Virtual Glyphosate Transfer Driven By Inter-Provincial Grain Trade In China And Implications For Potential Health Risks To Populations

The geographical and climatic conditions as well as development differences among regions in China make grain trade an important way to balance grain supply and demand and secure grain supply in many provinces in China.However,the transfer of resources and environmental pollution embodied in grain trade has received widespread attention.Glyphosate(GLP)is a highly efficient,low-toxic,broad-spectrum organophosphorus herbicide with great growth potential for application in food production in China with the development of biological breeding and planting technology,while the ultra-long service life of glyphosate has raised concerns about its safety for the environment and humans and other organisms.The international community has a mixed attitude toward glyphosate,but with more and more studies The International Agency for Research on Cancer(IARC)has classified glyphosate as a Class 2A probable carcinogen,and more and more countries are beginning to ban or restrict the use of glyphosate.To deal with the potential large amount of glyphosate pesticide use in China and the global trend of tightening restrictions on glyphosate use,and to strengthen further scientific management and inter-regional synergistic management of glyphosate pesticides in China,this dissertation investigates the use of glyphosate in interprovincial food trade by estimating the implied transfer of glyphosate use using interprovincial trade matrix on the basis of establishing the list of glyphosate use in China in 2020.The impact of virtual glyphosate transfer driven by interprovincial food trade on population health risk was explored by quantitatively assessing the potential exposure risk of glyphosate,and the main findings and conclusions of this paper are as follows:(1)The total glyphosate use of major food crops in China in 2020 was 17014.1tons,with the contribution of corn,rice,wheat and soybean accounting for 54.8%,28.6%,9.9% and 6.6%,respectively.Glyphosate use mainly occurred in large grainproducing provinces,and the province with the highest use was Heilongjiang Province,with 2,429.2 tons of use.The structure of glyphosate use in a certain region is related to the structure of local grain production and the intensity of pesticide application for different crops.The high hotspots of glyphosate application in China are mainly distributed in the central and western part of Heilongjiang Province,central Jilin Province,central Liaoning Province,central and southern Hebei Province,most of Henan Province,most of Shandong Province,and northern Anhui Province,while the Sichuan Basin,southern Hubei Province,eastern Hunan Province,and northern Jiangxi Province also have a relatively obvious distribution of glyphosate use.(2)China’s inter-provincial grain trade shows an overall pattern of "north to the south",with Heilongjiang Province being the largest grain transferring province,and Shandong Province and Guangdong Province being the main grain transferring provinces.Economically developed regions and large grain consuming provinces outsource more glyphosate pesticide use to other regions,while most of the glyphosate use in agriculturally developed regions is undertaken locally.The province with the largest outflow of glyphosate due to interprovincial grain trade is Guangdong Province,whose internal consumption of corn and rice has a major impact on glyphosate use in Guangdong;the province with the largest glyphosate use due to local grain consumption is Shandong Province,whose internal consumption of corn has a major impact on its glyphosate use;the province with the largest inflow of glyphosate due to interprovincial grain trade is Heilongjiang Province,whose external corn,rice and soybean The largest inflow of glyphosate due to interprovincial grain trade was in Heilongjiang province,where the external consumption of corn,rice and soybean was the main cause of glyphosate use.Interprovincial grain trade has led to a decrease in overall glyphosate consumption in China,with 21 provinces reducing glyphosate use through interprovincial grain trade and 10 provinces increasing glyphosate use.(3)Under the influence of population size,the spatial distribution of Population Annual Exposure(PE)index,which is used to characterize the potential exposure risk of glyphosate,is somewhat different from the spatial distribution of glyphosate use.By comparing the distribution of high risk areas in the "trade" scenario and the "no trade" scenario,it shows that the risk of population exposure to glyphosate shifts from south to north in China driven by grain trade.The inter-provincial grain trade resulted in more regions with lower potential exposure to glyphosate than the national average potential exposure to glyphosate in the "no trade" scenario,and the national potential exposure to glyphosate was overall reduced by 46.0%.Moreover,the virtual glyphosate transfer driven by inter-provincial grain trade reduced significantly the potential exposure risk in areas with high potential exposure to glyphosate,such as Beijing and Shanghai,but increased the potential exposure risk in Henan and Inner Mongolia.