Exposure to electromagnetic fields may cause breast cancer in women if it increases susceptibility to sex-hormone-related cancer by diminishing the pineal gland's production of melatonin. We have studied breast cancer incidence in female radio and telegraph operators with potential exposure to light at night, radio frequency (405 kHz-25 MHz), and, to some extent, extremely low frequency fields (50 Hz). We linked the Norwegian Telecom cohort of female radio and telegraph operators working at sea to the Cancer Registry of Norway to study incident cases of breast cancer. The cohort consisted of 2,619 women who were certified to work as radio and telegraph operators between 1920 and 1980. Cancer incidence was analyzed on the basis of the standardized incidence ratio (SIR), with the Norwegian female population as the comparison group. The incidence of all cancers was close to unity (SIR = 1.2). An excess risk was seen for breast cancer (SIR = 1.5). Analysis of a nested case-control study within the cohort showed an association between breast cancer in women aged 50+ years and shift work. In a model with adjustment for age, calendar year, and year of first birth, the rate ratio for breast cancer associated with being a radio and telegraph operator--in comparison with all Norwegian women born 1935 or later--analyzed with Poisson regression, was 1.5 after adjustment for fertility factors. These results support a possible association between work as a radio and telegraph operator and breast cancer. Future epidemiologic studies on breast cancer in women aged 50 and over, should address possible disturbances of chronobiological parameters by environmental factors.

Indoor tanning is common in spite of its classification as carcinogenic. Too high an ultraviolet (UV) irradiance and a lack of compliance with regulations have been reported. We measured UV irradiance from a large number of Norwegian solariums (sunbeds and stand-up cabinets) currently in use. Compliance (solariums and facilities) with national regulations and the effect of inspections delegated to local authorities (since 2004) were also studied. In 2008, 78 tanning facilities were selected from six regions throughout Norway that contained municipalities with and without local inspections. UV irradiance was measured with a CCD spectroradiometer in 194 out of 410 inspected solariums. Mean erythema weighted short (280-320 nm) and long (320-400 nm) wave UV irradiances were 0.194 (95% confidence interval (CI) 0.184-0.205) and 0.156 (95% CI 0.148-0.164) W m(-2), respectively. Only 23% of the solariums were below the UV type 3 limit (<0.15 W m(-2), short and long wave). Irradiances varied between solariums: spectral UVB (280-315 nm) and UVA (315-400 nm) irradiances were 0.5-3.7 and 3-26 times, respectively, higher than from Oslo summer sun. In total, 89.9% of the tanning facilities were unattended. Overall compliance increased since the first study in 1998-1999, but total UV irradiance did not decrease, mainly because of higher UVA irradiance in 2008. Solariums have become even less similar to natural sun due to higher UVA irradiance. Local inspections gave better compliance with regulations, but irradiances were significantly higher in municipalities with inspections (p ≤ 0.001, compared to without). Unpredictable UV irradiance combined with insufficient customer guidance may give a high risk of negative health effects from solarium use.

Indoor tanning increases skin cancer risk, but the importance of different parts of the UV spectrum is unclear. We assessed irradiance of tanning devices in Norway for the period 1983-2005. Since 1983, all tanning models needed approval before being sold or used. UV Type 3 limits were valid from late 1992 (<0.15 W m(-2) for CIE-weighted, i.e. erythemally weighted, short and long wave irradiances). We analyzed data from 90% of the approved tanning models (n = 446 models) and two large inspection surveys in 1998/1999 and 2003 (n = 1,341 tanning devices). Mean CIE-weighted short wave irradiance of approved models increased from 0.050 W m(-2) (95% confidence interval [CI] 0.045-0.055) in 1983-1992 to 0.101 W m(-2) (95% CI 0.098-0.105) in 1993-2005, and mean long wave from 0.091 W m(-2) (95% CI 0.088-0.095) to 0.112 W m(-2) (95% CI 0.109-0.115), respectively. Inspection surveys revealed short wave irradiances much higher than that approved. In 1998-1999, only 28% (293/1034) of the devices were equipped with correct sunlamps and only 1 out of 130 inspected establishments fulfilled all requirements. In 2003, corresponding numbers were 59% (180/307) of devices and 2 out of 52 establishments. Mean short and long wave irradiances of the inspected tanning devices in 2003 were 1.5 and 3.5 times, respectively, higher than the irradiance of natural summer sun in Oslo. In conclusion, the short wave irradiance has increased in indoor tanning devices in Norway over the last 20 years. Due to the high long wave irradiance throughout this period, the percentage of short wave irradiance was much lower than for natural sun.

Use of indoor tanning devices increases the risk of cutaneous melanoma and nonmelanoma skin cancer. Indoor tanning devices have become important sources of ultraviolet (UV) exposure, both UVB and UVA. This systematic review assessed UV measurements performed in indoor tanning devices related to irradiance level, wavelength distribution and similarities to natural sun. The study was performed in accordance with the MOOSE and PRISMA guidelines. We searched PubMed, Embase and Web of Science from inception to May 2015, and also examined the reference lists of the retrieved studies. Eighteen studies were included. Twelve studies examined the erythema-weighted UV irradiances of indoor tanning devices, 11 studies examined UVB and 13 studies studied UVA. Compliance with irradiance limits was reported in nine studies. Erythema-weighted irradiances were highest in the most recent studies. Most studies had mean values higher than from natural sun and with large variations between devices. All studies except two had mean unweighted UVB irradiances lower than from natural summer sun (at latitudes from 37°S to 35°N), while mean unweighted UVA irradiances were, with one exception, substantially higher than from natural sun. The high values of UVA exposure from modern tanning devices are alarming in light of the increased focus on UVA irradiance as a carcinogen, and as UVA exposure confers little protection against subsequent UV exposure.

The study is partly reassuring for occupationally exposed fathers.