Opinion on a request from EFSA related to the default Q10 value used to describe the temperature effect on transformation rates of pesticides in soil 1 Scientific Opinion of the Panel on Plant Protection Products and their Residues (PPR-Panel)

SUMMARY One factor affecting the degradation rate of chemicals (including plant protection products) is temperature. It is generally accepted that this dependency may be reasonably described by using the Arrhenius equation which gives the degradation rate coefficient as a function of the temperature and the activation energy Ea. Using this Ea value, the ratio of degradation rates between two temperatures can be calculated. The ratio between the rates at 20° and 10°C is usually written as the Q10 value. This value is used in environmental exposure assessment to account for the impact of different temperatures. As a default, the value of Q10 = 2.2 was proposed by FOCUS (1997). The Panel on Plant Protection Products and their Residues (PPR Panel) of the European Food Safety Authority (EFSA) issued an Opinion on the Q10 value in 2006.