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Chlorpyrifos has been used extensively for decades to control crop pests and disease-transmitting insects; its contribution to increasing food security and minimizing the spread of diseases has been well documented. Pymetrozine and Avermectin (also known as abamectin) have been used to replace the toxic organophosphate insecticides (e.g., Chlorpyrifos) applied to rice crops in China, where the overuse of pesticides has occurred. In addition, climate change has exacerbated pesticide use and pollution. Thus, farmers and communities are at risk of exposure to pesticide pollution. This study reviews the contamination, exposure, and health risks through environmental and biological monitoring of the legacy pesticide Chlorpyrifos and currently used insecticides Pymetrozine and Avermectin in China; it investigates whether changes in pesticide usage from Chlorpyrifos to Pymetrozine and Avermectin reduce pesticide contamination and health hazards to communities and residents. In addition, this review discusses whether Pymetrozine and Avermectin applications could be recommended in other countries where farmers largely use Chlorpyrifos and are exposed to high health risks under climate change scenarios. Although Chlorpyrifos is now banned in China, farmers and residents exposed to Chlorpyrifos are still experiencing adverse health effects. Local farmers still consider Chlorpyrifos an effective pesticide and continue to use it illegally in some areas. As a result, the concentration levels of Chlorpyrifos still exceed risk-based thresholds, and the occurrence of Chlorpyrifos with high toxicity in multiple environmental routes causes serious health effects owing to its long-term and wide application. The bioaccumulation of the currently used insecticides Pymetrozine and Avermectin in the environment is unlikely. Pymetrozine and Avermectin used in paddy water and soil for crop growth do not pose a significant hazard to public health. A change in pesticide use from Chlorpyrifos to Pymetrozine and Avermectin can reduce the pesticide contamination of the environment and health hazards to communities and residents. Finally, we recommend Pymetrozine and Avermectin in other countries, such as Vietnam, and countries in Africa, such as Ghana, where farmers still largely use Chlorpyrifos. [ABSTRACT FROM AUTHOR]

Pymetrozine is one of the most commonly used insecticides in China. This study was conducted to analyse Pymetrozine's potential exposures through various environmental routes beyond the treatment areas. The aim was to estimate the potential health risk for communities due to non-dietary exposures to Pymetrozine in soil and paddy water. Data on registration of pesticides in China, government reports, questionnaires, interviews and literature reviews as well as toxicological health investigations were evaluated to determine the hazard and dose–response characteristics of Pymetrozine. These were based on the US EPA exposure and human health risk assessment methods and exposure data from soil and paddy water samples collected between 10 and 20 m around the resident's location. The exposure doses from dermal contact through soil and paddy water were estimated. The potential cancer risk from the following exposure routes was evaluated: ingestion through soil; dermal contact exposure through soil; dermal contact exposure through paddy water. The potential total cancer risk for residents was estimated to be less than 1 × 10−6. These were relatively low and within the acceptable risk levels. The potential hazard quotient (HQ) from acute and lifetime exposure by dermal contact through paddy water and soil and acute and lifetime exposure by soil ingestion for residents was less than 1, indicating an acceptable risk level. This study suggested that there were negligible cancer risk and non-cancer risks based on ingestion and dermal contact routes of exposure to residents. [ABSTRACT FROM AUTHOR]

Pymetrozine has replaced toxic organophosphate pesticides previously used for controlling pests of rice crops in China. Existing data on its environmental behavior are usually related to studies on artificial plots that do not adequately address the natural dynamics and residues in actual field conditions. Therefore, studies under field conditions were carried out to investigate the natural dynamics and residues of pymetrozine in two typical rice-growing areas in China – Hunan and Guangxi provinces. Samples of paddy soil and water were collected in relation to spraying events in the study areas. The quick, easy, cheap, effective, rugged and safe (QuEChERS) method was used to extract pymetrozine residues from the samples by a Waters ACQUITY UPLC (Milford, MA, USA) system interfaced with a triple-quadrupole mass spectrometer (Xevo TQ-D, Waters Corp., USA). The initial deposition of pymetrozine in paddy soils was higher than in paddy waters in both areas. The decay of pymetrozine followed an exponential trend consistent with the first order kinetics. The half-life of pymetrozine in paddy water was determined to be 3.0 and 3.8 days, whereas the half-life in soil was 3.8 and 3.5 days in the Guangxi and Hunan samples, respectively. The decline rates of pymetrozine in paddy soil and paddy water in this field study were faster than those conducted under non-field conditions reported in previous studies. Compared to other pesticides used in China as reported in previous studies, the environmental persistence of pymetrozine in both paddy water and soils in Guangxi and Hunan provinces is very low. This has important implications for the use of pymetrozine in agricultural systems globally. • First study of natural dynamics of pymetrozine after spraying under field conditions in China. • The decline of pymetrozine in soil and paddy water was faster than those reported in previous studies conducted under non-field conditions. • The half-lives of Pymetrozine were 3.08 and 3.85 days in paddy water and 3.49 and 3.73 days in 0–10 cm soil layer, respectively. • Pymetrozine has no effective bioconcentration potential to aquatic organisms and low environmental persistence. [ABSTRACT FROM AUTHOR]

The concentration level related to toxicities of trace elements in drinking water, rice, wheat flour, and their associated negative impacts on human health have become an emergent issue in China. Because Xinjiang is the largest province in China with the majority of arable pasture land available for cultivation, it is important to analyze the concentrations of trace elements in relation to their toxicities in water, rice, and wheat flour and to investigate the health risk differences between agricultural and pastoral areas in Bay County, Xinjiang. The study results showed that (1) metal concentrations from drinking water, rice, and wheat flour were within the permissible limits; (2) concentration levels of trace elements and their total risk from drinking water and rice were higher in the agricultural areas than those in the pastoral areas, whereas concentration levels of trace elements and their total risk from wheat flour were higher in the pastoral areas than those in the agricultural areas; (3) the concentration level of the trace elements in rice were higher than in the wheat flour, but the risk from the wheat flour was higher than the risk from rice; (4) total non-cancer risk from the flour (HI f ) in both areas exceeded the respective safe reference doses; (5) total cancer risk from the wheat flour, rice, and water exceeded the safety limit (1 × 10 -4 ); (6) for the exposed population, arsenic was suggested as the most evident pollutant leading to carcinogenic concerns regarding the water, rice, and wheat flour; (7) the risk index from the wheat flour made up the highest percentage both in the total cancer risk and the non-cancer risk, followed by rice and then water; and (8) the human health risk was attributed to influence from the local environment in the agriculture areas, while it was attributed to the external environment in the pastoral areas. Graphical abstract.