A systematic review commissioned by the World Health Organization (WHO) concluded there is “high certainty” evidence that cellphone radiation exposure causes two types of cancer in animals.

The WHO-backed review, published online April 25 in Environmental International, determined radiofrequency-electromagnetic fields (RF-EMF) emitted by cellphones and other wireless devices were linked to an increased risk of malignant gliomas in the brain and malignant schwannomas, or nerve tumors, in the heart in studies on animals. The review noted that both tumor types had previously been found in studies on humans.

The WHO’s review also concluded there is “moderate certainty” evidence that cellphone radiation exposure causes an increased risk of rare liver and adrenal gland tumors.

Ron Melnick, Ph.D, chair of the International Commission on the Biological Effects of Electromagnetic Fields (ICBE-EMF) and a former senior toxicologist in the National Toxicology Program (NTP), said in a statement:

“The evidence is now clear — cell phone radiation can cause cancer in animals in concordance with the tumor types identified in human studies of mobile phone users. As animal studies are essential for predicting cancer risk in humans, governments should develop science-based safety standards to protect human health.”

The WHO review prompted leading scientists with the ICBE-EMF on April 27 to call for “immediate policy action” to protect people from possible harm from wireless radiation exposure.

“Given this high level of certainty,” ICBE-EMF said in a press release, “government policymakers worldwide should immediately move to revise their RF radiation exposure limits to protect public health and the environment.”

ICBE-EMF is a “consortium of scientists, doctors and related professionals” who study RF-EMF and make recommendations for RF-EMF exposure guidelines “based on the best peer-reviewed scientific research publications.”

The group warned that delaying such revisions “could have serious consequences amid the global surge in the use of wireless communication devices.”