A case-control study was conducted in UK to evaluate the cancer incidence among adults living near high voltage overhead power lines. The aim was to examine: (1) the risk of mouth, lung and respiratory system cancers in relation to modelled estimates of air ion density up to 600 m of power lines; and (2) the risk of non-melanoma skin cancers in relation to electric fields within 25 m of power lines.
In some previous studies an increased cancer risk was observed with the distance to power lines, but magnetic field exposure did not appear to explain the relationship. The alternative hypotheses that air ion density or electric fields in the vicinity of power lines were responsible should be investigated in this study.
Air ion density was estimated within 600 m of power lines at address locations of cases and controls for the year of diagnosis and for the 5 years prior to diagnosis. The modelling approach used the following core inputs: geography of the power lines network between 1969 and 2008, wind direction patterns for each year (1969 to 2008) and residential addresses. For comparison, the model of Swanson et al. (2014) was applied.
Electric fields were calculated based on estimates of electric fields for year of diagnosis for all addresses lying within 25 m of an operating high voltage power line.
|Reference group 1||air ion density: 0 - 0.1879 per cm3 (lower fifth)|
|Group 2||air ion density: 0.188 - 0.2869 per cm3|
|Group 3||air ion density: 0.287 - 0.3849 per cm3|
|Group 4||air ion density: 0.385 - 0.503 per cm3|
|Group 5||air ion density: 0.504 - 1 per cm3 (upper fifth)|
|Reference group 6||electric field strength: < 0.70 kV/m (lower third)|
|Group 7||electric field strength: 0.70 - 1.05 kV/m|
|Group 8||electric field strength: 1.06 - 4.11 kV/m (upper third)|
3,061 patients with mouth cancer, 26,087 patients with lung cancer, 28,134 patients with respiratory system cancers and 179 patients with non-melanoma skin cancer; 15,174 controls were used for more than 1 cancer type
No statistically significant increased risks were observed in the group of highest air ion density (group 5) compared with the reference group (mouth cancer: OR 0.94 (CI 0.82–1.08); lung cancer: OR 0.99 (CI 0.94-1.05); respiratory system cancers: OR 1.03 (CI 0.97–1.09)). The pattern of cancer risk was similar using air ion estimates from the model by Swanson et al. (2014).
In the group with highest electric field exposure (group 3) compared with the reference group the risk for non-melanoma skin cancers was non-significantly increased (OR 1.23; CI 0.65– 2.34).
The authors conclude that the results do not provide evidence to support the alternative hypotheses that air ion density or electric fields in the vicinity of power lines are associated with cancer risk in adults.