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Environmental fate & pathways

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TBBPA may undergo abiotic degradation. Degradation of TBBPA by light was investigated in both air and water.

Air

To investigate photolysis of the test material, 14-C TBBPA applied to a silica gel surface was irradiated with 254 nm UV light. To determine degradation products of 14-C TBBPA photolysis, larger amounts of the substance were applied to plates and irradiated for 5 days. After this, residues were subjected to analysis.

Initially, TBBPA decreased rapidly with a half-life of about 0.12 day. However, after 0.25 day of UV exposure, the rate of degradation decreased. The half-life of the second phase was determined to be 1.1 day.

Water

A method was developed for studying the phototransformation following UV irradiation of aqueous solutions of tetrabromobisphenol A (TBBPA) and related compounds at various pHs. The rates of decomposition were determined at a concentration of 77 µM in water with an illumination time of 50 minutes.  

TBBPA’s rate of decomposition in water under UV irradiation (k x 10³ (s^-1)) ranged from 0.7 (at pH = 10) to 0.033 (at pH = 5.5). Its half-life ranged from 16 (at pH = 10) to 350 (at pH = 5.5) minutes; TBBPA’s half-life at pH 7.4 = 24 minutes.  The disappearance quantum yield ranged from 0.045 (pH = 10) to 0.018 (pH = 5.5). 

The data indicated that TBBPA was readily photodegraded in aqueous solution. Degradation rates were sensitive to pH; the rate of decomposition of TBBPA was six times higher at pH 8 than at pH 6.