Certain foods may not be as healthy as you think

A recent study has found that mercury concentrations in certain fish popular on South African plates – such as Red Roman, Red Panga and Silver Fish caught along our coastline – exceeded the World Health Organization’s guideline value. Other research has shown that people living in areas sprayed with DDT are at risk of developing illnesses such as cancer when they consume the chicken, fish and vegetables produced in those areas.

Articles on the results of the two sets of research are published in the latest edition of the quarterly magazine of the South African Council for Scientific and Industrial Research (CSIR), "ScienceScope".

In the case of the mercury, the study by the CSIR was initiated by the former South African Mercury Assessment Programme and focused on assessing the potential health risk from consuming locally caught fish off the South African coastline. This initiative was broadened in 2008 to include a focus on a broader scope of heavy metals within the CSIR trace metal research programme.

The highest mercury concentrations recorded during the study occurred in False Bay, followed by the West Coast, Durban, Kalk Bay and Yzerfontein.

Limit intake

Judged against the standards of the American Environmental Protection Agency and taking into account the levels of mercury in the fish found by the CSIR, one should limit the consumption of Red Roman and Red Panga to less than twice a month. Kabeljou and Silver Fish can be eaten four times a month, and Yellowtail eight times. Snoek and Mullet are the safest, and can be consumed 16 times per month.

Mercury contamination is not unique to South African waters, but “we lack specific guidelines and information about the levels of mercury contamination in the country,” the article states.

“In the US, the Environmental Protection Agency and the US Food and Drug Administration warn people that nearly all fish and shellfish contain traces of methylmercury – therefore one should control one’s intake, and vulnerable groups like young children and pregnant women should be very careful.

"The best advice would be for consumers to be aware of these risks and to obtain information from advisory groups if they have questions.

“However, consumers should know that eating fish containing chemical pollutants may cause birth defects, liver damage, cancer and other serious health problems,” the article states.

Enquiries about the research and its results can be sent to Mampopeli Matooane via This e-mail address is being protected from spambots. You need JavaScript enabled to view it

DDT underestimated

While the use of DDT in the fight against malaria was in the news recently during the controversy surrounding the athlete Caster Semenya ("Leadership Intelligence Bulletin" also reported about it at the time), the article in "ScienceScope" states, “An estimated 880 000 people – most of them young children – die each year of malaria in the developing world, we may underestimate the potential effects of continued DDT use on future generations.”

Research by the CSIR and the University of Pretoria has shown that people living in areas sprayed with DDT are at risk of developing illnesses such as cancer when they consume the chicken, fish and vegetables produced in those areas.

Under the headline, “The devil you do, the devil you don’t”, the article refers to the fact that in South Africa and several other developing countries, use of DDT is allowed for malaria control in high-risk areas such as KwaZulu-Natal and Limpopo.

“However, DDT is also one of the ‘dirty dozen’ synthetically produced chemicals banned by the rest of the world, as well as an endocrine-disrupting chemical – meaning it can mimic or antagonise the function of hormones – giving rise to babies being born with severe genital ambiguity, or decreased semen quality in young men.”

It affects both the human and animal population and at the cellular level, the article states.

The study found disturbingly high levels of DDT and its byproduct DEE in water, sediment, soil, vegetables, chicken and fish meat of the Vhembe District Municipality in Limpopo, on the border with Zimbabwe and Mozambique. Under the Limpopo Malaria Control Programme, this area has been sprayed with DDT annually since 1966.

DDT is not toxic to humans in the sense that one could die if one swallowed it. “However, it is highly dangerous for the foetus of pregnant women during certain critical stages of its development,” one of the researchers quoted.

For more information on the research and its results, contact Bettina Genthe via This e-mail address is being protected from spambots. You need JavaScript enabled to view it

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Comments (2)

• |2010-02-02 11:31:36 Anonymous
  Interesting
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  Reply

• |2010-02-02 11:32:12 Anonymous
  interesting!
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