GI | Warburton et al., 1962 |
| Canned salmon | 650 mg/kg | Family of 3 affected (vomiting, weakness, diarrhoea or abdominal pain) | Kwantes, 1966 |
| Canned rhubarb in school canteen | 350 mg/kg | 64 of 127 students affected | Kwantes, 1966 |
Non-human oral studies (Section 6.2.3, Table 2)
Acute oral LD50 of divalent inorganic tin compounds:
| Compound | Species | LD50 (mg/kg bw) | Source |
|---|---|---|---|
| Stannous chloride | Mouse | 1,200 | Pelikan et al., 1968 |
| Tin-citric acid complex (30% tin) | Mouse | 2,700 | Omori et al., 1973 |
| Sodium pentafluorostannate (67% tin) | Mouse | 590 | Conine et al., 1975 |
| Stannous chloride | Rat | 700 | Calvery, 1942 |
| Stannous chloride | Rat (fasted) | 2,300 | Conine et al., 1975 |
| Stannous chloride | Rat (fed) | 3,200 | Conine et al., 1975 |
| Sodium pentafluorostannate (67% tin) | Rat (fasted, F) | 220 | Conine et al., 1975 |
| Sodium pentafluorostannate (67% tin) | Rat (fasted, M) | 220 | Conine et al., 1975 |
| Sodium pentafluorostannate (67% tin) | Rat (fed, M) | 570 | Conine et al., 1975 |
| Stannous chloride | Rabbit | 10,000 | HSDB, 1999; JECFA, 1982; RTECS, 1999; WHO, 1980 |
Cats given orange juice containing 540 or 1,370 mg/kg tin by stomach tube at 5 or 10 ml/kg bw showed vomiting; apple juice at 605 mg/kg and pear nectar at 750 mg/kg were not emetic (Benoy et al., 1971). A Japanese study reported vomiting in 5 of 6 cats given 10 ml/kg bw orange juice at 452 mg/kg tin but not at 337 mg/kg (Omori et al., 1973).
Chronic effects and absorption (Section 7)
| Finding | Reported value | Source cited in review |
|---|---|---|
| Diet causing zinc-metabolism effects | ~50 mg tin/day for 40 days | Johnson et al., 1982 |
| Oral absorption of Sn²⁺ in humans (high-tin diet, 49.7 mg/day, 20 days) | ~3% (range -7% to +9%) | Johnson and Greger, 1982 |
| Oral absorption at low daily diet, 0.1 mg/day | ~27% (range -4% to +71%) | Johnson and Greger, 1982 |
| Inorganic tin in faeces of humans/animals | >90% of administered dose | ATSDR, 1992; Codex, 1998; COT, 1998; JECFA, 1982; Fritsch et al., 1977; Haguenoer and Furon, 1982; Hiles, 1974; Kutzner, 1971; Piscator, 1979; WHO, 1996; Winship, 1988; Tipton, 1969 |
| Rat single 20 mg Sn²⁺/kg bw oral dose absorption | ~3%, half excreted within 48 h | Hiles, 1974 |
| Rat 1.02% Sn²⁺ vs 4% Sn⁴⁺ retention in bones (oral) | Bones 1.02% / 4%; liver 0.08% / 0.02%; kidney 0.09% / 0.02% | Haguenoer and Furon, 1982; Piscator, 1979 |
| Rat IV inorganic tin retention 2 days post-injection | 35% Sn²⁺, 46% Sn⁴⁺ | Haguenoer and Furon, 1982; Piscator, 1979 |
| Bone half-life in rat | 34 days (Sn²⁺), 40 days (Sn⁴⁺) | Piscator, 1979 |
| ¹¹³Sn kidney/liver clearance in rat | 10-20 days | Piscator, 1979 |
| Human clearance phases (three-phase) | First 20% with half-life 4 days; second 20% with half-life 25 days; final 60% with half-life ~400 days | Winship, 1988 |
| Rat biological half-life | Bone 30-40 days; spleen 50 days; liver 85 days | Codex, 1998; JECFA, 1982; WHO, 1996 |
| Inorganic tin absorption (overall) | 2.8% for Sn²⁺ compounds, 0.64% for Sn⁴⁺ compounds | Review’s overview statement |
Overview-section worst-case dose calculation (Section 8)
If all canned foods and beverages contained 200 mg/kg tin and a 1 kg daily diet consisted of 4-8% canned foods (MAFF 1998), average daily intake would be 8-16 mg/day or 0.13-0.3 mg/kg bw/day for a 60 kg adult, which is approximately 7-fold below the JECFA reference of 2 mg/kg bw/day (the daily equivalent of the JECFA Provisional Tolerable Weekly Intake of 14 mg/kg body weight per week; JECFA 1988a, 1988b). The UK is described as the highest per capita European consumer of canned food and the largest consumer of plain unlacquered cans (~2,500 million annually, MPMA 2000); approximately 4% probably contain at least 150 mg/kg tin, implying contents of ~25 million such cans containing this concentration are consumed annually in the UK without published acute-effect reports in the prior 25 years.
