Barbee et al., 1987

Community sample (N = 1,333; Arizona)

39

51

Ages 8–60

Rates with retesting 8 years later

Gergen et al., 1987

Nationwide sample (N = 16,204; NHANES^b)

20.2

Some people with disease were excluded; the skin test flare was used as the response

Freidhoff et al., 1981

Workplace study (N = 174; Maryland)

24

Lower rates are seen in other workplace studies

Barbee et al., 1976

Community sample (N = 3,012; Arizona)

34

Ages 5–55

Hagy and Settipane, 1969

College freshmen (N = 1,243)

30.9

Henderson, 1993 (personal communication 1-26-93)

Schoolchildren (N = 225; North Carolina)

40