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Metal contamination, significant public health issue
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Monday, 28 April, 2025, 08 : 00 AM [IST]
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N Indra
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Food safety is a critical concern worldwide, and among the various contaminants, heavy metals pose significant health risks. These metals, including lead, cadmium, mercury, and arsenic, can accumulate in the human body over time, leading to chronic health issues. This essay explores the sources, health effects, detection methods, and preventive measures related to metal contamination in foods.
Metal Contamination
Metal contamination refers to the presence of toxic metals in food products. These metals can enter the food chain through various means, including polluted soil, water, and air, as well as through industrial activities and agricultural practices. The primary metals of concern are Lead (Pb); Cadmium (Cd); Mercury (Hg); Arsenic (As); Chromium (Cr); Nickel (Ni); and Aluminium (Al).
While some metals are essential in trace amounts, excessive exposure can be harmful.
Sources of Metal Contamination
1. Environmental Pollution
Industrial activities, mining, and improper waste disposal can lead to the release of heavy metals into the environment. These pollutants can contaminate soil and water, which in turn affects crops and livestock.
2. Agricultural Practices
- Use of Contaminated Water: Irrigating crops with water containing heavy metals can lead to contamination.
- Pesticides and Fertilisers: Some agricultural chemicals contain metals like arsenic and cadmium, which can accumulate in the soil and crops.
Food Processing and Packaging- Equipment and Utensils: Metals can leach into food from processing equipment and utensils.
- Packaging Materials: Improperly manufactured packaging materials can introduce metals into food products.
4. Seafood and Aquatic Sources
Fish and shellfish can accumulate metals like mercury and arsenic from contaminated water sources, leading to bioaccumulation.
5. Atmospheric Deposition
Airborne metals from industrial emissions and vehicle exhaust can settle on crops and soil, leading to contamination.
Health Effects of Metal Contamination
1. Neurological Disorders
Lead exposure, even at low levels, can affect the nervous system, leading to cognitive deficits and developmental delays in children.
2. Kidney and Liver Damage
Cadmium and mercury are nephrotoxic and hepatotoxic, causing damage to the kidneys and liver over time.
3. Cancer Risk
Arsenic and cadmium are classified as carcinogens, with long-term exposure increasing the risk of various cancers.
4. Developmental and Reproductive Issues
Exposure to heavy metals during pregnancy can lead to developmental delays and reproductive health issues.
Detection and Monitoring
1. Analytical Techniques
Modern laboratories employ various methods to detect heavy metals in food, including:
- Atomic Absorption Spectroscopy (AAS)
- Inductively Coupled Plasma Mass Spectrometry (ICP-MS)
- X-ray Fluorescence (XRF)
- High-Performance Liquid Chromatography (HPLC)
2. Regulatory Standards
Organisations such as the World Health Organization (WHO), U.S. Food and Drug Administration (FDA), and European Food Safety Authority (EFSA) have established permissible limits for heavy metals in food to protect public health.
Food Safety and Standards (Contaminants, Toxins and Residues) Regulation, 2011, has specified maximum limits of metal contaminants in different food categories based on risk assessment studies. A robust food testing ecosystem has been established by FSSAI by strengthening primary food testing labs and referral food labs. Heavy metals are commonly analysed by equipment like AAS, ICP-OES and ICP-MS, which have capabilities of quantitatively analysing toxic heavy metals viz. lead, cadmium, chromium and, mercury at sub ppb level with high accuracy.
Recent Incidents and Studies
- Dark Chocolate Contamination: A study found that 43% of dark chocolate products tested contained unsafe levels of lead and cadmium, highlighting the prevalence of heavy metals in food products.
- Arsenic in Rice: Research indicates that rice, particularly from regions with contaminated water sources, can contain high levels of arsenic, posing a risk to consumers.
- Baby Food Concerns: Elevated levels of heavy metals have been found in various baby foods, raising concerns about the potential health risks to infants.
Preventive Measures
1. Good Agricultural Practices (GAP)
- Water Management: Use clean water sources for irrigation.
- Soil Monitoring: Regularly test soil for heavy metal contamination.
- Safe Use of Chemicals: Avoid using pesticides and fertilisers containing heavy metals.
2. Food Processing and Packaging
- Material Selection: Use food-grade materials that do not leach metals.
- Regular Inspections: Conduct routine checks of equipment and packaging materials.
3. Consumer Awareness
- Diversified Diet: Consume a variety of foods to minimise the risk of exposure to a single contaminant.
- Proper Food Handling: Wash and peel fruits and vegetables to reduce surface contamination.
- Source Transparency: Purchase food from reputable sources that adhere to safety standards.
Metal contamination in foods is a significant public health issue that requires coordinated efforts from governments, industries, and consumers. By understanding the sources and risks associated with heavy metals, implementing preventive measures, and staying informed about food safety, we can mitigate the impact of metal contamination on health.
(The author is assistant professor, Department of Nutrition and Dietetics, Sengunthar Arts and Science College (Autonomous), Tiruchengode, Tamil Nadu. She can be reached at indrapoovendran1992@gmail.com)
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