Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information

Indirect photochemical degradation of neo-decanoic acid (NDA) as mediated by OH-attack is estimated to have a half-life of 1.2 days or 13.9 hours based on a 12 -hour sunlight day. A 12-hour day half-life value normalizes degradation to a standard day light period during which hydroxyl radicals needed for photolysis are generated in the atmosphere. Although NDA has the potential to degrade rapidly by OH-attack, multimedia distribution modeling indicates NDA is predicted to partition negligibly (0.1%) to the air compartment. Although NDA has a relatively short atmospheric oxidation half-life (13.9 hours), this process is unlikely to contribute significantly to the loss of NDA from the environment.

Direct photochemical degradation in water occurs through the absorbance of solar radiation by a chemical substance. If the absorbed energy is high enough, then, in the resultant excited state, the chemical may undergo a transformation. A prerequisite for direct photodegradation is the ability of one or more bonds within a molecule to absorb ultraviolet (UV) /visible light in the 290 to 750 nm range. Light wavelengths longer than 750 nm do not contain sufficient energy to break chemical bonds, and wavelengths below 290 nm are shielded from the earth by the stratospheric ozone layer. An approach to assessing the potential for NDA to undergo direct photochemical degradation is to assume that degradation will occur in proportion to the amount of light wavelengths >290 nm absorbed by NDA molecules. NDA does not absorb light within a range of 290 to 750 nm. Therefore, direct photolysis will not contribute to the degradation of NDA in the aquatic environment.