Introduction

Sulcotrione is a new kind of triketone-type herbicide, which inhibits the activity of plant 4-hydroxyphenylpyruvate dioxygenase (HPPD). It has been widely applied to control and prevent wild grass and weeds for crops such as barley, wheat and maize in Europe, the USA and many other countries, including China, since 2000 . HPPD also exists in mammals for the catabolism of tyrosine. Although sulcotrione shows low toxicity in subchronic and chronic toxicity testing, it can also, through the food chain, be continuously transferred to and accumulate in the human body when it is widely used and applied and when part of its residue in the soil is absorbed by and aggregated in plants. Another part of its residue pollutes the water table through surface runoff and the underground permeable layer. Therefore, sulcotrione, as an HPPD inhibitor, has potential risks to human health, and its possible role as an environmental pollutant must raise attention and vigilance.  The residual level of sulcotrione in the soil directly affects its accumulation in agricultural products and is closely related to the level of human exposure. Currently, there is a standard for sulcotrione residue in the soil. Therefore, the investigation of the sulcotrione soil residual levels can provide scientific evidence for the rational application of sulcotrione and the establishment of pesticide residue standards. In addition, this investigation also can supply more data for soil pesticide monitoring databases and provide an informative source for scientific research. HPPD, a target molecule of sulcotrione, exists universally in prokaryotes and eukaryotes. The catabolism of tyrosine is repressed when HPPD is inhibited by sulcotrione. Epinephrine is derived from tyrosine. The detection of tyrosine and epinephrine levels in the blood of rats exposed to sulcotrione can reflect the inhibiting effect of HPPD on epinephrine levels. The regulatory mechanisms for blood glucose are complicated. There are many possible pathways for sulcotrione to interfere with blood glucose levels. The rats were exposed to different doses of sulcotrione for different times to get blood glucose levels, enzyme activity, hormone levels, etc. The correlations between blood glucose levels and different parameters were analyzed in the rats exposed to sulcotrione to establish or exclude the possible interference of sulcotrione with blood glucose regulation. In vitro experiments have already shown that sulcotrione can specifically, effectively and reversibly inhibit hepatic HPPD activity. However, there are few in vivo reports on this question. In this study, we investigate, the effects of sulcotrione on hepatic enzyme activity, tyrosinemia and cornea damage through subacute and chronic toxicity tests in rats.