STANFORD – The earthquake- and tsunami-related problems at Japan’s Fukushima Daiichi nuclear-power plant have inspired endless commentary and speculation. Unfortunately, much of the debate about the disaster and its implications has been uninformed and problematic.
Radiation levels have increased by as much as 400 times the normal level 12 miles from the Fukushima plant; increased radioactivity has been found in milk, fish, and a variety of vegetables farmed in the region; and drinking water in Tokyo, 140 miles (225 kilometers) from Fukushima, has been declared unsuitable for consumption by infants. Several countries have banned imports of milk and vegetables from the affected region.
What are we to make of all this?
Radiation at these levels poses a minimal threat to human health for anyone outside the immediate area of the nuclear-power station itself. Most of the radiation is Iodine-131, which is good news for several reasons. First, this isotope has a short half-life – only about eight days – so it decays to negligible levels in a short time (in 10 weeks, less than 0.1% is left.) Second, it indicates that the source of the radiation is the reactor itself, rather than spent fuel rods (which harbor much longer-lived and more dangerous radioisotopes). Third, a readily available and effective antidote exists for those at risk: non-radioactive iodine, available in tablets or liquid, which blocks the uptake of I-131 into the thyroid gland.