Occurrence of Tin in Foods and Dietary Exposure Assessment in Zhejiang Province, China

TL;DR

This study assesses tin exposure in Zhejiang Province, China, finding that canned foods pose the highest risk, especially for young children.

Contribution

The study provides the first systematic assessment of tin occurrence and dietary exposure in Zhejiang Province, including a novel evaluation of organotin compounds.

Findings

Canned foods had higher tin concentrations compared to other food categories.

Children under 6 years are most vulnerable to organotin exposure from canned foods and aquatic products.

Overall tin exposure is low, but high consumption of processed foods may increase health risks.

Abstract

The food system of Zhejiang Province, a major coastal province in China, includes a wide variety of products, such as canned foods, aquatic products, vegetables, fruits, and tea, all of which may serve as potential sources of tin (Sn) exposure. However, no systematic study has assessed the distribution and dietary exposure risk of Sn across food categories in the province, and a compound-specific evaluation of organotin compounds is lacking. Therefore, we investigated the occurrence of Sn in commonly consumed foods and assessed dietary exposure risks among different age groups in Zhejiang Province. In total, 2014 samples from five major food categories—fresh vegetables, fresh fruits, tea, fresh aquatic products, and canned foods—were collected using a multistage stratified random sampling strategy. The Sn concentrations were measured using inductively coupled plasma mass spectrometry, with non-detection replaced by half the detection limit. Dietary intake data were derived from the 2015–2017 Nutrition and Health Surveillance using a 3-day, 24 h recall. The estimated daily intake and total hazard quotient (THQ) were calculated for age-specific risk assessments under multiple exposure scenarios. Fresh vegetables, fruits, tea, and most aquatic products had low Sn concentrations, whereas canned foods, particularly fruits, fungi, and meat products, had higher Sn concentrations. THQ values remained well below 1 across all food categories, indicating minimal health risks under typical consumption patterns, although lifetime exposure estimates suggested that canned foods could approach toxicological benchmarks earlier under high-consumption scenarios. A supplementary assessment of organotin compounds, which are highly toxic even at low fractions of total Sn, used a reverse dietary risk approach and probabilistic modeling. Canned foods and fresh aquatic products exhibited the lowest minimum conversion rates (0.16% and 0.37%, respectively), indicating that they are the most susceptible to organotin risk, whereas fresh fruits (7.77%) and tea (18.67%) required much higher proportions. Due to limited literature, further scenario- and probabilistic-based assessments focused on fresh aquatic products, revealing that typical exposure levels are generally safe, but children ≤ 6 years of age are the most vulnerable. Although overall Sn exposure is low, intake of highly processed foods, particularly canned products, should be limited in young children’s diets. These findings highlight that even small shifts in Sn speciation within high-risk food categories can lead to excessive tolerable daily intakes. This study provides a scientific reference for dietary Sn risk assessment and food safety management.

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