I have never seen an American edition of this work originally published by McClelland & Stewart, the noted Canadian Publisher.
This book details the Canadian WW II research effort in chemical and biological warfare. The author interviewed surviving participants, and thoroughly mined the Canadian and US National Archives and the British Public Records Office. Bryden is a noted researcher on the Canadian scientific war effort and has published a work on Canadian WW II SIGINT, Best Kept Secret (c.f.)
After the first edition came out, the National Defense Establishment of Canada began a review of what happened to all the materials left over from the program. On page 256 and following the author discusses the way records can be controlled and hidden just by depositing them somewhere and thus adding a layer of processing when they are finally requested. Archivists very seldom declassify anything that someone does not ask for as they have limited time. And if the indexing system is destroyed for a randomly accessioned collection then the requestor must go through the entire file box by box. Even without intent to obfuscate this is discouraging to the "jump and run" type researcher working on a deadline.
And archivists always leave the original files in the order as recieved even if, as sometimes is apparent, they were figuratively shoveled into the boxes for shipment. Archivists do not sort as a matter of routine. Some make a fetish of leaving files in disarray caused by later researchers and archival copier technicians. I have encountered some of these obtacles in my research and I was working in originally innocuous files which had long before been declassified.
Many of the relevent files on this sensitive subject have yet to be released, especially in Great Britain. But the main story is here, and it is a very cautionary one; recall the tale from antiquity about the genie, once released, which can never be put back, the recent anthrax alerts have served to remind us once again of that.