HUMIC ACID MEDIATED PHOTOCHEMICAL DEGRADATION OF FIRE RETARDANT CHEMICALS (PBDEs) IN NATURAL WATERS

A study was conducted to determine the effect of ultraviolet radiation on the degradation of fire retardant chemicals such as polybrominated diphenylethers, or PBDEs. PBDEs have been shown to cause health risks to animals and humans such as infertility in women, reduced metal development in children, and disruption of the endocrine system. Human exposure to fire retardant chemicals has been increasing due to the large number of household items that are sprayed with PBDEs, such as furniture, electronics, clothing, carpets, and plastics, and the flame retardants either bleed or leach over long period of time and eventually settling as very fine dust particles on common household items or get discharged into the environment. Recent studies have shown that PBDEs are even present in breast milk. Certain PBDE congeners, such as the hexabrominated diphenylether, have been banned by the European Union. The ability of higher brominated PBDE congeners, such as the deca-brominated diphenylether (BDE-209), to degrade into this harmful form was investigated. Specifically, the influence of UV radiation and humic acids in the degradation was the focus of this study. Direct exposure to UV radiation produces hydroxyl radicals that can breakdown many types of complex organic compounds. The presence of humic acids may further enhance this degradation as UV radiation of dissolved humic can also produce additional hydroxyl radicals. These effects have been observed in the photodegradation of herbicides and pharmaceutical chemicals. In this study, aqueous solutions containing BDE-209 and other congeners were exposed to UV radiation in the presence and absence of humic acid. Preliminary experiments indicate the presence of degradation products such as tri-, tetra-, penta-, and hexa- forms of BDEs. Further results will be discussed in this paper.