Talk:Second event theory

Counter-consensus additions

Counteraction, you added a bunch of studies without understanding what they are about, as if they overturn the consensus position of the CERRIE. The cites only superficially support his theory. For example, the alpha particle study suggests not that low-level risks are underestimated, but that they are overestimated, contradicting the theory. And it has no relevance to strontium, which emits beta and gamma radiation, not alpha. --Tweenk (talk) 03:41, 21 March 2011 (UTC)

Wrong, the low-level risks are underestimated. The alpha particle study shows that a single alpha particles does less damage than you would expect. This is because most damage is done by multiple particles hitting the same cell, which is a confirmation of second event theory, the idea that the second particle does damage while the first particle does not. Hence I'm going to put back my addition. You also deleted the study I posted on X-ray radiation. Counteraction (talk) 16:04, 22 March 2011 (UTC)

Both of your studies are purely in vitro studies. You can't use them to predict organism response. The carcinogenicity data for strontium-90 and strontium-89 are a much stronger argument, because they were determined from studies on complete organisms. No excess risk postulated by the second event theory was found. Therefore, the theory is incorrect.

The study about radon does not support Busby's theory. Radon carcinogenicity data is only available for high radon concentrations, where multiple alpha particles strike a single cell. The study says that when radon concentrations are reduced to the point that only 1 particle strikes a cell, carcinogenesis is reduced. So the study indicates the risk for low exposures predicted from data for high exposures is too high. What Busby says is that risk calculated from high exposures is too low. --Tweenk (talk) 23:56, 23 March 2011 (UTC)

Addendum, the X-ray study has little to do with Busby's theory (in addition to being in vitro). The pattern they observe is not linear because they choose to present their data as % of cells transformed relative to surviving cells. The carcinogenicity or survival rate plots do not show any interesting patterns. It could theoretically --Tweenk (talk) 00:16, 24 March 2011 (UTC)

The radon study doesn't indicate that the risk predicted from low exposure is too high. That's a misinterpretation. It indicates that in case of a single cell, carcinogenesis requires multiple hits. Second Event Theory provides an explanation for this by claiming that the first hit can be repaired but the second hit, which takes place during replication, can not be repaired. As a result, the total carcinogenic potential of a single cell hit twice, including once during the division cycle, may exceed the carcinogenic potential of a large number of different cells all hit only once, outside of the division cycle.

There is little data comparing the carcinogenic potential of Strontium 89 and 90. The studies quoted in the Cerrie paper are specifically about high doses. Second event theory predicts that the greatest difference in carcinogenicity will be found in low doses of the isotypes.

From the paper:

The cumulative doses are high because excess bone cancer is not seen at low doses - none below ~0.63 krad bone dose for strontium-90.

You would need a high number of animals to find a difference in bone cancer rates if you expose the animals to low doses. However to test Busby's Second Event Theory, low doses are required to observe the effects in vivo, because, as I explained in the article, the greatest difference in carcinogenic potential will be seen at low doses according to Busby.

I've already posted in vitro evidence that provides backing to the Second Event Theory, which you have removed. Counteraction (talk) 02:32, 26 March 2011 (UTC)

The phrase "unverified assumption and an elaborate statistical model" sounds like the work of someone unfamilar with the scientific method or research. Theoretically useful but "unverified" assumptions are made all the time in science. They need only be explicit and not subject to immediate empirical verification. Statistical models are often "elaborate" when they are about complex processes. That sounds rather like a phrase a mathphobic undergad would use because his head was hurting from unfamiliar quantitative analysis. Thorvelden (talk) March 23, 2011

I should rather call this "unverified hypothesis", because it could be verified. The X-ray study provided by Counteraction indicates that the hypothesis is at least plausible, so I'll remove the "unverified" bit, but since the theory was disproved experimentally it doesn't change its status. --Tweenk (talk) 00:16, 24 March 2011 (UTC)