Tuesday, January 29, 2013
Elevated airborne beta levels in Pacific/West Coast US States and trends in hypothyroidism among newborns after the Fukushima nuclear meltdown*
ABSTRACT Various reports indicate that the incidence of con- genital hypothyroidism is increasing in developed nations, and that improved detection and more inclu- sive criteria for the disease do not explain this trend entirely. One risk factor documented in numerous studies is exposure to radioactive iodine found in nu- clear weapons test fallout and nuclear reactor emis- sions. Large amounts of fallout disseminated world- wide from the meltdowns in four reactors at the Fu- kushima-Dai-ichi plant in Japan beginning March 11, 2011 included radioiodine isotopes. Just days after the meltdowns, I-131 concentrations in US precipita- tion was measured up to 211 times above normal. Highest levels of I-131 and airborne gross beta were documented in the five US States on the Pacific Ocean. The number of congenital hypothyroid cases in these five states from March 17-December 31, 2011 was 16% greater than for the same period in 2010, com- pared to a 3% decline in 36 other US States (p < 0.03). The greatest divergence in these two groups (+28%) occurred in the period March 17-June 30 (p < 0.04). Further analysis, in the US and in other nations, is needed to better understand any association between iodine exposure from Fukushima-Dai-ichi and con- genital hypothyroidism risk.