Table 2. Subgroup analysis of the included epidemiological studies.

Subgroup	NO. of studies	Weight	Summary OR (95%CI)	Q test (p)	I2
PCB-153
Background exposure	10	76.6%	1.57(1.13–2.19)	0.0004	65%
Specific exposure	3	23.4%	-	0.05	66%
Total	13	100%	1.52(1.19–1.94)	0.0002	64%
Perspective study	4	23.5%	1.05(0.78–1.40)	0.60	0%
Cross-sectional study	9	76.5%	1.69(1.24–2.31)	<0.0001	72%
Total	13	100%	1.50(1.18–1.92)	0.0002	63%
General population	10	74.7%	1.69(1.23–2.33)	<0.0001	71%
Women	3	25.3%	1.11(0.85–1.46)	0.41	0%
Total	13	100%	1.52(1.19–1.94)	0.0002	64%
Serum	6	38.8%	1.36(0.95–1.95)	0.002	74%
Serum lipid	10	61.2%	1.62(1.18–2.24)	0.0002	67%
Total	13	100%	1.44(1.18–1.76)	<0.00001	74%
PCBs
Background exposure	4	31.6%	1.74(1.22–2.48)a	0.22	30%
Specific exposure	7	68.4%	2.39(1.52–3.77)	0.001	67%
Total	11	100%	2.14(1.53–2.99)	0.002	59%
Case-control study	2	10.9%	2.83(1.18–6.81)a	0.14	55%
Cross-sectional study	8	89.1%	2.28(1.55–3.34)	0.001	66%
Total	10	100%	2.36(1.64–3.41)	0.0008	64%
General population	9	80.4%	2.18(1.50–3.16)	0.006	59%
Women	2	19.6%	1.88(0.56–6.26)	0.02	74%
Total	11	100%	2.19(1.54–3.13)	0.001	62%
Serum	6	48.3%	2.31(1.71–3.11)a	0.36	8%
Serum lipid	7	51.7%	1.91(1.20–3.04)	0.009	62%
Total	11	100%	2.24(1.62–3.10)	0.001	58%
p,p′-DDE
Background exposure	12	45.2%	1.39(1.16–1.67)a	0.18	25%
Specific exposure	6	54.8%	1.20(1.01–1.43)	0.001	75%
Total	18	100%	1.33(1.15–1.54)	0.0007	56%
Perspective study	4	14.7%	1.16(0.87–1.55)a	0.64	0%
Cross-sectional study	13	85.3%	1.33(1.13–1.56)	0.0006	62%
Total	17	100%	1.29(1.12–1.48)	0.003	52%
General population	15	72.9%	1.41(1.17–1.71)	0.0008	59%
Women	3	27.1%	1.27(1.10–1.46)a	0.79	0%
Total	18	100%	1.33(1.15–1.54)	0.0007	56%
Serum	8	24.4%	2.22(1.32–3.73)	0.005	66%
Serum lipid	14	75.6%	1.34(1.14–1.57)	0.001	58%
Total	18	100%	1.45(1.24–1.70)	<0.0001	62%

^aBased on fixed model, others based on random model.