Pharmaceutical residuals pose a serious threat to Marine life

A study led by Prof. Noa Shenkar and graduate student Gal Navon, from the Tel Aviv University (TAU) School of Zoology and the Steinhardt Museum of Natural History, has found significant concentrations of residual pharmaceuticals at 11 sampled sites along the Israeli coastline. As the medication we take is not fully metabolized by our bodies, and residual pharmaceuticals are discharged through sewage water into the sea.

The research team looked for residuals of three frequently used pharmaceuticals, and their findings are worrisome. All three substances were detected at 4 of the tested sites (Ashdod, Ashkelon, Sdot Yam and Haifa). Residuals of two of the pharmaceuticals were detected at 5 of the tested sites (Achziv, Acre, Herzliya, Bat-Yam and the Eilat Marina).

The damage to marine life may be especially great, since pharmaceuticals, in contrast to other sea pollutants, are designed to affect biological systems even at very low concentrations. Severe impact on a variety of marine animals has already been detected in studies worldwide. This of course directly affects us as well, since marine animals are an important source of protein for people around the world.

This study was conducted with the participation of the Hydrochemistry Lab of the Water Research Center of the Porter School of the Environment and Earth Sciences, Raymond & Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, headed by Prof. Dror Avisar. The study was published in the journal “Marine Pollution Bulletin” in August 2020.

The study involved sampling of ascidians from 9 different sites along the Mediterranean coastline (Achziv, Acre, Haifa Marina, Sdot Yam, Hadera power station, Acadia beach in Herzliya, HaSela beach in Bat-Yam, Ashdod Marina and Ashkelon Marina) and 2 different Red Sea sites (Eilat Marina and Dolphin Reef).

Since ascidians feed on small particles found in the water, large quantities of particles from the marine environment accumulate in their bodies over time - including different pollutants. The researchers performed chemical analysis of the collected ascidians, searching for active compounds of three frequently used pharmaceuticals: Bezafibrate, which reduces blood lipids content; Carbamazepine, an antiepileptic, and mood stabilizer; and Diclofenac, an anti-inflammatory agent present in the well-known medicine Voltaren. These three substances are extremely durable, barely degrade during sewage treatment, and are long-lasting in the marine environment.

The findings are extremely worrisome: in 10 out of 11 sampled sites significant concentrations of the tested pharmaceuticals were found. 

Gal Navon samples Styela plicata at the Kishon marina (Photograph: Leon Novak)

Prof. Shenkar and the researcher Gal Navon explain that various pharmaceuticals consumed by humans are not fully metabolized in the body, and a high percentage of their active compounds are later excreted in their original form. In addition, lack of public awareness often results in the disposal of unused drugs in toilets or home garbage bins. Currently existing sewage treatment facilities are not suitable for the treatment of medication residuals, and, unlike other pollutants, their final concentrations at the endpoint of sewage treatment are not monitored. Eventually, a substantial amount of pharmaceuticals is discharged into the sea by sewage water. According to the research team, a variety of pharmaceutical residuals can be found in marine ecosystems worldwide - antibiotics, anti-inflammatory drugs, analgesics, anti-depressants and many more.

"Many of these compounds are very stable," the researchers say. "These take a long time to degrade in the marine environment, and the damage they cause to marine life could be extremely excessive, since these pharmaceuticals are designed to affect biological systems (the human body). For example, various studies performed at different sites around the world have shown that Estrogen, present in birth control pills, leads to the development of female features in male fish of certain species, thus damaging their fertility; Prozac triggers increased aggressiveness and risk-taking in crustaceans; anti-depressants impair memory and learning in cuttlefish, and more”.

Prof. Avisar: "We have been studying the chemo-physical fate of drug residuals in groundwater and surface water for the past 15 years, and their detection in marine ecosystems has been surprising. The results indicate a chronic large-scale pharmaceutical residuals contamination, as well as the absorption of micro- and nano-pollutants, measured at very low concentrations in marine organisms."

"Our study shows that Israel is no stranger to the serious global issue of seawater pharmaceutical contamination," Prof. Shenkar concludes. “The medications we use end up in the sea, mainly through sewage discharge, and cause great damage to the marine environment, indirectly affecting humans, who feed on sea foods that are exposed to such contamination. There are different ways to tackle this problem: on the individual level, we recommend that the population as a whole takes personal responsibility, disposing of unused pharmaceuticals into designated containers which can be found at pharmacies and health maintenance organizations' facilities. In addition, we are working to expand research on monitoring pharmaceutical contamination along the Israeli coastline, using advanced analysis of a greater variety of widely used medication, while examining the changes exerted upon the various organisms exposed to the environmental concentrations of those pharmaceuticals."