Which Scientific Findings Support the WHO’s Decision to Categorize Magnetic Fields as Possibly Carcinogenic?

One specific type of magnetic field, known as extremely low-frequency magnetic fields (ELF-MF), has been classified by the World Health Organization (WHO) as “possibly carcinogenic to humans.”

This means there is limited evidence suggesting that long-term exposure might raise the risk of developing cancer, though research is still ongoing.

So, is this something to worry about? To answer that, it helps to break things down, understand what ELF-MF actually are, why this classification matters, and how these fields appear both in everyday life and inside electric and hybrid vehicles.

Why Did WHO Define ELF-MF as “Possibly Carcinogenic”?

The classification by the World Health Organization (WHO) of extremely low-frequency magnetic fields (ELF-MF) as “possibly carcinogenic to humans” (Group 2B) is based on three categories of evidence: epidemiological findings (studies on people), laboratory experiments, and mechanistic data explaining how magnetic fields might affect biological systems.

1. Studies on Human Health (Epidemiology)

Several studies have examined whether there is a statistical link between long-term exposure to ELF-MF and childhood leukemia (a type of blood cancer). In one example, magnetic field levels were measured inside homes. When levels consistently exceeded 0.4 microteslas, researchers noticed a higher occurrence of leukemia in children living in those homes.

It’s important to clarify that these are observational findings. They show a correlation, meaning the two factors (higher exposure and leukemia) appear together, but they do not confirm that one causes the other.

2. Experimental Data

In controlled lab settings, scientists have investigated how ELF-MF might influence biological processes at the cellular level. Some studies have reported:

• Changes in how cells multiply
• Signs of DNA damage
• Altered patterns of gene expression

However, not all studies reach the same conclusions. The findings vary depending on the methods and conditions used, which is why further investigation is necessary to confirm any consistent biological effects.

3. Theories on What It Could Do to Our Body

While there is no confirmed mechanism explaining how extremely low-frequency magnetic fields (ELF-MF) might cause cancer, several working theories exist. One proposal is that ELF-MF can interfere with the body’s natural electrical signals. Nerve and muscle cells rely on small electrical impulses to function. Disruption to these signals, even at low levels, may affect how cells operate.

Another theory involves reactive oxygen species (ROS). These are molecules that can form under stress and are known to damage cellular components, including DNA. A study has shown that exposure to ELF-MF may increase ROS levels, possibly contributing to cancer development through oxidative damage.

Could Magnetic Fields in Cars Be a Concern?

Electric and hybrid vehicles produce magnetic fields due to the operation of high-current systems such as batteries and motors. These fields are typically strongest near the vehicle floor, closest to the powertrain components. Field strength drops significantly with distance—higher up in the cabin, exposure levels are lower.

What’s Next?

The International Agency for Research on Cancer (IARC) classifies ELF-MF as a Group 2B possible carcinogen. This designation is based on limited evidence from human studies and insufficient evidence from animal models. Ongoing scientific research is focused on refining our understanding of how ELF-MF might affect long-term health, especially in everyday environments like vehicles.

Until more definitive conclusions are available, minimizing prolonged exposure, especially in enclosed settings such as car cabins, is considered a prudent course of action.