October 2009, Vol. 21, No.10

Research Notes

Estrogen in Effluent Reduces Minnow Egg Production

Estrogenic chemicals found in wastewater treatment effluent can take a toll on local fish populations, according to a recent study, the first to study the effects of effluent on fish egg production.

The study, reported in the April issue of Environmental Science & Technology (“Estrogenic Wastewater Treatment Works Effluents Reduce Egg Production in Fish”), exposed mating pairs of fathead minnows to three different wastewater treatment effluents at full strength and various dilutions for 3 weeks. The researchers compared pre-exposure egg-production levels to levels during exposure and found that egg production dropped by as much as 44% in one of the effluents studied.

According to Karen Thorpe, lead author of the study and professor at the University of Basel (Switzerland), regulation of hormone levels in wastewater effluent is necessary. “In highly efficient [treatment] works more than 75% of the steroidal oestrogens entering the influent are removed, however, many wastewater treatment works do not work to this level of efficiency,” she said.

Thorpe noted that the U.K. Environment Agency released a report in 2004 that predicted “no effect” concentrations for two estrogens. However, the report also recognized that current technologies may not accurately measure the specified levels in treated effluent, she said.

“More efficient wastewater treatment works with increased hydraulic retention times would help [strip estrogens from wastewater],” Thorpe said, “but many works already struggle to cope.”

Other remediation technologies for removing estrogen exist, but the cost of implementation prevents them from being widely used, according to Thorpe.

Previous research has established the detrimental effects of estrogenic chemicals on the reproductive processes of fish, including intersexuality, feminization of male reproductive ducts, and sex reversal in males, according to the paper.

Thorpe explained that fish, such as the fathead minnows used in the study, “are excellent sentinels of environmental health” and that the effects of many estrogens in fish have been shown to have comparable effects in mammals.


Detecting Arificial Sweeteners

A team of scientists in Germany has developed a new method for identifying and analyzing artificial sweeteners in water. They applied this method, which can detect up to seven different artificial sweeteners, to samples of surface water and wastewater in Germany, finding four of the seven sweeteners persisted through wastewater treatment.

The artificial sweeteners detected were acesulfame, saccharin, cyclamate, and sucralose, the study said. Neotame, neohesperidin dihydrochalcone, and aspartame were not detected.

Published in the July issue of the journal Analytical and Bioanalytical Chemistry, the article was written by Marco Scheurer, Heinz–Jürgen Brauch, and Frank T. Lange at the Water Technology Center (Karlsruhe, Germany).

Though the safety and health risks of artificial sweeteners are a source of regular debate, Lange asserts that the results imply no adverse health effects on humans.

“If there are traces [of artificial sweeteners] in tap water comparable to the levels measured so far in some German surface waters, these are far (several orders of magnitude) away from both organoleptic threshold values and from [acceptable daily intake] values, which are on the mg/L level,” Lange said.

In fact, it is the chemical qualities that make artificial sweeteners desirable for low-calorie foods that allow them to persist through wastewater treatment.

The sweeteners detected by the study are designed not to degrade within the body to prevent them from turning into energy. They also must remain stable during storage and cooking.

The study found that acesulfame had the highest concentration in surface waters, with concentrations exceeding 2 µg/L. However, Lange suggested different sweeteners may be predominant in different regions, based on local manufacturing preferences.

The researchers also noted that because they did not significantly degrade in aquatic environments and are specific to municipal wastewater, sucralose and acesulfame conceivably could be used as tracers of “anthropogenic contamination.”