In a surprising and concerning discovery, researchers in Brazil have found significant levels of cocaine and its metabolites in the system of Brazilian sharpnose sharks (Rhizoprionodon lalandii) swimming in South America’s coastal waters. This finding, spearheaded by environmental scientist Gabriel de Farias Araujo from the Oswaldo Cruz Institute, underscores the pervasive issue of pharmaceutical pollution affecting marine life.
The research team tested 13 juvenile and young adult Brazilian sharpnose sharks, finding high concentrations of cocaine in all of them. Additionally, the drug’s main metabolite, benzoylecgonine, was present in all but one shark. These findings are particularly alarming given that these predators play a crucial role in the marine food chain.
While Hollywood might depict coked-up sharks on drug-fueled rampages, the reality could be more insidious. The effects of cocaine on marine predators like sharks might not be immediately obvious but could be significantly detrimental. Previous studies have shown that cocaine exposure can lead to lower cell viability and increased DNA fragmentation in zebrafish embryos. European eels exposed to environmental concentrations of cocaine exhibited altered muscle physiology, hinting at potential disruptions in vital biological processes.
Broader Issue of Pharmaceutical Pollution
Pharmaceutical pollution is a global problem, with active ingredients from drugs such as antibiotics, synthetic estrogen, and recreational drugs like cocaine entering waterways. Brazil faces a particularly severe challenge with cocaine pollution. A 2017 study revealed that water samples from the Bay of Santos contained as much cocaine as caffeine, highlighting the extent of the contamination.
Cocaine enters waterways primarily through sewage systems after being excreted by consumers. However, Brazil’s status as a major cocaine exporter and the presence of illegal refining facilities contribute to this pollution. Drug packages lost or discarded by traffickers further exacerbate the problem.
Cocaine can be easily absorbed by marine organisms lower in the food chain, such as molluscs and crustaceans, and then accumulate in higher-order consumers like sharks. The study revealed that cocaine and benzoylecgonine concentrations in the tested sharks were up to a hundred times higher than levels reported for other marine organisms, suggesting significant bioaccumulation through the food chain.
This discovery calls for immediate surveillance and awareness programs to address the potentially serious problem of environmental drug pollution. With a third of shark and ray species facing extinction due to overfishing, it is crucial to identify and monitor all potential threats to their populations.