Early in my coverage of the ongoing nuclear crisis I succumbed to peer pressure and a basic understanding of the science to reassure readers that Fukushima Daiichi could never become another Chernobyl, and in a sense that remains true. The technology of the former just can't produce the same kind of explosion and graphite fire as the latter that suddenly ejected massive amounts of radioactive materials into the atmosphere and onto the surrounding landscape. But that doesn't mean that the environmental impact of the Fukushima disaster couldn't ultimately be as bad as Chernobyl, or even worse.

No, the better metaphor for Fukushima is turning out to be last year's Deepwater Horizon oil spill, a disaster that dragged on for months, steadily spilling millions of gallons of toxic crude oil into the Gulf of Mexico. Like last year's Gulf spill, corporate and government incompetency/misinformation has made the severity of the Fukushima leak impossible for the public to measure. Likewise, Japanese government officials are now admitting that the release of radioactive materials may too continue for months.

And the similarities don't end there.

In both Japan and the US, government regulators knew about the potential for a massive environmental disaster, yet left responsibility for preventing and reacting to such an event in the hands of corporate interests who proved totally unprepared for dealing with such a foreseeable scenario. And, just like in the Gulf, it will take years before we learn the true environmental and human health impact of the Fukushima disaster... if ever.

At Chernobyl, the worst was over in days, and the last of the graphite fires were extinguished within two weeks. Compared to Fukushima, the initial release of radioactive materials was immense, the fallout setting off radiation alarms 680 miles away in Sweden. But with a half-life of eight days, the threat from iodine-131, the radioactive contaminant with the most immediate health impact, dissipated quickly.

Fukushima is different, emitting a steady stream of iodine-131 and other radioactive materials, potentially over a much longer period of time. Most of the reported incidents of radioactive contamination of food and water have been at levels below those set as "safe" by government regulators, or not dramatically above, but testing has been sparse, and these regulations do not presume prolonged consumption and exposure. The health impact of radiation exposure is cumulative, and even safe levels are only safe statistically. Causality may be exceedingly difficult for individual victims to prove—just ask Hanford's "downwinders"—but expose a large enough population to even relatively low levels of radiation over a long enough period of time, and statistically, you will increase both morbidity and mortality.

Fukushima is a slow motion disaster, one which will likely fade from the headlines, possibly long before its emissions are capped. But whatever its ultimate health impact, here's hoping this incident will result in technological and regulatory changes that will help prevent some future nuclear disaster from being referred to as "another Fukushima."