Toxicity of the blue‐green alga (cyanobacterium) Microcystis aeruginosa in drinking water to growing pigs, as an animal model for human injury and risk assessment

Abstract

Hepatotoxins from blue‐green algae are increasingly recognized as a potential hazard in drinking water supplies. The clinical consequences of ingestion include acute or chronic liver injury, with the possibility of enhanced susceptibility to, and growth of, liver tumors. To establish guidelines for water safety requires the demonstration of dose‐dependent effects of toxicity and experimental determination of maximum “no‐adverse‐effect levels.” This paper describes the use of growing pigs as a model for human injury resulting from Microcystis toxins in drinking water. Risk assessment calculations using a series of safety factors are carried out, resulting in a guideline level after incorporating an additional safety factor for tumor promotion of approximately 1.0 μg toxins/L. With the Microcystis used for this trial, that concentration corresponds to 5000 cells/mL. © 1994 by John Wiley & Sons, Inc..

Cyanobacterial toxins: removal during drinking water treatment, and human risk assessment.

“…Applying a total uncertainty factor of 1,000 (10 for intra-and interspecies variability, respectively, and 10 for limitations in the database, especially lack of data on chronic toxicity and carcinogenicity), a provisional TDI of 0.04 pg/kg bw per day has been derived for microcystin-LR. This TDI was supported by a 44-day pig oral study that determined a lowest observable adverse effect level (LOAEL) of 100 jig microcystin-LR equivalents/kg bw per day (56). In this study, the cyanobacterial material fed to the pigs contained several microcystin congeners, but only microcystin-YR was tentatively identified.…”

“…The liver is the major target organ for microcystin toxicity; it was shown to accumulate 20-70% of a radioactively labeled toxin dose (intravenous) (48)(49)(50)(51)(52)(53)(54). Studies in mice and pigs exposed to extracts of a toxic M. aeruginosa bloom demonstrated dosedependent toxicity (55,56). Increased mortality, liver weight, and plasma alanine aminotransferase levels were associated with loss of body weight.…”

“…This guideline value is based on a tolerable daily intake (TDI) value derived from two animal studies (56,132). The first study is a 13-week mouse oral study that determined a no-observable adverse effect level (NOAEL) of 40 jg/kg bw per day based on serum enzyme levels and liver histopathology (132).…”

Identification of microcystins in waters used for daily life by people who live on Tai Lake during a serious cyanobacteria dominated bloom with risk analysis to human health

“…In this study, 2 L of V and 60 kg of BW were defined according to Chinese habit. Applying a total uncertainty factor of 1000, a provisional TDI of 0.04 lg/kg BW per day was derived for MC-LR by the animal experiment (Falconer et al, 1994). The hazards ratio, the value of ADI divided by TDI, was used as an index to assess the risk of the drinking water.…”

Hepatosplenomegaly caused by an extract of cyanobacterium Microcystis aeruginosa bloom collected in the Manguaba Lagoon, Alagoas - Brazil

“…Recently, in Caruaru/ Brazil, 1996, there was an accident in a hemodialysis center, and the death of 56 patients was attributed to a hepatic intoxication caused by toxins present in the water. The toxic effects and the risks to the population due to the presence of cyanobacteria in water sources are very big and the critical examples are diarrhea, nausea, muscle weakness, cutaneous paleness and liver tumors (4,6,13). Another aggravating point is the persistence of cyanobacterial toxins in water when they are not removed or destroyed by the conventional treatment system exposing the population to the consequences of these toxins (1,14).…”