Photo: Yoel Ben-Avraham/Flickr
Given that recent research has revealed that drugs, pharmaceuticals, beauty products, and caffeine pass through our bodies and into wastewater in high enough levels that it can be used to track how well people are following their prescriptions, a new study, presented at the American Chemical Society national meeting, provides some good news: Food crops irrigated with processed and recycled sewage water pick up only "reassuringly" low levels of these substances.
Irrigating with recycled wastewater is common practice in some parts of the world, notably arid places like Israel, which currently reuses 80 percent of wastewater for irrigation—though in the United States single digit percentages of wastewater are reused for agriculture.
Even after passing through sewage treatment plants, water which is otherwise considered safe enough to drink or be discharged into waterways without risk of pollution still can contain remnants of drugs, anti-bacterial soaps, and on and on.
The study is the first to examine crops under field conditions and for some twenty different pharmaceutical and personal care products, and found that although plants do take up these from the recycled wastewater, the levels, "were quite low and most likely do not pose any health concern."
The specific crops examined—carrots, peppers, tomatoes, cucumbers, lettuce, spinach, celery, and cabbage—were chosen because they are often eaten raw, which increases the chances of exposure. Of the crops examined, leafy vegetables absorbed the greatest amount of pharmaceuticals.
Even though the general conclusion is that there is little health concern from the amount of pharmaceuticals and personal care products absorbed by the crops, the authors note that young children, the elderly, and people with chronic diseases may be more susceptible than the general population to the levels detected.
So at what sort of levels are drugs being found in our water supplies? One analysis, looking at the drinking water supply in Erie, Pennsylvania, found ibuprofen at 2.5 parts per trillion, a cholesterol-lowering drip at similar levels; caffeine was found at up to 60 ppt. Such levels are so low that for a person to receive an effective dose of ibuprofen, for example, they'd have to drink 25 million gallons of water. The odds are that if you live in an urban area, your water contains at least similar levels of pharmaceuticals.
Leaving aside assurances that drinking millions of gallons of public water are required in order the receive an effective does of medication, earlier this year it came out that even extremely low levels of antidepressants, anti-anxiety, and anti-insomnia medications found in water supplies appear to be having an effect on fish in Europe—making them bolder and less social, and more vulnerable to predators. Research from the University of Wisconsin shows similar effects on fish in American waterways.
While it's a leap to draw a conclusion about the effect on humans of persistent low-level exposure from a study on fish, this research does show that exposure at the parts-per-trillion level can certainly affect wildlife.