Israeli activists for the environment have for years been trying to awaken the country’s residents about the dangers to the health of man and marine life from plastic refuse strewn along the coast that enter the Mediterranean and Red Seas.
With paper bags expensive, everything is carried in plastic bags manufactured from petroleum waste products. Placing a fee on handled, throw-away plastic bags at supermarkets has put only a small dent in the mounds of plastic. With Israelis among the heaviest per-capita users of plastic packaging and wrapping, and recycling way behind those in other Western countries, the message has not been turned into significant action.
But now there is an additional threat to the Israeli coastline. Researchers at Tel Aviv University (TAU) have detected pharmaceutical residues at 10 different sites along the Israeli Mediterranean, posing serious danger of environmental contamination to fish and other marine life.
The research team looked for residuals of three frequently used medications, which – after being taken by humans are not fully metabolized in the body. As a result, they are discharged through sewage water into the sea. All three substances have been detected at four of the tested sites – in Ashdod, Ashkelon, Sdot Yam and Haifa. Residuals of two of the pharmaceuticals have been detected at five of the tested sites – Achziv, Acre, Herzliya, Bat-Yam and the Eilat Marina.
Damage to marine life might 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.
The study was led by Prof. Noa Shenkar and graduate student Gal Navon of TAU’s School of Zoology and the Steinhardt Museum of Natural History. The concentrations of residual medications were found in ascidians – marine, filter-feeding, sessile (immobile) invertebrates.
This study, just published in the journal “Marine Pollution Bulletin,” was conducted with the participation of the Hydrochemistry Lab of the Water Research Center of TAU’s Porter School of the Environment and Earth Sciences, Raymond and Beverly Sackler Faculty of Exact Sciences, headed by Prof. Dror Avisar.
The study involved sampling of ascidians from nine different sites along the Mediterranean coastline and two different Red Sea sites . Ascidians are marine invertebrates just few centimetres in size that attach to hard surfaces such as rocks, peers or breakwaters. Since the tiny creatures feed on small particles found in the water, large quantities of particles from the marine environment, including different pollutants, accumulate in their bodies over time.
The researchers performed chemical analyses 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, are hardly degraded by sewage treatment facilities, and they last for a long period in the marine environment.
The findings are extremely worrisome, the researchers declared. In 10 out of 11 sampled sites significant concentrations of the tested pharmaceuticals have been found. Signs of one drug, diclofenac, were found at significant concentrations at the Eilat Dolphin Reef. Ascidians collected from deep water at the Hadera power station were the only ones to show no traces of pharmaceuticals. Especially high concentrations of diclofenac and bezafibrate were found in Acre, Ashdod and Ashkelon.
Shenkar and Navon note that since the various pharmaceuticals are consumed by humans and a high percentage of their active compounds are later excreted in their original form, they cause harm in the sea. 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, pain relievers anti-depressants and many more.
“Many of these compounds are very stable,” the researchers said. “They 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 the human body. For example, various studies performed in different sites around the world have shown that estrogen, present in birth-control pills, leads to the development of female features in male fish in certain species, thus damaging their fertility; Prozac triggers increased aggressiveness and risk-taking in crustaceans; and anti-depressants impair memory and learning in cuttlefish.
“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,” concluded Avisar. “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 global serious issue of seawater pharmaceutical contamination,” added Shenkar. “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,” she said. “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.”
