Determination of Toxic Products Released during Combustion of Selected Pyrethroids

Synthetic pyrethroids are widely used for pest control in modern industrial agriculture. These substances largely replace pesticides, which are being withdrawn. However, wide use of pyrethroids results in production, storage and distribution of those chemicals posing other hazards for human and the environment than pest control. Unwanted combustion during incidents, accidents or major accidents may lead to formation of more dangerous substances than those involved in an emergency event. Dangerous gaseous substances released during fire are a threat not only to employees of industrial plants and warehouses, where the incident occurred, but also to firefighters, people involved in rescue operations and local residents. Therefore, knowing what toxic substances may be formed as a result of a fire is significant for an analysis and risk management of production processes, storage and distribution of those pesticides. In this paper, the thermal degradation of three representatives of pyrethroids: beta-cyfluthrin, deltamethrin and lambda-cyhalothrin were studied. In the first stage of research the Simultaneous Thermal Analysis (STA) that combines thermogravimetry (TG) and differential scanning calorimetry (DSC) was used to determine thermal characteristics of pyrethroids, e.g. the relation between mass loss and temperature (TG), melting temperature and initial decomposition temperature. The second stage was for identification of gaseous combustion products. Also a Purser furnace was used to heat the substances and made it possible to identify substances formed during side reactions of combustion of the pyrethroids. Newly-formed substances were identified with an infrared spectroscope with Fourier transformation (with on-line connection) and, additionally, with a gas chromatograph with mass spectrometry. The obtained results led to conclusion that the major compounds identified in the gaseous products were organic compounds, polycyclic aromatic hydrocarbons and halogenated aromatic hydrocarbons, which all are carcinogenic and mutagenic pollutants.