Pesticides vary in class and function, and in high concentration often lead to highly toxic environmental risks.[9] Of the over-500 types of pesticides in current use, two serious issues are their general lack of biodegradability and unpredictability.[10] In Kyrgyzstan, researchers assessed soil around a pesticide dump and discovered not only that the soil had poor microflora diversity, but that some of the species that were present used metabolic pathways to digest the pesticides.[9] The two most-efficient species found were Pseudomonas fluorescens and Bacillus polymyxa, with B. polymyxa degrading 48.2% of the pesticide Aldrin after 12 days.[9] However, when the strains were combined with each other as well as some other less-efficient yet native bacteria, pesticide degradation increased to 54.0% in the same conditions.[9] Doolatkeldieva et al. discussed their findings, saying