Nanotech system detects toxic herbicide picloram

[NEW DELHI] Biochemical researchers say they have developed a novel system for the precise detection of the ultrasensitive herbicide picloram in rice water and soil samples.

A study published June in the journal Scientific Reports says the system is simple, rapid, cost-effective and highly accurate in detecting the substance, which can cause a number of health problems.

Picloram is a chlorinated derivative of picolinic acid which is sprayed on foliage, injected into plants, applied to cut surfaces, or allowed to leach to the roots. Once absorbed at any of these points, the herbicide is transported throughout the plant.

“We have focused the study on rice water detection as it is a common food crop and several studies have reported the presence of this herbicide in rice.”

Pranjal Chandra, associate professor, School of Biochemical Engineering, Indian Institute of Technology

Human exposure to a high concentration of picloram can cause health issues including central nervous system disorders, weight loss, weakness, and diarrhoea, according to the study.

“The severity of the effects of picloram on human health and the environment can vary depending on factors such as concentration, duration of exposure, and individual susceptibility,” said Pranjal Chandra, author of the study and associate professor at School of Biochemical Engineering, Indian Institute of Technology.

“We have focused the study on rice water detection as it is a common food crop and several studies have reported the presence of this herbicide in rice.”

Conventional techniques for detecting and quantifying picloram have a low limit of detection and usually need lengthy sample preparation, purification processes, and sophisticated laboratory setups, Chandra told SciDev.Net.

“Therefore, a more practical approach was required,” he explained.

“One such approach is electrochemical study of diverse molecules which are on the rise in the fields of clinical, biomedical and environment.”

Picloram was discovered in the early 1960’s by the Dow Chemical Company and introduced to the market in 1963.

It was combined with other herbicides to make and enhance Agent Orange, the notorious chemical herbicide used during the Vietnam War. Picloram is currently one of the most commonly used herbicides in forest management. It is also effective in controlling invasive weed particularly in electric powerlines, railroad tracks, roadsides and pipelines.

Syam Chand, researcher in chemistry and associate professor at the University College, said the findings would enable the herbicide to be easily detected.

“The study is significant and can benefit the environment by detecting pollution-causing substances,” he said.

Daphika S Dkhar and Rohini Kumari, co-authors of the study, said that the nanohybrid was found to be highly catalytic and efficient in facilitating the electro-oxidation or neutralisation of picloram.

“In the future, the new system can be made deployable for field testing since the detection range falls under the permissible limit,” said the authors.

Herbicide contamination

Anoop Kuttiyil, researcher in plant pathology and assistant professor at Zamorin’s Guruvayurappan College, says that picloram is toxic to living beings even at low-dose exposures and has the potential to contaminate surface as well as groundwater supplies.

“Herbicide residue in the soil has a significant impact on crop, human and animal health, as well as water and soil quality,” Kuttiyil told SciDev.Net.

“Herbicides used in modern agriculture along with poor management are the primary sources of herbicide contamination,” Kuttiyil added.

“Many herbicides are linked to the risk of genotoxicity (damage to genes), cytotoxicity (damage to cells), developmental and reproductive toxicity. The biomagnification (abnormal concentration) of these chemicals is a great threat to both targeted and nontargeted .”

Pranjal Chandra said the new sensor system was currently in the prototype stage with the aim of eventually producing and distributing it on an industrial scale.

The researchers say the sensor is versatile and can be used on other crop samples, not just rice.

“The broad applicability allows for the assessment and monitoring in different environmental conditions and agricultural settings,” the study says.

According to the researchers, the capability to extend the sensor’s analysis to various real samples opens up a wide range of possibilities for its implementation in different fields, including environmental monitoring, agriculture, and water resource management.

By providing accurate data for these applications, the sensor can contribute to informed decision-making and sustainable practices in various industries, they said.

According to  Market Watch, the global picloram market is anticipated to rise at a considerable rate over the course of this decade.

This piece was produced by SciDev.Net’s Asia & Pacific desk.