Table 3.

Association between childhood blood-lead levels and two primary outcomes at age 38 years: adult IQ (Panel A) and adult socioeconomic status (Panel B). Secondary outcomes were Verbal Comprehension, Perceptual Reasoning, Working Memory, and Processing Speed.

(A)
	Sex adjusted			Fully adjusted
	b	95% CI	P	b	95% CI	P
WAIS-IV Full-Scale IQ	−1.97	(−3.34, −0.59)	0.005	−1.61	(−2.48, −0.74)	<0.001
WAIS-IV Verbal Comprehension IQ	−1.39	(−3.01, 0.23)	0.09	−1.01	(−2.18, 0.16)	0.09
WAIS-IV Perceptual Reasoning IQ	−2.36	(−3.69, −1.03)	<0.001	−2.07	(−3.14, −1.01)	<0.001
WAIS-IV Working Memory IQ	−1.52	(−2.95, −0.08)	0.04	−1.26	(−2.38, −0.14)	0.03
WAIS-IV Processing Speed IQ	−0.91	(−2.19, 0.37)	0.16	−0.70	(−1.85, 0.45)	0.23
(B)
	Sex adjusted			Fully adjusted
	b	95% CI	P	b	95% CI	P
Socioeconomic status	−1.94	(−3.50, −0.37)	0.02	−1.79	(−3.17, −0.40)	0.01

Note. CI = Confidence Interval. Covariates in the fully adjusted model were sex, maternal IQ, participants’ childhood IQ and childhood socioeconomic status. N= 533–541. Of the Study participants alive at age 38 years with childhood blood-lead measured, 533 (94%) also had present data on all the covariates and the IQ outcome measures. Of those alive at age 38 years with childhood blood-lead measured, 541 (96%) had present data on all the covariates and the socioeconomic status outcome measure. IQs are standardized to M=100, SD=15. Socioeconomic status was assessed at age 38 years using the New Zealand Socioeconomic Index-2006 (NZSEI-06; range 10 lowest – 90 highest). Regression coefficients indicate change in outcome per 5μg/dL increase in childhood blood-lead level.