More than 75% of waste is toxic to the environment and humans. The aim of the study was to invistigate the toxic effect of ecotoxicants on the rudiments of the teeth of laboratory animals. The experiment was carried out on 30 white outbred rats weighing 180–250. All animals were divided into 2 groups: control (Group 1) and experimental (Group 2). During the experiment, all animals of the experimental groups were subjected to inhalation exposure to gasoline and formaldehyde vapors. Animals of the control group were supplied with normal air around the clock. The jaws of rats were decalcified for 30 days in a 10% formic acid solution in a 10% buffered formalin solution. After dehydration of the material in a battery of alcohols of increasing concentration (ethanol - concentration from 70% to 100% absolute) was poured into paraffin according to the generally accepted method. Using a rotary microtome brand LEICA RM 2145 (LEICA, Germany), histological sections 5–8 µm thick were made. The sections were stained with hematoxylin and eosin and picrofuchsin according to the Van Gieson method. Stained sections were examined and photographed using an AXIO IMAGER-Z1 light microscope (CARL ZEISS, Germany). In the control group of rats, a morphological picture of normal tooth histogenesis was observed at a late stage of development. In the structure of the tooth germs of rat pups of the 2nd group, a violation of the processes of histogenesis of most tooth germs and a change in the structure of the periodontal tissues were found. In the epithelium of the gingival mucosa, signs of dystrophic changes were determined, up to cell destruction; in the connective tissue plate of the gingival mucosa, in the periodontium and in the zone of formation of the alveolar bone, signs of inflammatory phenomena were determined in the form of cell infiltrations and circulatory disorders in the form of expansion of the lumens and blood filling of the vessels. In the area of the tooth germs, destructive changes in odontoblasts and enameloblasts were manifested, which was probably one of the reasons for the disruption of the processes of dentinogenesis and enamel formation, expressed in the heterogeneity of the formation of dentin and enamel layers. This confirms the toxic effect of ecotoxicants on the rudiments of the teeth of laboratory animals.