Although aquaculture in treated wastewater is practiced worldwide, there is scant scientific research concerning whether organic micropollutants are present at safe levels for consumption, according to an announcement from the American Associates of Ben-Gurion University of the Negev.

A new study published in Aquaculture by researchers at Ben-Gurion University of the Negev (BGU) in Israel has determined that organic micropollutants (OMPs) in the water — trace elements of heavy metals, pharmaceuticals and personal care products as well as pesticides, solvents and detergents — result in minimal accumulation in fish. Additionally, the wastewater does not appear to affect other commercially important traits of fish, the announcement said.

"The presence of micropollutants in water can lead to toxic biological effects in fish including mutations, and feminization of male fish from being exposed to endocrine disrupting OMPs," said professor Dina Zilberg, a researcher in the BGU French Associates Institute for Agriculture & Biotechnology of Drylands, Jacob Blaustein Institutes for Desert Research.

Tertiary wastewater treatment (TTWW) is the third and final stage of the cleaning process that improves wastewater quality before it is reused, recycled or discharged to the environment, the announcement said, adding that the treatment removes remaining inorganic compounds and substances, such as nitrogen and phosphorus but not the organic compounds.

In the laboratory study, juvenile carp (Cyprinus carpio) were raised in 0%, 50% and 100% TTWW for five months. Seven out of 40 screened OMPs were detected in the water samples at least once.

Out of the 19 analyzed OMPs in fish tissues, four were detected in exposed fish, the researchers reported. The anticonvulsant carbamazepine and the anti-inflammatory diclofenac were each detected in the muscle and liver of fish grown in 50% and 100% TTWW at measurable concentrations. Carbamazepine-epoxide and Benadryl (diphenhydramine) concentrations were below the limit of quantification (LOQ) in the muscle of the exposed fish, while diphenhydramine was detected above the LOQ level in two liver samples of fish grown in 100% TTWW, according to the researchers.

"Based on the findings, TTWW can be successfully used for growing fish, and TTWW-grown fish met all the existing standards for heavy metals accumulation," Zilberg said. "However, further investigation on OMPs accumulation in different species of edible fish with different feeding habits is required to ensure public health when using TTWW for aquaculture."

The work was supported by the Jewish Charitable Assn. (ICA) and by a doctoral scholarship to Inbal Zaibel from the Israel Ministry of Science & Technology.

Other BGU researchers that participated in this study include Dr. Shai Arnon, Inbal Zaibel, Gal Dagan and the BGU Blaustein Institutes. Other researchers include Frieda Schwartsburd and Malka Britzi with The National Residue Control Laboratory, The Kimron Veterinary Institute, Israel Ministry of Agriculture, as well as Shane Allen Snyder with the University of Arizona.