-By Du Vo
Back in high school, my uncle heard some rumors from the mainstream media that drinking from plastic bottles that have been left in the car or out in the sun could cause cancer. Since one of our relatives passed away a couple years ago due to cervical cancer, my whole family has tried to avoid drinking from water bottles. During session three of our PH511 class, we had a chance to discuss the correlation between health and poverty. Somehow the topic of Solar Water Disinfection (SODIS) was introduced. This is the research and development done to help purify water in developing countries. However, the method seems ideal and too good to be true. Thus, it causes a conflict with what I have been told at home. If microwaving food in plastic could leak some dangerous substances into the food, why couldn’t this? Weighing the pros and cons between diseases caused by polluted drinking water or chronic diseases like cancer, I wonder whether it is ideal to support SODIS if it could possibly cause cancer in developing countries, as the new cases of cancer grow.
SODIS is a method of disinfecting water using the heat from sunlight. Users basically pour water into a clean PET water bottle and leave it out in the sun for six hours or more. The PET bottle is a bottle made out of polyethylene terephthalate, and is one of the most common consumer plastics used. If the weather appears to be cloudy, the bottle has to be out for at least two days. The ultraviolet rays will kill most bacteria after that amount of time. According to the study, “exposure to sunlight has been shown to deactivate diarrhea-causing organisms in polluted drinking water.” The purpose is to improve the supply of drinking water and reduce infant mortality in developing countries.
After the Food and Drug Administration (FDA) banned the controversial chemical bisphenol-A, or BPA, in baby bottles and sippy cups, consumers have been more concerned about materials of these products. The claim about plastic bottles states that PET bottles “contains a potentially carcinogenic element called diethylhydroxylamine, or DEHA.” Repeated washing and rinsing can cause the carcinogens to leak into the water, even though Food and Drug Administration approved the reuse of these bottles. However, according to the U.S. Occupational Safety & Health Administration, DEHA is “neither regulated nor classified as a human carcinogen to cause cancer.” Moreover, it does not exist in PET used to make water bottles. Therefore, the claim about SODIS causing cancer turned out to be false.
While SODIS does not cause cancer, reusing plastic bottles still poses a health risk if consumers do not clean the bottle properly. It could lead to the ingestion of harmful bacteria. On the other hand, whether or not heating up the plastic bottle increases the leakage of harmful phthalates into the water is still undetermined. Phthalates are a group of chemicals that are sometimes added to plastics to make them more flexible. Also, non-biological agents such as toxic chemicals or heavy metals can make the water unsafe to drink. As a result, SODIS is a solution for temporary need rather than long-term as there are more steps beyond the disinfection to take into consideration.
American Cancer Society. Cancer Facts and Statistics. http://www.cancer.org/ [Last Accessed 12 February 2014]
Associated Press. “FDA: BPA banned in Baby Bottles.” NBCNews.com. 17 July 2012.
CBC News. “Study Links Plastics Chemical with Cancer.” 28 August 2006.
Meierhofer R, Wegelin M. “Solar water disinfection — A guide for the application of SODIS.” Swiss Federal Institute of Environmental Science and Technology (EAWAG) Department of Water and Sanitation in Developing Countries (SANDEC). October 2002.