Note: data in my graph of Tanaka 2009 are from Dr Tanaka (email).
Below is my letter to the editors of Environmental Health Perspectives (EHP) who published Olipitz et l. (2012). My letter below was in response to the author's response to a letter from Peter Melzer that raised some issues addressed in this video.
However, it turns out that the EHP does not accept replies to a reply by authors to a response letter. Nevertheless the points I raised below are salient to critique of the defense by colleagues of Olipitz against some critiques raised in this video...
In their response to Melzer, Engelward and Yanch (2012) make an erroneous claim about the methods of Tanaka et al. (2009). They claim:
"In his letter, Melzer correctly points out that data of Tanaka et al. (2009) show a statistically significant increase in chromzosome aberrations in cells from mice exposed to 1 mGy/day up to a total of 1,000 mGy. However, after exposure to that same dose-rate for a longer period (up to 8,000 mGy), there was no statistically significant change in the number of chromosome aberrations."
Even before consulting Tanaka et al. (2009) the careful reader can see a problem. For a dose-rate of 1 mGy per day to accumulate to a total dose of 8,000 mGy requires 8,000 days, or about 22 years. However, mice only live 2 to 3 years. So immediately we can see that their claim cannot be true.
And in fact, consistent with mouse lifespan, Tanaka et al. (2009) only exposed the 1 mGy/day dose group for 615 days for a cumulative dose of 615 mGy. This is stated throughout its text, tables and figures and was additionally confirmed in my personal correspondence with Tanaka.
So Engelward and Yanch rebutted Melzer's report of an error in Oliptiz et al. (2012) with yet another error. Contrary to their portrayal of Tanaka et al. in Oliptiz et al., Tanaka and colleagues did in fact report a statistically significant increase in chromosomal aberrations at an even lower dose-rate than Oliptiz and colleagues used.
The source of Engelward and Yanch's confusion is that Tanaka et al. contains a mathematical model of hypothetical exposure of the 1 mGy/day dose group for 8,000 days. However, while significance disappeared in that model, it did not reflect real empirical data as Engelward and Yanch errantly assert. Given this, perhaps they will consider the recommendation they made (Yanch & Engelward, 2012) in reply to Beyea that "we need to begin relying on data and not on hypothetical models."
Olipitz W, Wiktor-Brown D, Shuga J, Pang B, McFaline J, Lonkar P, et al. 2012. Integrated molecular analysis indicates undetectable change in DNA damage in mice after continuous irradiation at ~ 400-fold natural background radiation. Environ Health Perspect 120:1130--1136. @ http://ehp.niehs.nih.gov/1104294/
Tanaka K, Kohda A, Satoh K, Toyokawa T, Ichinohe K, Ohtaki M, et al. 2009. Dose-rate effectiveness for unstable-type chromosome aberrations detected in mice after continuous irradiation with low-dose-rate γ rays. Radiat Res 171(3):290--301. @ http://pubmed.com/19267556
Yanch J, Engelward B. 2012. DNA Damage after Continuous Irradiation: Yanch and Engelward Respond. Environ Health Perspect. 120:a383--a384. @ http://ehp.niehs.nih.gov/1205564r/