--- title: Ingested Drugs, Passed Through Sewers, Reportedly Threaten Lake Michigan Fish description: Researchers warned that a cocktail of ingested medications has slipped past sewage treatment plants and gradually accumulated in Lake Michigan, threatening to alter the hormonal balance of local fish. canonical: https://time.com/3666985/pharmaceutical-drugs-sewers-lake-michigan-fish/ author: Dan Kedmey article:opinion: false article:content_tier: free article:published_time: 2015-01-14T15:38:25.000Z article:modified_time: 2026-02-22T03:33:44.282Z article:section: Science og:title: Ingested Drugs, Passed Through Sewers, Reportedly Threaten Lake Michigan Fish og:description: Researchers warned that a cocktail of ingested medications has slipped past sewage treatment plants and gradually accumulated in Lake Michigan, threatening to alter the hormonal balance of local fish. og:url: https://time.com/3666985/pharmaceutical-drugs-sewers-lake-michigan-fish/ og:site_name: TIME og:image: https://static.time.com/v3/assets/bltea6093859af6183b/bltde093bcdab65f2d0/6988d9b9bc6cfc69913e2a3c/time-logo.jpg?branch=production og:image:width: 1200 og:image:height: 675 og:image:alt: TIME og:type: article twitter:card: summary_large_image twitter:title: Ingested Drugs, Passed Through Sewers, Reportedly Threaten Lake Michigan Fish twitter:description: Researchers warned that a cocktail of ingested medications has slipped past sewage treatment plants and gradually accumulated in Lake Michigan, threatening to alter the hormonal balance of local fish. twitter:image: https://static.time.com/v3/assets/bltea6093859af6183b/bltde093bcdab65f2d0/6988d9b9bc6cfc69913e2a3c/time-logo.jpg?branch=production --- # Ingested Drugs, Passed Through Sewers, May Threaten Lake Michigan Fish  by [Dan Kedmey](https://time.com/author/dan-kedmey/)  ## Dan Kedmey Jan 14, 2015 3:38 PM UTC  by [Dan Kedmey](https://time.com/author/dan-kedmey/)  ## Dan Kedmey Jan 14, 2015 3:38 PM UTC Researchers warned that a cocktail of ingested medications has slipped past sewage treatment plants and gradually accumulated in Lake Michigan, threatening to alter the hormonal balance of local fish. Researchers from the University of Wisconsin – Milwaukee’s School of Freshwater Sciences have detected traces of coffee, birth control pills and antibiotics in Lake Michigan’s waters, the _Detroit Free-Press_ [reports](http://www.freep.com/story/news/local/michigan/2015/01/13/metformin-diabetes-drug-pollution-lake-michigan/21734507/). The most prevalent drug was Metformin, a medication commonly used to treat Type 2 diabetes. Fathead minnows exposed to Metformin at the same concentrations found in the lake exhibited unusual hormonal imbalances four weeks later. Male minnows, for instance, began to produce a hormone typically associated with female egg production, though researchers say they have not yet ascertained the long-term effects of the hormonal changes. “It’s enough to raise an alarm bell that this might be something that causes changes in reproduction of fish,” study author Rebecca Klaper said. [Read more at _Detroit Free-Press._](http://www.freep.com/story/news/local/michigan/2015/01/13/metformin-diabetes-drug-pollution-lake-michigan/21734507/) ```json [{"@context":"https://schema.org","@type":"NewsArticle","@id":"https://time.com/3666985/pharmaceutical-drugs-sewers-lake-michigan-fish/","mainEntityOfPage":{"@type":"WebPage","@id":"https://time.com/3666985/pharmaceutical-drugs-sewers-lake-michigan-fish/"},"headline":"Ingested Drugs, Passed Through Sewers, May Threaten Lake Michigan Fish","datePublished":"2015-01-14T15:38:25.000Z","dateModified":"2026-02-22T03:33:44.282Z","description":"Study finds exposure to a diabetic drug can throw a minnow's hormones off balance","url":"https://time.com/3666985/pharmaceutical-drugs-sewers-lake-michigan-fish/","keywords":["Environment","Detroit","Michigan","Pharmaceuticals","diabetes"],"thumbnailUrl":"","author":[{"@type":"Person","name":"Dan Kedmey","jobTitle":null,"url":"https://time.com/author/dan-kedmey/"}],"articleSection":"Science","image":[],"publisher":{"@type":"Organization","name":"Time","url":"https://time.com/","logo":{"@type":"ImageObject","url":"https://time.com/images/logo.png","width":528,"height":156},"foundingDate":"March 3, 1923","sameAs":["https://www.facebook.com/time","https://www.instagram.com/time/?hl=en","https://twitter.com/time","https://www.pinterest.com/timemagazine"]}},{"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"item":{"@id":"/section/science/","name":"Science"}},{"@type":"ListItem","position":2,"item":{"@id":"/tag/environment/","name":"Environment"}},{"@type":"ListItem","position":3,"item":{"@id":"https://time.com/3666985/pharmaceutical-drugs-sewers-lake-michigan-fish/","name":"Ingested Drugs, Passed Through Sewers, May Threaten Lake Michigan Fish"}}]}] ```