Effect of age on toxicokinetics among human volunteers exposed to propylene glycol methyl ether (PGME)

Aging adults represent the fastest growing population segment in many countries. Physiological and metabolic changes in the aging process may alter how aging adults biologically respond to pollutants. In a controlled human toxicokinetic study (exposure chamber; 12 m3), aging volunteers (n = 10; >58 years) were exposed to propylene glycol monomethyl ether (PGME, CAS no. 107-98-2) at 50 ppm for 6 h. The dose-dependent renal excretion of oxidative metabolites, conjugated and free PGME could potentially be altered by age.Aims(1) Compare PGME toxicokinetic profiles between aging and young volunteers (20-25 years) and gender; (2) test the predictive power of a compartmental toxicokinetic (TK) model developed for aging persons against urinary PGME concentrations found in this study.MethodsUrine samples were collected before, during, and after the exposure. Urinary PGME was quantified by capillary GC/FID.ResultsDifferences in urinary PGME profiles were not noted between genders but between age groups. Metabolic parameters had to be changed to fit the age adjusted TK model to the experimental results, implying a slower enzymatic pathway in the aging volunteers. For an appropriate exposure assessment, urinary total PGME should be quantified.ConclusionAge is a factor that should be considered when biological limit values are developed.

► PGME toxicokinetic profiles differed between age groups (>58 years vs <25 years). ► Gender differences in PGME profiles were not observed among aging volunteers. ► For an appropriate exposure assessment, urinary total PGME should be quantified. ► Biological limit values and toxicokinetic models should include age as a factor.