Jet fuel, a kerosene-based substance used to power turbine engines in both commercial and military aircraft, is a topic of significant public health concern. The fuel’s widespread use and the potential for human contact have led to questions regarding its long-term health consequences, particularly its potential to cause cancer. This article examines the scientific evidence surrounding jet fuel exposure and its link to cancer, focusing on the composition of the fuel mixture and the findings from major health organizations and epidemiological research.
Chemical Composition and Known Carcinogenic Components
Jet fuel, such as the civilian Jet A and the military JP-8, is not a single chemical but a complex blend of hundreds of different hydrocarbon compounds refined from crude oil. The composition is primarily a mix of paraffins, naphthenes, and aromatic hydrocarbons. Aromatic hydrocarbons are of particular concern because they can constitute up to 25% of the fuel mixture by volume, depending on the specific type and blend of the fuel.
Within this complex blend are several components classified as known or suspected carcinogens by international health agencies. Benzene, a substance present in low concentrations—typically less than 0.8% in military jet fuels like JP-8—is classified as a known human carcinogen (Group 1) by the International Agency for Research on Cancer (IARC). The mixture also contains Polycyclic Aromatic Hydrocarbons (PAHs) and related compounds like naphthalene, which is considered a possible human carcinogen based on animal studies. Toluene and xylenes are also present as part of the aromatic hydrocarbon fraction, contributing to the fuel’s overall toxicity profile.
Scientific Research Linking Exposure to Cancer
When assessing the cancer risk of the entire fuel mixture, the IARC classifies jet fuel in Group 3, meaning it is “not classifiable as to its carcinogenicity to humans.” This classification is assigned when the evidence is inadequate for human exposure and limited or inadequate for animal studies. This reflects the difficulty in definitively linking the mixture itself to cancer, even while acknowledging the presence of known hazardous components.
Epidemiological studies, which track cancer rates in exposed populations, have produced mixed and sometimes conflicting results. Some occupational studies, particularly those involving military personnel and aircraft mechanics, have suggested a potential link between chronic jet fuel exposure and specific cancers. For instance, a case-control study identified an elevated risk for kidney cancer among individuals with substantial workplace exposure to jet fuel, with one analysis finding an increased odds ratio of 3.4 compared to unexposed groups.
However, other large-scale cohort studies, including those of the United States Air Force and the Swedish armed forces, have reported no significant association between occupational jet fuel exposure and an overall increased incidence of invasive cancer. The limitations in human studies often stem from confounding factors, such as simultaneous exposure to other chemicals, lifestyle variables like smoking, and the challenge of accurately measuring long-term cumulative exposure.
Animal toxicology studies offer additional evidence of carcinogenicity. When jet fuel mixtures are applied directly to the skin of laboratory mice, they have been shown to induce the formation of skin tumors. Furthermore, studies have reported the development of renal and dermal cancers in animals exposed to jet fuel, with mechanistic evidence suggesting that exposure can induce inflammation and oxidative stress. This body of evidence points toward a suggestive carcinogenic potential, especially in high-exposure scenarios.
Primary Routes of Human Exposure
Human exposure to jet fuel occurs primarily through two major routes: occupational and environmental. Occupational exposure represents the highest risk, mainly affecting workers like aircraft maintenance crews, refuelers, and military personnel who handle the fuel directly.
Occupational Exposure
The most common occupational exposure pathway is dermal contact, where liquid fuel soaks into the skin during spills, leaks, or routine maintenance, allowing chemical absorption into the body. Inhalation is another significant route, as workers breathe in jet fuel vapors and aerosols, particularly during cold engine starts, refueling operations, or when working in confined spaces like aircraft fuel tanks. Inadvertent ingestion can also occur through hand-to-mouth contact in contaminated work environments.
Environmental Exposure
Environmental exposure, which affects the general public, is typically much lower than occupational levels. This exposure usually involves living near airports or military bases where fuel is stored and used, or contact with contaminated soil or groundwater resulting from large spills or leaks. The low volatility of kerosene-type jet fuels like Jet A and JP-8 at ambient temperatures means that vapor inhalation is less likely for the general public, but aerosolized fuel from engine exhaust remains a potential exposure source near active flight lines.
Safety Measures for Reducing Risk
Given the presence of known carcinogens in jet fuel, strict safety measures are implemented to minimize human contact, particularly in high-risk occupational settings. Personal Protective Equipment (PPE) is the first line of defense against direct exposure.
Workers should use chemical-resistant gloves, protective clothing, and footwear to prevent dermal absorption, immediately washing any skin that comes into contact with the liquid fuel. Engineering controls, such as ensuring adequate ventilation in hangars, maintenance bays, and confined spaces, are implemented to reduce the accumulation of fuel vapors and aerosols. Proper workplace hygiene is also a protective measure. This includes avoiding the consumption of food or drink in work areas and immediately changing any clothing that becomes saturated with the fuel to prevent prolonged skin contact. Regular air monitoring and mandatory safety training on handling procedures, spill response, and the proper use of PPE are necessary components of a comprehensive risk reduction program.