Fate and occurrence of indoxacarb during radish cultivation for multi-risk assessment

Agrochemical indoxacarb is an important tool for selective pest control in radish that be consumed globally. A rapid and sensitive analytical method UHPLC-MS/MS was developed for tracing indoxacarb in radish leaves and roots with LOQ of 0.001 mg/kg and RT within 2 min, which were confirmed the satisfied storage stability of indoxacarb in radish matrixes with degradation rates less than 30 %. The occurrence, pharmacokinetics dissipation and concentration variation of indoxacarb were reflected by the original deposition of 2.23-4.12 mg/kg, half-lives of 2.6-8.0 d and terminal magnitude of 0.17 × 10^-2-25.46 mg/kg in radish, and the influencing factors were further illustrated in terms of climate factors, crop cultivars and soil properties. The highest residues of indoxacarb were 25.46 mg/kg in leaves and 0.12 mg/kg in roots, which were higher than international maximum residue limits. A probabilistic model, as well as deterministic model, were introduced to evaluated the health risks of indoxacarb offering a better description for uncertainty. The total chronic dietary risk values of indoxacarb were 146.961-482.065 % in 12 registered crops, of which ADI % in radish was accounted for 19.8 % with risk dilution effects. The unacceptable acute dietary risks of 121.358-220.331 % were observed at 99.9th percentile, whereas the high-potential non-carcinogenic effects were observed over 90th percentile (105.035-1121.943 %). The health risks should be continuously emphasized given the increasing applications and persistent characteristics of indoxacarb, which is vital to protect the human population from hazardous effects, particularly for vulnerable children.

Polycyclic aromatic hydrocarbons in the Yellow River estuary: Levels, sources and toxic potency assessment

This paper presents a systematic but preliminary study on the levels, sources and risk of exposure to polycyclic aromatic hydrocarbons (PAHs) in the Yellow River estuary by examining 16 priority PAHs listed by the U.S. EPA in four main environmental media (soil, surface water, groundwater and sediment). The concentration of individual PAHs in each medium in the study area was compared with the reported PAH values in China and abroad and to related environmental quality standards. The pollution levels of PAHs were found to be moderate in the soil and sediment, and low in the surface water and groundwater. Wood, coal combustion and petroleum inputs are the main PAH sources in soil and sediment, while petroleum inputs and petroleum combustion are the main PAH sources in surface water and groundwater. This indicates that PAH input caused by the high-speed inflow of external water over a long time has made a definite contribution to the occurrence of PAHs in surface water and groundwater in the study area. Furthermore, the mean value of the sum of the Excess Lifetime Cancer Risk (∑ELCR) exposure to PAHs in all media exceeded the generally acceptable risk level of 1.0E-06 recommended by the USEPA for carcinogenic chemicals, and the relative proportion contributed by DBA to the ∑ELCR was the greatest.

Sources, concentrations and risk factors of organochlorine pesticides in soil, water and sediment in the Yellow River estuary

The environmental occurrence, sources and risk factors of organochlorine pesticides (HCHs and DDTs) and their isomers or metabolites were studied using comprehensive surveys (including soil, surface water, groundwater and sediment sampling) conducted in the Yellow River Delta (YRD). HCHs and DDTs were all detected in multi environmental media. Compared with reported organochlorine pesticide values in China and abroad and with related environmental quality standards, the concentrations of HCHs and DDTs were generally at low levels in the YRD. Composition of OCPs (DDT metabolites and HCH isomers) showed that DDTs in the multiple environments of the YRD not only came from residues of dicofol but also from atmospheric deposition, while HCH pollution results from the historical usage of a mixture of technical HCH and lindane. Furthermore, the sum of Excess Lifetime Cancer Risk (∑ELCR) exposure to HCHs exceeded the generally acceptable risk level of 1.0E-06 recommended by the USEPA for carcinogenic chemicals.