Case-control study on occupational exposure to extremely low-frequency electromagnetic fields and glioma risk

Exposure to extremely low-frequency electromagnetic fields (ELF-EMF) was in 2002 classified as a possible human carcinogen, Group 2B, by the International Agency for Research on Cancer (IARC) at WHO. In the international Interphone study on mobile phone use and glioma risk, glioma was associated with occupational ELF-EMF exposure in recent time windows. The authors concluded that such exposure may play a role in late stage carcinogenesis of glioma.

We assessed life time occupations in case-control studies during 1997-2003 and 2007-2009 on e.g. use of wireless phones and glioma risk. An ELF-EMF Job-Exposure Matrix was used for associating occupations with ELF exposure (μT). Cumulative exposure (μT-years), average exposure (μT), and maximum exposed job (μT) were calculated.

Cumulative exposure gave for astrocytoma grade IV (glioblastoma multiforme) in the time window 1-14 years before diagnosis odds ratio (OR) = 1.9, 95% confidence interval (CI) = 1.4-2.6, p linear trend <0.001, and in the time window 15+ years OR = 0.9, 95% CI = 0.6-1.3, p linear trend = 0.44 in the highest exposure categories 2.75+ and 6.59+ μT-years, respectively.

We concluded that we found an increased risk in late stage (promotion/progression) of astrocytoma grade IV for occupational ELF-EMF exposure. No statistically significant interaction was found between exposure to ELF-EMF and use of wireless phones (exposure to radiofrequency radiation; RF-EMF). They were independent risk factors for astrocytoma grade IV.

Maternal cell phone use during pregnancy and child behavioral problems in five birth cohorts

Previous studies have reported associations between prenatal cell phone use (exposure to radiofrequent fields) and child behavioral problems. In this study  data from 83,884 mother-child pairs in the five cohorts from Denmark (1996-2002), Korea (2006-2011), the Netherlands (2003-2004), Norway (2004-2008), and Spain (2003-2008) were analyzed. Cell phone use was grouped into none, low, medium, and high, based on frequency of calls during pregnancy reported by the mothers. Evidence for a trend of increasing risk of child behavioral problems through the maternal cell phone use categories was observed for hyperactivity/inattention problems; ADHD (OR for problems in the clinical range: 1.11, 95%CI 1.01, 1.22; 1.28, 95%CI 1.12, 1.48, among children of medium and high users, respectively). Thus, maternal cell phone use during pregnancy may be associated with an increased risk for behavioral problems, particularly hyperactivity/inattention problems, in the offspring. Increased risk was also found in the high cell phone use category for overall behavioral problems and emotional problems, although not statistically significant. The study can be found here.

In all analyses low cell phone use was used as the reference category. For no cell phone use decreased risk was found for all studied behavioral problems (overall problems, ADHD and emotional problems). It is unclear why low cell phone use instead of no cell phone use was used as the reference category. Using subjects that never used a cell phone would have given higher risk estimates in the high use category.

In the Dutch cohort cordless phone use was assessed yielding similar results as for cell phone use.