Table 1

Summary of studies included in the meta-analysis

									Adjusted?
First author	Year	Occupational group strata	Exposed (n)	Unexposed (n)	Exposed (mean BPb)	Unexposed (mean BPb)	BPb range <70μg/dl?	Observers blinded?	Age	Educat ion	Alcohol	Other	Test results before exposure?
*Authors state that groups were comparable; †authors used vocabulary test as a measure of “pre-morbid state”; ‡data available for strata, but not for the entire exposure group.
N, no; Y, yes; M, male; F, female; BPb, blood lead concentration.
Araki²⁵	1986	Gun metal foundry workers	19	12	42	13	Y (8–64)	?	N*	N*	N*	N	N
Baker³	1984	Foundry workers	160	0	32.8	not given	N (10–80)	N	Y	Y	Y	Y	N
		BPb 0–20	26	‡	not given	Not given	0–20
		BPb 21–40	97	‡	Not given	Not given	21–40
		BPb 41–60	28	‡	Not given	Not given	41–60
Bolla¹⁹	1995	Organolead manufacturing	190	52	24	Not given	?	Y	Y	N*	N*	Y	N†
Braun²⁶	1991	Secondary lead smelter workers	41	37	52.75	Not given	Y (30–66)	N	N*	N*	N*	Y	N
Campara²⁰	1984	Electric storage battery	40	20	‡	20.4	Y (11.11–60)	Y	Y	Y	Y	Y	N
		Low exposure	20	‡	31.7	‡	25.9–35
		High exposure	20	‡	52.2	‡	45.9–60
Chia²¹	1997	Lead battery manufacturing	50	97	37.1	6.1	Y (2.4–64.6)	Y	Y	Y	Y	Y	N
Espinosa²⁷	1990	Lead exposed workers; no other information	31	31	41	7	?	?	Y	Y	N*	N	N
Haenninen²⁸	1978	Storage battery or machine shop	49	24	32.3	11.9	Y	?	Y	Y	N	Y	N
Hogstedt²⁹	1983	Lead smelter or battery factory	49	27	42	14.7	?	N	Y	Y	N*	Y	N
Jeyaratnam²	1986	Lead based stabiliser manufacturing	49	36	49.35	14.7	?	N	N	Y	N	Y	N
Johnson³⁰	1980	Lead smelter (high exposure) or zinc plant (low exposure)	358 M; 45 F	108 M; 31 F	‡	‡	?	Y	Y	N	Y	Y	N
		Male controls	‡	108	‡	15.2	?
		Male zinc exposure	194	‡	39.3	‡	?
		Male lead exposure	164	‡	56.1	‡	?
		Female controls	‡	31	‡	10.3	?
		Female lead exposure	45	‡	29.5	‡	?
Maizlish²²	1995	Smelter workers	43	47	42.6	15.3	Y(9–67)	?	Y	Y	Y	Y	N
Milburn³¹	1976	Lead acid battery manufacturing	16	15	61	28	N	?	Y	N	N	N	N
Morgan²⁴	1974	Automobile storage battery manufacturing	195	‡	Not given	Not given	N (<29–80+)	N	N	N	N	N	N
		BPb ≤ 29	6	‡	Not given	Not given	≤ 29
		BPb 30–39	14	‡	Not given	Not given	30–39
		BPb 40–49	38	‡	Not given	Not given	40–49
		BPb 50–59	43	‡	Not given	Not given	50–59
		BPb 60–69	45	‡	Not given	Not given	60–69
Parkinson⁵	1986	Battery plant workers	288	179	40.01	Not given	?	?	Y	Y	N	Y	N
Pasternak³²	1989	Electrical components manufacturing	24	29	47.46	Not given	Y (4.0–67.67)	Y	N*	N*	N*	Y	N
Pfister³³	1999	Non-ferrous metal smelter workers	26	48	37.7	Not given	?	?	N	N	Y	Y	N
Repko³⁴	1978	Storage battery manufacturing	83–84	52–55	46	18	N (all < 79)	?	Y	Y	N	Y	N
Repko³⁵	1975	Storage (lead acid) battery manufacturing	316	112	63.09	15.07	N (0–243)	?	Y	Y	N	Y	N
Ryan³⁶	1987	Auto and motorcycle storage battery manufacturing	288	181	40.1	7.2	?	?	Y	Y	N*	N*	N
		Age 21–30	121	54	40.6	7.5	?
		Age 31–40	90	45	40.3	7.1	?
		Age 41–50	43	44	39.6	7.3	?
		Age 51–60	34	38	38.6	7.9	?
Valciukas⁴	1978	Secondary lead smelter workers	86–90	25	Not given	Not given	N (<40–≥80)	Y	Y	Y	N	N	N
Williamson²³	1986	Battery manufacturing and lead smelter	59	59	49.8	Not given	N (25.0–82.3)	?	Y	Y	Y	Y	N