Risk analysis of irrigating lettuce, carrots and strawberry with microcystine-contaminated water

Main research question/goal

The CYANTIR project aims to investigate whether irrigation with water contaminated by microcystins poses a risk for human health in terms of residual concentrations of microcystins that accumulate on or in the edible parts of plants. Microcystins (cyanotoxins) are produced by blooms of the algae-like bacteria known as "blue-green algae"; ingesting cyanotoxins via polluted water or food is an important source of exposure for humans. In our regions exposure usually occurs during recreation (water sports); the symptoms normally are limited to skin irritations, headaches, and gastric distress. 

The project explores in a controlled environment the potential concentration of microcystine in lettuce, carrot and strawberry. This methodolody will contribute to formation of a policy and proposals of recommended maximum values for the concentration of microcystine in irrigation water, especially for fruit and vegetables consumed raw.

Research approach

In greenhouse trials, three types of crops consumed raw (lettuce, carrot and strawberry) are exposed during their last month of growth to irrigation water contaminated with two commercially available concentrations of the microcystine congener (MC-LR). These concentrations take into account known toxicological values (WHO guideline value for drinking water of 1 µg/L, and national guideline value for recreational water of 20 µg/l). In strawberry, the dynamic of uptake in the plant according to irrigation regime is also studied. The level of MC-LR present on and in the crop is determined by Sciensano using LC-MS/MS at 3 different times (1 week before harvest, at harvest and 1 week after storage). 

Relevance/Valorisation

Due to climate change and eutrophication, an increase of cyanobacteria (blue-green algae) blooms is observed in canals and open surface basins, water sources that are also used for irrigation of agricultural crops during droughts. Microcystis aeruginosa is the most important cyanobacterial bloom in Belgium and produces microcystin (MC), a hepatotoxin that damages the liver and has tumor-stimulating effects. It is known from the literature that microcystins can be transferred to plants through the use of contaminated irrigation water. 
For carrots, lettuce and strawberries, the edible parts of the plant, respectively the root, the leaves and the fruit, are analyzed for cumulative exposure to microcystin (MC) concentrations. This method will contribute to a risk assessment for the edible parts of the crops. Specifically, this study will generate quantitative data to calculate the risk of human exposure to MC through consumption of fresh fruits and vegetables. Based on toxicological data, a safe limit for MC in irrigation water could be proposed.

Funding provider(s)
FOD Volksgezondheid, Veiligheid van de voedselketen en Leefmilieu