Natural gas leaks kill trees. It's a big problem around Boston. E.g.: https://arlington.wickedlocal.com/news/20180726/guest-column... and https://stateimpact.npr.org/pennsylvania/2015/11/27/gas-leak...
A gas transmission pipeline is hundreds of times higher pressure, they will shut down a pipeline as soon as a leak is detected.
"Everything is correlated." The land next to HV lines is cheaper, poorer people have higher mutational load, therefore a higher cancer rate. You get a real, authentic correlation between power lines and cancer, without power lines actually directly causing cancer.
Actually, it is.
I used to live very near a major natural gas pipeline in New England and each year the operators would send us a leaflet in the mail reminding us not to be alarmed by the helicopters that would fly up and down the route because they were just looking for dead or yellowing trees, which were the first signs of a pipeline leak.