Toledo triggered new WHO guidance for cyanotoxin risk assessment

In 2014, the Toledo "do not drink advisory" spotlighted the need for short-term cyanotoxin guideline values. These are particularly relevant for cyanotoxins because concentrations may fluctuate widely as blooms wax and wane, with concentrations above the values for safe lifetime daily consumption of 2 L of drinking water often being short-lived events. Allowing slightly higher concentrations for up to 2 weeks enables focusing investments on remediation (rather than on supplying bottled water). In 2016. a second independent chronic exposure study with cylindrospermopsin (conducted at US EPA) finally provided the data that the World Health Organisation needed for deriving a CYN guideline value. Thus, WHO now provides a far more comprehensive set of guideline values for short-term and lifetime exposure through drinking water as well as for recreational exposure, including all 4 major groups of cyanotoxins (MCs, CYNs, STXs, ATXs). The presentation will explain their derivation in the context of other hazardous substances in water to which people may be exposed because among these, cyanotoxins are probably the most widely occurring. It will also show how these values serve as guidance for short-term responses to blooms in the context of Alert Levels Frameworks for drinking water and for recreation.