Cyanobacteria (blue-green algae) produce toxins that may present a hazard for drinking water safety. These toxins (microcystins, nodularins, saxitoxins, anatoxin-a, anatoxin-a(s), cylindrospermopsin) are structurally diverse and their effects range from liver damage, including liver cancer, to neurotoxicity. The occurrence of cyanobacteria and their toxins in water bodies used for the production of drinking water poses a technical challenge for water utility managers. With respect to their removal in water treatment procedures, of the more than 60 microcystin congeners, microcystin-LR (L, L-leucine; R, L-arginine) is the best studied cyanobacterial toxin, whereas information for the other toxins is largely lacking. In response to the growing concern about nonlethal acute and chronic effects of microcystins, the World Health Organization has recently set a new provisional guideline value for microcystin-LR of 1.0 pg/L drinking water. This will lead to further efforts by water suppliers to develop effective treatment procedures to remove these toxins. Of the water treatment procedures discussed in this review, chlorination, possibly micro-/ultrafiltration, but especially ozonation are the most effective in destroying cyanobacteria and in removing microcystins. However, these treatments may not be sufficient during bloom situations or when a high organic load is present, and toxin levels should therefore be monitored during the water treatment process. In order to perform an adequate human risk assessment of microcystin exposure via drinking water, the issue of water treatment byproducts will have to be addressed in the future.

Just recently the problem of pharmaceutical residues in the environment has been emphasized by OECD. Especially antibiotics are of concern due to their widespread use and diverse modes of actions including ones that can affect the photosynthetic activity of primary producers and subsequently primary biomass production and carbon dioxide fixation. The EU regulatory authority, the European Medicines Agency (EMA), has therefore proposed to implement a new tailored environmental risk assessment scheme, published in a new draft guideline 2018. Threshold effect levels to three fixed representative species of green algae and cyanobacteria will be required. This article reviews and compares the contamination of waters with antibiotics in Switzerland and Germany and also presents an overview of published effect data on eukaryotic algae and prokaryotic cyanobacteria in order to discuss the representativeness of the selected species. Since no full datasets as demanded by the EMA were publically available yet, the gaps for four antibiotics have been experimentally completed. In summary the results support the species selection of the EMA published in the revised draft guideline, however it remains unclear whether diatoms should also be considered.

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Soil microbial communities which are essential for soil ecosystems can be disturbed by a manifold of environmental variables, including pesticides. Among others, fungicides are frequently applied as effective crop protection...

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