Letter to the Editor RE: ‘‘NIGHTTIME EXPOSURE TO ELECTROMAGNETIC FIELDS AND CHILDHOOD LEUKEMIA:

In a recent pooled analysis, Schüz et al. (1) examined the link between nighttime extremely low frequency (ELF) electric and magnetic field (EMF) exposure and childhood of their paper: ‘‘The fact that these estimates were similar to those derived using 24-/48-hour geometric mean values... indicates that the nighttime component cannot, on its own, account for the pattern observed’ ’ (1, p. 263). This reads as if nighttime exposure could not on its own be the main or sole component underlying, or accounting for, the observed association with the elevated incidence of childhood leuke-mia. That would be wrong. Consider the hypothetical exam-ple of an underlying association solely with the nighttime component and none with daytime exposure, examined un-der constant intensity of exposure over 24 hours. The appar