The COSMOS study concluded that heavy cellphone use was not associated with an increased risk of developing brain tumors. Some scientists criticized the study’s methodology and suggested that funding by the telecommunications industry may have led to bias.

A new peer-reviewed study concluded that heavy cellphone use was not associated with an increased risk of developing brain tumors. But some critics questioned the results, citing methodological flaws and bias from industry funding.

The authors of the COSMOS study (Cohort Study on Mobile Phones and Health) promoted it as the world’s largest multinational prospective cohort study on the potential health risks of cellphone use.

They said the study, published in Environmental International, found “no evidence” of increased risk for developing three common brain tumors linked to heavy cellphone use.