Stakeholders in Brazil are growing increasingly concerned over pollution and waterway contamination caused by cocaine.
“Cocaine today is, in fact, a contaminant of the Bay of Santos. We found drug contamination spread throughout the region,” said Camilo Dias Seabra, a professor at UNIFESP, in a panel discussion on water during FAPESP Week Illinois, which took place April 9-10 in Chicago.
Researchers discovered in 2017 cocaine and other substances derived from medicines in surface water in the Bay of Santos may be causing biological effects in environmentally relevant concentrations. Utilizing funding supported by FAPESP, the researchers discovered cocaine in water samples collected in the area, as well as ibuprofen, paracetamol, diclofenac, and other medicines. The cocaine found was in a concentration similar to caffeine, a traditional indicator of contamination as it is commonly found in both beverages like coffee, tea, and soft drinks, as well as medicines.
“It’s a huge concentration of cocaine if we imagine the consumption of caffeine,” Seabra said. “These findings were very surprising.”
The emerging problem is particularly concerning as São Paulo is the largest seaport in Latin America and is already facing a growing pollution problem.
Researchers from the Federal University of São Paulo (UNIFESP) found through laboratory analysis that cocaine can cause serious toxicological effects in wildlife including brown mussels (Perna perna), mangrove oysters (Crassotrea gasar) and fish (eels).
One potential explanation that may skew the results is when the actual samples were collected. Because the samples were collected shortly after the Brazilian carnival, the high contamination might be an outlier caused by increased tourist population and recreational drug use.
“We thought it might be a carnival phenomenon. But we did seasonal monitoring and found that, throughout the year, cocaine and its metabolites were present not only in the water but also in mussels, for example,” Seabra stated.
In the research, the investigators specifically looked at the effects cocaine exposure had on brown mussels. The bioaccumulation found in the brown mussels was more than 1000 times higher than what was found in water samples from the same period.
“This is a high bioaccumulation factor. Therefore, the seafood in the Bay of Santos may be contaminated by cocaine, but not only by cocaine,” Seabra noted.
The researchers also found elevated levels of dopamine and serotonin in brown mussels after just one week of exposure, likely caused by a neuroendocrine response that could affect the reproductive system of the animals. The investigators tested this theory using other marine wildlife, including eels. Here, they found that chronic exposure to cocaine impacted oogenesis (egg formation) and steroidogenesis (production of steroid hormones) for eels.
“Eel eggs exposed to cocaine had a lower maturation rate. In this way, cocaine can be understood as an endocrine disruptor in these animals,” Seabra said.
The research team also analyzed the ecological risk of cocaine exposure in mangrove oysters using benzoylecgonine as a biomarker and found it causes severe cytotoxic and genotoxic effects.
While there might be some credence to the carnival theory, the contamination has been building up for decades. The investigators found - based on geochemical studies of estuarine sediment samples - the drug has been accumulating since at least the 1930s, but use has skyrocketed in recent decades in the region.
In response to the study, the São Paulo State Environmental Corporation (CETESB) released a statement. “CETESB systematically monitors the quality of the state’s coastal waters, including the area of influence of the Santos submarine outfall, and conducts ecotoxicological tests on samples from this area to assess the possible effects of the presence of contaminants on aquatic fauna. The monitoring results are available in the reports on the CETESB website.”