Pharmaceutical Residues in Edible Oysters along the Coasts of the East and South China Seas and Associated Health Risks to Humans and Wildlife

Abstract

The investigation of pharmaceuticals as emerging contaminants in marine biota has been insufficient. In this study, we examined the presence of 51 pharmaceuticals in edible oysters along the coasts of the East and South China Seas. Only nine pharmaceuticals were detected. The mean concentrations of all measured pharmaceuticals in oysters per site ranged from 0.804 to 15.1 ng g^-1 of dry weight, with antihistamines being the most common. Brompheniramine and promethazine were identified in biota samples for the first time. Although no significant health risks to humans were identified through consumption of oysters, 100-1000 times higher health risks were observed for wildlife like water birds, seasnails, and starfishes. Specifically, sea snails that primarily feed on oysters were found to be at risk of exposure to ciprofloxacin, brompheniramine, and promethazine. These high risks could be attributed to the monotonous diet habits and relatively limited food sources of these organisms. Furthermore, taking chirality into consideration, chlorpheniramine in the oysters was enriched by the S-enantiomer, with a relative potency 1.1-1.3 times higher when chlorpheniramine was considered as a racemate. Overall, this study highlights the prevalence of antihistamines in seafood and underscores the importance of studying enantioselectivities of pharmaceuticals in health risk assessments.

Keywords: Antibiotics; antihistamines; enantiomers; nonsteroidal anti-inflammatory drugs; psychiatric drugs; seafood safety.

Figure 1

13 sampling sites (red circles) from where edible oysters of the genera Magallana and Saccostrea were collected along the coasts of the East and South China Seas in 2019. The oyster soft tissue was used to quantify 51 compounds of pharmaceuticals and their metabolites as well as the associated health risks to humans and wildlife.

Figure 2

(a) Tissue concentrations of detectable pharmaceuticals in oysters collected from 13 sites along the coasts of the East and South China Seas (ng g dw^–1; n = 5). The lines inside the boxes indicate the 25th, 50th, and 75th percentiles, while the whiskers represent the minimum and maximum levels of the detected pharmaceuticals. Bars with different letters indicate significant spatial differences (p < 0.05, the Kruskal–Wallis test followed by Dunn multiple comparison tests). For sites where pharmaceuticals were not detected, no bars are shown. Levels of promethazine found in oysters are shown as 0 when not detected and as 0.5 ng g dw^–1 when below the quantification limit (QL) of 1 ng g dw^–1. (b) Composition profiles of the detected pharmaceuticals in oysters collected from these sites. Refer to Figure 1 for the locations and abbreviations of the oyster sampling sites.

Figure 3

Health risks of nine pharmaceuticals through consumption of oysters: (a) for the overall population (left) and regular consumers of bivalve shellfish (right) at four age intervals and (b) for three groups of wildlife, measured in terms of hazard quotient (HQ). (c) Probabilistic risk assessment on brompheniramine for oyster drills under the worst-case scenario. When the estimated daily intake (EDI) exceeds the acceptable daily intake (ADI), there is a potential health risk. Results of the regression model suggest that 18.6% of the oyster drills population in the East and South China Seas is at risk of brompheniramine exposure.

Figure 4

Left scale and blue circles indicate the changes in the enantiomeric fraction (EF) of (a) chlorpheniramine and (b) brompheniramine determined in edible oysters sampled along the coasts of the East and South China Seas (mean ± SD). The circles with different letters denote significant differences among the sampling sites where chlorpheniramine and brompheniramine were detected in the oysters (p < 0.05, the Kruskal–Wallis test followed by Dunn multiple comparison tests). The dotted line represents the EF value of the racemic standard of (a) chlorpheniramine and (b) brompheniramine. On the right scale, the solid bars indicate the relative therapeutic potency of (a) chlorpheniramine and (b) brompheniramine when treated as racemates. Refer to Figure 1 for the locations and abbreviations of the oyster sampling sites.