Science Panel: C8 levels tied to thyroid disease in kids

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Science Panel: C8 levels tied to thyroid disease in kids

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Science Panel: C8 levels tied to thyroid disease in kids

Charleston Gazette - August 18, 2011

By Ken Ward Jr.

Two weeks ago, we reported on the findings of a West Virginia University study that raised serious concerns about the relationship between exposure to C8 and the function of the thyroid gland.

And today, the C8 Science Panel has made public a summary of its latest report on the matter — raising more questions about how exposure to C8 and similar chemicals affects thyroid function and thyroid disease in kids.

The most significant new piece of information?

Science Panel members found a 50 percent higher risk of thyroid disease among kids exposed to higher levels of C8.

In a three-page status report, the Science Panel concludes its latest results:

"… Suggest that exposure during childhood to two perfluoroalkyl acids, PFOS and PFNA, may be capable of disturbing thyroid hormone levels. Reported thyroid disease in children was found to be associated with PFOA but not PFOS or PFNA,

The panel cautioned that “the results are not sufficient to prove that PFOA is leading to increased thyroid disease” but also concluded:

"Taken together, these new findings suggest that normal thyroid function may be affected by exposure to one or more of the family of pefluoroalkyl acids."

The Science Panel explains the importance of any connection between C8 exposure levels and the thyroid this way:

"Disturbances to the thyroid system, particularly in children, may have a number of negative effects, as thyroid hormones play important roles in regulating metabolism, growth and development, especially in normal brain maturation and development."

In this particular study, the Science Panel compared blood levels of thyroid-stimulating hormone, or TSH, and total thyroxine (TT4) to levels of C8 and similar chemicals in the blood of 10,725 children ages 1 to 18 years. They also compared the hormone levels to the C8 in the blood of mothers at the time of pregnancy.

And, the Science Panel looked at the number of children for whom a diagnosed thyroid disease was reported.

The three-scientist panel found that thyroid disease “was positively associated with” C8 levels in the child “with borderline statistical significance.” The panel reported a 50 percent higher risk for hypothyroidism for those with higher levels of C8 versus lower levels of the chemical. Similar associates were found for both C8 levels in the child’s blood and the mother’s blood while pregnant.

The Science Panel also said it found that, overall, three was no association found between C8 levels and thyroid hormones amount children. Associations were found for both PFOS and PFNA, including 8 percent higher levels of thyroxine among those with higher levels of the chemicals in their blood.

Science Panel members said that these higher hormone levels were statistically significant. But they went on to say that it would not be considered “clinically significant.”

Now, the Science Panel didn’t explain at all what they meant by that, and this is another example of the challenge in trying to report on the panel’s work when they don’t actually release more detailed information.

Statistically significant, simply put, means the association is strong enough that it is unlikely caused by chance. But clinical significance is a different thing altogether. Frequently, the term is used in describing whether a particular medical treatment’s effect is large enough to be or practical importance to patients — in other words, does it fix the problem it’s being used to treat? In this context, it would be used to described whether the difference in thyroxine levels observed from this association with PFOS and PFNA would be — in its most blunt terms — problematic or harmful to the kids involved. But the Science Panel’s report doesn’t provide any additional information about how exactly they reached that conclusion. And how all of the body’s systems interact is complicated, making it more difficult to understand — without more information — what the panel is talking about here.

As the panel always does, they warn us in this status report:

"Caution is needed interpreting these findings as the results based on measured chemicals are cross-sectional and one cannot be sure that the hormones are actually affected by levels of PFOA (or PFOS or PFNA)."

The panel and its publicists don’t even bother to explain what they’re talking about here … A cross-sectional study examines all of the information from a defined point in time. In this case, both the C8 levels in the blood and the thyroid levels (and thyroid disease) were measured at the same time — so the Science Panel believes it should use caution in interpreting the results because it can’t be known which came first — the chemical exposure or the hormone level or thyroid disease. The Science Panel has sometimes explained this in their press releases and their briefings, but not in the Status Reports themselves.

The Science Panel also offered this cautionary statement:

"For the estimated PFOA during pregnancy, there is extra uncertainty from estimating past exposures. Also, the disease data are based on small numbers [61 reported cases] and there is not a consistent pattern for each contaminant between the hormone findings and the disease results."

Still, other studies have found C8 exposure associated with higher incidence of thyroid disease, and the Science Panel notes in its new Status Report that other studies have suggested that either C8 or PFOS “may be associated with disturbances in markers of thyroid function.”

As the Science Panel said in its new report:

"Taken together, these new findings suggest that normal thyroid function may be affected by exposure to one or more of the family of pefluoroalkyl acids."


I’ve just confirmed that lawyers for DuPont had sought to delay the release of this Status Report for at least three days, to give company officials an opportunity to review it, perhaps raised questions about it, and prepare their own responses to the findings.

Wood Circuit Judge J.D. Beane told me an in interview that he declined that request:

They wanted to have a chance to review the report and discuss it. I just thought that the report is what it is, and it’s not going to change, so why not release it. You all should get it as soon as you can so that the public is informed.

And the Science Panel has added this very brief description of the study results (with the increased risk of disease downplayed) on its Website:

"The Science Panel has filed a status report to the Wood County Court on August 18, 2011 summarizing new results on markers of thyroid function and PFOA (also known as C8) among children 1-18 years old who participated in the C8 Health Project. Overall, there was no evidence of an association for thyroid hormones and PFOA for children aged 1-18 years. However, the results suggest that childhood exposure to two other perfuoroalkyl acids, PFOS and PFNA, may disturb thyroid hormone levels. There was some evidence of an association between reported childhood thyroid disease and PFOA, but not PFOS nor PFNA."

SOURCE: ... e-in-kids/
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