Action News vol 10 no 1, June 2010 ISSN 1324-6011
Incorporating Lead Aware Times ( ISSN 1440-4966) and Lead Advisory Service News (ISSN 1440-0561)
The Journal of The LEAD (Lead Education and Abatement Design) Group Inc.
Guest Editor: Monica Maharjan, Master of Science Management and Master of Applied Sciences (Biotechnology).
Editor-in-Chief: Anne Roberts
Lead Contamination of Food
By Alex Giblin, Intern, The LEAD Group, Australia, 4 June 2010.
Edited by Monica Maharjan, Robert Taylor and Anne Roberts
Lead contamination of food is more common in third world countries that do not have strong food standards. It has recently become an issue in countries that have been importing food products from such countries. Food can become contaminated where it is grown, or by cooking vessels or the containers in which it is exported or stored.
There have been many ‘lead scare’ news stories involving recalling products due to lead contamination. In 2005 the New Zealand Food Safety Authority recalled a brand of baby custard and a number of brands of cornflour that were imported from China, due to ‘unacceptably high’ levels of lead.1 In May of 2008, lead was discovered in a piggery feed supplement, imported from China, at Linley Valley abattoir of Western Australia. This resulted in the quarantining of several piggeries. The W.A. Department of Health found that the lead accumulation in the pig meat was in the liver, kidneys and bones, and could pose a risk if sold on the bone. In the United States, on August 3, 2007, beverage containers and glass water tanks were recalled, of which approximately 12,592 had been sold from May 2005 to July 2007, from a chain of stores.2 The containers used for acidic beverages had a metal spigot containing lead, which leached out into the liquors. A number of other drinking vessels containing lead or decorated with paint containing lead have been recalled in the United States in recent years. Similarly, in the United States in March 2009, a recall was issued of approximately 2500 cordless kettles because they leached lead into boiling water.3 Lead contamination of food has also occurred in the process of countries’ production of food intended for local consumption: in Oregon, U.S.A., in 2006, a chocolate manufacturer recalled a range of organic chocolate bars as they contained high levels of lead.4
In March 2010, certain chocolate products from Darrell Lea Chocolate Shops Pty Ltd were recalled, due to trace elements of lead above the accepted Australian standard. Contamination occurred due to a third party source. The product was recalled in Australia, New Zealand, The U.K. and U.S.A.
This is by no means a complete list; food products contamination extends beyond the small number of examples given above.
There are a number of ways in which lead contamination of food occurs. The most common way has been during the growth and development of plants grown in soil containing an unusually high amount of lead. The plant surfaces become contaminated with dust or soil, or the plants may take up the lead from the soil as they mature. Lead contamination of food can and does occur even in commercial farming. The lead contamination of soil occurs when lead, lead dust, biosolids (sewage sludge), fertilisers made from waste acids from lead smelters or any liquid containing lead is introduced to the soil. Improperly lined lead soldered cans or plastics with leaded paint or ink can also result in lead contamination of food.5 Lead contamination can also occur when food is stored, served, or heated in any vessel which contains lead – including any decorated with paint or poorly fired ceramic glaze which contains lead. Additionally, some food cans, sold even today, may be sealed with lead solder; easily recognisable for their irregular shape, a thick seam and horizontal depressions as compared to non-lead can with a flat-welded seam.
Similarly, lead may be present in meat, as cattle may ingest lead as they graze, feeding on grasses and plants which have grown in soils with unusually high in lead due to sump oil, lead batteries, paint chips, discarded paint tins, scrap lead,6 and a number of other items containing lead that are used for running a farm but not always safely disposed of. It has been found that cattle are attracted to contaminated plants because of their sweet taste.7
Lead contamination of food, which occurs in both developed and developing nations, poses a serious health issue. Consumption of even a small amount of lead can cause lifelong health problems and repeated exposure will have lasting and detrimental effects. If a woman is carrying a child or breastfeeding and has heightened lead levels, this will also pose a problem. The study had found that about 1-5% of mother’s lead level will likely be present in her breast milk and will pass on to her child. Even if it has been some time since the mother came into contact with lead, the lead may be stored in her bones and be released in her breast milk, usually at very low levels.8 Similarly, lead may be transferred through the placenta.9 It must be emphasised that exposure to lead in breast milk has a smaller effect on infant lead levels than the cumulative exposure of the foetus during pregnancy.10 This is of particular concern as unborn babies, infants and young children are more susceptible than adults to the lasting effects of lead consumption11 – particularly the degenerative effects on cognition.
However, it should be noted that breast milk is still the best food for a child. If the mother is concerned about her lead level, it is best to ask a doctor/obstetrician to test her blood lead level and, if it’s elevated, attempt to reduce it through identification and elimination of the sources of lead, plus improved nutrition. As a preventative measure, eating certain foods - chiefly those which are high in calcium, iron and Vitamin C12 - can lessen the absorption of lead into the body,
For more information on breastfeeding if you suspect yourself of having elevated lead levels refer to www.lead.org.au/lanv6n2/update002.html.
Testing food for the presence of lead can be expensive and often it is not easy to discern which foods contain lead. Frequently it is cheaper to test a person’s blood lead level and try to work out what other lead sources might be contributing to a blood lead level (>2 µg/dl).
As a preventive measure it is a good idea to test the level of lead in the soil before planting any fruit and vegetables in your backyard or allotment. Whenever there is a product recall, it should be followed. Even if a product is found to contain an amount of lead which is claimed to be not immediately dangerous, food containing lead contributes to your total lead burden. Even small amounts of lead are stored in the bones and can have lifelong effects on health.13
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