“…All the studies to be cited find that the IQof the high-lead group is lower than that of the low-lead group by 2-11 points. Some find that the difference between groups is still significant when confounders are allowed for (Fergusson, Fergusson, Horwood & Kinzett, 1988;Hansen, Trillingsgaard, Beese, Lyngbye & Grandjean, 1988;Hatzakis ^/«/., 1988;Needleman ^/a/., 1979;Yule, Urbanowicz, Lansdown & Millar, 1984); others find that statistical significance disappears (Lansdown, Yule, Urbanowicz & Hunter, 1986;Smith, Delves, Lansdown, Clayton & Graham, 1983;Landrigan ^^ «/., 1975;McNeil & Ptasnik, 1975;Ratcliffe, 1977;Winneke, Hrdina & Brockhaus, 1982). I have reviewed these studies in more detail elsewhere, and could not account for the disparities on the basis of details of methodology (Taylor, in press).…”