National Agriculture and Food Research Organization (NARO) has integrated multiple ecological risk assessment techniques that has been developed so far and enabled the visualization of nationwide changes in ecological risks to aquatic organisms due to pesticide usage over time and in regions. As an application example, we assessed the ecological risks, associated with 67 major paddy rice pesticides used in Japan at 350 river sites nationwide and examined the transition over the period from 1990 to 2010. From the result it was revealed that the ecological risk of insecticides was decreased by 92.4% and by 53.1% for herbicides. This study proposes a method to "visualize" the degree of ecological risks rather than the use of pesticides. Hence it can be used to support scientific decision-making by the government, etc.
Overview
Pesticides are widely used as materials for stable food production. However, there are concerns about adverse effects on aquatic organisms that are non-target of pesticides, for example the pesticides used in paddy fields may flow into rivers along with drainage. (The degree and likelihood of such adverse effects are defined as "ecological risks"). In addition, the shipment volume of pesticides (in terms of active ingredients) peaked in the 1980s and declined thereafter, while the number of active ingredients has been on an increasing trend. Due to this progressive trend of "small amount, large variety" of pesticides, it is becoming increasingly important to evaluate the ecological risks of individual pesticides, as well as to evaluate the combined effects of multiple pesticides.
NARO has developed a method to "visualize" the changes in ecological risks over time and in regions across the country by integrating several of the ecological risk assessment techniques that has been developed so far. As a concrete application example of this method, we assessed the ecological risks of 67 major paddy rice pesticides used in Japan at 350 river sites nationwide, and also assessed the transition for every five years from 1990 to 2010. As an indicator of ecological risks, we calculated the potentially affected fraction of species by multiple pesticides and found that the 20-year reduction rate was 92.4% for insecticides and 53.1% for herbicides. It is thought that this drastic decrease attributed to the development of low-risk pesticides by pesticides manufacturers, measures to prevent the leakage of pesticides such as thorough water management by rice farmers, and revise of the pesticide registration system by the government.
The clarification of changes in ecological risks by time and region in this research is unprecedented worldwide. This makes it possible to visualize the ecological risk reduction effect on aquatic organisms, and to support scientific decision-making by the government, etc. It can also be used to study various environmental impact reduction initiatives, including the Strategy for Sustainable Food Systems, MeaDRI formulated by the Ministry of Agriculture, Forestry and Fisheries (MAFF) in 2021.
Publication
Nagai T, Yachi S, Inao K (2022) Temporal and regional variability of cumulative ecological risks of pesticides in Japanese river waters for 1990-2010. Journal of Pesticide Science, 47 (1). 22-29. https://doi.org/10.1584/jpestics.D21-054
For Inquiries
Contact: http://www.naro.go.jp/english/inquiry/index.html
