Sunday, March 20, 2016

Some Background for the Study

A 1978 report raise the question of low-dose ionizing radiation risk to nuclear workers at the Portsmouth, New Hampshire, shipyard. [Identified as "Najarian, 1978" in the Johns Hopkins Report Introduction, referring to brief study done by Dr. Thomas Najarian, a hematologist at the Boston Veterans Administration hospital.]

In 1980, a U.S. Department of Energy contract was granted to the Department of Epidemiology at The Johns Hopkins University to study "Health Effects of Low-Level Radiation in Shipyard Workers." [DOE Contract Number DE-AC02-79EV10095.]

It is apparent from the introduction that this was expected to be a confirmation of the earlier "limited study" and certainly had nothing to do with verification of the hormesis principle - which it ended up being. [The term "radiation hormesis" had not even been used yet, as Luckey's first book was still a year or two away when the contract was awarded.]

The study involved an initial pool of 700,000 workers - including 108,000 nuclear workers - at two private and six government shipyards. Most were weeded out because of missing or incomplete records. Then too, many of the non-nuclear workers did not work in a shipyard during the time when nuclear overhauls were done and were therefore not considered to be comparable to nuclear workers. Two other steps - a crosscheck of records and a questionnaire to the worker or next of kin - pared the list down to 72,356 qualified subjects. Workers were divided into three categories:

1. Those with duties not involving radiation, the Non-Nuclear Workers (NNW's - or in our case, the Nones). This group of 33,352 workers was used as the control.

2. Those who had cumulative exposure of less than 500 mrem. These were termed NW<0.5, which we will call the Lows, and totaled 10,462 workers.

3. Those with cumulative exposures greater than or equal to 500 mrem. They were referred to as NW>0.5, which we'll refer to as the Highs, numbering 28,542 workers.

Results of the study were tabulated to show mortality ratios of the above cohorts from various types of cancer and from all causes. By the way, althought the Johns Hopkins report to the Department of Energy was completed nearly fifteen years ago, the Energy Department has yet to acknowledge the results and issue its report on the study.