Abstract
This review identifies understudied areas of emerging contaminant (EC) research in wastewaters and the environment, and recommends direction for future monitoring. Non-regulated trace organic ECs including pharmaceuticals, illicit drugs and personal care products are focused on due to ongoing policy initiatives and the expectant broadening of environmental legislation. These ECs are ubiquitous in the aquatic environment, mainly derived from the discharge of municipal wastewater effluents. Their presence is of concern due to the possible ecological impact (e.g., endocrine disruption) to biota within the environment. To better understand their fate in wastewaters and in the environment, a standardised approach to sampling is needed. This ensures representative data is attained and facilitates a better understanding of spatial and temporal trends of EC occurrence. During wastewater treatment, there is a lack of suspended particulate matter analysis due to further preparation requirements and a lack of good analytical approaches. This results in the under-reporting of several ECs entering wastewater treatment works (WwTWs) and the aquatic environment. Also, sludge can act as a concentrating medium for some chemicals during wastewater treatment. The majority of treated sludge is applied directly to agricultural land without analysis for ECs. As a result there is a paucity of information on the fate of ECs in soils and consequently, there has been no driver to investigate the toxicity to exposed terrestrial organisms. Therefore a more holistic approach to environmental monitoring is required, such that the fate and impact of ECs in all exposed environmental compartments are studied. The traditional analytical approach of applying targeted screening with low resolution mass spectrometry (e.g., triple quadrupoles) results in numerous chemicals such as transformation products going undetected. These can exhibit similar toxicity to the parent EC, demonstrating the necessity of using an integrated analytical approach which compliments targeted and non-targeted screening with biological assays to measure ecological impact. With respect to current toxicity testing protocols, failure to consider the enantiomeric distribution of chiral compounds found in the environment, and the possible toxicological differences between enantiomers is concerning. Such information is essential for the development of more accurate environmental risk assessment.
Highlights
In surface waters, a broad range of inorganic and organic contaminants are controlled by legislation outlined by the European Commission (European Commission, 2008)
Legislation is expected to broaden to encompass a greater number of municipal derived chemicals described as ECs following the recent proposal of the pharmaceuticals 17b-estradiol (E2), 17a-ethinylestradiol (EE2) and diclofenac as priority hazardous substances (European Commission, 2012)
To date, >200 different pharmaceuticals alone have been reported in river waters globally, with concentrations up to a maximum of 6.5 mg lÀ1 for the antibiotic ciprofloxacin (Hughes et al, 2013)
Summary
A broad range of inorganic and organic contaminants are controlled by legislation outlined by the European Commission (European Commission, 2008). Single compound acute toxicity testing (including crustaceans, algae and bacteria) conducted under controlled laboratory conditions have found median effective concentrations (EC50's e concentration at which the toxicological response to an organism is halfway between a normal and maximum response for a pre-set time period) for a number of these ECs to be < 1 mg lÀ1 (Bruce and Versteeg, 1992; Holten Lutzhøft et al, 1999; Halling-Sørensen, 2000; Brooks et al, 2003; Andreozzi et al, 2004; Brain et al, 2004; Eguchi et al, 2004; Cleuvers, 2005; Isidori et al, 2005a,b; DellaGreca et al, 2007; Isidori et al, 2007; DeLorenzo and Fleming, 2008; Terasaki et al, 2009; Giudice and Young, 2010) Such effect concentrations classify the chemical as potentially very toxic to aquatic organisms as described under the EU-Directive 93/67/ EEC (Commission of the European Communities, 1996; Cleuvers, 2003).
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