Industrial vegetable oils show dangerous levels of toxic elements, surpassing traditional oils

By Dr. Chinta SidharthanReviewed by Lily Ramsey, LLMJan 22 2024

In a recent study published in the journal BMC Public Health,  a team of researchers analyzed samples of industrially and traditionally made edible vegetable oils, such as sunflower, sesame, olive, and peanut oil, to determine whether they contained potentially toxic elements such as cadmium, lead, iron, arsenic, and zinc.

Study: A probabilistic health risk assessment of potentially toxic elements in edible vegetable oils consumed in Hamadan, Iran. Image Credit: Naypong Studio/Shutterstock.com

Background

Food security is rapidly becoming a major health concern with increasing environmental pollution. Pollutants such as heavy metals, microbes, fungal toxins, antibiotics, and pesticides in the water, air, and soil could be carcinogenic or cause many other diseases.

These pollutants often move from contaminated soil or water to crops grown as a food source, such as wheat, rice, legumes, etc.

Vegetable oil is a food item that is now experiencing high demand in other areas, such as medicine, chemical science, and cosmetics, and the number of industries producing different types of vegetable oils has increased in recent years.

Vegetable oils are largely composed of long-chain fatty acid esters but also contain a variety of compounds such as stearic, palmitic, oleic, and linoleic acids, as well as antioxidants, vitamins, and proteins that are essential for human health.

They are essential for the absorption of fat-soluble vitamins and for supplying cholesterol to maintain the lipid membranes of the cells.

About the study

In the present study, the researchers aimed to evaluate potentially toxic elements in the vegetable oils traditionally or industrially produced in the Hamadan province of Iran.

They used a method called ICP-OES, or Inductivity Coupled Plasma Optical Emission Spectrometry, to estimate the concentrations of potentially toxic elements in samples of sesame, olive, sunflower, and peanut oils available in the markets of Hamadan.

The researchers also aimed to compare these concentrations to the maximum limits set by the Iranian and European standards and evaluate the risks associated with consumer exposure to these potentially toxic elements.

This information could then be used to inform the public health authorities to carry out more stringent monitoring of edible oils that are produced for consumption.

Twenty samples (five each) of traditionally produced sunflower, sesame, peanut, and olive oils were obtained from farmers’ markets and local shops in Hamadan.

In comparison, another five samples, each of all four oil types manufactured in industries, were obtained from various cities of Hamadan province.

The method was validated by calculating the limit of detection (LoD) and limit of quantification (LoQ), and the samples were analyzed for potentially toxic elements through ICP-OES.

The health risk assessments included determining non-carcinogenic risk factors, for which target hazard quotient, chronic daily intake, and total target hazard quotient of the potentially toxic elements ingested through vegetable oils were calculated. Additionally, the carcinogenic risk of these potentially toxic elements was also determined.

Results

The results indicated that the potentially toxic elements found in edible vegetable oils were iron, zinc, arsenic, lead, and cadmium in decreasing order of concentrations.

The concentrations of these elements were higher in industrially produced vegetable oils than in those produced traditionally. Furthermore, the concentrations of toxic chemicals were lower than the permitted levels according to the Iranian standards and Codex.

While the levels of potentially toxic elements ingested by consumers were within the acceptable range concerning the risk of non-carcinogenic diseases, these levels were above the acceptable range for the risk of cancer for individuals of all ages.

The scientists believe that a wide range of factors, such as the breed and species of the plant from which the oil is extracted, changing bioavailability of the potentially toxic elements from one region to another, improper use of fertilizers, proximity to large roads with a high thoroughfare of vehicles, active mines, or large factories, and improper storage can all contribute to the contamination of food sources with toxic elements.

Furthermore, processing methods such as bleaching, deodorizing, and refining edible oils, which are part of the industrial oil production process, could increase the concentrations of toxic elements in the oil.

Conclusions

The study found that traditionally and industrially manufactured edible vegetable oils such as sunflower, sesame, peanut, and olive oils have iron, arsenic, zinc, cadmium, and lead in varying concentrations.

While these do not pose a high risk of non-carcinogenic diseases, the risk of cancers due to these potentially toxic elements is increased since the concentrations are beyond the acceptable ranges.