Some studies did not have enough subjects at high exposures to allow them to statistically detect the association. No study exhibited an association of leukemia with typical household magnetic fields. Asher Sheppard, the study's principal investigator and an assistant research professor in the Department of Physiology and Pharmacology at Loma Linda University, also cautioned that while the new analysis exhibits an association between elevated magnetic fields and childhood leukemia, more research is needed to determine if a causal relationship exists. Considerable uncertainty remains about the source of the association of leukemia with high magnetic field exposures. For example, other factors related to both magnetic fields and childhood leukemia may be responsible for the association.
Magnetic fields originate from everything with an electrical current.
A field spreads from a source in a manner analogous to a ripple emanating from a pebble thrown in a pool of water, but penetrates objects in its path. Elevated field levels can occur in homes close to power lines. Improper household wiring occasionally can increase exposure to these fields as well. The National Institute of Environmental Health Sciences funded the study, with initial support from Southern California Edison.