Table 2.

Comparison of the average BLLs and rate of high BLLs between groups

	BLLs, µg/dL					BLLs 5.0–9.9 µg/dL				BLLs ≥ 10.0 µg/dL
	N	median	25th-75th percentile	Z value	P value	n	Rate (%)	χ2 value	P value	n	Rate (%)	χ2 value	P value
Exposed group	222	8.5	6.6–10.9	− 8.71	0.00a	115	51.8	0.41	0.52b	74	33.3	19.99	0.00b
Control group	204	6.0	4.8–7.9			112	54.9			30	14.7

^aP value calculated by the Mann–Whitney U test

^bP value calculated using the χ² test