Chemical compounds from pharmaceutical and personal care products can remain in wastewater even after treatment. But what happens to these trace chemicals when the treated wastewater is used to irrigate crops?

With reclaimed water increasingly being considered for irrigation in drought areas, it is an important question.

Alison Franklin and her team at Pennsylvania State University have been investigating what happens to four different chemical compounds found in effluent when it is used to spray-irrigate wheat crops.

Franklin told the American Society of Agronomy: “As I learned about pharmaceutical and personal care products in the environment, I became very interested in where these compounds were ending up. What were the possible implications of these low level compounds in the environment on human, animal and ecological health?”

First, Franklin measured the amounts of three types of antibiotics and one anti-seizure medicine in effluent from the University Park wastewater treatment plant. The water from the treatment plant was then used to irrigate wheat crops at Penn State’s Living Filter site, a special area for testing the reuse of effluent.

Researchers collected samples of the wheat straw and grain before and at harvest time and analyzed the samples for the four different compounds.

Even though concentrations of the compounds in the effluent were low, traces were found in the wheat samples.

The pre-harvest samples showed most of the compounds on the outer surfaces of the plant, but insignificant amounts in the plant parts (grain and straw). The samples collected at harvest time had trace amounts of all four compounds on the plant surface and three of the compounds were also detected in the plant parts. Two compounds were detected only in the grain and not in the straw, while the third compound was detected in both the grain and the straw.

None of the compounds were at toxic levels.

According to the study, which has been published in the Journal of Environmental Quality, many factors affect the path of a compound into and within the plant, such as the pH level of the soil and the plant, the plant species, and even the specific plant part.

Next, the researchers will investigate whether the small amounts of compounds in the wheat plants pose potential health risks for humans and animals. They aim to determine the best options for water reuse.

“It’s a fine balance of protecting the health of the environment and organisms, yet managing water resources that are diminishing,” Franklin said.