The piped water you get at home could be laced with toxins. Yes, you read it right. The concentration of toxins found in Veeranam Lake, one of Chennai's main sources of water, contains cyanotoxins above the recommended levels prescribed by the World Health Organisation (WHO), according to a study conducted by the University of Madras and Presidency College.
Cyanotoxins, produced by the Cyanobacteria (blue-green algae) found in the lake's water, could be harmful to humans, affecting the liver, nervous system, and skin. It could also cause gastrointestinal illnesses.
The sample for the study, published in the Springer Nature Environmental Sciences Europe journal on January 2, was collected between August 2018 and March 2019 across three seasons.
It was found that the lake had more than 10 cyanobacteria producing toxins, however, the team took two cyanobacteria for the study.
The study found the levels of toxins produced by two bacteria -- 'Leptolyngbya' and 'Desertifilum'-- at 17.72 microgram per litre and 19.38 microgram per litre, while the WHO-recommended toxin limit in potable water is just one microgram per litre.
While the bacteria leptolyngbya is found in various ecological habitats including marine, fresh water, swamps, and rice fields, desertifilum is usually found in hot and dry conditions.
The existence of cyanobacteria in the water has been associated with the seepage of fertilizers and untreated industrial effluents into water bodies. Water containing nitrogen and phosphorus mixed in the water from nearby farms is believed to be one the major reasons.
There are no quick fixes to control blue-green algae once they appear in a lake or pond. By reducing the overall amount of nutrients within a water body, bloom frequency and intensity may be reduced. However, it may take a long time to effectively change the nutrient concentrations in a water body.
Researchers also suggest creating vegetative buffers to filter nutrients.
Meanwhile, the Chennai Metro Water Supply and Sewerage Board (CMWSSB) told The New Indian Express that the department is taking samples and testing them daily. "We will send the samples and verify the water for Cyanobacteria," said the Engineering Director (ED), CMWSSB.
Cyanobacterial toxins are among the most hazardous substances found widely in water bodies. They occur naturally, but human activity influences the extent to which toxic cyanobacteria proliferate. Therefore, management of lakes, reservoirs and rivers to prevent cyanobacterial blooms is critical to protect human health.