UC Berkeley team finds connection with benzene, non-Hodgkin lymphoma

zoom screenshot from a meeting between researchers
Lemaan Rana/Courtesy
Four UC Berkeley researchers smile on a Zoom meeting. These researchers found that exposure to benzene likely increases the risk of non-Hodgkin lymphoma in a study led by Luoping Zhang, pictured on the bottom right.

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In a study published Aug. 24, UC Berkeley researchers found that exposure to benzene likely increases the risk of non-Hodgkin lymphoma, or NHL.

According to the study, which was led by Luoping Zhang, a campus adjunct professor of toxicology, and funded by the National Institute of Environmental Health Sciences, while benzene was recognized by the International Agency for Research on Cancer to cause leukemia, evidence it caused non-Hodgkin lymphoma, a form of cancer originating in white blood cells, was “widely debated.” The team sought to reach a more definitive conclusion.

“We identified a statistically significant association between exposure to benzene and non-Hodgkin lymphoma,” said Iemaan Rana, a graduate student on the research team. “This association was also dose-dependent, meaning greater exposures to benzene yielded a higher risk of NHL.”

Rana added that millions of people are exposed to benzene, a chemical compound often used in the production of plastics and gasoline, and has even been detected in household products like sunscreen.

An estimated 50% of household benzene exposure comes from second-hand smoke, the study noted, and in 2016, the American petrochemical industry produced nearly 2 billion tons of benzene. As such, exposure to benzene is both “widespread and unavoidable,” Rana said in the email.

The team of researchers used an electronic review process to comb through 2,481 previously conducted studies from PubMed and Embase, distilling these down to just 28 studies for a meta-analysis covering 9,587 patients with non-Hodgkin lymphoma. According to the study, this is the “most comprehensive and updated analysis done to date.”

“Because NHL comprises numerous cancers, we then tested to see whether benzene was more closely related to a particular subtype of NHL and found a doubling of the risk for the diffuse large B-cell lymphoma subtype,” Rana said in the email.

The study also states, however, that because the pathophysiology of NHL continues to evolve and NHL comprises a vast number of lymphomas, benzene exposure is not necessarily statistically associated with all subtypes of NHL.

Now that a strong link between benzene and NHL has been established, future research into this subject would study the mechanism driving this relationship.

“An important next step in comprehending the exposure-disease relationship is to investigate how benzene can modulate non-Hodgkin lymphoma disease progression,” the study states.

Contact Christopher Ying at [email protected], and follow him on Twitter at @ChrisYingg.