The science behind EtO and stomach cancer: What studies reveal

EtO (ethylene oxide) has been identified as a human carcinogen used to sterilize medical equipment and other industrial processes for many years.

The alkylating agent ethylene oxide forms adducts with DNA, causing mutations and chromosomal damage. If stomach cells are sufficiently exposed to this mutagenic activity, the presence of this activity could lead to stomach cancer. Biologically, EtO causes malignant transformation in gastric tissue by chemically modifying DNA.

In animal experiments, direct gastric exposure through intragastric instillation or gavage produced tumors in the rodent forestomach, specifically squamous cell tumors in rats. These findings demonstrate that high local doses to the stomach lining tissue can initiate cancer development. Animal studies have also demonstrated that EtO is capable of causing cancer throughout the body after systemic inhalation exposure.

What human studies show about EtO and stomach cancer

Many occupational cohort studies have found that workers exposed to EtO are more likely to develop stomach cancer. Among the notable findings of these studies were:

• Six stomach cancer cases were reported among workers exposed to EtO versus 0.65 expected, indicating a significant increase in risk
• Excess stomach cancer deaths have been documented in Swedish production worker cohorts and early sterilization worker reports
• Meta-analyses indicate a moderately increased risk of stomach cancer based on a standardized mortality ratio of 1.28

Human studies have shown that stomach cancer cases are significantly higher according to the National Toxicology Program (NTP), the International Agency for Research on Cancer (IARC), and the Environmental Protection Agency (EPA).

Exposure routes and risk factors

Occupational inhalation represents the dominant real-world exposure route for workers in sterilization facilities and EtO production plants. While EtO is a gas and ingestion exposure is uncommon, contaminated surfaces or foods in fumigation settings have historically created occasional oral contact scenarios. Direct contact with stomach tissue increased cancer risk when EtO reached the gastric mucosa directly through gavage, according to animal studies.

Despite limited data, studies of communities near EtO-emitting facilities suggest stomach cancer is associated with chronic low-dose exposure. A number of long-term animal studies and some human cohort data are consistent with gastrointestinal tract irritation and tumor formation, suggesting that the digestive system may be at risk of cancer.

Regulatory recognition

The IARC, NTP, and EPA list EtO as carcinogenic and acknowledge that some human studies reported excess stomach cancer among exposed workers. While agency risk assessments focus primarily on lymphoid and breast cancers due to stronger epidemiologic signals, stomach cancer observations have contributed to the overall weight of cancer evidence. Recent EPA actions to tighten EtO emissions reflect updated exposure and epidemiologic data across all cancer types, including stomach cancer.

ELG Law can evaluate your stomach cancer claim

If you developed stomach cancer after working with EtO or living near a facility that emits the chemical, you may be eligible for compensation. The toxic exposure attorneys at Environmental Litigation Group have more than 30 years of experience handling these types of cases. We can build a convincing case on your behalf based on the evolving scientific evidence linking EtO to stomach cancer. Let's discuss your diagnosis and legal options in a free consultation.