Tin

Tin (Sn, atomic number 50) is a soft silvery metal that is overwhelmingly encountered in the modern food system through tinplated steel cans, where the elemental tin lining contacts the food and dissolves into it as inorganic tin in proportion to the food’s acidity, the can’s lacquering status, and the storage time and temperature. Tin’s relevance as a food-safety analyte is dominated by this canned-food-and-beverage pathway and by a structurally separate organotin pathway that derives principally from seafood (legacy tributyltin antifouling paint contamination of marine sediments), from PVC food-contact materials and drinking-water pipes, and from historic organotin pesticide and biocide use.

The wiki maintains the inorganic-tin and organotin species split throughout, because the toxicology of the two classes differs by approximately three orders of magnitude in derived oral MRLs (inorganic tin MRL 0.3 mg/kg/day intermediate; tributyltin oxide MRL 0.0003 mg/kg/day chronic; ATSDR 2005). Total tin reported by an occurrence survey in canned food matrices is treated as inorganic tin context; total tin in seafood, drinking water from PVC distribution, or food in PVC food-contact materials is treated as a mixed signal that requires speciation evidence before any toxicological interpretation. The species pages tin-inorganic and organotins carry the species-specific toxicology, occurrence, regulatory, and testing synthesis. This parent page covers tin as element and the cross-species framing.

Toxicology

The toxicology of tin is split fundamentally along the inorganic-versus-organotin line. Inorganic tin (the form ingested from canned food) is poorly absorbed (around 5 percent absorption from typical exposures, more than 90 percent excreted in feces) and produces toxicity primarily through local gastrointestinal irritation rather than systemic accumulation. The threshold for symptomatic effects from ingested inorganic tin is approximately 1,000 to 1,400 ppm in fruit juices in controlled human single-dose challenges (Benoy 1971), well above the canned-product regulatory caps in any major jurisdiction. Organotin compounds, by contrast, are lipophilic and well-absorbed, distribute systemically, and produce immune-system, central nervous system, and reproductive endpoints at exposures three orders of magnitude lower than the inorganic tin symptomatic threshold (ATSDR 2005).

The species-distinction principle was established in the European regulatory toxicology literature by Schafer and Femfert 1984 and is the basis of the wiki’s separate-species-page architecture. Tin shares this dual-species pattern with chromium (where Cr-VI and Cr-III differ by orders of magnitude in toxicity) and with arsenic (where iAs and the various organic species differ by orders of magnitude in carcinogenicity). For all three elements, total-element measurement without speciation produces values that cannot be honestly mapped to toxicity-derived guidance.

Typical exposure routes

Ingestion of canned acidic foods (fruit juices, fruit cocktails, tomato products, pickled foods, some vegetables, alcoholic beverages in cans) is the dominant inorganic-tin dietary route; see tin-inorganic for full detail. Ingestion of seafood from coastal waters with historic tributyltin-paint loading is the dominant dietary organotin route, with bivalve molluscs and crustaceans the highest-organotin categories; see organotins. Drinking water from PVC distribution can carry organotin from pipe stabilizers; food in PVC food-contact materials can carry migrating organotin stabilizers; vegetable oils have been flagged in some legacy datasets as organotin-bearing. Inhalation exposure is occupational (smelting, electronics, PVC manufacturing) and outside dietary scope.

Food sources and occurrence

Canned acidic foods are the dominant high-tin matrix in dietary surveillance. The FDA Total Diet Study FY2018-FY2020 dataset includes canned-corn, canned-fruit-cocktail, canned-green-beans, canned-mushrooms, canned-tomatoes, ketchup, tomato-soup, and similar acidic canned matrices in its ingredient roster; per-ingredient tin values are integrated on the corresponding ingredient pages. Tarigan 2016 reports Indonesian canned-beverage tin between 2.5 and 5.8 mg/kg with the expected acidity-and-storage-time release pattern. ATSDR 2005 Tables 6-2 and 6-3 (Biego et al. 1999 source data) report canned-vegetable category means in the high tens of mg/kg versus non-canned dietary staples at or below 0.003 mg/kg, a three-order-of-magnitude separation.

Organotin food-occurrence data is thinner in the loaded corpus. ATSDR Table 6-4 summarizes tributyltin levels in seafood across multiple geographic surveys with central tendencies in nanograms per gram wet weight; primary sample-level organotin datasets are not yet loaded on the wiki and are a documented evidence gap.

Regulatory limits

The single loaded regulatory framework with binding inorganic-tin maximum levels is 915: 200 mg/kg in canned food other than canned beverages; 100 mg/kg in canned beverages; 50 mg/kg in canned infant formula, follow-on formula, and young-child formula; 50 mg/kg in canned baby food and processed cereal-based food; 50 mg/kg in canned infant and young-child medical foods. The U.S. has no equivalent FDA action level for tin in food; FDA addresses tin through Total Diet Study surveillance and contact-material guidance. Codex CXS 193-1995 sets a 250 mg/kg general food maximum for inorganic tin in canned foods other than canned beverages and 150 mg/kg for canned beverages, looser than EU 2023/915.

Finished-food regulatory limits for organotin compounds are not loaded in the wiki corpus. Organotins are addressed through plastic food-contact-material migration limits (EU 10/2011) and through the IMO global ban on TBT antifouling paints (in force 2008) rather than through finished-food caps. See organotins for the regulatory discussion.

Testing methods

Atomic absorption spectrophotometry (AAS) at 286.3 nm with air-acetylene flame is the historical method for total tin; ICP-MS after microwave digestion is the routine modern multi-element method and produces total-tin values. Speciation-preserving methods using gas chromatography or HPLC with element-specific detection are required to distinguish inorganic tin from organotin. The species pages tin-inorganic and organotins cover the methodological detail and tradeoffs.

Microbiome effects

The current corpus is largely silent on tin-microbiome interactions. Inorganic tin is poorly absorbed and would interact mostly with the gastrointestinal mucosa and gut microbiota during transit. Organotins are documented antimicrobial agents at sub-toxic concentrations and would plausibly perturb microbial communities at chronic dietary exposures. Both are candidate gaps for WikiBiome crosswalk when source material is identified.

Vulnerable populations

Infants and young children fed canned baby food are the principal vulnerable group for inorganic tin, recognized in EU 2023/915 by the 50 mg/kg infant-and-young-child cap (one-quarter of the general canned-food cap). Frequent seafood consumers are the principal vulnerable group for organotins, particularly populations with high reliance on bivalves and crustaceans from coastal waters with legacy TBT contamination. Body-weight-normalized intake makes both populations more vulnerable than absolute concentrations alone suggest.

Sources

• ATSDR 2005 — Comprehensive ATSDR Toxicological Profile for Tin and Tin Compounds. Foundation source for both species pages.
• Benoy, Hooper, Schneider 1971 — Primary canned-juice toxicity study; symptomatic-threshold and absorption-mechanism evidence for inorganic tin.
• Tarigan, Silalahi, Muchlisyam 2016 — Indonesian canned-beverage tin release with pH-and-storage dependence; supporting context.
• Schafer & Femfert 1984 — Historical European review establishing the species-distinction principle.
• 915 — Binding maximum levels for inorganic tin in canned food and canned infant/young-child foods.
• Ufelle & Barchowsky 2021 — Toxic Effects of Metals chapter; brief tin context.