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 reviewed?
This review article, “Hazards of heavy metal contamination” by Lars Järup, systematically evaluated the health threats posed by environmental and occupational exposure to four prominent heavy metals: lead, cadmium, mercury, and arsenic. The review synthesized findings from WHO assessments, epidemiological studies, toxicological data, and regulatory trends to provide a comprehensive overview of sources, exposure pathways, biomonitoring, and adverse health outcomes. The article emphasized changes in global production and emissions, regulatory responses in developed countries, and persistent or growing exposures, particularly in less developed regions. Special attention was paid to the mechanisms of toxicity, exposure-response relationships, and the critical levels at which adverse health effects occur. The review contextualized these metals within historical and current industrial use, highlighting the enduring relevance of heavy metal exposure to public health and the urgent need for further risk reduction and regulatory vigilance.
Who was reviewed?
The review encompassed a wide range of populations exposed to heavy metals, drawing on occupational cohorts (industrial workers, miners, dental staff), population-based studies in both developed and developing countries, and specific vulnerable groups such as children, pregnant women, and residents near industrial sites or consuming contaminated water or food. Data sources included large-scale epidemiological cohorts, case-control studies, and national health surveys. The review also incorporated animal experimental data for mechanistic insights, where human data were limited. Studies included diverse geographical settings, with special mention of high-exposure incidents in Japan (Minamata and itai-itai diseases), Iraq (methyl mercury poisoning), and Bangladesh (arsenic in groundwater). This broad evidence base enabled a nuanced understanding of heavy metal risk across demographic, socioeconomic, and geographic variables, with a focus on both acute and chronic health endpoints.
Most important findings
| Critical Point | Detail |
|---|---|
| Cadmium exposure | Food is the main source for non-smokers, while smokers have 4–5 times higher blood cadmium. Adverse renal and bone effects now occur at lower exposure levels than previously thought (urinary Cd 2–3 µg/g creatinine). Many in Europe exceed these levels; kidney damage is largely irreversible. Cadmium is classified as a probable human carcinogen, but the evidence is weak for oral exposure. |
| Mercury exposure | General population primarily exposed via fish and dental amalgam. Most are not at significant risk, but high fish consumers may approach neurological risk thresholds. Pregnant women are particularly vulnerable; certain fish (shark, swordfish, tuna, and fish from polluted waters) should be avoided. No evidence links dental amalgam to disease despite public concern. Contradictory data on cardiovascular risk. |
| Lead exposure | Lead exposure now mainly from food and air. Children are especially vulnerable due to higher absorption and a permeable blood–brain barrier. Even blood lead levels previously considered “safe” (<10 µg dl) may cause neurotoxicity and reduced iq. acute chronic kidney damage possible. carcinogenicity evidence is weak. lead use in petrol, paints, food containers remains a concern, especially some regions.< td> |
| Arsenic exposure | Main sources are food and drinking water; high-risk areas include Bangladesh, Chile, and China due to contaminated groundwater. Chronic ingestion linked to skin, lung, bladder, and kidney cancers, as well as skin lesions such as hyperkeratosis. Occupational inhalation is associated with excess lung cancer risk. Biomonitoring by urine, hair, and nails is effective, with caution for confounding by seafood intake. |
| Regulatory and public health relevance | Many adverse effects now recognized at lower exposure levels than previously anticipated. Developed regions have seen reduced emissions due to regulation, but exposures persist elsewhere. Vulnerable subpopulations (children, pregnant women, the elderly, high fish consumers, those near industrial sites) require targeted risk mitigation. Continued reduction of environmental and consumer exposures is essential. |
Key implications
The findings underscore the need for stringent heavy metal limits in HTMC certification, with a focus on lower exposure thresholds, vulnerable groups, and regular biomonitoring. Regulatory programs must prioritize phasing out hazardous uses, improving consumer awareness (especially regarding food containers and diet), and harmonizing global standards to protect public health.
Citation
Järup L. Hazards of heavy metal contamination. British Medical Bulletin. 2003;68:167–182. doi:10.1093/bmb/ldg032
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.
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.
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.
