These may (or may not be) helpful:
Environmental Radiation Factsheet
https://hps.org/documents/environmental_radiation_fact_sheet.pdf
Radioactivity in Nature
http://www.physics.isu.edu/radinf/natural.htm
Thanks, MS: there's much baseline, survey and assumptions information in these two resources that I didn't have. The difference between the NCRP-95 (1987) and NCRP-160 (2006) documents was particularly interesting. Average annual exposure nearly doubles.
The WHO did issue a report regarding the negative health effects:
Increased cancer risks for affected children in the region between 4% (solid cancers), 7% for leukemia, 70% for thyroid cancers.
That organizations such as IAEA & UNSCEAR, whose members have substantial interest in more nuclear declare that Fukushima doesn’t harm human health, says little.
Research after Chernobyl clearly showed that extra levels of only 1mSv/year harm next generations already substantial:
http://tchie.uni.opole.pl/ecoproc10a/ScherbVoigt_PECO10_1.pdf
Here is one example from that report from Chernobyl using a vast amount of data over a long period of time. CLP is Cleft Lip.