LOS-ANGELES STUDY OF RESIDENTIAL MAGNETIC-FIELDS AND CHILDHOOD BRAIN-TUMORS

A measurement study of residential magnetic fields and brain tumors in children that was added onto an ongoing case-control interview study in Los Angeles County, California, included 298 children under age 20 years with a primary brain tumor diagnosed from 1984 to 1991 and 298 c ontrol children identified by random digit dialing. Magnetic fields we re determined for all Los Angeles homes where these 596 children lived from conception to diagnosis (1,131 homes) by mapping and coding the wiring configurations outside the home and by taking a series of exter ior spot and profile measurements. In addition, for a subset of subjec ts (35%; 211 homes) 24-hour measurements were taken in the child's roo m and one other room. Although measured fields are consistently highes t in the highest of the five wire code categories, fields in homes in this category are much lower in Los Angeles than in Denver, where the code originated. Brain tumor risk appears not to relate to measured fi elds inside (p for trend for child's room = 0.98) or outside (p for tr end for front wall = 0.82) the home. An apparent increase in risk amon g children living at diagnosis in homes with underground wiring appear s to be an artifact introduced by using current controls for historica l cases because this apparent excess risk disappeared in an analysis r estricted to the later years of the study when cases and controls were accrued concurrently, Our study does not show an overall association of pediatric brain tumors with measured fields, with ''very high'' wir ing configurations, or with any of several other potential sources of exposure, such as use of various electrical appliances, but the preval ence of high fields (>2 mG) and very high fields (>3 mG) in Los Angele s homes was too low to detect a moderate effect of the magnitude repor ted in other studies.