The occurrence of selected antibiotics in Hong Kong coastal waters.

Pharmaceuticals and personal care products (PPCPs) are a group of emerging chemicals of environmental concern that have remained largely unrecognized until recent advances in low level analytical measurements (Cha et al., 2006; Erickson, 2002; Gros et al., 2006; Lindsey et al., 2001). The growing concern over the occurrence and fate of PPCPs has been attributed not only to the induction of adverse effects in terrestrial or aquatic organisms, but also the potential of some antibiotics to induce resistant bacterial strains in the environment (Hirsch et al., 1998). Over 3000 chemical substances are used in human and veterinary medicine, including aquaculture and farming practices (Ternes et al., 2004). Such pharmaceuticals include antiphlogistics/anti-inflammatory drugs, b-blockers, lipid regulators, antiepileptics and antibiotics, the latter being amongst the most important environmentally (Petrović et al., 2005). Unlike other micro-pollutants and pesticides, antibiotics are not rigorously tested for environmental fate and effects (Jones et al., 2001), resulting in their ubiquitous distribution in the environment. The occurrence of pharmaceuticals in the environment has been reviewed in detail by Heberer (2002) and Halling-Sørensen et al. (1998) and references therein. Antibiotics and their metabolites primarily enter the aquatic environment via wastewater treatment systems following human consumption and excretion (Daughton and Ternes, 1999). Many researchers have demonstrated the incomplete removal of pharmaceuticals during wastewater treatment processes (Daughton and Ternes, 1999; Hirsch et al., 1999; Öllers et al., 2001; Stumpf et al., 1999; Ternes, 1998); in addition, the high water solubility and poor degradability of antibiotics enhances their passage through filtration, and thus their entry into groundwater and drinking water (Reddersen et al., 2002; Ternes et al., 2002). Other potential sources include unintentional discharges during manufacturing processes; agricultural application of veterinary drugs (including poultry production and fish farming applications); and discharges from landfill leachate (Daughton and Ternes, 1999; Holm et al., 1995; Ternes et al., 2004). In order to maintain the medicinal effects of pharmaceuticals for prolonged periods, most compounds are lipophilic, able to pass throughmembranes, andmanufactured to resist inactivation before providing their effect (Halling-Sørensen et al., 1998). Although the environmental concentrations of pharmaceuticals are generally low, their properties, together with their continuous usage, eventually result in concentrations that may be sufficient to provoke toxic effects in aquatic or terrestrial ecosystems. Importantly, the synergistic effects of different chemicals sharing common mechanisms of action could be substantial (Daughton and Ternes, 1999). The objective of BASELINE is to publish short communications on different aspects of pollution of the marine environment. Only those papers which clearly identify the quality of the data will be considered for publication. Contributors to Baseline should refer to ‘Baseline—The New Format and Content’ (Mar. Pollut. Bull. 42, 703–704).