The Physics Police

The Physics Police

Sunday, June 15, 2014

Fukushima's Children are Safe

posted an op-ed on EcoWatch with the outrageous title Fukushima's Children are Dying wherein he claims:
More than 48 percent of some 375,000 young people—nearly 200,000 kids—tested by the Fukushima Medical University near the smoldering reactors now suffer from pre-cancerous thyroid abnormalities, primarily nodules and cysts.
These blatantly misrepresented and severely up-rounded numbers come from a recent health survey conducted by the Japanese government. In the survey, kids from the Fukushima area underwent ultrasound thyroid screening.

Only 2,070 of the 295,511 participants had significant thyroid nodules. This is consistent with the worldwide average prevalence of such nodules in children, between 0.2% and 5%.

These poor kids had a follow-up screening. Those that still had nodules underwent biopsy. In the end, only 91 cases were found to be malignant or suspicious.

This rate is very low when you consider upwards of 50% of children with symptomatic nodular thyroid enlargement end up diagnosed with thyroid carcinoma. In this Japanese health survey, the ratio was 4.4%, ten times lower.

Why was the false positive rate so high in this screening? Because of something called selection bias.

Whenever a healthy population is screened for disease you get a higher rate of false positives than for an unscreened population, who aren't tested unless they come to their doctor with symptoms. This is because the rate of disease is higher among patients with symptoms than it is for the entire screened population.

If we screened everyone as thoroughly as the Japanese government screened these kids from Fukushima, we'd expect to find the same high rate of false-positive nodules, and the same low rate of true-positive carcinomas. Luckily, childhood thyroid cancer is very rare and has a long-term survival rates greater than 95%.

The Japanese government is screening kids for safety. They have NOT found an elevated rate of precancerous thyroid abnormalities. Many of Fukushima's children have been displaced from their homes to keep them safe.

They're safe. Not dying.