Toxins in the water you should know about

Some algae produce chemical molecules, which are a danger to human health, food and the environment.

Cyanotoxins are considered the most toxic and worrisome compounds in water bodies due to their high distribution. They are secondary metabolites that are generated and accumulated during the production of photopigments. Under unfavorable environmental conditions, cyanobacteria die and release their contents into the environment.

Algae Bloom in El Pañe reservoir, Peru. Source: Toxicrop project

Several species of cyanobacteria can produce potent toxins; however, within the same species there can be toxin-producing and non-toxic-producing strains. Cyanotoxins are chemically classified as cyclic peptides, alkaloids, and lipopolysaccharides, but they are mainly known and classified by their toxicological effects:

  • Hepatotoxins: These can be considered the most important cyanotoxins due to their abundance in nature and high toxicity. They can cause liver hemorrhages leading to death from hypovolemic shock, as well as gastrointestinal disorders.  In high doses they are related to liver cancer. One of the most important and studied cyanotoxin is the microcystin, produced by cyanobacteria Anabaena, Microcystis, Planktothrix, Nostoc and Anabaenopsis; In this group we also found to nodularins.
  • Neurotoxins: As their name suggests, these are toxins that affect the nervous system. They are less common than hepatotoxins, but they have severe and rapid effects, preventing the correct transmission of nerve impulses, ultimately leading to death due to cardiovascular and/or respiratory failure. The most common cyanotoxins are anatoxin-a and saxitoxins produced by cyanobacteria Anabaena, Oscillatoria Aphanizomenon.
  • Dermatoxins: These are not lethal to organisms, but they cause skin irritation upon contact. Lyngbyatoxin and aplysiatoxin, produced by cyanobacteria such as Lyngbya and Oscillatoria are notable.

  • The main health hazards arise primarily from two routes of exposure:
    • Direct contact with exposed parts of the body (ears, eyes, mouth) or areas covered by swimwear (where algae accumulate algae and promote cell rupture and release of contents).
    • Accidental ingestion by swallowing or inhaling water or consuming food exposed to contaminated water.

    At the ecological level, the most important problem is the reduction of biodiversity due to the presence of toxins, which can lead to changes in zooplankton species, they are food for fish, and as a result the trophic chain can be altered.

    Consumption of this water, without proper treatment to remove microorganisms and their toxins, can be responsible for acute or chronic diseases, depending on the dose and the time of exposure.