Schafer & Femfert 1984 — Tin: a toxic heavy metal? A literature review
Summary
This 1984 review by Schafer and Femfert (Institut fur Pharmakologie und Toxikologie, Ludwig-Maximilians-Universitat Munchen, with Bergmannsheil Bochum) synthesizes the literature on tin toxicology to address whether tin properly belongs in the toxic-heavy-metal category alongside lead, cadmium, and mercury. The authors trace tin’s history from antiquity (Bronze Age tin alloys, Murano flat-glass mirrors, Dutch cochineal-tin lakes), summarize human and animal data on inorganic tin absorption, distribution, and toxicity, and review the distinct organotin literature. The review is the European-perspective counterpart to the later ATSDR 2005 monograph and is widely cited in subsequent occupational, food-safety, and regulatory tin reviews.
Key conclusions
Schafer and Femfert position tin as a borderline case among the heavy metals: dietary inorganic tin is poorly absorbed (around 5 percent absorption from typical exposures, with most ingested tin recovered in feces) and produces toxicity primarily through local gastrointestinal irritation rather than systemic accumulation, supporting the conclusion that ingested inorganic tin from canned food is a relatively low-concern toxicant compared to ingested lead or cadmium at comparable concentrations. The authors flag the very different organotin profile (alkyltins, especially tributyltin and triethyltin compounds, with central nervous system, immune, and reproductive endpoints at substantially lower doses) and argue that any treatment of “tin toxicity” that does not separate the species is of limited regulatory utility.
Implications
- Certification: This review pre-dates the modern HMTc analyte vocabulary but established the species-distinction principle that the wiki and HMTc both maintain. It is a foundational secondary source supporting the wiki’s separation of inorganic tin and organotin into distinct species pages.
- Courses: Useful for teaching the historical arc of metals in human use and why tin’s “heavy metal” classification has been contested across regulatory frameworks. The Schafer and Femfert framing prefigures the modern emphasis on species-specific risk assessment.
Limitations
The 1984 review predates substantial subsequent tin literature including the modern organotin exposure assessments, the ATSDR profile, EU 2023/915, and the FDA Total Diet Study extractions. It is cited here as a historical and synthetic reference, not as a current quantitative source for tin concentrations or thresholds.