Some drugs used to treat covid have been detected in wastewater entering and leaving some Pennsylvania sewage plants, according to researchers who carried out the study, published in Journal of Environmental Quality, the levels of some medicines would be high enough to have a potential harmful to aquatic organisms. “The increase in drug concentrations may be linked to increased use of them during the pandemic,” explains Heather Preisendanz, one of the authors.
From May 2020 to May 2021, researchers collected weekly samples of the tributary (inbound) and effluent (outbound) wastewater from two wastewater plants in Pennsylvania. They then analyzed them to detect the possible presence of the SARS-CoV-2 coronavirus and several drugs, including painkillers, antibiotics and specific drugs for the treatment of covid. In the midst of the pandemic, explains Preisendanz, those presenting symptoms were invited to treat themselves at home with painkillers such as naproxen or paracetamol; bacterial infections that arose along with covid were treated with antibiotics; with the most severe patients, requiring hospitalization, remdesivir or dexamethasone was sometimes attempted.
Pain relievers. Among the drugs analyzed, painkillers were the most present in wastewater, but their use would not be related to covid: however naproxen, often used to treat arthritis, was found in concentrations such as to represent a risk from low to medium for aquatic organisms.
Remdesivir and dexamethasone. The concentrations of remdesivir and dexamethasone are instead connected to covid, and in particular to patients admitted to a hospital in the area where one of the two analyzed plants stood: in the affluent waters concentrations of remdesivir equal to 28% and dexamethasone equal to 31%. The plant was able to purify 39% and 56% respectively. “It is not possible to calculate the precise risk that these two drugs pose to aquatic organisms, as studies on the subject have not yet been conducted,” explains Preisendanz, who points out, however, that the quantities of dexamethasone detected could be harmful to fish.
Antibiotics. Regarding antibiotics, the researchers found that trimethoprim concentrations represent a low to medium risk for marine organisms, while those of sulfamethoxazole could be very harmful especially to algae, food for many aquatic animals.
Monitor wastewater. “Importantly, these calculations do not take into account the combined effect of the different drugs, which could be much worse,” warns Preisendanz. Their study, concludes the expert, highlights the importance of wastewater monitoring to understand the effects that drugs can have on water quality and ecology.