Research progress of combined toxicity induced by organophosphorus pesticides in fruits

Abstract: With the continuous improvement of quality of life, people concern nutrition and health more and more. The proportion of fruits on agricultural production and consumption is gradually increasing forits rich nutrition. And people has higher requirement for fruit quality and safety. In the process of fruittree planting, people often use a variety of pesticides to control the disease, insects and pests. The protec⁃tive effect of pesticides on fruit trees is worth affirmation. But pesticides have neurotoxicity, genotoxicity,immunotoxicity, reproductive and developmental toxicity, and other potential toxicity. Using high dose ofpesticides can produce residue in the environment and fruits. It will enter the body through diet and causegreat threat to human health. The pesticide residue in fruits has always been the focus on fruits qualityand safety. In order to reduce the resistance of pests and achieve better control effect, people usually usedcompound pesticides or used different pesticides simultaneously in the process of fruit tree planting. Thisleads to that food products such as fruits may simultaneously contain residues of several different pesti⁃cides. It was also found in the actual detection that two or more kinds of pesticide residues can be detect⁃ed in a fruit sample. As a result, the human body exposure to the complex mixtures of pesticides unavoid⁃ably through diet and environment. However current risk assessments of pesticide residues in fruits athome and abroad are mostly based on single pesticide toxicity evaluation. China has established some pes⁃ticide residue detection technologies for citrus, apples and other fruits. But the formulation of the stan⁃dards about maximum residue limits for pesticides is limited to single pesticide. In fact, although a singlepesticide may be limited within a standard, a variety of low dose pesticides exposure at the same time canbring harm to human body, increasing or decreasing the toxicity of each other and leading to a combinedeffect different from the single toxicity. According to the targets and mechanisms of the different compo⁃nents in the pesticide mixture, the combined effect mainly includes the following three modes: additive ac⁃tion, independent action and interaction. When the several kinds of pesticides in mixture have the sametarget and the similar action mechanisms, their combined toxicity effect presents additive action. Whenthe several kinds of pesticides in mixture have the different targets and action mechanisms, their com⁃bined toxicity effect presents independent action. When the several kinds of pesticides in mixture havethe same target and their action mechanisms may influence each other, their combined toxicity effect pres⁃ents interaction. And this interaction is called synergism or antagonism respectively as the combined toxic⁃ity is stronger or weaker. The combined toxicity of pesticide mixture can be predicted by CA (concentra⁃tion addition), IA (independent addition) and CI (combination index) methods. Organophosphorus pesti⁃cides are widely used as insecticides on citrus, apple and other fruit trees. It is also the first group of pesti⁃cides to carry out joint exposure risk assessment in many countries and organizations. Organophosphoruspesticides are often used with pyrethroid and carbamate insecticides. Because they are all typical nervepoisons, having the same target organ and similar toxicity mechanism. Therefore, the combined toxicity oforganophosphorus pesticides includes the joint toxicity effect induced by several organophosphorus pesti⁃cides and the joint toxicity effect induced by organophosphorus with pyrethroid or carbamate pesticides.Consequently, using genomics, proteomics and metabolomics methods to analyze the interaction patternsand the toxicity mechanisms between different pesticides, and then carrying out research of combined tox⁃icity induced by organophosphorus pesticide mixtures in fruits have great important significance. This willnot only provide the toxicological basis for the formulation of the standards about maximum residue limitsfor pesticide mixtures and risk assessments of organophosphorus pesticide residue mixtures in fruits in thefuture. When evaluating the combined toxicity of pesticide mixtures, in-vivo and in-vitro experiments canbe used. In-vivo experiments commonly use mammals and aquatic animals as experiment models such asrats and fish. Most of the experimental animals have similar physiology, pathology and pharmacology me⁃tabolism to human, the results can be extrapolated to human. So the traditional studies on combined toxici⁃ty of organophosphorus pesticide mixtures mostly use living animals as experimental model in vivo. But an⁃imal experiments are time-consuming, high-energy and high cost. Cell culture in vitro is rapid, simpleand low cost. And cell models can specifically study the toxic effect of pesticide mixtures to target cells,ruling out the interference of matrix and other systems. So this method is gradually used for evaluation oforganophosphorus pesticide mixtures safety in recent years. This paper summarized the effects of organo⁃phosphorus pesticide on human health, the interaction patterns and evaluation methods of pesticide mix⁃tures. It also reviewed the applications and research progress of different experimental models in com⁃bined toxicity induced by organophosphorus pesticides, comparing the advantages and disadvantages ofdifferent evaluation methods as well as in vivo and in vitro models. At the same time, it is worth noting thatthe current evaluations on the combined toxicity effect of organophosphorus pesticide mixtures have someproblems, and putting forward the development directions in the future, so as to provide relevant referenceabout the risk assessment of organophosphorus pesticide residue mixtures in fruits in the future.