Pequenos Libombos: Toxic cyanobacteria levels above the established by WHO

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Pequenos Libombos: Toxic cyanobacteria levels above the established by WHO

9:52 CAT | 01 Aug 2016

Notícias (File photo) / Pequenos Libombos dam

Levels of toxic cyanobacteria in the Pequenos Libombos reservoir in Maputo province are 44 times higher than the maximum laid down by the World Health Organisation, according to a study by a researcher at the Biotechnology Centre of the Eduardo Mondlane University presented at a veterinary congress in Maputo recently.

Olivia Pedro has been conducting research in Mozambique, Uganda, Zambia and Tanzania for a PhD dissertation funded by the Norwegian government, and investigated the deaths of wild animals that had consumed polluted water from rivers in Tanzania and South Africa.

In all, 40 samples of water were collected from the Pequenos Libombos dam between October 2009 and June 2010, which were then subjected to analysis to measure hydrogenionic potential and check for the flowering cyanobacteria known as “bloom”.

The survey found levels of cyanobacteria well above the minimum limit of one microgram per litre established by WHO, associated with the presence of high pH levels.

Pedro says that the results of the study have been submitted to the Regional Water Company of Maputo which manages the Umbelúzi Water Treatment Plant (ETA), which in turn supplies the cities of Maputo and Matola and Boane district with water from the Pequenos Libombos dam.

Pedro reported that test samples were collected in the water treatment plant in order to assess whether the bacteria remain a health risk even after the water is treated. She explained that the direct consumption of the water by the surrounding population does constitute a danger to their health, although no poisoning incidents have not yet been reported.

Pedro noted that poisoning by toxic cyanobacteria has been cited as the cause of death from gastrointestinal problems, liver and kidney damage in countries as far apart as the United States, Australia, China, Sweden and Zimbabwe.

Meanwhile, the researcher explains that the results of research at the Umbelúzi Water Treatment Plant have not be established a direct link between water consumption and increased risk of cancer in Mozambique.

The presence of “bloom” is due to eutrophication, a pollution process in rivers and lakes involving low oxygen levels and a greenish colour which harms aquatic ecosystems and causes the death of many animal and plant species.

The pollution is a matter of concern because of its public health dimension and the increasing shortage of drinking water. It can have several causes, including domestic, industrial and agricultural discharges into rivers and lakes.

Pedro explained that some cyanobacteria are capable of producing toxins that can infect plants and animals by the ingestion of water, contaminated food, skin contact, inhalation or even during the course of hemodialysis, an artificial blood filtration process for removing toxic substances.

Source: Notícias