Aluminium cookware can add lead to everyday meals: Study

Locally-made aluminium cooking pots can release lead, a toxic metal, into cooked food, with the highest levels found during the first uses of a new pot, according to a study by icddr,b and Stanford University.

Lead can cause lasting harm to children’s brain development. The researchers are calling for safer cookware and clearer guidance for households.

In Bangladesh, exchanging old aluminium utensils for new cookware, or for old clothes, is a familiar practice. The study did not look at these exchanges, but its findings show that a pot’s newness or shine does not prove it is safe.

Many locally-made pots are produced by melting scrap metal. Without checks on that scrap, lead can end up in the finished pots.

Lead can damage children’s learning and behaviour, and the World Health Organization says there is no known safe level of lead in blood.

Published in the Journal of Exposure Science; Environmental Epidemiology by Nature, the study aimed to measure how much lead moves from locally made aluminium pots into food, and how acidity, cleaning and cooking habits change this.

The researchers tested seven used pots collected from local households and 20 new pots bought from a supplier. They first estimated how much lead was in the metal of each pot.

They then heated the pots, and cooked plain rice and khichuri, a lentil and rice dish. Finally, they measured the lead in the liquid and the food using a highly sensitive laboratory method.

“We measured lead in both the pots and the food cooked in them, so we could see how an everyday cooking pot becomes a source of exposure,” said Dr Jenna Forsyth, director, Project Unleaded, Human and Planetary Health, Stanford University.

Lead was released from every pot tested, whether new or used. In the first cooking in new pots, rice contained up to 305 microgrammes of lead per kilogramme, and khichuri up to 420 microgrammes per kilogramme.

For comparison, the US Food and Drug Administration FDA) limit for food intended for babies and young children is 10 microgrammes per kilogramme. Lead levels fell with repeated use, but they were still found the third time the pots were used. Rice cooked in six of the seven used pots also contained lead.

How a pot was used and cleaned made a difference. Scrubbing a new pot with a steel-wire sponge released about five times more lead than not scrubbing, and stirring with a metal spatula also increased release. Based on how much rice children in rural Bangladesh typically eat, the authors estimate that a child eating rice cooked in such a pot could take in more than five times the FDA’s reference level for daily lead intake from food.

“Families prepare rice and khichuri with great care, and they should not have to worry that the pot is adding lead,” said Dr Jesmin Sultana, assistant scientist, Environmental Health and WASH at icddr,b.

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“Choose cookware with credible evidence of food safety, especially for young children. If you must use these pots, clean them gently without steel-wire scrubbers and avoid cooking acidic dishes in them, though these steps cannot make a contaminated pot reliably safe.”

“Lead can’t be seen, smelled or tasted, so a pot that looks perfectly good can still be adding it to a family’s food. Families have no way to tell which pots are safe.” Dr Jenna Forsyth added.

The researchers say responsibility cannot rest with households alone. Lead exposure in Bangladesh has several sources, including lead added to turmeric, and cookware is one more pathway that needs attention.

They see a role for authorities, including the Bangladesh Food Safety Authority (BFSA) and the Bangladesh Standards and Testing Institution (BSTI). This could include reviewing cookware safety rules, screening scrap metal, testing finished pots for lead release into food, and helping small producers access safer materials and testing services.

“We urge the Bangladesh Food Safety Authority to establish clear safety requirements for lead leaching from cookware into food and Bangladesh Standards and Testing Institution (BSTI) to set and enforce clear lead safety requirements for cookware ,” said Dr Md Mahbubur Rahman, Environmental Health and WASH, icddr,b.

“Affordable cookware should also be safe cookware. Better manufacturing and effective oversight can help families prepare daily meals without this avoidable risk.”

The researchers note that this was a technically rigorous yet small laboratory study. The child intake estimate comes from a model, not from measuring children, so more research is needed on other cookware and everyday cooking practices.

The study was supported by the Stanford University King Center on Global Development.