Table 1 The characteristics of participants

Age (years)

56.6 ± 10.8

63.0 ± 11.4

<0.001

Sex

 Male

45.5%

50.0%

0.006

 Female

54.5%

50.0%

Race/Ethnicity

 Non-Hispanic White

63.3%

74.8%

<0.001

 African American

11.8%

7.2%

 Non-Hispanic Asian

6.3%

2.7%

 Hispanic

14.1%

10.5%

 Others

4.6%

4.9%

Body mass index (kg/m²)

30.1 ± 7.0

30.3 ± 6.3

0.245

Income to poverty ratio^a

 <1

9.9%

8.6%

0.138

 1-3

30.3%

29.5%

 >3

48.9%

52.3%

Smoke≥100 cigarettes (%)

41.8%

52.0%

<0.001

Hemoglobin

14.2 ± 1.4

14.1 ± 1.4

0.814

Tap water^a

 No

47.8%

45.4%

0.001

 Yes

46.1%

50.7%

Shellfish^a

 No

43.2%

39.1%

<0.001

 Yes

50.4%

56.5%

Fish^a

 No

26.1%

22.1%

<0.001

 Yes

67.6%

73.6%

Blood chromium

0.364 ± 0.358

0.438 ± 0.585

<0.001

Blood cobalt

0.180 ± 0.314

0.273 ± 0.650

<0.001