(Beyond Pesticides, September 23, 2014) A new study finds that the increasingly common use of treated wastewater on food crops can result in contamination from chemicals like DEET, triclosan, and pharmaceutical drugs.
The study, titled “Treated Wastewater Irrigation: Uptake of Pharmaceutical and Personal Care Products by Common Vegetables under Field Conditions” and published in Environmental Science & Technology, measures levels of 19 commonly occurring pharmaceutical and personal care products (PPCPs) in eight types of vegetables irrigated with treated wastewater under field conditions. The analytes studied include compounds that are commonly detected in treated wastewater, including 16 pharmaceuticals (acetaminophen, caffeine, meprobamate, atenolol, trimethoprim, carbamazepine, diazepam, gemfibrozil, and primidone) and three personal care products (DEET, triclosan, and triclocarban). The vegetable species included in the study are carrot, celery, lettuce, spinach, cabbage, cucumber, bell pepper, and tomato, which were included because they are often consumed raw by people and are also among the most important cash crops in arid and semi-arid regions, such as southern California, where there has been a rapid increase in irrigation with treated wastewater.
The study points to water shortages in many parts of the world and the U.S. as factors contributing to the increase in use of recycled water in agriculture. In 2009, 13% of treated municipal wastewater in California was recycled, while about 37% of the reuse was for agriculture irrigation. The state also formulated a policy calling for a three-fold increase in total water reuse by 2030. Over a third of the country’s vegetables and nearly two-thirds of the country’s fruits and nuts are produced in California, according to the U.S. Department of Agriculture’s (USDA) most recent 2012 statistics.
The study finds that 64% of the edible portions of vegetables grown with treated wastewater have at least one PPCP detected, while fortified water-irrigated vegetables have a detection frequency of 91%. In treated wastewater-irrigated vegetables, meprobamate (31%) and carbamazepine (31%) are the most frequently detected compounds. In fortified water-irrigated vegetables, the detection frequencies of carbamazepine, dilantin, and primidone significantly increased to 89%, 57%, and 39%.
Regarding dietary intake, the study’s researchers found that, based on their results, the greatest annual exposure due to the consumption of contaminated vegetables is caffeine, followed by triclosan, and carbamazepine, while meprobamate is the lowest. The researchers also note that caffeine and triclosan are mostly detected in carrot, while carbamazepine is detected widely in all vegetables.
The detection of chemicals like triclosan is not surprising and has dire implications for human health and the environment. Triclosan is one of the most commonly detected chemicals in U.S. waterways; about 96 percent of triclosan from consumer products is disposed of in residential drains. This leads to large quantities of the chemical entering wastewater treatment plants, which are never completely removed during the wastewater treatment process. According to Bill Arnold, Ph.D., co-author of a study that found triclosan to be increasing in concentration since it was first introduced in the 1960s, “Triclosan goes through the wastewater treatment system, and the wastewater treatment plant actually does a pretty darn good job of removing it. 90 to 95 percent of it is taken out, but we use so much triclosan that the rest of it gets through, and three of the compounds we found are chlorinated triclosan derivatives, and they’re formed in the last step of wastewater treatment, when the wastewater is disinfected before it’s discharged and the disinfectant is chlorine. So that creates these three new compounds. And then triclosan and these three new compounds, when they’re exposed to sunlight, each of them undergoes a reaction that forms a dioxin, so that’s where the other four compounds come from.”
Triclosan is an endocrine disruptor and has been shown to affect male and female reproductive hormones and is also shown to alter thyroid function. Due to its extensive use in consumer goods, triclosan and its metabolites are present in, fish, umbilical cord blood and human milk. One study shows that triclosan from sewage sludge can be taken up by soybean plants and translocated into the beans themselves, then consumed by people and animals. The Centers for Disease Control and Prevention in an updated National Report on Human Exposure to Environmental Chemicals notes that triclosan levels in people increased by over 41% between just the years 2004 and 2006.
The study also finds that some PPCPs displays a higher tendency for accumulation in plants than others, which may have harmful implications for vulnerable human populations like pregnant women. For example, carbamazepine, an anticonvulsant and antidepressant drug used to treat epilepsy, bipolar disorder, and other conditions, is detected consistently in all plant samples, including fruits, leaves, and fruits. According to the study, the chemical is known to be immune to wastewater treatment processes and is found ubiquitously in wastewater treatment plant effluents. There is evidence that pregnant women’s exposure to carbamazepine may result in congenital malformations in offspring
Interested in learning about how to prevent harmful chemicals like triclosan and carbamazepine from contaminating our waters? Keep up-to-date on Congressional and government agency actions on water quality by signing up for Beyond Pesticides’ action alerts and visiting our Threatened Waters page.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.