I have a new favorite blog. Dr. James Conca, who we visited last week in Richland, is a scientist who is able to take a complicated issue like nuclear power and nuclear waste, which also has complicated regulatory and policy components and an added layer of public fear and mistrust, and distill it down into the important components.
He has compelling arguments for why the linear no threshold (LNT - something my ESCI 333 students should know about) is an inaccurate and overly burdensome approach to limiting risk from radioactive materials. The implications sometimes of being overly protective can be beneficial, but in the case of radioactive materials, the fear can be more damaging. Complicated issues, for sure, but important ones for all of us to understand...
Showing posts with label In the US. Show all posts
Showing posts with label In the US. Show all posts
Sunday, May 19, 2013
Sunday, February 5, 2012
Dioxins... Uh-Oh
The sordid history of industry, government, and the public... throw in a chemical group like dioxins and it makes for interesting reading... yes, there is a novel in here somewhere.
Understanding risk of contaminants to humans is a difficult task. Since toxicologists can't ethically conduct controlled experiments on humans, the agencies evaluating the risk have to rely on many different types of studies - for example, epidemiological studies from accidental exposures to humans (as in Vietnam), laboratory studies with animals (in vivo), and laboratory studies without animals (ex vivo). Some of the studies support toxicity, some don't. The level at which effects are seen depends on what the effect is and what the test organism is... it just isn't easy. Period. Most of the work, however, does support that dioxins are quite bad for humans and one specific dioxin (2,3,7,8-TCDD) has been called one of the most toxic chemicals known to man. Dioxins can be lethal, they can cause a skin condition called chloracne, they can cause reproductive damage and birth effects, they can weaken the immune system, and they can cause cancer (ATSDR, 1998), but again, whether these effects occur and at what exposure level they occur depends on what animal is being tested and how the exposure occurs.
And so, the EPA is charged with determining how much of a toxic substance like dioxins can be in our food without causing an increased risk of cancer and non-cancer effects to humans. This was last completed in the 1980s. Reassessments of dioxins risks, based on new science since the last assessment has been on-going. The short story is that there was a reassessment completed in 2003 and evaluated by the National Academy of Sciences (NAS). Three years later, the NAS provided comments to the EPA on that reassessment. In 2010, the EPA released a draft reassessment incorporating comments from the NAS. They also decided in 2010 to separate cancer risk from non-cancer risk and had a goal of releasing the final Dioxin Reassessment for non-cancer risk by the end of January, 2012, which hasn't happened yet. According to Bottemiller (2012), the allowable level for non-cancer effects is expected to be 0.7 picograms per kilogram of body weight per day. The problem... industry, such as the American Chemical Council isn't happy about this level (see Bottemiller for a great summary of all of this). In the meantime, we are all exposed to dioxins from the meats, dairy products, and fish that we eat.
As of now, I suppose we watch what happens and make comments whenever the public gets a chance... this is a story to pay attention to.
Additional Information:
Understanding risk of contaminants to humans is a difficult task. Since toxicologists can't ethically conduct controlled experiments on humans, the agencies evaluating the risk have to rely on many different types of studies - for example, epidemiological studies from accidental exposures to humans (as in Vietnam), laboratory studies with animals (in vivo), and laboratory studies without animals (ex vivo). Some of the studies support toxicity, some don't. The level at which effects are seen depends on what the effect is and what the test organism is... it just isn't easy. Period. Most of the work, however, does support that dioxins are quite bad for humans and one specific dioxin (2,3,7,8-TCDD) has been called one of the most toxic chemicals known to man. Dioxins can be lethal, they can cause a skin condition called chloracne, they can cause reproductive damage and birth effects, they can weaken the immune system, and they can cause cancer (ATSDR, 1998), but again, whether these effects occur and at what exposure level they occur depends on what animal is being tested and how the exposure occurs.
And so, the EPA is charged with determining how much of a toxic substance like dioxins can be in our food without causing an increased risk of cancer and non-cancer effects to humans. This was last completed in the 1980s. Reassessments of dioxins risks, based on new science since the last assessment has been on-going. The short story is that there was a reassessment completed in 2003 and evaluated by the National Academy of Sciences (NAS). Three years later, the NAS provided comments to the EPA on that reassessment. In 2010, the EPA released a draft reassessment incorporating comments from the NAS. They also decided in 2010 to separate cancer risk from non-cancer risk and had a goal of releasing the final Dioxin Reassessment for non-cancer risk by the end of January, 2012, which hasn't happened yet. According to Bottemiller (2012), the allowable level for non-cancer effects is expected to be 0.7 picograms per kilogram of body weight per day. The problem... industry, such as the American Chemical Council isn't happy about this level (see Bottemiller for a great summary of all of this). In the meantime, we are all exposed to dioxins from the meats, dairy products, and fish that we eat.
As of now, I suppose we watch what happens and make comments whenever the public gets a chance... this is a story to pay attention to.
Additional Information:
- Hamilton. A Chemical Conundrum: How Dangerous is Dioxin. NPR Morning Edition: Dec 28, 2010.
- World Health Organization. Dioxins and Their Effects on Human Health. Fact sheet N°225: May 2010.
- Tomson. EPA Misses Deadline on Dioxin Guidelines. The New York Times: Feb 1, 2012.
- Williams. EPA misses deadline to issue dioxin health assessment. NPR Environment: Feb 2, 2012.
- Bottemiller. EPA Misses Key Deadline for Dioxin Assessment. Food Safety News: Feb 3, 2012.
Wednesday, September 14, 2011
An opportunity to comment on Atrazine....
1) EPA Seeks Comment on Save the Frogs! Atrazine Petition (from Mary-Jean Lormand, EPA Pesticide Program Updates)
EPA is seeking public comment on a May 2011 petition from the amphibian conservation group, Save the Frogs, requesting that the Agency ban the use and production of atrazine. EPA asks that comments on the Save the Frogs petition be submitted within 60 days, by November 14, 2011, to docket EPA-HQ-OPP-2011-0586 at Regulations.gov. EPA will review all comments submitted before responding to the petition.
For further information about EPA's regulation of atrazine, visit its Atrazine Updates Web page, http://www.epa.gov/oppsrrd1/reregistration/atrazine/atrazine_update.htm .
Interesting Articles:
EPA is seeking public comment on a May 2011 petition from the amphibian conservation group, Save the Frogs, requesting that the Agency ban the use and production of atrazine. EPA asks that comments on the Save the Frogs petition be submitted within 60 days, by November 14, 2011, to docket EPA-HQ-OPP-2011-0586 at Regulations.gov. EPA will review all comments submitted before responding to the petition.
For further information about EPA's regulation of atrazine, visit its Atrazine Updates Web page, http://www.epa.gov/oppsrrd1/reregistration/atrazine/atrazine_update.htm .
Interesting Articles:
- Rohr JR, McCoy KA 2010. A Qualitative Meta-Analysis Reveals Consistent Effects of Atrazine on Freshwater Fish and Amphibians. Environ Health Perspect 118:20-32. http://dx.doi.org/10.1289/ehp.0901164
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