Beoordelingskader voor gebruik gezuiverd stedelijk afvalwater in de landbouw : Fase 1: wettelijke inkadering en voedselveiligheid

In dry summers, there may not be enough water for irrigation of agricultural and horticultural crops. Since 2020, there has been EU legislation to stimulate the use of purified urban waste water for this purpose. However, this may still contain chemicals and pathogens (bacteria and viruses) that are harmful to humans, animals and plants. That is why criteria have now been determined for the safe use of purified waste water on crops in the Netherlands. The criteria for chemicals are different from those for pathogens. For many chemicals, existing standards have been used that limit the maximum amount of the substance in water. Additionally, criteria have been developed for purified urban waste water for the safe consumption of crops and animal products. This was needed because there were no food safety standards for waste water. The resulting risk limits were compared, with the strictest determining the criteria. As for pathogens, the risks associated with types that are harmful to humans and crops have been identified. There are many types of pathogens that can make humans ill. The ‘measure’ that has been chosen is the number of E. coli (‘poop bacterium’) in waste water, due to the prevalence of this bacterium. The amount of E. coli allowed in water depends on the type of vegetable (to be eaten raw, such as lettuce or not) and the method of spraying (on leaf or not). For crops, only negligible amounts of pathogens that are generally present in soils are added with irrigation water. The only identified risk concerns crops from greenhouses, because they are grown in a sterile environment. In this case, small amounts of additional pathogens can cause more damage compared to the sterile environment. A number of uncertainties have led to stringent criteria. This can be restrictive for use of purified municipal wastewater. Follow-up research into these uncertainties can provide insight into how wastewater can be better utilized, without compromising safety. The next phase of this research will look specifically at the impact of chemicals and pathogens on drinking water sources. There is also a focus on local residents who may inhale water particles released during spraying. This will be completed by 2025. RIVM has determined the criteria and identified the risks in cooperation with Wageningen Environmental Research (WUR) and the Netherlands Food and Consumer Product Safety Authority (NVWA).