Accumulation of toxic substances in Nairobi’s river sediments

Researchers have warned of the presence of toxic contaminants and untreated wastes accumulating in Nairobi’s Mathare, Ngong and Nairobi rivers. More than half the population of Kenya’s capital, Nairobi, live in extremely poor conditions in informal settlements. In January 2020, researchers collected samples of mud sediment from the rivers in areas where five of Nairobi’s biggest and most congested informal neighbourhoods are located on the rivers’ banks. Scientists at BGS and Nairobi University found that toxicity is highest in these regions of Nairobi and have expressed concern that pollution found within river sediments poses a dangerous health risk to local communities and the environment. The researchers identified multiple groups of organic contaminants and high levels of untreated sewage and faecal matter that together pose a threat to ecological and human health.