People living near Lake Victoria are at risk when drinking the water

In 2020, research showed that people who use water from the Nyanza Gulf in Lake Victoria take in a high level of toxins, or poisonous chemicals, even after they clean the water. They are in danger since these toxins may damage their liver and could cause cancer. 

Lake Victoria is filled with cyanobacteria, which are bacteria that live in the water and make their own food. These bacteria are commonly known as blue-green algae and they produce poisonous chemicals called microcystins.

The researchers wanted to find out how much microcystins are in Lake Victoria, and how much of it is being ingested by the community. Most of the community filters, boils or adds chlorine to the water before using it, but researchers wanted to see if the microcystins are still present after cleaning.

They collected water from 6 beaches along the Nyanza Gulf in Lake Victoria, and 127 household water samples along those beaches, between May and October, 2015. They checked if microcystins were present, and then calculated how much of the poisonous chemical the communities might be ingesting. The researchers also used surveys to find out how households treat, or clean, their water. 

They noticed that more than 80% of all the water samples contained microcystins, but beach water was more toxic than household water. 

Most people did treat their water before using it by filtering out as much dirt as possible. Unfortunately, filtering does not get rid of all microcystins, and so the community could be taking in 4 times more poisonous chemicals than they should, said researchers.

Before this study, researchers knew that Lake Victoria is home to cyanobacteria, however its toxicity on the surrounding communities was uncertain. This study clearly shows that indeed people are consuming high amounts of the toxins in the water, and that filtering or boiling doesn’t get rid of these toxins. 

The scientists recommended that the government should educate and spread awareness to the surrounding communities about the dangers of drinking this contaminated water.

The authors of this paper were from Kenya.

Abstract

Cyanotoxins are produced by cyanobacteria which are single-celled algae that thrive in warm and nutrient rich water bodies including lakes. There are different kinds of cyanotoxins and microcystin is the most common. Microcystin mostly affects the liver. Epidemiological studies in China and Serbia have shown an association between cyanotoxins and occurrence of Primary Liver Cancer. Cyanobacteria have been reported in Lake Victoria, which is an important source of drinking water for the riparian communities, thus posing a danger to human health. However, the health risk from exposure to toxic cyanobacteria in the Nyanza Gulf water remains unknown. The purpose of this study was to assess the health risk of toxic cyanobacteria to the riparian communities in the Nyanza Gulf. In a longitudinal study adopting survey and experimental design, 127 samples were collected monthly from both households and six beaches over six months. Cyanobacterial levels were determined using an enzyme assay method (PP2A). Different methods of household water treatment were compared. Two-way ANOVA was done to determine statistical significance of microcystins levels. 84% of water samples contained microcystins. Concentration of microcystins was 3.44µg/L which is over the WHO limit of 1µg/L. There was no variation between beaches and water treatment (ANOVA: F=0.97, p=0.47). Filtration proved to be the most efficient method of water treatment. The health risk factor of cyanotoxins in drinking water is 3.86. There is a health risk posed by cyanotoxins to the residents of the Nyanza Gulf who use the lake water for drinking since is over the WHO limit. This information provides an insight into the quality of Lake Victoria water for drinking. The study recommends development of cyanobacteria removal methods as well as sensitizing the riparian communities on the health risk of cyanotoxins in drinking water.

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