# Emerging Technologies for Degradation of Dichlorvos: A Review
## 1 Introduction  
The overly common use of organophosphorus pesticides (OPs) has led to a high risk of exposure to acute toxic compounds for various kinds of creatures, including humans [1]. As a representative organophosphorus pesticide, dichlorvos (\(O\),\(O\)-dimethyl) O-(2,2-dichlorovinyl)phosphate, DDVP) has been commonly used in developing countries and many other regions for more than 40 years [2]. DDVP has the molecular formula C\({}_{4}\)H\({}_{7}\)Cl\({}_{2}\)O\({}_{4}\)P, with a molecular weight of 220.98, vapor pressure of 1.2 \(\times\) 10\({}^{-2}\) mmHg at 20 \({}^{\circ}\)C, and density of 1.415 g/mL at 25 \({}^{\circ}\)C. It is classified by the World Health Organization (WHO) as class 2B: possible carcinogens [3]. In addition, the United States Environmental Protection Agency (EPA) has also classified it as a Class I pollutant (highly toxic) [4]. Since DDVP came into commercial use in 1961, it could be seen in many countries due to its significant advantages in terms of controlling internal and external parasites in cropsand livestock and its ability to eliminate several pests in houses and farmlands [1]. The yearly sales in 2019 around the world were about USD 88 million [5]. In many developing countries, the excessive use or misuse of DDVP in agricultural production leads to serious environmental problems and hazardous conditions. This situation usually has an impact on the soil biome and becomes people's environmental concern because of its residue toxicity in the ecological system. This issue has caused an organophosphorus pesticide contamination problem. The massive application of DDVP can affect non-target organisms profoundly through various kinds of pathways (Figure 1). Some reports have shown that exposure to DDVP in childhood is related to an increased risk of diabetes and may lead to the increasing risk of breast cancer in adulthood [6]. Scientific research has demonstrated certain effects of chronic exposure to DDVP on mouse. Those animals exposed to DDVP showed nigrostriatal neuron degeneration and remarkable behavioral impairment. Such animals have representative symptoms called catalepsy which is similar to those of [PERSON]'s disease in humans [7]. However, the current situation shows that OPs, including DDVP, are still widely used in China, India, Brazil, and many other developing countries. Exposure is inevitable for people in those countries. Therefore, there is an extremely urgent need to deal with DDVP residues in the environment and to protect people from further physiological damage. Many studies have tested the degradation of DDVP using different kinds of physicochemical methods, including gas phase surface discharge plasma, physical adsorption, hydrodynamic cavitation, and nanoparticles [8]. These approaches are not cost-effective and hard to apply to large contaminated areas. Therefore, microbial degradation of DDVP has become a powerful and attractive method to solve the exposure problem of this hazardous pesticide. Several microbes, including _Cunningham allegans_, _Fusarium solani_, _Talaromyces atroroseus_, _Aspergillus oryzae_, _Ochrobaratum intermedium_, _Pseudomonas aeruginosa_, and _Penicillium_ sp., have been isolated and play vital roles in DDVP degradation. It has been reported that the organic pollutants can be used by adaphon including soil bacteria and soil fungi as a sole carbon source [9; 10; 11; 12; 13]. These studies showed that microbial degradation seems to be a more environmentally friendly and convenient treatment method to reduce hazardous effects of toxic pollutants or contaminants [14; 15; 16; 17; 18; 19]. In addition, there are a few studies on degrading enzymes with correlative genes in microbes. However, most of the  
Figure 1: Contamination and removal of dichloros from natural environment. studies have paid little attention to the mechanisms and degradation pathways of DDVP. This review summarizes different kinds of solutions to the DDVP contamination problem and describes the promising application prospect of microbial degradation.