Integrated Science Assessments

Is this Hazardous?

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By Kacee Deener 

How do you know when something isn’t good for you? Sometimes it goes without saying (rattlesnake venom), and sometimes it’s not as obvious and requires deeper evaluation.

I recently kicked off a blog series about human health risk assessment and described its four-step process.  Remember that hypothetical factory? How do we know if the chemicals being released are harmful? We use a process known as “hazard identification” to identify the types of health problems a chemical could cause (like cancer or respiratory effects).

IRISExamples of two EPA programs that develop hazard identifications are:  (1) the Integrated Risk Information System (IRIS) program and (2) the Integrated Science Assessment (ISA) program.  Through IRIS, Agency researchers provide health effects information on environmental chemicals. ISAs provide health effects information to inform the National Ambient Air Quality Standards for the six criteria air pollutants.

So, how do we do this? We start by searching the scientific literature to compile all of the studies that look at a chemical’s effects. In IRIS assessments, we describe how we search the literature using, in part, a diagram.  You can see an example of that here (pages 1-2).  We then organize the information into the categories of health effects seen in the studies, (e.g., kidney or reproductive effects) and summarize certain features of each study, such as the level and route of exposure. We also look at each study’s quality (e.g., was the study designed and conducted well? was it peer reviewed?).  Finally, we evaluate the overall “weight of evidence” to answer the question “does the agent cause the health effect?”

In some cases, EPA has developed “descriptors” for doing this. The Preamble to IRIS assessments provides more information (you can see an example here on page xxii). In other words, we provide text describing how likely it is that a health effect is associated with a chemical exposure. For example, in the recent IRIS assessment of 1,4-dioxane, we found that the chemical is likely to be carcinogenic to humans. In our recent ISA for Lead, we found, among other things, that there is a “causal relationship” between lead exposure and cognitive function decrements in children and a “likely causal relationship” between lead exposure and inflammatory responses in adults.

We’ve been working to improve the way we systematically review evidence when identifying hazards.  In fact, we recently held a workshop on this topic. We’ve also started releasing the literature search strategy, along with evidence tables summarizing the critical studies, early in the process of developing an assessment. We follow that up with a public meeting to discuss the materials. We held the first of these meetings on December 12-13. Our next meeting is scheduled for April 23.  Join us to provide your input, and don’t forget to check back in a few weeks for my next post!

About the Author: Kacee Deener is the Communications Director in EPA’s National Center for Environmental Assessment.  She joined EPA 13 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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Progress in Communities: It All Starts with Science

This week is the 43rd Anniversary of the establishment of the Environmental Protection Agency, and we are marking the occasion by revisiting how our collective efforts on behalf of the American people help local communities become cleaner, healthier, and more sustainable. As the Assistant Administrator for the Agency’s Office of Research and Development, I can’t help but see a strong undercurrent of science and engineering in every success story.

Over the past four plus decades, EPA scientists and engineers, along with their partners from across the federal government, states, tribes, academia, and private business, have supplied the data, built the computer models and tools, and provided the studies that have helped communities take action to advance public health and protect local environments.

In every area of environmental and human health action, EPA researchers have helped local communities make progress. While examples abound, here are just a few:
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Editor's Note: The views expressed here are intended to explain EPA policy. They do not change anyone's rights or obligations.

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EPA’s Continuing Effort to Reduce Lead Exposure

Three images in a line: child and adult hands together, lake shore, lead from periodic table.By Ellen Kirrane

As a kid growing up in the 1970s, I can remember my mom pulling up to the filling station and asking for “regular” gasoline.  At the time, I didn’t realize what this meant, but as I got older I found out that “regular” gasoline had lead in it; the other option – “unleaded” gas – did not.

Now, as a scientist working for EPA, I have a true appreciation for what lead is and how the next generation of kids can benefit from living in an environment that is cleaner because “regular” gasoline is no longer the norm.

