R+D CSIC

Residues of drugs and personal care products can affect crops

Residues of drugs and personal care products in wastewater can affect the morphology and metabolism of plants, as a research by CSIC scientists demonstrate. The research is aimed at establishing improved safety conditions for treated wastewater for irrigation.

Given the growing shortage of water resources, treated wastewater is an increasingly frequently used source for agricultural irrigation. However, the possible presence of residues of drugs and personal care products can affect both crops and human health.

In Spain, the use of wastewater for different uses is regulated (Royal Decree 1620/2007). However, in relation to the occurence of drugs and personal care products (or PPCPs), including their transformation products, the acceptable maximum content in irrigation waters is not well established yet, nor how these residues can affect the crops.

Researching the use of treated wastewater  

An European COST Action has been launched for helping to establish new regulations to ensure the safety of treated wastewater for crop irrigitation and recharging aquifers. Scientists and partners from around 40 countries from Europe, Asia, America, Middle East and Australia are contributing to this project.

Scientists at the CSIC’s Institute of Environmental Assessment and Water Research (IDAEA) are researching the effects of pharmaceuticals and personal care product residues in crops. In a recent study, Dr. Josep Maria Bayona, CSIC scientist at the IDAEA, and his team, observed that the PPCPs  usually present in treated wastewater can significantly affect the morphology and metabolism of lettuce growth. The study was developed in experimental greenhouses of the Universitat Poiltècnica de Catalunya (UPC), located in the Baix Llobregat (Barcelona).

In this study, lettuce crops were irrigated with water that had a mixture of substances usually detected in treated wastewater. Concentrations of every substance were from 0.05 to 50 micrograms per liter. A control crop was watered with rain water.

When lettuces were harvested, scientists analyzed the presence of residues in the leaves. Virtually all samples had carbamezepine (an antiepileptic drug), although in very small amount, which supposes no risk to human health. In the plants irrigated with water containing higher concentrations of residues, other substances such as alkyl phosphates, bisphenol A, caffeine, parabens and triclosan were found in the edible part of lettuce.

Plant metabolism is affected

The results also shown that residues affect plant metabolism, and consequently  the plant morphology and chlorophyll leave’s content. About these effects, scientists highligth that the dose-response relationship was non-linear.

Residues affect plant metabolism, and consequently also the plant morphology and chlorophyll leave’s content

“From a certain level of PPCPs , there are effects on the plant enzymes and metabolism”, says Dr. Benjamín Pinya, a scientist at the CSIC-IDAEA. “The presence of these substances PPCPs  triggers the activity of the plant enzymatic system, which detoxificates breaking and changing the structure of pollutants. Nevertheless, higher levels of PPCPs  overwhelm the enzymatic system capacity and the plant metabolism is jeopardized”.  

Using chemometrical techniques developed by Dr. Romà Tauler and his team, at the IDAEA-CSIC, the scientists found out that residues affect the carbohydrate metabolism, related to the chlorophyll production, as well as the citric acid cycle, among others. The effects are noticeable on the morphology (more elongated lettuces than normal) and on the chlorophyll levels, which are lower (therefore, lettuces are whiter). Other studies realized by the same group shown similar results when antibiotics and biocides are present in amounts like in non treated wastewater.

Field studies are not conclusive

“If these effects on the plant metabolism can be seen, probably effects could be evidenced also in crop productivity and on the vegetable nutritional and organoleptic characteristics”, adds Dr. Victor Matamoros, a scientist at the IDAEA. “But more deeper studies are necessary to demonstrate the latest”.

The experimental results from greenhouses assays are consistent, but the ones obtained in plots from field studies are not conclusive. In this latter case, the plots produce commercial commodities and are placed also in the Baix Llobregat (Barcelona). The scientists measured the crop exposure to substances but the results are not conclusive. As Dr. Nuria Cañameras, a scientist at the UPC, says, “in real conditions there are too many uncontrolled factors that  affect on the crop development, such as soil fertility, type and frequency of irrigation, or the soil amendment practices chosen by every farmer”.

Reference studies:

Carlos Hurtado, Hadi Parastar, Víctor Matamoros, Benjamín Piña, Romà Tauler & Josep M. Bayona. Linking the morphological and metabolomic response of Lactuca sativa L exposed to emerging contaminants using GC × GC-MS. Scientific Reports Volume 7, Article number: 6546 (2017)  https://www.nature.com/articles/s41598-017-06773-0

Anna Margenat, Víctor Matamoros, Sergi Díez , Núria Cañameras, Jordi Comas, Josep M. Bayona.  Occurrence of chemical contaminants in peri-urban agricultural irrigation waters and assessment of their phytotoxicity and crop productivity. Science of the Total Environment. http://dx.doi.org/10.1016/j.scitotenv.2017.05.025

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