Cancer Risk from Exposure to Plutonium and Uranium

I. GENERAL COMMENTS

The purpose of this report is to improve the knowledge of the cancer risk from exposure to plutonium and uranium. The results of Mayak cohort studies indicate the lung, liver and bone cancer risk from plutonium exposure, as the description in the abstract. In the text, the review of lung cancer is very detailed. However, the review of liver cancer from plutonium-only contains only one reference (Sokolnikov, 2008), and the length of this part is even shorter than that of leukaemia and other cancers. It is too simple to draw attention from readers.

The liver is the most important target tissue after the plutonium uptake into blood. The baseline of liver cancer is much lower than lung cancer in Europe population, so cases of liver cancer in Mayak cohort are not enough to get detailed analysis of risk like lung cancer. However, still there are several references with available information on liver cancer from plutonium, eg. Gilbert et al.(2000) Liver Cancers in Mayak Workers, Labutina et al.(2013) Radiation Risk of Malignant Neoplasms in Organs of Main Deposition for Plutonium in the Cohort of Mayak Workers with Regard to Histological Types,etc.. The paper of Labutina (2013), which is referred in the review of lung cancer, used latest dose system of Mayak(MWDS-2008).

It is suggested to increase the length of the review of liver cancer from plutonium.

The report reviews the cancer risk from exposure to plutonium and uranium. In the Contents, plutonium is listed before uranium, just like the order in the title. However, some description in the text is not consistent with this order. As following:

• L25, L410, L2786, “uranium and plutonium”

          Change to “plutonium and uranium”

• L30, “Keywords: Uranium, Plutonium,…”

          Change to “Keywords: Plutonium, Uranium,…”

• P4, MAIN POINTS, the second paragraph is about uranium.

          Suggest to put it at the end of this part.

• P9, Para6 is about uranium.

          Suggest to put it after Para8.

In 2.3 Epidemiological studies, the subsections of two parallel parts are as following:

It is suggested to keep the structure of parallel parts consistent. The order of cancer in 2.3.1.3 is better, because it is based on target organs of plutonium.

In addition, in the field of radiation protection, the term “leukaemia” means, except solid cancer, general malignant tumors, equals to “lymphatic and haematopoietic cancers”.

The description of uranium chemical toxicity (except kidney) in Para244 is not clear. Especially the reference “Kurttio, 2005”, which studied natural uranium in drinking water, is the only reference in this paragraph and is not consistent with former point (Para239, “In contrast to the UNSCEAR Report 2016 (2017), the focus here is on studies of uranium workers…”). On the other hand, both Para243 and Para245 introduce the kidney toxicity separately.

It is suggested to adjust the contents of this part according to the general conclusion of annex D, UNSCEAR 2016 Report, especially Para322.

In Para253, described as “In this publication, we focus on studies that reported uranium-specific risks for the three most plausible cancer outcomes following uranium exposure: lung cancer (…), kidney cancer (…), and leukaemia and other lympho-haematopoietic malignancies (…).”

But in section 3.3.3, the order is 3.3.3.1 Lung cancer, 3.3.3.2 Lymphatic and haemapoietic cancers, and 3.3.3.3 Kidney cancer.

It is suggested to move the review of kidney cancer ahead in section 3.3.3, according to the order in Para253.

II. COMMENTS ON LOCAL MISTAKES