Identifying potential paraben transformation products and evaluating changes in toxicity as a result of transformation

Parabens are a class of compounds often used as preservatives in personal care products, pharmaceuticals, and food. They have received attention recently due to findings that demonstrate estrogenic impacts and other adverse effects of parabens. Release into wastewater effluent is considered a major contributor to the spread of parabens into surface water. Current regulations in areas such as Japan, Europe, and Southeast Asia limit the concentrations of parabens that can be used in formulations but do not address concentrations discharged into waterbodies. Recent studies suggest that parent parabens are effectively eliminated by transformation during the wastewater treatment processes. Common tertiary treatments include ultrafiltration, chlorination, UV disinfection and ozonation. Ultrafiltration is used to remove solids before a disinfection step. Of the disinfection steps, ozonation is often the most effective at removing parabens. Not much is known about the toxicities of paraben transformation products. Of the transformation products, chlorinated parabens and PHBA are the most studied. Previous studies have shown that chlorinated parabens have greatly reduced estrogen agonistic activity when compared with the activity of parents. However, more recent studies have found that halogenated parabens actually have estrogen antagonistic activity. Further research involving chlorinated parabens could include other toxic endpoints. No known studies have evaluated adverse effects of oxygenated parabens. Parabens can interact with chlorine residues in the environment and form chlorinated products, this will occur at a faster rate during chlorination. Ozonation will oxidize parabens and UV disinfection can both oxidize and halogenate parabens. All studies determining potential transformation products have been done in laboratory settings or specific conditions. Further research is needed to determine if these transformations occur in situ. PRACTITIONER POINTS: Common chemical processes utilized by wastewater treatment facilities are effective at transforming parabens. Paraben transformation products are released in greater concentration in effluent than parent paraben compounds. Halogenated transformation products have been identified as estrogen receptor antagonists.