Pesticides play an important role in agricultural development. However, pesticide application can result in both acute and chronic human toxicities, and the adverse effects of pesticides on the environment and human health remain a serious problem. There is therefore a need to discuss the application methods for pesticides, the routes of pesticide exposure, and the health risks posed by pesticide application. The health problems related to pesticide application and exposure in developing countries are of particular concern. The purpose of this paper is to provide scientific information for policymakers in order to allow the development of proper pesticide application technics and methods to minimize pesticide exposure and the adverse health effects on both applicators and communities. Studies indicate that there are four main pesticide application methods, including hydraulic spraying, backpack spraying, basal trunk spraying, and aerial spraying. Pesticide application methods are mainly selected by considering the habits of target pests, the characteristics of target sites, and the properties of pesticides. Humans are directly exposed to pesticides in occupational, agricultural, and household activities and are indirectly exposed to pesticides via environmental media, including air, water, soil, and food. Human exposure to pesticides occurs mainly through dermal, oral, and respiratory routes. People who are directly and/or indirectly exposed to pesticides may contract acute toxicity effects and chronic diseases. Although no segment of the general population is completely protected against exposure to pesticides and their potentially serious health effects, a disproportionate burden is shouldered by people in developing countries. Both deterministic and probabilistic human health risk assessments have their advantages and disadvantages and both types of methods should be comprehensively implemented in research on exposure and human health risk assessment. Equipment for appropriate pesticide application is important for application efficiency to minimize the loss of spray solution as well as reduce pesticide residuals in the environment and adverse human health effects due to over-spraying and residues. Policymakers should implement various useful measures, such as integrated pest management (IPM) laws that prohibit the use of pesticides with high risks and the development of a national implementation plan (NIP) to reduce the adverse effects of pesticides on the environment and on human health.

Water quality is closely associated with human health and socio-economic sustainable development. With the increasingly intensive anthropogenic activities, pollutants especially trace elements, enter water aquatic system and cause harm to humans. This study conducted the first systematic comparison on the pollution status of surface water and groundwater in China. Water quality and health risk assessment of 12 trace elements were evaluated according to the water quality index (WQI), hazard quotient (HQ), hazard index (HI), and carcinogenic risk (CR). The results showed that the average values of trace elements in the majority of surface water were higher than those in groundwater. The WQI values demonstrated that 86.02% of surface water and 83.11% of groundwater were suitable for drinking water. Arsenic served as the predominant pollutant and contributed significantly to cause the non‑carcinogenic risk on human health in both surface water and groundwater, children were more vulnerable to the adverse effects than adults. In surface water, the priority non-carcinogenic risk sites were mainly distributed in Anning River, Taizi River, Middle reaches of Huai River and Jilin section of Songhua River. For groundwater, the high-risk sites were located in Huhhot Basin, Kuitun, Jianghan Plain, Datong Basin and Yucheng County. Arsenic posed potential carcinogenic risk to local resident in some water sites, and it presented higher in groundwater than surface water. More concerns should be paid on Songhua, Yangtze and Huai River Basins, in addition, Pearl, Southeast Coastal, Southwest and Northwest River Basins still need attention. The future work should be carried out more extensive range of the water sites and long-term monitoring in China. In particular, more attention should be dedicated to assess high As water bodies.

This study provides an overview of the studies of heavy metal pollution regarding As, Cd, Cr, Hg, Pb, Cu, Zn and Ni in the urban soils throughout 71 cities of China, based on data from online literature, during the period 2003–2019. The concentrations, spatial distributions, contamination degrees and health risks of heavy metals in the urban soils were evaluated. The results demonstrated that the mean values of eight heavy metals all exceeded the soil background values in China, and the kriging interpolation method showed that the hot-spot cities with heavy metal contamination in urban soils were mainly concentrated in the southwest, southcentral, southeast coast, northcentral and northwest regions of China. The geoaccumulation index (Igeo) indicated that Hg and Cd were at moderate contamination levels and that the levels of the other six metals did not appear contamination. The pollution index (PI) showed that Cd and Hg reached high contamination levels, and the other metals reached moderate contamination levels. The integrated pollution index (IPI) and potential ecological risk index (PRI) indicated that the integral urban soils in the study areas ranked high contamination levels and moderate ecological risk degree, respectively, and Cd and Hg should be labeled as priority metals for control in the urban soils around China. The human health risk assessments for the heavy metals indicated that ingestion was the dominant exposure pathway for having adverse effects on human health. The mean Hazard index (HI) values of eight heavy metals all showed that adverse effects on human health were unlikely, and the mean carcinogenic (CR) values of As, Cr and Ni for children and adults all suggested an acceptable carcinogenic risk to human beings. In addition, children exposed to these heavy metals faced more serious non-carcinogenic and carcinogenic health threats compared to adults. The results could provide valuable information for demanding the better control of heavy metal pollution and mitigation of the adverse effects on residents by environmental regulators in national urban regions.

This study investigated the bioaccumulation and transfer of heavy metals including Cd, Cr, Cu, Mn, Ni, Pb and Zn in soil-crop system in Lhasa, and assessed the health risks of the edible part of the crops. The results showed that the average values of Cd, Cr, Cu, Mn, Ni, Pb and Zn were 0.15, 44.55, 24.68, 532.40, 22.47, 38.18 and 73.99 mg kg^-1 in natural soil, and 0.16, 46.93, 38.45, 559.13, 23.23, 40.03 and 83.29 mg kg^-1 in cultivated soil, respectively. Highland barley and wheat had the strongest ability to accumulate Zn in grain, the BCF values were 0.24 and 0.27, respectively, significant differences in the distribution of metal contents in crop root, stem, leaf and grain were observed. Root presented larger accumulation capacity in most metals, Zn and Cu was easily transferred in the plant organs, most metals in this study presented difficult to migrate from root to grain. The transfer peak of most metals in soil-crop system appeared from stem to leaf. The concentrations of Cr and Mn in crop grains could be predicted according to the multiple linear regression models. THQ and HI values of heavy metals in edible parts of both highland barley and wheat were below the safety threshold of 1, indicating no detrimental effects posed to adults health. This study helps to understand the accumulation and transfer of heavy metals in soil-crop system in plateau region.