My big issue is that studies find a lot of things, and not all of them are reinforced by further studies.
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The one-year study involved a hairless mouse strain (SKH-1), a well-recognized model for photocarcinogenicity research (Bucher 2002; FDA 2009; Halliday 2000; Yan 2007). Both male and female animals were used, with 34-36 animals per group. Testing included two concentrations of retinyl palmitate, 0.1% and 0.5%, administered topically in a cream vehicle.
Good, but a slightly larger sample size might be nice for future studies.
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Most were withdrawn and sacrificed when at least one skin tumor or lesion reached a significant, defined size. Though FDA did not publish the size at sacrifice for this study
Most is unspecific and we have unpublished, though relevant data.
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Some animals may have been withdrawn before tumors and lesions reached that size if skin lesions began to merge (which would make it difficult to assess skin effects), or if the animals were otherwise ill.
Some and may are both unspecific. Also, we now have multiple reasons for removal from testing.
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The reason for withdrawal is not available in the public data, so EWG was unable to distinguish between animals withdrawn because of large tumors, large lesions, or other reasons.
No data presented on the reasons for removal from testing. We are now dealing with lesions, tumors, and anything else in unspecified amounts, and all recorded as being the same thing.
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EWG analyzed differences in the number of days recorded for each animal’s survival, a proxy for rate of tumor or lesion development.
We're mixing terms here and using data that doesn't necessarily mean anything at this point.
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The data show that at least 89 percent of vitamin-A exposed animals developed one or more tumors during the study, and large tumors were likely a significant reason for withdrawals.
They're exposing them to a lot of radiation, so of course they're going to develop tumors. In fact, these mice are used because they're likely to develop tumors: "The hairless mouse is highly susceptible to skin cancer, tumors and lesions under the conditions of this test." What percent of the non vitamin A coated animals developed tumors? We apparently don't even know whether or not the tumors were the cause for withdrawal (which we've somehow managed to redefine as survival in this article).
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As a result, the speed at which these types of skin damage develop is an accepted indicator of harm
Good bull! Show me a data set that includes time till first incidence of lesion or tumor and the growth rate and this study will shed some light on the issue at hand! But wait... we having nothing.
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EWG analyzed differences in the number of days recorded for each animal’s survival, a proxy for rate of tumor or lesion development.
Lets go back to this one again. We're using withdrawal under dubious circumstances as a proxy for survival, which we're using as a proxy for rate of tumor or lesion development.
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Animals treated with retinyl palmitate were withdrawn from the study 11-to-21 percent sooner than animals whose skin was treated with a neutral cream and exposed to the same doses of UV.
When did we get back to withdrawn? Also, how did we come to this 11-to-21 percent? The study took place over a year and is getting results that are a function of time. If Matthias mouse gets chlamydia and decides to bail on the study early (since we aren't controlling for non vitamin A related withdrawals) then all of our results get raped if we take an average.
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Mice treated with only UV or only neutral cream combined with UV survived longer than animals exposed to vitamin A
Glad to see that we're surviving again- it feels more heroic. What this should say is that the mice in this study exposed to vitamin A were, on average, removed for a variety of reasons sooner than mice treated with only UV or only neutral cream. While caution is always advised, and being informed is important, this really is quite silly.
