Table 5.

HEMA in urine 2 and 3: multiple linear regression models in the subgroups of workers with HEMA concentrations above the detection limit

Dependent variable
HEMA in urine 2
HEMA in urine 3
HEMA (μg/g creatinine)PHEMA (μg/L)PHEMA (μg/g creatinine)PHEMA (μg/L)P
Sample size31312525
Exposure (whole shift)6.510.00055.750.0080.630.82.120.2
HEMA in urine 10.450.060.640.02NINI
HEMA in urine 2NINI0.480.040.300.08
Cigarettes/d (number)−0.0030.8−
Adjusted R20.320.230.200.16
Pr > F0.0040.020.050.09
  • NOTE: All subjects had detectable HEMA concentrations in both urine samples used in each regression equation (urine 1 and 2 or urine 2 and 3). Dependent variable is HEMA either in urine 2 (end of shift) or in urine 3 (next morning). HEMA concentrations in every model are consistently expressed with the same units (microgram per liter or microgram per gram creatinine, respectively). With respect to the other variables, the following codes or units were used: exposure (ppm) and smoking (number of cigarettes per day). Figures indicate partial regression coefficients and corresponding significance levels. Pr > F: statistical significance of the R2.