Clinical Pharmacist and Master’s student in Clinical Pharmacy with research interests in pharmacovigilance, behavioral interventions in mental health, and AI applications in clinical decision support. Experience includes digital health research with Bloomsbury Health (London) and pharmacovigilance practice in patient support programs. Published work covers drug awareness among healthcare providers, postpartum depression management, and patient safety reporting. 
Clinical Pharmacist and Master’s student in Clinical Pharmacy with research interests in pharmacovigilance, behavioral interventions in mental health, and AI applications in clinical decision support. Experience includes digital health research with Bloomsbury Health (London) and pharmacovigilance practice in patient support programs. Published work covers drug awareness among healthcare providers, postpartum depression management, and patient safety reporting. What was studied?
This original research study measured heavy-metal-certification–relevant contaminants in three widely consumed canned foods in Iran—tomato paste, olives, and pickled cucumbers—because can materials, solder, and processing conditions can contribute to metal migration into food. The authors collected market samples and quantified cadmium (Cd), copper (Cu), arsenic (As), iron (Fe), lead (Pb), and zinc (Zn) using flame/graphite furnace atomic absorption spectrometry, while mercury (Hg) and tin (Sn) were measured using ICP-MS. Samples were homogenized, digested with an HNO₃/H₂O₂ mixture, filtered, and analyzed in triplicate with QA/QC controls supported by calibration linearity and spike recoveries. The core aim was practical: compare metal burdens across these canned foods and evaluate whether measured concentrations align with national/international limits, with special attention to Pb and Sn as plausible packaging-linked hazards.
Who was studied?
No human participants were enrolled; the “study population” was 49 canned food samples of tomato paste, olives, and pickled cucumbers purchased from stores in Tehran, representing five popular brands. This design reflects typical consumer exposure pathways by focusing on ready-to-eat, commercially packaged products rather than farm-gate raw produce. Because sampling was limited to one major city and a modest number of brands, the results function best as a market snapshot rather than a national surveillance estimate. Still, for an HMTC-style program, this kind of retail sampling is exactly where compliance signals appear, since it captures the combined influence of ingredient sourcing, processing, and packaging integrity in the final product consumers actually eat.
Most important findings
The standout HMTC-relevant outcome was that lead was detected in all three product categories and the average Pb values were above the stated permissible limit for canned products, while most other metals were low or non-detectable. Pickled cucumbers showed a narrow metal profile (only Pb and Sn detected), suggesting either fewer ingredient-related inputs or limits of detection relative to true background levels, whereas tomato paste had the broadest detection pattern, consistent with multi-step processing and potentially greater contact/migration opportunities. Statistically, Pb did not differ significantly between product types, but Cd did, with tomato paste higher than olives and pickles.
| Critical point | Details |
|---|---|
| Lead exceeds a key safety benchmark | Mean Pb (mg/kg): pickled cucumbers 0.22 ± 0.08, tomato paste 0.19 ± 0.07, olives 0.19 ± 0.04; authors note this is above the Codex limit for canned products (0.1 mg/kg). |
| Tin detected but far below regulatory ceilings | Mean Sn (mg/kg): pickles 0.11 ± 0.05, tomato paste 0.4 ± 0.2, olives 0.32 ± 0.17; discussed as well below EU/Codex ranges for tin in canned foods (hundreds of mg/kg). |
| Cadmium differs by product type | Cd (mg/kg): tomato paste 0.008 ± 0.005, olives 0.005 ± 0.001, pickles ND; Kruskal–Wallis showed a significant difference with tomato paste higher. |
| Mercury not detected | Hg was ND in all samples, reducing concern about Hg for these specific canned categories in this market snapshot. |
| Tomato paste shows broader metal presence (low levels) | In tomato paste only, Cu (0.16 ± 0.1), Fe (0.48 ± 0.4), Zn (0.0071 ± 0.007), and trace As (0.0005 ± 0.0004) were detected, consistent with ingredient/processing contributions rather than can solder alone. |
Key implications
For heavy-metal-certification, the data argue that regulatory impacts should prioritize Pb control as a routine compliance trigger, while treating Sn as a packaging-integrity indicator rather than an exceedance risk in these samples. Certification requirements should mandate batch Pb testing with method sensitivity aligned to low mg/kg thresholds, plus packaging and ingredient-source audits that can isolate Pb entry points. Industry applications include supplier qualification for salt/spices and water/irrigation inputs alongside can/lid and seam validation. Research gaps remain in pinpointing Pb sources (ingredients versus packaging), evaluating storage-time migration, and expanding sampling across regions and more brands; practical recommendations include targeted Pb corrective actions, periodic market surveillance, and traceability workflows that link test failures to specific lots and packaging components.
Citation
Shavali-gilani P, Abedini A, Irshad N, Maleknezhad S, Yazdanfar N, Sadighara P. Investigation of heavy metal levels in canned tomato paste, olives, and pickled. Scientific Reports. 2025;15:20923. doi:10.1038/s41598-025-06896-9
Heavy metals are high-density elements that accumulate in the body and environment, disrupting biological processes. Lead, cadmium, arsenic, mercury, nickel, tin, aluminum, and chromium are of greatest concern due to persistence, bioaccumulation, and health risks, making them central to the HMTC program’s safety standards.
Cadmium is a persistent heavy metal that accumulates in kidneys and bones. Dietary sources include cereals, cocoa, shellfish and vegetables, while smokers and industrial workers receive higher exposures. Studies link cadmium to kidney dysfunction, bone fractures and cancer.
Arsenic is a naturally occurring metalloid that ranks first on the ATSDR toxic substances list. Inorganic arsenic contaminates water, rice and consumer products, and exposure is linked to cardiovascular disease, cognitive deficits, low birth weight and cancer. HMTC’s stringent certification applies ALARA principles to protect vulnerable populations.
Lead is a neurotoxic heavy metal with no safe exposure level. It contaminates food, consumer goods and drinking water, causing cognitive deficits, birth defects and cardiovascular disease. HMTC’s rigorous lead testing applies ALARA principles to protect infants and consumers and to prepare brands for tightening regulations.
Mercury (Hg) is a neurotoxic heavy metal found in various consumer products and environmental sources, making it a major public health concern. Its regulation is critical to protect vulnerable populations from long-term health effects, such as neurological impairment and cardiovascular disease. The HMTC program ensures that products meet the highest standards for mercury safety.
