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Increase of Blue-Green Algae in South African Water: Significant Health Dangers

Written by Janice M on . Posted in Water & Environmental

Recently, there has been a Press Release regarding the increase of blue-green algae in water at dams around South Africa (SA). January, 2018.

Many are unaware that the overgrowth of algae leads to the increased growth of cyanobacteria and associated, dangerous cyanotoxins.

The problem of increased algal blooms has been escalating in numerous countries, especially with the effect of global warming. Internationally, scientists are expressing concern over dangerous risks to our drinking water and much research has been conducted.

Cyanobacteria produced by blue-green algae in SA specifically

Two specific cyanobacteria, anabaena and microcystis, are relevant to SA.* These bacteria produce, respectively, anatoxins, which are fast-acting nerve poisons, and microcystin, which is more common.

Microcystin levels in SA water

The World Health Organisation (WHO) has set a safety level of 1.0 micrograms per litre for microcystin because of its toxicity. But levels in SA rivers tower above the WHO safety levels, measuring between 10 000 and 18 000 micrograms per litre (Oberholster et al., 2004), with two-thirds of the country’s large dams now affected by eutrophication (Matthews and Barnard, 2015).

Microcystin levels in tap water are much lower, about 10 micrograms per litre, according to scientists – but still ten times higher than WHO safety standards.

Pictured: algal blooms in the Vaal river
Source: Carte Blanche by Derek Watts, July 2017

The dangers of microcystin

Research has shown that microcystin causes brain damage that can take decades to be detected (Spencer et al., 1987).

It has the potential to cross the placenta from mother to unborn child (karlsson et al., 2009a; 2009b).

More importantly, it bio-accumulates (Bradley and Cox, 2009), meaning that vegetables and fruit irrigated with contaminated water can transmit this poison.

It is also linked to Alzheimers (Murch et al., 2004) and other serious disorders in the chart below.

What International Peer Reviewed Science Tells Us About Microcystin from Blue-Green Algae

Fact # 1: A substance identified as β-methylamino-L-alanine (BMAA), a from of microcystin synthsised by cyanobacteria (blue-green algae), bio-accumulates in seeds and is capable of entering the mammalian food chain (Bradley & Cox, 2009).
Fact # 2: BMAA causes motor neuron degeration in monkeys resembling Parkinson’s Disease (Spencer et al., 1987).
Fact # 3: Microcystin is linked to a range of liver pathologies (Ito et al., 1997; Nishiwaki-Matushima et al., 1991; Ueno et al., 1996).
Fact # 4: Lettuce absorbs microcystin from contaminated irrigation water (Codd et al., 1999).
Fact # 5: Microcystin contaminated irrigation water alters plant biochemistry (Abe et al., 1996).
Fact # 6: Colon pathology is related to microcystein (Humpage et al., 2000).
Fact # 7: BMAA is causally linked to Alzheimers (Murch et al., 2004).
Fact # 8: BMAA injures motor neurons in the mammalian brain (Rao et al., 2006)
Fact # 9: BMAA causes necrosis of tissue in the hippocampus of the mammalian brain (Buenz & Hower, 2007).
Fact # 10: BMAA crosses the placenta in mammals where it bio-accumulates in the foetal brain (Karlsson et al., 2009a).
Fact # 11: Mammalians born after BMAA exposure to their parents are cognitively impaired with reduced capacity for problem solving (Karlsson et al., 2009a).
Fact # 12: BMAA is selectively toxic to motor neurons (Liu et al., 2010).

Extracted from Water Pollution and South Africa’s Poor, a document produced by the South African Institute of Race Relations and authored by Dr. Anthony Turton.

Cause of blue-green algae overgrowth

Excess nitrogen and phosphorus from sewage, industrial effluent and fertilisers flowing into water systems.

Find out more about nitrates in South Africa

Water Testing – Phosphates in Water

Improving water quality

Not polluting our waterways and improving water quality through the release of clean water into our environment is more important than ever before.

Find out more

EPA suggested measures to control and treat cyanobacterial blooms in surface waters

Historical comments (2)

  • Jo Kruger


    Please let me have details of the source documents and who exactly carried out the tests and when – I would like to do a follow-up article

    • Janice M


      Hi Jo, thanks for your interest in this important water quality issue. The links in the article are in dark blue, you can follow them to see much of the source content. I also discussed this issue with Dr. Anthony Turton, a well-known South African Scientist. Please email me at janicem@selectech.co.za if these do not suffice.

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