By removing lead from gasoline and tightening industrial emissions standards, EPA has drastically reduced lead air emissions in the U.S.; they declined by more than two orders of magnitude (100 times) between 1970 and 2008.  But even with such important progress, by 2008 scientists realized that it was not enough, and that a young child’s cognitive function could be impacted by much lower lead exposures than previously understood. Supported with such science, EPA lowered its National Ambient Air Quality Standard for lead tenfold.

In June 2013, EPA released its most recent review of the science on the health and ecological effects of lead. Scientists who study lead consider it one of the “dirtiest” chemicals because it affects so many different systems in the body.  It does this by interfering with molecules called “ions.” When lead exposure affects ion status in the cells, it disrupts how calcium is regulated and how proteins are used for essential bodily functions.  This can lead to a wide array of health and ecological effects.

In children, lead exposure can cause IQ reductions and decreased academic performance. Lead can also cause behavioral changes in children, have harmful effects on blood cells and blood producing organs, and may cause decreased auditory and motor function, as well as immune effects.  Some of these effects may be irreversible and there is no evidence of a threshold below which scientists can be confident that there are no harmful cognitive effects from lead exposure. In adults, long-term lead exposure can cause increased blood pressure and hypertension, lead to coronary heart disease and affect many other organ systems. Just as lead can harm humans, it can also harm animals and other organisms that live on land and in the water by reducing survival, growth and reproduction, as well as affecting behavior, development and blood producing organs.

In addition to setting standards for lead in air, EPA continues to protect human health and the environment from the harmful effects of lead through a variety of programs.  EPA’s assessment of the science on the health and ecological effects of lead underpins these efforts. I am proud to be part of an agency that’s been working for four decades to keep lead out of our air, water, and soil.

To find out more about what EPA is doing to protect the American public from lead exposure, visit the Agency’s lead website at http://www2.epa.gov/lead.

About the Author:  Ellen Kirrane is an epidemiologist in EPA’s National Center for Environmental Assessment. She works on Integrated Science Assessments, which form the scientific basis for the National Ambient Air Quality Standards.

 

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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Science Does Truly Matter

By: Dahnish Shams

As an EPA summer intern, I got a firsthand look at how essential science is to the operations of the Agency and of its immense importance to us all.

Stationed at EPA’s National Center for Environmental Assessment, I was quickly introduced to some of the science products that support so much of what EPA does to protect human health and the environment. Chemical assessments in EPA’s Integrated Risk Information System (IRIS) Program and Integrated Science Assessments (ISAs) for the six criteria air pollutants (ozone, particulate matter, carbon monoxide, sulfur oxides, nitrogen oxides, and lead) inform the public and decision makers of the potential hazards threatening public health and the environment. These scientific products provide the basis for many of the rules the agency generates.

Yet, when you look beyond the products and their implications, what I have learned during my 10-week internship is that so much of the Agency’s work is truly defined by individuals, such as the scientists, communications staff, and support specialists that work as a team to conduct assessments. I saw that despite numerous obstacles, there is continued determination by this team of professionals to consistently devise strategies and methods to overcome the challenges that naturally arise as chemicals and humans interact in increasingly complex ways with the environment.

So as I conclude my internship, this blog post is meant to acknowledge the passion, determination, and teamwork exemplified by the people that I have met at the Agency this summer. These qualities are reflected through the continued efforts to improve IRIS chemical assessments, through climate assessments of ecosystems from across the country, and by the continual production of high quality ISAs – all of which provide a critical part of the scientific foundation for EPA’s decisions to protect human health and the environment.

If there is one message that I will take away from the Agency this summer, and one that I hope you gather from this post, is that I am proud to have been associated with EPA, and with the National Center for Environmental Assessment and the people that work here in particular. Though there are challenges in assessing the environment in the 21st century, they showed me through their passion, dedication, and teamwork that producing high quality science does truly matter.

About the Author: Dahnish Shams was a summer intern with EPA’s National Center for Environmental Assessment.

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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