Pharmaceutical compounds comprise a group of over 4000 chemicals, widely used to maintain human and animal health (Waleng and Nomngongo 2022). This group includes antibiotics, non-steroidal anti-inflammatory drugs (NSAIDS) and analgesics, beta blockers, steroid hormones, antiretrovirals, antidepressants, and many others (Ford and Fong 2016; Waleng and Nomngongo 2022). The occurrence of pharmaceuticals in the environment was first documented over 45 years ago (Tabak and Bunch 1970). This emerging class of contaminants has been extensively studied over the past two decades, due, in part, to the development of better analytical detection techniques.

Pharmaceuticals and their metabolites (transformation products) primarily enter the aquatic environment through wastewater effluent, as they are not removed from wastewater treatment plants (Caldwell 2016). Industrial discharge from pharmaceutical manufacturing can create localized “hot spots” with concentrations of pharmaceuticals in the ppm range (Phillips et al. 2010b; Sanchez et al. 2011; Cardoso et al. 2014).  To a lesser extent, pharmaceuticals can enter aquatic systems via runoff from human and animal excrement on the ground, direct disposal of drugs into the environment, and veterinarian and agricultural practices (Caldwell 2016; Branchet et al. 2021). Generally, pharmaceuticals are found in rivers and estuaries at concentrations <100 ng/L, and the concentrations lessen as these chemicals move into the ocean (Kolpin et al. 2002; Glassmeyer et al. 2005; Kostich et al. 2014; Ebele et al. 2017).

Pharmaceuticals are non-volatile, polar organic compounds, with long residence times in aquatic systems (Waleng and Nomngongo 2022). However, these chemicals can differ widely in their physiochemical properties, which influences their distribution (Bogdal et al. 2010). Given the increased reliance on pharmaceuticals in modern societies, there has been growing concern about their ecological consequences (Schoenfuss et al. 2016). Currently, concentrations in waterbodies are generally much lower than those used for human therapeutics; however, aquatic biota may be at risk (Kolpin et al. 2002; Schoenfuss et al. 2016). Bioaccumulation of pharmaceuticals has been documented in a variety of aquatic biota and currently there are no maximum allowable limits developed for pharmaceuticals in the environment (Waleng and Nomngongo 2022).

Pharmaceuticals may be transformed in the environment or after ingestion, metabolization and excretion; and both pharmaceuticals and their metabolites may be taken up by biota (Tixier et al. 2003; Li et al. 2012).  Because pharmaceuticals have a variety of modes of action for therapeutic purposes, they also have a wide range of effects on nontarget species (Franzellitti et al. 2014; Franzellitti et al. 2015). Generally, pharmaceuticals can act individually or as mixtures to disrupt the endocrine system, affecting neurochemistry, physiology, behavior, and possibly micro ribonucleic acid (miRNA) expression (Franzellitti et al. 2014; Franzellitti et al. 2015; Cameron et al. 2016; Fabbri and Franzellitti 2016). This disruption can lead to altered development, growth, and reproduction in aquatic animals (Franzellitti et al. 2014; Franzellitti et al. 2015; Cameron et al. 2016; Fabbri and Franzellitti 2016). Observed effects of pharmaceuticals at environmentally relevant concentrations in aquatic biota include induction of spawning in bivalves, changes in snail mobility, decreased cognition and ability to camouflage in cuttlefish, and changes in activity, reproduction and development in fish (Lin and Pivorun 1990; Anderson et al. 1991; Owens et al. 1997; Overli et al. 1999; Clotfelter et al. 2007; Kreke and Dietrich 2008; Winder et al. 2009; Medeiros et al. 2010; Li et al. 2012; Fabbri and Franzellitti 2016).

Due to their prevalence in the LSJR, this year’s report will include the NSAIDs, acetaminophen and ibuprofen, and the opiate analgesic, hydrocodone. More pharmaceuticals will be added in future reports.

Waterborne concentrations of pharmaceuticals in the LSJR have been available since 2015 for acetaminophen, and 2018 for hydrocodone and ibuprofen (Figures 5.45, 5.46, 5.47). Mean and maximum acetaminophen concentrations increased from 2015 to 2018, with a maximum value of 590 ng/L observed in 2018 (Figure 5.45). Since then, mean acetaminophen values have been stable. Mean ibuprofen concentrations were stable from 2018 to 2021, and then increased in 2022 with the highest maximum value of 380 ng/L observed (Figure 5.46). Similarly, mean hydrocodone has increased in the LSJR since 2018, with the highest maximum value of 20 ng/L observed in 2022 (Figure 5.47). These compounds are not naturally occurring, and their increased prevalence may threaten aquatic life in the LSJR over time.

The STATUS of pharmaceuticals in the water column is uncertain, while the TREND is worsening.