Online ratings of fibroyalgia symptom severity were gathered by the Fibromyalgia Wellness Project (link), for the period October 1, 2009 to July 31, 2010. The symptoms rated included pain, stiffness, fatigue, mental focus impairment, memory impairment, anxiety, depression, gastrointestinal problems, and sleeping problems. Each symptom was rated on a scale of 0 to 10, with 10 being most severe.
Gross beta radiation levels, as measured by air filters (link), were obtained from the EPA Radnet site, for the time period and nearest location of each rater and her rating. The radiation levels were computed by attributing the levels for each collection period to the day included in this period, and averaged over the prior 5 days, including the day of the rating. Kendall’s tau-b was employed to yield correlations between symptom ratings and beta radiation levels.
A power analysis revealed that 67 ratings were needed to supply enough statistical power for the analysis. 17 female subjects were selected according to this criterion. In all, 1,961 ratings were analyzed.
A multisample permutation method was employed to perform an effect strength meta-analysis, where each subject was considered to be an independent experiment. The effect strength criterion was the value of tau multiplied by the square root of the sample size for each subject, and summed together. This method generated 25,000 Monte Carlo iterations, and a P-value was estimated for each symptom.
Symptom severity positively associated with beta radiation and statistically significant: Mental focus impairment, memory impairment, anxiety, depression, gastrointestinal problems, sleeping problems
Symptom severity positively associated with beta radiation and not statistically significant: Pain, fatigue
Symptom severity negatively associated with beta radiation and not statistically significant: Stiffness
This result corresponds to recent research on environmental triggers for fibromyalgia, and other diseases like chronic fatigue syndrome and multiple chemical sensitivity (link).