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What is a Safe Distance to Live from Power Lines?
The short answer: There is no conclusive evidence that electromagnetic fields from power lines cause any health effects.
Electromagnetic radiation (electromagnetic fields; EMF) and its intensity follows the inverse-square law, which states that the intensity of the electromagnetic emission diminishes by the inverse of the distance squared. So, the applied intensity of a radiation source on a surface is basically diluted in intensity over the surface area as the distance increases.
For example, the intensity of a source on a target over a distance is 1.0, twice that distance becomes 0.25 for the same area, three times that distance becomes 0.11, and so on.
For the question of how far away from a source of electromagnetic radiation is safe, keep in mind that the intensity diminishes quickly with distance. What intensity is safe is a matter of the intensity of the source and the distance.
The threshold for human safety is a debated quantity and there is no consensus, although there are regulatory limits in some countries. The official position from regulatory agencies is that current safety factors are adequate and power lines pose no health threat to people.
There are well-done studies that corroborate these positions. Here we will review the evidence collected to date citing recent reviews and provide our conclusions.
The has been and continues to be a lot of discussion and investigation into the effects of electromagnetic radiation on mammalian systems. Apart from the hot button issue of cell phones and EMF (electromagnetic field), there has also been long-standing concern about power lines, particularly high-tension power lines.
These high-tension lines are so called because of the size of electric cables strung between towers under high-tension. They also form the main electricity conduits ferrying current between powerplants and communities, therefore they are also known as high voltage transmission lines.
High voltage transmission line towers come in various sizes based on the amount of voltage in the line and safety regulations regarding safe distances to prevent accidental discharge. A discharge would kill animals or set fire to structures, so those safety factors are always followed.
What seems a matter of concern is not electrical discharge, but magnetic and radio frequency emissions from the power cables. All lines which transmit current produce magnetic fields.
Shielding insulation, in the form of plastic or other inert materials, serves to prevent contact with the metal portions of the wires and discharge. Shielding insulation does not, however, contain magnetic fields or prevent EMF emissions. That is not its purpose.
When considering whether or not power lines pose a health hazard from long-term exposure to EMF or magnetic fields, it is best not to listen to anecdotal reports from people who lived near them or the opinions of people who write blogs about the dangers of living in industrial civilization. The best source of information with the least amount of bias comes from peer-reviewed, scientific studies.
In science, you cannot fool your colleagues, at least not for long. Those who fabricate results are eventually caught and discredited.
This is not to say that science is infallible, but rather that scientific studies are some of the most reliable sources of information you will find.
If you search out information on power line and health studies, you should go to a verified source, such as the National Library of Medicine’s PubMed search engine (ncbi.nlm.hih.gov/pubmed/). Through this portal, you can search the entirety of medical literature (30 million records) since 1966 and selected publications going as far back as 1809.
When searching, you will find two types of articles: primary literature (scientific studies) and secondary literature (reviews of scientific studies).
Within the primary literature, you will find laboratory studies involving effects on cells and laboratory animals as well as epidemiological studies that compile real-world data from study subject histories. Those latter studies are the ones that provide the most useful data regarding whether or not there are effects produced by exposure to power line emissions.
We recommend starting with a good, recent review of the literature written by scientists familiar with the subject. They will index all the pertinent research studies and serve as a guide for you to find the source data.
Most reviews, especially meta-analysis reviews, will present both sides of the argument, citing studies that support a position and those that refute it.
We conducted a recent review of the literature and this is what we found. Petri and colleagues (Environmental Health 16:41, 2017) performed a meta-analysis using PRISMA (Moher et al.  Preferred Reporting Items for Systematic Reviews and Meta-Analyses. PLoS Medicine 6:e1000097) guidelines which examined 48 epidemiology studies (8 on humans, 40 on animal life) focusing on effects produced by living in proximity to high voltage transmission lines.
After compensating for confounder effects, the group found no definitive evidence of health effects produced by electrical field emissions from these sources. From this study, they created an EMF database that currently catalogues over 30,000 studies and nearly 7000 research summaries which can be publicly accessed at www.emf-portal.org.
A meta-analysis by Lewis and colleagues (Journal of Environmental Health B Critical Reviews 19:29, 2016) examined 12 years of epidemiology data (2002-2015) for people living near power lines with a focus on studies of reproductive effects. A total of 13 studies were conducted during this period, some concluding health effects, others failing to find evidence.
Collectively, the group failed to find anything conclusive in the studies they reviewed when confounders and study size limitations were considered.
A case-control study by Crespi and colleagues (British Journal of Cancer 115:122, 2016) examined rates of childhood leukemia in relation to 200 kV power line proximity (two groups: <50 m and >50 m). They found a slightly higher rate of childhood leukemia for residents living within 50 meters of power lines, but this was a trend only and not significant (odds ratio 1.4).
An odds ratio of less than 2.0 is not considered to be statistically different from an odds ratio of 0, therefore no conclusions could be reached. Similarly, Pedersen and colleagues (PLoS One 9:e107096, 2014) also examined rates of childhood leukemia under similar conditions, controlling for radon exposure as a confounder, and reached similar conclusions.
Most nations set daily (24-hour) exposure limits to EMF at 1000 mG (milliGauss); the US currently has no set guidelines for EMF exposure limits, citing a lack of conclusive evidence they pose a public health threat. Exposure to the large power transmission lines (345 kV) directly under the tower is only 96 mG, diminishing to less than 20 mG beyond 50 m.
Smaller transmission line emissions drop to single digits or zero at these distances. A compilation of public health data and studies is provided by NIOSH (National Institute for Occupational Safety and Health-NIH) at cdc.gov/niosh/topics/emf/, if you wish to read further.
For concerned people that believe big business is attempting to hide the truth for the sake of money, bear in mind that the majority of research studies are funded through the government by NIH or other national health institutes which will only fund impartial unbiased research. There are a few of the studies that were industry-funded, mainly by insurance companies looking to adjust their rates upward for clients living near power lines.
These studies failed to find anything conclusive that would prompt insurers to increase their rates. Remember, that sword cuts both ways and if insurance companies cannot use the issue of power lines to get more money out of you, then there is likely no risk living near them.