Ethylene oxide is a cancer-causing agent that can raise the risk of breast cancer, as well as cause damage to the DNA, the brain, and the nervous system in humans.

The carcinogen has been found in four products from two big spice brands in India at levels exceeding the permissible limit.

What is ethylene oxide?

The Spices Board, under the Ministry of Commerce and Industry, defines ethylene oxide as a "flammable, colourless gas at temperatures above 10.7 Celsius".

It serves as a "disinfectant, fumigant, sterilising agent and insecticide". It is mainly used to sterilise medical equipment and to reduce microbial contamination in spices.

Besides being produced from natural sources, it can also be generated from water-logged soil, manure, and sewage sludge.

What are the health effects?

The World Health Organization's International Agency for Research on Cancer (IARC) classifies ethylene oxide as a 'Group 1 carcinogen', meaning it has "enough evidence to conclude that it can cause cancer in humans".

Short-term exposure to the carcinogen can affect the human central nervous system, and cause depression and irritation of the eyes and mucous membranes but prolonged exposure can irritate the eyes, skin, nose, throat, and lungs, and damage the brain and nervous system, as per the US Environmental Protection Agency (EPA).

The EPA said "Ethylene oxide is carcinogenic to humans by the inhalation route of exposure", and has also been linked to reproductive problems.

"Evidence in humans indicates that exposure to ethylene oxide increases the risk of lymphoid cancer and, for females, breast cancer," it noted.

Further, according to the US National Cancer Institute, ethylene oxide is frequently reported to be associated with lymphoma and leukaemia.

Stomach and breast cancers may also be associated with ethylene oxide exposure, the institute said.

It stated that people can be exposed to ethylene oxide via inhalation and ingestion, which may occur through occupational, consumer, or environmental exposure.

According to the latest estimates of cancer's global burden by the WHO, India has more than 14.1 lakh new cancer cases and over 9.1 lakh deaths in 2022.

The number is projected to go up to 15.7 lakh in 2025, according to the Indian Council of Medical Research-National Cancer Registry Programme (ICMR-NCRP).