Peel Apples to Remove Pesticides, Study Says

Researchers have developed a new imaging method to detect pesticide contamination, which suggests that washing apples may not be sufficient to remove potentially harmful chemicals.

Pesticides are substances widely used in agriculture to kill or control pests. High-level exposure to pesticides — typically greater than found in foods — is harmful to human health.

A new study published in ACS Nano Letters describes a novel high-tech imaging method for detecting pesticide contamination at low levels.

The researchers employed surface-enhanced Raman spectroscopy (SERS), an increasingly popular nondestructive analytical method for detecting chemicals from modern farming on produce.

With SERS, metal nanoparticles or nanosheets are used to amplify molecules' signals when exposed to a Raman laser beam. The patterns created by the metal-enhanced scattered light serve as molecular signatures and can be used to identify small amounts of specific compounds.

For the new study, researchers worked on improving SERS sensitivity for pesticide detection. They designed a metal-coated membrane that could be laid atop farm-grown produce.

Researchers stretched cellulose hydrogel film to form aligned nanoscale wrinkles along its surface. They then immersed the film in a solution of silver nitrate to coat the grooves with SERS-enhancing silver nanoparticles.

This made the membrane highly flexible and practically transparent in visible light, essential features for SERS signal detection.

Then, the researchers sprayed the pesticides thiram and carbendazim, alone or together, onto apples and air-dried the fruits. The products were washed to mimic everyday practices.

When scientists laid the silver-embedded membrane over apples, SERS detected pesticides, even though the chemicals were present at low concentrations. Pesticide contamination was detected through the fruit's peel and into the outermost layer of pulp.

The findings suggest that washing alone could be insufficient to prevent pesticide ingestion; therefore, peeling would be required to remove potential contamination in the skin and outer pulp.

A 2011 study looked into the health risks associated with the Dirty Dozen, which is fruits and vegetables with the highest pesticide residue. Researchers found that these products posed insignificant risks to consumers, and replacing them with organic versions did not reduce any risks.

According to the Environmental Protection Agency (EPA), aggregate exposure to thiram, one of the pesticides analyzed in the study, via food and drinking water will not result in acute or chronic risk in humans.

Meanwhile, the application of carbendazim, another pesticide tested in the new research, to human food has been prohibited in the United States.

Moreover, apple peel is packed with vitamins, minerals, antioxidants, and phytonutrients, which are essential for a healthy diet. Apple skin is also a rich source of fiber, which helps digestion and weight management and reduces the risk of chronic health conditions.

How dangerous are pesticides?

Over 1,000 pesticides are used worldwide, but not all are made equal. Some are generally more toxic than others, and their toxicity can also depend on the dose and the route of exposure, such as swallowing, inhaling, or direct contact with the skin.

According to the World Health Organization, no pesticides currently authorized for use on food in international trade are genotoxic, meaning that they damage DNA, leading to mutations or cancer.

Agricultural workers who apply pesticides are at risk of experiencing their harmful effects, such as respiratory issues, endocrine dysfunction, infertility, and some types of cancer.

Other individuals in the immediate area during or shortly after pesticides are spread are also vulnerable to their effects.