Published: 26 February 2026
By EMFSA

Class 2B Possible Human Carcinogens

Class 2B Possible Human Carcinogens are substances or exposures identified by the International Agency for Research on Cancer (IARC) as possibly carcinogenic to humans. This classification is based on limited or inconclusive evidence in humans, supported by preclinical studies in animals or mechanistic research. Importantly, being classified as possibly carcinogenic indicates hazard, not proven risk at typical environmental exposure levels.

Evidence and Examples of Class 2B Agents

To illustrate the diversity of evidence, consider two notable examples. In November 2025, IARC classified vinclozolin, a pesticide, as “possibly carcinogenic to humans,” based on animal studies showing liver and reproductive effects, including multigenerational impacts. Human data remain limited, but the experimental findings were sufficient to support a Group 2B designation.

Radiofrequency (RF) electromagnetic fields were classified earlier, in 2011, based primarily on limited human epidemiological evidence suggesting a potential association with certain brain tumors, alongside mechanistic data from preclinical studies available at that time. Following this classification, additional research, such as the NTP 2018 animal study, investigated high-dose RF-EMF exposure in both rats and mice and observed small increases in certain tumors in male rats, particularly cardiac schwannomas and some brain gliomas. Although these post-classification studies contribute to ongoing research, they did not influence the original Group 2B designation. Evaluations by the WHO EMF Project and IARC continue to assess new evidence to determine whether future reclassification may be warranted.

At the same time, international review efforts have continued. The WHO EMF Project and IARC are assessing newer evidence to determine whether the existing classification remains appropriate or whether future reassessment may be warranted.

Taken together, these examples show that Class 2B agents represent signals of potential carcinogenicity that warrant further research, regulatory attention, and precautionary measures, while reinforcing that current evidence in humans remains limited or inconclusive.

Regulatory and Precautionary Approaches

Regulatory responses vary depending on the type of agent and the strength of evidence available. In some jurisdictions, vinclozolin has been restricted or phased out following toxicological concerns. By contrast, regulators manage RF-EMF exposure primarily through guidelines and public health recommendations.

It is important to clarify that the World Health Organization does not set exposure limits directly. Instead, independent scientific bodies such as ICNIRP and IEEE develop exposure guidelines, while WHO evaluates the broader health evidence and provides risk assessments to governments.

Understanding Class 2B Possible Human Carcinogens

Overall, Class 2B Possible Human Carcinogens indicate that credible scientific signals exist, yet the evidence is not strong enough to establish causation in humans. As a result, the designation encourages further research, careful monitoring, and proportionate precaution, without implying confirmed human cancer risk.

IARC Classification System

The International Agency for Research on Cancer classification system is defined as follows:

• Group 1 — Carcinogenic to humans
• Group 2A — Probably carcinogenic to humans
• Group 2B — Possibly carcinogenic to humans
• Group 3 — Not classifiable as to carcinogenicity in humans

More on the topic: : IARC Monographs evaluation of the carcinogenicity of night shift work https://www.emfsa.co.za/research-and-studies/iarc-monographs-evaluation-of-the-carcinogenicity-of-night-shift-work/

References:

1. International Agency for Research on Cancer (IARC). List of Classifications, including Radiofrequency Electromagnetic Fields. Last updated 25 February 2026.https://monographs.iarc.who.int/list-of-classifications
2. US Right to Know. One Exposure, Twenty Generations Later: The Damage is Unfolding. 2025. https://usrtk.org/healthwire/one-exposure-twenty-generations-later-the-damage-is-unfolding/
3. World Health Organization. International EMF Project https://www.who.int/initiatives/the-international-emf-project
4. WHO Radiation and health https://www.who.int/teams/environment-climate-change-and-health/radiation-and-health/non-ionizing/wireless
5. ICNIRP. Guidelines for limiting exposure to electromagnetic fields (100 kHz – 300 GHz). 2020. https://www.icnirp.org/en/publications/article/rf-guidelines-2020.html

* Image adapted from Photo by Milad Fakurian on Unsplash

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Note added by EMFSA: This study is about power-line ELF-EMF

Extract

There is a growing concern that the decline in pollinators spells problems for humans. However, there is debate as to what causes decline in e.g. bee populations. What modifications to environment, introduced by humans, cause death and misbehavior of bees. Many claim that pesticides are to blame. Many, afraid to be called foil-hats, are afraid to say that EMF might be involved too.

Just published study from Italy has demonstrated that pesticides alone are not good for bees but that pesticides combined with ELF-EMF from power line is even worse, the multi-stressors environment:

Lupi et al., Combined Effects of Pesticides and Electromagnetic-Fields on Honeybees: Multi-Stress Exposure, Insects 2021, 12(8), 716; https://doi.org/10.3390/insects12080716

In simple terms, it looks like pesticides kill bees whereas pesticides + EMF cause behavioral changes.

Not good news for humans and for the rest of fauna kingdom that eats what plants produce…

The post A nifty study showing that pesticides + EMF are more unhealthy for the bees than pesticides alone… appeared first on EMFSA.

Simple Summary

In light of the shortcomings of using insecticides, there is an urgent need to explore alternative compounds that are effective for mosquito control with minimal adverse effects. The terahertz-based functional mineral water used in the current study exhibited concentration-dependent toxicity to mosquito larvae, pupae and larvivorous predatory copepods and could be a potential biodegradable and eco-friendly bioinsecticide.

Abstract

Functional mineral water and related products are popular in some Asian countries as health drinks and, recently, have been employed in agricultural crop production as well as pest control. This study aimed to investigate the survival of mosquito vectors exposed to plant-derived functional mineral water produced by terahertz technology. The terahertz-based functional mineral water used in the current study not only decreased the hatching of Culex quinquefasciatus (Say) larvae but also showed concentration-dependent toxicity to the 3rd instar larvae and pupae of the three mosquito species tested. Aedes albopictus (Skuse) and Cx. quinquefasciatus pupae were more susceptible to terahertz-based functional mineral water than the larval stage, as indicated by their lower LC₅₀. Lower concentrations (<100 ppm) of terahertz-based functional mineral water were not lethal to the pupae; however, these low concentrations still resulted in a reduced adult emergence. Although terahertz-based functional mineral water did not significantly affect Aedes aegypti (Linnaeus) hatching, it could potentially be used for vector control at the larvae and pupae stages. The larvicidal and pupicidal activity of diluted terahertz-based functional mineral water gradually diminished after 24 h, indicating that it is a biodegradable and eco-friendly bioinsecticide. However, as the terahertz-based functional mineral water is also toxic to larvivorous predatory-copepods, it should not be utilized in aquatic environments where predatory-based mosquito control programs are employed.

https://www.mdpi.com/2075-4450/12/3/211

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