Nature, environmental fate, and potential human and aquatic toxicity of polar metabolite mixtures in groundwater at biodegrading fuel release sites

In 2014, CRC Care identified the metabolites of petroleum biodegradation (termed "weathered hydrocarbons" or "polar transformation products") as potential contaminants of emerging concern in their Technical Reports 29 and 31 and recommended that a review of overseas guidance and the best available scientific data be used to evaluate whether guidance or screening levels need to be developed for the metabolites. The Study described herein was conducted in 2011-2014 to provide a detailed understanding of the chemical nature of these metabolites, their environmental fate and potential toxicity to humans and aquatic receptors, thus providing significant information in line with the CRC recommendation. In this Study, groundwater from biodegrading fuel sites was collected and served as real-world samples of petroleum biodegradation metabolite mixtures. The samples were analysed using targeted and non-targeted techniques, and toxicity evaluations of the mixtures were conducted for human and aquatic receptors. Although the Study was conducted using groundwater from fuel release sites in the US, these results should be directly applicable to fuel release sites in Australia. We note that CRC Care cited the initial publications for this Study (Zemo et al 2013, Groundwater Monit. & Remed. v33n4; and Mohler et al 2013, Environ. Sci. Technol. v47) in its 2014 Technical Reports, but did not describe the results. The Study has expanded significantly since the first publications, and the updated results are presented herein. (author)