DescriptionIngestion of contaminated food, such as aquaculture products, algal supplements and irrigated crops, might lead to human exposure to cyanobacterial toxins. In the Netherlands, crops cannot be irrigated with water in which the cyanobacterial toxin concentration exceeds 1 µg L-1. However, more data are needed to underpin this guideline. We tested whether lettuce, beetroot and strawberries accumulate cyanobacterial toxins (microcystins, cylindrospermopsins and homoanatoxin-a) when irrigated with water containing cyanobacteria. Although the crops were exposed to toxin concentrations up to 170 µg L-1, no toxins were detected in the edible parts of beetroot and strawberries. Only lettuce which was irrigated on the plant contained detectable amounts of microcystins. The fate of the toxins (adsorption to the soil, accumulation in inedible parts, biotransformation) is still under investigation. Cyanobacterial toxins can also accumulate in shellfish. In the Netherlands, some of the official production areas are located in a delta which receives an influx of freshwater. We performed a survey on the presence of cyanobacterial toxins in shellfish from these areas. Microcystins and anatoxins were only detected in a few samples, but cylindrospermopsins were detected in 60 of the 165 samples. The highest detected cylindrospermopsin concentration (sum cylindrospermopsin and 7-deoxy-cylindrospermopsin) was 64 µg kg-1. Phytoplankton samples were taken at the same locations and times as the shellfish, but cylindrospermopsins were only detected in one of these samples. Also during routine phytoplankton monitoring, no high abundances of cyanobacteria were observed. The source of cylindrospermopsins in Dutch shellfish areas is therefore still unknown.
|12 Oct 2021
|The 19th International Conference on Harmful Algae: ICHA 2021
|La Paz, Mexico
|Degree of Recognition