Japanese fishermen exposed to BRAVO fallout were found to have had about 7 times as much external as thyroid exposure. / They had lived with the external exposure for two weeks during their return to their home port, but probably avoided all but ingestion exposure to iodine. At the Sedan cratering explosion, one man remained in the open without facemask protection during cloud passage. His resultant thyroid exposure wasslightly more than his external gamma exposure. He thus had exposure to inhaled iodine, but avoided subsequent external exposure; his experience is evidence that the inhalation danger is real during cloud passage, Also on Sedan there were three air samplers in the fallout field that were changed often enough to distinguish cloud- passage iodine from later volatized iodine; the results showed that there wgs no more than 10 percent as much volatilized as cloud-passage iodine. This observation does not answer the concern about volatilization because it was made in dry, not wet, circumstances. Dr. Conard, the medical doctor in charge of the study of the effects of the BRAVO fallout on the Rongelap people, points out that data are lacking as to the importance of the inhalation process at Rongelap. His opinion is that, under those particular circumstances, ingestion and not inhalation probably was the process that produced most of their thyroid dose.!9,11 Thus the Marshallese evidence neither establishes or denies an inhalation threat, | ws ‘i 7 “4 rs | nn m4 = pris The opinion of the Subcommittee is that inhalation is far less of a threat than ingestion, and does not justify countermeasures such as filters in the ventilating systems of shelters.