Environmental Health Perspectives

Evaluating Studies to Understand if a Chemical Causes Cancer

IRIS graphic identifier

By Kacee Deener

When friends ask me what I do, I always mention the Integrated Risk Information System (IRIS) Program and explain that through IRIS, EPA scientists help protect public health by evaluating scientific information on the health effects that may result from exposure to environmental contaminants.  The questions inevitably come up—how do you do that, and what kind of information do you look at?

Scientists around the world contribute to the knowledgebase about the health effects of chemicals.  A particular area of interest has been chemicals’ potential to cause cancer.

Because EPA’s work must be grounded in the best possible science, we recently updated how we consider some of the cancer research of the Ramazzini Institute (RI), a laboratory in Italy known throughout the world for their extensive work in this area, completing cancer studies for more than 200 compounds.

A few years ago, the National Toxicology Program (NTP) identified differences of opinion between their own scientists and those from the Ramazzini Institute in diagnosing certain types of cancers in a study on methanol.  The scientific community—including EPA—was concerned, since Ramazzini data was included in IRIS evaluations.  We reviewed all of our IRIS assessments to determine which, if any, relied substantially on RI data; we found four that did, and we put those assessments on hold.

To follow up, EPA and the National Institute of Environmental Health Sciences cosponsored a group of scientists with expertise in evaluating tissue samples and making disease diagnoses, a Pathology Working Group (PWG), to review several Ramazzini Institute studies. They found some instances where respiratory infections in Ramazzini study animals made definitive diagnoses difficult, and disagreed with some Ramazzini diagnoses, primarily certain leukemias and lymphomas that had been identified. Therefore, EPA decided not to rely on RI data on lymphomas and leukemias in IRIS assessments. There was agreement, though, in diagnosing solid tumors, and EPA decided to continue to consider Ramazzini Institute solid tumor data in IRIS assessments.

This has been an important issue in the world of chemical risk assessment. Last week, this was highlighted once again when a paper authored by EPA scientists, Scientific Considerations for Evaluating Cancer Bioassays Conducted by the Ramazzini Institute, was published in Environmental Health Perspectives.  The article interprets Ramazzini Institute study results and compares their testing protocols with those used by other federal agencies.  The results were consistent with the PWG findings—Ramazzini Institute results for cancer endpoints other than lymphoma and leukemias, and some cases of tumors of the inner ear and cranium, are generally consistent with those of the National Toxicology Program and other laboratories.  The paper also notes that, while differences in Ramazzini Institute testing protocols can complicate the interpretation of study results, they may also provide chemical risk assessors with insights that might not be observed in other laboratories.

The short answer to my friends’ questions is that EPA works to use the best available science—from across the U.S. and around the world—to support IRIS and our other assessments designed to protect public health.

About the Author:  Kacee Deener is the Communications Director in EPA’s National Center for Environmental Assessment, home of the IRIS Program.  She joined EPA 12 years ago and has a Masters degree in Public Health.

Editor's Note: The opinions expressed here are those of the author. They do not reflect EPA policy, endorsement, or action.

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EPA Science Wednesday: EPA Study Shows Health Hazards Associated with Peat Wildfire Smoke

Each week we write about the science behind environmental protection. Previous Science Wednesdays.

By Sarah Blau

A few weeks ago my eyes wouldn’t stop itching. That intense, burning itch you know you shouldn’t scratch, but eventually you do. My irritated eyes were telling me that something was wrong, that some foreign species was polluting the air I breathe and my body did not like it.

The source of this relentless itch I discovered from the news on the drive home—wildfires! Wildfire smoke, to be more exact, wafting some 200 miles from the North Carolina coast where peat fires have been smoldering since early May.

As it turns out, I had only one minor symptom of something that can actually cause serious health problems.

In fact, I recently learned that a team of scientists led by EPA investigated the cardiovascular health effects of a similar eastern NC peat fire in 2008. A paper describing the results of this study was published Monday by Environmental Health Perspectives.

Researchers collected emergency room (ER) records from counties directly affected by the 2008 fire’s smoke plume and compared those records to ER records from smoke-free neighboring counties. Research statistics show that the smoke affected counties had an increase in ER visits by 65% for asthma, 59% for pneumonia and bronchitis, and 37% for symptoms of heart failure.

Photo courtesy US Fish and Wildlife Service

Photo courtesy US Fish and Wildlife Service

Peat fires differ from western canopy wildfires in both the way they burn and the chemical composition of their smoke. This is the first known study to show that exposure to a peat fire can cause both respiratory and cardiovascular effects, and the first study to conclusively show associations between a wildfire and emergency department visits for heart failure symptoms.

Wildfires are inevitable, but we are not completely helpless to suffer their mal-effects. EPA’s AIRNow website is an excellent source for information on both the air quality in your region, and how to protect yourself from the hazard of wildfire smoke.

Whether it’s severe cardiovascular illness or minor allergy-type symptoms, research by EPA and others has shown that wildfire smoke can have harmful health effects. Keep yourself informed of your local air quality and when conditions are poor, take appropriate actions. Maybe if I had taken a shorter morning walk outside with my dog, I wouldn’t have had itchy eyes all day!

About the author:  Sarah Blau is a student services contractor working with EPA’s Science Communication Team.

Editor’s Note: The opinions expressed in Greenversations are those of the author. They do not reflect EPA policy, endorsement, or action, and EPA does not verify the accuracy or science of the contents of the blog.

Editor's Note: The opinions expressed here are those of the author. They do not reflect EPA policy, endorsement, or action, and EPA does not verify the accuracy or science of the contents of the blog.

Please share this post. However, please don't change the title or the content. If you do make changes, don't attribute the edited title or content to EPA or the author.