Evidence Fitness
This is a narrative literature review without explicit search-and-selection protocol or PRISMA-style inclusion criteria, sponsored by ITRI Ltd (the International Tin Research Institute). It contributes no primary heavy-metal measurements and no occurrence distributions of its own; all quantitative figures it presents are second-hand summaries of the underlying primary studies that should be obtained as primary evidence. Public evidence label “Context only” is appropriate.
The source supports literature-context claims about (i) the magnitude and variability of tin dissolution from unlacquered tinplate into canned acidic foods and beverages, (ii) the approximate concentration threshold (700 mg/kg and above) at which controlled clinical studies have detected acute gastrointestinal effects from divalent inorganic tin, (iii) the absorption-limited and local-irritation mechanism of inorganic tin GI effects, and (iv) the historical regulatory framework (JECFA PTWI 14 mg/kg bw, Codex 250 mg/kg solid / 150 mg/kg beverage, UK 200 mg/kg statutory). It should not be used as the basis for HMTc threshold work for tin in canned product categories, which should reference the primary occurrence studies (Biégo 1999, Greger and Baier 1981, Ratana-Ohpas 1996, MAFF/FSA UK surveys) and the primary clinical studies (Benoy 1971, Calloway and McMullen 1966, Johnson 1982) directly, and should account for the review’s industry-sponsored framing when interpreting its overall position.
Methods (brief)
Narrative literature review with no stated search strategy, inclusion/exclusion criteria, quality appraisal, or quantitative pooling. The authors restrict the review (with stated exceptions for particular relevance) to reports published after 1970, citing changes in can-making technology (elimination of soldered side-seams, improvements in filling procedures) as the rationale for the cutoff. The review organises evidence into seven thematic sections: introduction and packaging context, background tin chemistry, factors affecting tin dissolution, surveyed levels in foods, toxicology overview, acute effects (clinical studies and consumption episodes), and chronic effects (including absorption, distribution and excretion). No new measurements are reported. Quantitative figures in tables and prose are reproduced verbatim from cited primary sources.
Implications
Certification: Process and toxicology context only. The review supports the general claim that tin in canned acidic foods and beverages is associated with acute gastrointestinal irritation at concentrations of approximately 700 mg/kg and above in controlled studies, with episode reports at 250-2,000 mg/kg, and that the JECFA PTWI of 14 mg/kg bw/week is approximately 7-fold above the worst-case daily intake estimable from a diet at the 200 mg/kg statutory limit. HMTc threshold-setting for tin in canned product categories should reference the primary occurrence and clinical studies directly rather than this review, and should treat the review’s “little evidence of acute effects at up to 200 mg/kg” framing with the caution appropriate to industry sponsorship.
Courses: A useful entry point to the tin-canned-food acute-effect literature for course modules covering the local-irritation versus systemic-absorption distinction (tin is one of the few heavy metals where the principal acute effect is gastrointestinal irritation and absorption is below ~3% for divalent forms), the relationship between can construction (unlacquered tinplate, nitrate-driven detinning, storage temperature) and tin migration, and the regulatory landscape for tin in canned foods. The review provides convenient pointers to the primary studies and should be presented to learners alongside source-sponsorship context.
App: No ingredient contamination_profile impact directly from this review. Per-product caution flags for canned acidic juices and fruits in unlacquered tinplate, particularly after extended storage at warm temperatures, are supported by the underlying primary literature this review compiles.
Related evidence
- Tin
- Tin, Inorganic
- Tomato
- Canned tomatoes
- Orange juice
- Grapefruit juice
- Pineapple
- Peach
- Asparagus
- Guava
- Mango
- Canned Foods, General
- Canned Fruit — REDIRECT (Cat 7 sub-variant of Canned foods, general)
- Canned Tomatoes — REDIRECT (Cat 7 sub-variant of Canned foods, general)
- Canned Vegetables — REDIRECT (Cat 7 sub-variant of Canned foods, general)
- Fruit Juices, Non-Apple
- Fruit Juices, Apple-Containing
- Codex CXS 193-1995 - Tin maximum levels for canned foods
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