--- title: Study: reusable shopping bags can harbor potentially harmful bacteria description: A new study from researchers at the University of Arizona and Loma Linda University finds that reusable shopping bags can harbor potentially harmful bacteria if... canonical: https://time.com/archive/7144561/wash-your-reusable-shopping-bags/ author: TIME Staff article:opinion: false article:content_tier: free article:published_time: 2010-06-25T21:35:21.000Z article:modified_time: 2026-03-16T11:38:55.218Z article:section: Health og:title: Study: reusable shopping bags can harbor potentially harmful bacteria og:description: A new study from researchers at the University of Arizona and Loma Linda University finds that reusable shopping bags can harbor potentially harmful bacteria if... og:url: https://time.com/archive/7144561/wash-your-reusable-shopping-bags/ 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: Study: reusable shopping bags can harbor potentially harmful bacteria twitter:description: A new study from researchers at the University of Arizona and Loma Linda University finds that reusable shopping bags can harbor potentially harmful bacteria if... twitter:image: https://static.time.com/v3/assets/bltea6093859af6183b/bltde093bcdab65f2d0/6988d9b9bc6cfc69913e2a3c/time-logo.jpg?branch=production --- * [Health](/section/health/) # Wash your reusable shopping bags by [TIME Staff](https://time.com/author/time-staff/) Jun 25, 2010 9:35 PM UTC by [TIME Staff](https://time.com/author/time-staff/) Jun 25, 2010 9:35 PM UTC  Woman with reusable bag --- Image by © Rick Gomez/Corbis © Rick Gomez/Corbis—© Corbis. All Rights Reserved. A new study from researchers at the University of Arizona and Loma Linda University finds that reusable shopping bags can harbor potentially harmful bacteria if they aren’t cleaned — and 97% of people surveyed said they’d never washed theirs. Yet the study, funded by the American Chemistry Council, also found that washing the reusable bags, either by hand or machine, cut bacterial contamination by more than 99%. more The analysis of 84 bags collected from shoppers entering supermarkets in Los Angeles, Tucson, Arizona and the San Francisco Bay area, found that nearly all bags tested had some bacterial contamination. Roughly half had coliform bacteria, and 12% had _Escherichia coli_ (E. coli). The researchers found that if the reusable bags — most of which are made of woven polypropylene — were exposed to juices from meat products, and then stored in the warm trunk of a car for two hours, bacteria grew 10-fold. The study was released as debate continues over a California bill that would ban single-use plastic grocery bags. (The American Chemistry Council, which funded the study, represents some of the plastic bag manufacturers, NPR [points out](http://www.npr.org/blogs/health/2010/06/25/128105740/plastics-industry-funded-study-finds-bacteria-in-reusable-grocery-bags?ft=1&f=1003).) Single-use plastic bags are unlikely breeding grounds for bacteria, but washing reusable bags is also a reliable way to limit contamination risk, the authors conclude. They write: --- > “” --- Read the full study [here](http://uanews.org/pdfs/GerbaWilliamsSinclair%5FBagContamination.pdf). ```json [{"@context":"https://schema.org","@type":"NewsArticle","@id":"https://time.com/archive/7144561/wash-your-reusable-shopping-bags/","mainEntityOfPage":{"@type":"WebPage","@id":"https://time.com/archive/7144561/wash-your-reusable-shopping-bags/"},"headline":"Wash your reusable shopping bags","datePublished":"2010-06-25T21:35:21.000Z","dateModified":"2026-03-16T11:38:55.218Z","description":"A new study from researchers at the University of Arizona and Loma Linda University finds that reusable shopping bags can harbor potentially harmful bacteria if...","url":"https://time.com/archive/7144561/wash-your-reusable-shopping-bags/","keywords":["Bacteria"],"thumbnailUrl":"","author":[{"@type":"Person","name":"TIME Staff","url":"https://time.com/author/time-staff/"}],"articleSection":"Health","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/health/","name":"Health"}},{"@type":"ListItem","position":2,"item":{"@id":"https://time.com/archive/7144561/wash-your-reusable-shopping-bags/","name":"Wash your reusable shopping bags"}}]}] ```