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Measured data are not available for photodegradation for any of the HABs.  A photodegradation study for the base material, LAB, resulted in less than 1% degradation in 14 days, although sensitized photolysis could not be ruled out as a possible transformation process.   Photodegradation was estimated with EPI Suite (USEPA 2000) using the same four representative constituents used to estimate log Kow and water solubility, p-bis (1-methylundecyl) benzene,  2,11-diphenyldodecane, 1,4-dipropyl-6-(1-methylundecyl)-tetralin, and 1,4-dihydro-1,4-dipropyl-6-(1-methylundecyl)-naphthalene, plus a representative trialkylbenzene with similar molecular weight (1-methyl-5-(1-methylundecyl)-2-(1-pentyl) benzene).  These materials were also used in the fugacity modelling.  Results indicate that in the presence of OH radicals at 25 °C, half-lives of these representative constituents would range from approximately 1.3 to 10 hours (based on 1.5 x 106 OH radicals/cm3). The rate constants ranged from 25.95 x 10-12 to 96.42 x 10-12 cm3/molecules-sec for the five materials.  However, relative to the aerobic biodegradation, photolysis would be too slow to significantly alter the environmental levels of LAB.  Therefore, based on the similarity of chemical structure, and the low volatility of these compounds, photodegradation would not be expected to be a significant mechanism for degradation of the HABs.