Table 1.
Characteristics and Chemical Concentrations in Breast Milk of Participant Mothers Who Provided Breast Milk at 3 Months in the PIN Babies Study and also of the Mother-Child Pairs Included in this Paper, Central North Carolina, United States, 2004–2006.
| Milk Samples (n=304) |
Growth Card Subgroup (n=210) |
|||
|---|---|---|---|---|
| No. | % | No. | % | |
| Maternal characteristics | ||||
| Race | ||||
| White | 262 | 86 | 189 | 90 |
| Non-white | 42 | 14 | 21 | 10 |
| Education (years) | ||||
| <16 | 54 | 18 | 28 | 13 |
| ≥16 | 250 | 82 | 182 | 87 |
| Parity | ||||
| 0 | 160 | 53 | 107 | 51 |
| ≥1 | 144 | 47 | 103 | 49 |
| Age (years) | ||||
| Mean (SD) | 31 (5) | 31 (5) | ||
| Percent of 2001 poverty level during pregnancy (%) |
||||
| Mean (SD) | 490 (199) | 509 (186) | ||
| Missing | 5 | 4 | ||
| Pre-pregnancy body mass index (kg/m2) |
||||
| Mean (SD) | 23.8 (4.9) | 23.5 (4.8) | ||
| Median (range) of chemical concentrations in breast milk (ng/g lipid) a |
||||
| PCB153 | 17 (2–199) | 18 (2–199) | ||
| ΣPCBs b | 77 (9–708) | 81 (12–708) | ||
| p,p’-DDT | 5 (<LOD-80) | 5 (<LOD-36) | ||
| p,p’-DDE | 121 (1–2,140) | 113 (15–2,140) | ||
| Infant characteristics | ||||
| Baby gender | ||||
| Male | 163 | 54 | 113 | 54 |
| Female | 141 | 46 | 97 | 46 |
| Preterm birth | ||||
| Yes | 22 | 7 | 16 | 8 |
| No | 282 | 93 | 194 | 92 |
| Birthweight (g) | ||||
| Mean (SD) | 3406 (624) | 3358 (474) | ||
| Duration of breast feeding (months) |
||||
| Mean (SD) | 10 (2) | 11 (2) | ||
| Missing | 40 | 0 | ||
| Months of exclusive breast feeding |
||||
| Mean (SD) | 4 (2) | 5 (2) | ||
| Missing | 40 | 0 | ||
| Median (range) of LEM at 12 months (ng/g lipid - months) a |
||||
| PCB153 | 119 (12–1,194) | 126 (19–1,194) | ||
| ΣPCBs b | 546 (64–4,249) | 574 (100–4,249) | ||
| p,p’-DDT | 33 (1–523) | 34 (1–326) | ||
| p,p’-DDE | 871 (134–19,260) | 880 (134–19,260) | ||
Abbreviation: <LOD, lower than detection limit; p,p’-DDE, 2,2-bis(p-chlorophenyl)-1,1-dichloroethylene; p,p’-DDT, 2,2-bis(p-chlorophenyl)-1,1,1-trichloroethane; LEM, lactational exposure metrics; PCB, polychlorinated biphenyls; and SD, standard deviation.
There was 1 subject missing ΣPCBs concentration and the LEM of ΣPCBs and 1 subject missing p,p’-DDT concentration and the LEM of p,p’-DDT. Additional 40 subjects in the milk sample group were missing LEM because of missing duration of breast feeding through 12 months.
ΣPCBs is the sum of the concentrations of PCB66, PCB74, PCB99, PCB105, PCB118, PCB138_158, PCB146, PCB153, PCB156, PCB170, PCB177, PCB178, PCB180, PCB183, PCB187, PCB194, PCB196_203 and PCB199, in which <LOD is treated as median(LOD) divided by a square root of 2.