Abstract
Background
In 2003 the teachers at La Quinta, California middle school complained that they had more cancers than would be expected. A consultant for the school district denied that there was a problem.
Objectives
To investigate the cancer incidence in the teachers, and its cause.
Method
We conducted a retrospective study of cancer incidence in the teachers' cohort in relationship to the school's electrical environment.
Results
Sixteen school teachers in a cohort of 137 teachers hired in 1988 through 2005 were diagnosed with 18 cancers. The observed to expected (O/E) risk ratio for all cancers was 2.78 (Pβ=β0.000098), while the O/E risk ratio for malignant melanoma was 9.8 (Pβ=β0.0008). Thyroid cancer had a risk ratio of 13.3 (Pβ=β0.0098), and uterine cancer had a risk ratio of 9.2 (Pβ=β0.019). Sixty Hertz magnetic fields showed no association with cancer incidence. A new exposure metric, high frequency voltage transients, did show a positive correlation to cancer incidence. A cohort cancer incidence analysis of the teacher population showed a positive trend (Pβ=β7.1βΓβ10^β10^) of increasing cancer risk with increasing cumulative exposure to high frequency voltage transients on the classroom's electrical wiring measured with a Graham/Stetzer (G/S) meter. The attributable risk of cancer associated with this exposure was 64%. A single year of employment at this school increased a teacher's cancer risk by 21%.
Conclusion
The cancer incidence in the teachers at this school is unusually high and is strongly associated with high frequency voltage transients, which may be a universal carcinogen, similar to ionizing radiation. Am. J. Ind. Med. 51:579β586, 2008. Β© 2008 WileyβLiss, Inc.