Unrecognized substances released by algae blooms may act as endocrine disruptors

Scientists are reporting for the first time that previously unrecognized substances released by algae blooms have the potential to act as endocrine disruptors, which can interfere with the normal activity of reproductive hormones. The effect is not caused by microcystin toxins, long recognized as potentially harmful to humans and aquatic animals, but as yet unidentified substances. As a result, the scientists are calling for a revision of environmental monitoring programs to watch for these new substances. The findings appear in ACS's journal Environmental Science & Technology.

Theodore Henry and colleagues note that harmful blooms of toxin-producing algae, called cyanobacteria or blue-green algae, occur in waters throughout the world and are a growing health and environmental concern. The algae produce microcystins that can harm fish, plants, and human health. Possible human health effects include skin rashes, fever, and liver damage. Although scientists have focused mainly on microcystins' biological effects, new evidence suggests that other potentially harmful substances also may be present.

In an effort to find out, Emily Rogers supervised by Theodore Henry, and co-authors Michael Twiner, Julia Gouffon, Jackson McPherson, Gregory Boyer, Gary Sayler, and Steven Wilhelm turned to zebrafish, often used as a stand-in for people and other animals in laboratory experiments. They found that something released by algae, other than microcystins, had an endocrine disrupting effect on the fish. The report recommends that environmental protection agencies may need to update monitoring programs for algae blooms to include potential endocrine-disrupting substances.