Wednesday, January 4, 2012

Dioxin and Disease

The Wall Street Journal has an interesting article today, Jan 4, on new dioxin guidelines being proposed by the EPA: "Industry Wary of Dioxin Guidelines" 

The article explains that dioxin is widely found in meat and dairy. The EPA is proposing new daily limits on dioxin consumption through food.

A food industry group complained that "Nearly every American--particularly young children--could easily exceed the daily [dioxin limit proposed by the EPA] after consuming a single meal or heavy snack."

A toxicologist quoted in the article states that all age groups typically consume at least twice the EPA limit that was initially proposed.

The article observes that children are much more vulnerable to the detrimental effects of dioxin.

I decided to do some quick research to determine the health effects of dioxin.

In the literature I found a debate about the threshold for dioxin effects. 

A growing number of scientists is claiming that there exists NO threshold for dioxin's effects. 

I am sympathetic to the challenges posed by the food industry because how can they reduce dioxin exposure when dioxin bio-accumulates up the food chain?

However, I think growing research on the no-threshold effects of dioxin need to be examined in the context of the vast range of chemicals that we are slowly poisoning ourselves with, including BPA, lead, arsenic, mercury, etc.

Add ionizing radiation to the chemical soup and one wonders how long this can continue without very overt consequences. 

Maybe we are already seeing them in our cancer and autism rates yet we turn a blind eye to our own destruction...

No Evidence of Dioxin Cancer Threshold. David Mackie1, Junfeng Liu1, Yeong-Shang Loh2, Valerie Thomas3.  Environ Health Perspect 111(9): doi:10.1289/ehp.5730

[Asbtract]" The U.S. Environmental Protection Agency (EPA) has developed an estimate of the human cancer risk from dioxin, using the standard low-dose linear extrapolation approach. This estimate has been controversial because of concern that it may overestimate the cancer risk. An alternative approach has been published and was presented to the U.S. EPA Science Advisory Board's Dioxin Review Panel in November 2000. That approach suggests that dioxin is a threshold carcinogen and that the threshold is an order of magnitude above the exposure levels of the general population. We have reexamined the threshold analysis and found that the data have been incorrectly weighted by cohort size. In our reanalysis, without the incorrect weighting, the threshold effect disappears.

I also found evidence of other disease linkages

Birnbaum LS, 1995 Developmental effects of dioxins. Environ Health Perspect 103(Suppl 7): doi:10.1289/ehp.95103s789
[Asbstract] The potent developmental toxicity of dioxin in multiple species has been known for a number of years. However, recent studies have indicated that dioxin also induces functional developmental defects, many of which are delayed. Subtle structural deficits, not detectable at birth, have also been described in multiple species and in both sexes. Certain defects have been reported not only in animals but also in children prenatally exposed to complex mixtures containing dioxinlike compounds. None of the effects can be attributed to modulation of any one endocrine system. For example, dioxin does not bind to the estrogen receptor, but it can cause effects that are both estrogenic and antiestrogenic. However, viewing dioxin and related compounds as endocrine disruptors that may alter multiple pathways sheds some light on the complexities of this potent class of growth dysregulators.

Humblet O, Birnbaum L, Rimm E, Mittleman MA, Hauser R, 2008 Dioxins and Cardiovascular Disease Mortality. Environ Health Perspect 116(11): doi:10.1289/ehp.11579


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