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Duncan J. Gilroy,¹ Kenneth W. Kauffman,¹ Ronald A. Hall,¹ Xuan Huang,² and Fun S. Chu²

¹Environmental Services and Consultation Section, Oregon Health Division, Portland, Oregon, USA
²Department of Food Microbiology and Toxicology, University of Wisconsin-Madison, Madison, Wisconsin, USA

Abstract

The presence of blue-green algae (BGA) toxins in surface waters used for drinking water sources and recreation is receiving increasing attention around the world as a public health concern. However, potential risks from exposure to these toxins in contaminated health food products that contain BGA have been largely ignored. BGA products are commonly consumed in the United States, Canada, and Europe for their putative beneficial effects, including increased energy and elevated mood. Many of these products contain Aphanizomenon flos-aquae, a BGA that is harvested from Upper Klamath Lake (UKL) in southern Oregon, where the growth of a toxic BGA, Microcystis aeruginosa, is a regular occurrence. M. aeruginosa produces compounds called microcystins, which are potent hepatotoxins and probable tumor promoters. Because M. aeruginosa coexists with A. flos-aquae, it can be collected inadvertently during the harvesting process, resulting in microcystin contamination of BGA products. In fall 1996, the Oregon Health Division learned that UKL was experiencing an extensive M. aeruginosa bloom, and an advisory was issued recommending against water contact. The advisory prompted calls from consumers of BGA products, who expressed concern about possible contamination of these products with microcystins. In response, the Oregon Health Division and the Oregon Department of Agriculture established a regulatory limit of 1 µg/g for microcystins in BGA-containing products and tested BGA products for the presence of microcystins. Microcystins were detected in 85 of 87 samples tested, with 63 samples (72%) containing concentrations > 1 µg/g. HPLC and ELISA tentatively identified microcystin-LR, the most toxic microcystin variant, as the predominant congener. Key words: Aphanizomenon flos-aquae, blue-green algae, cyanobacteria, dietary supplements, microcystins, Microcystis aeruginosa. Environ Health Perspect 108:435-439 (2000) . [Online 27 March 2000]

http://ehpnet1.niehs.nih.gov/docs/2000/108p435-439gilroy/ abstract.html

Address correspondence to D.J. Gilroy, Oregon Health Division, 800 NE Oregon Street, Suite 608, Portland, OR 97232 USA. Telephone: (503) 731-4015. Fax: (503) 731-4077. E-mail: duncan.j.gilroy@state.or.us

We thank M. Dourson (Toxicology Excellence for Risk Assessment) and the Oregon Department of Agriculture for their assistance with this work.

Received 30 August 1999 ; accepted 1 December 1999.