Table 6.
Final semen volume and sperm morphology linear regression models,a considering multiple metals and other covariates.
| Variable | Regression coefficient (95% CI) | p-Value |
|---|---|---|
| Semen volume | ||
| As | ||
| 25th–50th percentile | 0.43 (−0.13 to 0.99) | |
| 50th–75th percentile | 0.39 (−0.19 to 0.97) | |
| > 75th percentile | 0.54 (−0.07 to 1.15) | 0.05* |
| Zn | ||
| 25th–50th | −0.36 (−0.91 to 0.20) | |
| 50th–75th | −0.24 (−0.82 to 0.34) | |
| > 75th | −0.78 (−1.38 to −0.18) | 0.02* |
| Smoking status | ||
| Current smoker | −0.42 (−0.91 to 0.07) | 0.09 |
| Household incomeb | ||
| $30,000–$60,000 | 0.40 (−0.24 to 1.04) | |
| $60,000–$90,000 | 0.82 (0.15 to 1.49) | |
| > $90,000 | 0.83 (0.18 to 1.49) | 0.07* |
| Racec | ||
| White | 0.49 (0.01 to 0.98) | 0.04 |
| Sperm morphology | ||
| Mo | ||
| 70th–85th | −0.26 (−1.74 to 1.22) | |
| > 85th | −1.59 (−3.03 to −0.15) | 0.03* |
| Cu | ||
| 25th–50th | −0.84 (−2.28 to 0.60) | |
| 50th–75th | −1.45 (−2.88 to −0.01) | |
| > 75th | −1.50 (−2.98 to −0.02) | 0.05* |
| BMI | ||
| Unit increase | −0.05 (−0.14 to 0.03) | 0.08 |
a
Backward elimination; same results obtained with forward selection and stepwise procedures.
b
Reference group, household income < $30,000/year.
c
Reference group, nonwhite.
*
p-Value for trend.