Penta treated wood should be aged three months after treatment and prior to submersion. This aging period will allow time for some of the carrier oil to evaporate and for the binding of penta with lignin in the middle lamella

via a photolytic condensation reaction. After exposing small pieces of penta-treated wood for 20 days to natural and artificial light, measured OCDD concentrations of about 70 ppm (ng OCDD/mg PCP). The OCDD in turn degraded to HpCDD and HxCDD (heptaand hexa-chlorodibenzodioxin). The final concentration of HxCDD was approximately 15 20 ppm. When P-9 oil was used as the solvent for penta, concentration of OCDD formed from penta ranged from 2 4 ppm. Of the three contaminants identified above, the most toxic is the hexachlorodibenzo-p-dioxin (HxCDD)