Time-weighted mean arsenic levels (in milligrams per liter) and milligram-years per liter of arsenic exposure were estimated for each subject.
(Time-weighted mean arsenic levels (in milligrams per liter) and milligram-years per liter of arsenic exposure; were estimated; for each subject)
Time-weighted mean arsenic levels (in milligrams per liter) and milligram-years per liter of arsenic exposure
were estimated
for each subject