Table 2.
Baseline Characteristics of Children, Overall and by Cumulative Exposure to Composites during the 5-Year Study
| Overall | 5-Year Cumulative Exposure Levela (surface-years category) | ||||
|---|---|---|---|---|---|
| 0 | 0.1–16.0 | 16.1–40.0 | >40.0 | ||
| N | 444 | 136 | 102 | 104 | 102 |
| Age, mean (SD) | 8.1 (1.4) | 8.2 (1.3) | 7.9 (1.4) | 8.1 (1.3) | 7.9 (1.5) |
| Sex, n (%) | |||||
| Female | 237 (53.4%) | 73 (53.7%) | 42 (52.9%) | 49 (47.1%) | 61 (59.8%) |
| Male | 207 (46.6%) | 63 (46.3%) | 48 (47.1%) | 55 (52.9%) | 41 (40.2%) |
| Race/ethnicity, n (%)b | |||||
| Non-Hispanic White | 290 (65.3%) | 83 (61.0%) | 76 (74.5%) | 63 (60.6%) | 68 (66.7%) |
| Non-Hispanic Black | 88 (19.8%) | 36 (26.5%) | 14 (13.7%) | 21 (20.2%) | 17 (17.7%) |
| Hispanic (non-mixed) | 30 (6.8%) | 8 (5.9%) | 4 (3.9%) | 12 (11.5%) | 6 (5.9%) |
| Other | 36 (8.1%) | 9 (6.6%) | 8 (7.8%) | 8 (7.7%) | 11 (10.8%) |
| Socioeconomic status, n (%)c | |||||
| Low | 136 (30.6%) | 51 (37.5%) | 26 (25.5%) | 41 (39.4%) | 18 (17.7%) |
| Medium | 153 (34.5%) | 44 (32.4%) | 40 (39.2%) | 29 (27.9%) | 40 (39.2%) |
| High | 155 (34.9%) | 41 (30.2%) | 36 (35.3%) | 34 (32.7%) | 44 (43.1%) |
| Geographic location, n (%) | |||||
| Urban (Boston, MA) | 229 (51.6%) | 81 (56.6%) | 38 (37.3%) | 57 (54.8%) | 53 (52.0%) |
| Rural (Farmington, ME) | 215 (48.4%) | 55 (40.4%) | 64 (62.8%) | 47 (45.2%) | 49 (48.0%) |
| Drinking water source, n (%) | |||||
| Bottled | 127 (31.1%) | 39 (31.7%) | 28 (29.5%) | 29 (29.9%) | 31 (33.0%) |
| Tap | 158 (38.6%) | 46 (37.4%) | 40 (42.1%) | 38 (39.2%) | 34 (36.2%) |
| Mixed | 116 (28.4%) | 36 (29.3%) | 24 (25.3%) | 28 (28.9%) | 28 (29.8%) |
| Don’t Know | 8 (2.0%) | 2 (1.6%) | 3 (3.2%) | 2 (2.1%) | 1 (1.1%) |
| Blood lead level, mean (SD) μg/dL | 2.3 (1.8) | 2.5 (1.9) | 2.3 (1.9) | 1.9 (1.2) | 2.5 (1.7) |
| Birth weight, mean (SD) g | 3360 (542) | 3333 (515) | 3353 (554) | 3371 (595) | 3390 (514) |
a
Composites exposure included exposure to both polyacid-modified compomer and traditional composite.
b
Race/ethnicity was self-reported by the parent of the child. The “other” category included individuals who identified themselves as Asian, Native American, multiracial (specified) or other (specified).
c
Socioeconomic status index was calculated using household income and education level of the primary caregiver and standardized to the U.S. population .(Green, 1970)