Environmental fate and health risks of phthalate acid esters in soils: A review

Phthalic acid esters (PAEs) are classified as environmental hormone organic compounds, commonly contained in plastic, resin and rubber, accounting for 20%60%, as plasticizers with potentially hazardous impacts on the environment and human health. In soils, the main anthropogenic sources of PAEs are agricultural chemicals, sewage water irrigation and atmospheric precipitation. PAEs can abundantly accumulate in the soil and be transported to different environmental systems via a series of environmental, geochemical processes such as volatilization, leaching, adsorption, biodegradation, plant uptake and food chain. This article combined the results of domestic and international studies to summarize the state of soil PAEs pollution in China. Anthropogenic activities and land use changes were the main factors responsible for seasonal and spatial distributions of PAEs. The contents of PAEs in soils in most regions of China reached dozens milligram per kilogram, which obviously exceeded the standards for the US and the European countries. Di-n-butyl phthalate (DnBP) and di (2-ethylhexyl) phthalate (DEHP) were the dominant PAEs in soils, similar to those observed in other countries. Also the environmental behavior of PAEs in soil-gas interface (volatilization and atmospheric precipitation), soil-plant system (phytoremediation and plant uptake) and soil-water interface (sediment adsorption and desorption) were analyzed to determine the causes of soil PAEs transfer between air, water, sediments and plants. There were significant differences in the characteristics of PAEs absorption, accumulation, distribution and transformation among the different interfaces. Because of the widespread application of PAEs and its occurrence in most common daily chemicals, humans are exposed to PAEs through foods contaminated during crop growth in soil or during packaging. Humans are also at risk through exposure to air (for breathing or absorption by skin), causing severely ecological and health risks in many regions of China. It was recommended that future soil PAEs research should focus on regional soil pollution and environmental behavior, PAEs transmission and evolution regularity in space and time, medium migration mechanisms, risk reduction and remediation measure research. There was need to use knowledge about the environmental fate and health risks of PAEs in soils to improve the regulation of organic pollution transformation in soils. This knowledge was also necessary for providing theoretical basis for the protection of ecological environments and soil health.