Vol. 86, Iss. 2, February 2013
Evaluation of occupational exposure: comparison of biological and environmental variabilities using physiologically based toxicokinetic modeling
Riassunto
Purpose Few studies compare the variabilities that characterize environmental (EM) and biological monitoring (BM) data. Indeed, comparing their respective variabilities can help to identify the best strategy for evaluating occupational exposure. The objective of this study is to quantify the biological variability associated with 18 bio-indicators currently used in work environments.
Method Intra-individual (BVintra), inter-individual (BVinter), and total biological variability (BVtotal) were quantified using validated physiologically based toxicokinetic (PBTK) models coupled with Monte Carlo simulations. Two environmental exposure profiles with different levels of variability were considered (GSD of 1.5 and 2.0).
Results PBTK models coupled with Monte Carlo simulations were successfully used to predict the biological variability of biological exposure indicators. The predicted values follow a lognormal distribution, characterized by GSD ranging from 1.1 to 2.3. Our results show that there is a link between biological variability and the half-life of bio-indicators, since BVintra and BVtotal both decrease as the biological indicator half-lives increase. BVintra is always lower than the variability in the air concentrations. On an individual basis, this means that the variability associated with the measurement of biological indicators is always lower than the variability characterizing airborne levels of contaminants. For a group of workers, BM is less variable than EM for bio-indicators with half-lives longer than 10–15 h.
Conclusion The variability data obtained in the present study can be useful in the development of BM strategies for exposure assessment and can be used to calculate the number of samples required for guiding industrial hygienists or medical doctors in decision-making.
Commento
Diversi studi di letteratura, inerenti il rischio chimico, trattano il complesso argomento delle criticità riguardanti gli indicatori di esposizione lavorativa.
Ai fini di una scelta ponderata del miglior indicatore di esposizione, devono essere presi in considerazione alcuni importanti fattori. I principali riguardano le caratteristiche ambientali, la natura dell'esposizione, il tempo di dimezzamento biologico della sostanza e la variabilità relativa dei monitoraggi ambientali e biologici.
Tramite l’utilizzo di modelli basati sulla tossicocinetica, questa ricerca pubblicata recentemente sugli International Archives of Occupational and Environmental Health presenta dati originali, riguardanti la variabilità biologica di 18 bio-marcatori di 11 differenti composti chimici, inclusi 13 indicatori i cui dati relativi alla variabilità non sono mai stati pubblicati fino ad ora.
La variabilità dei monitoraggi ambientali e biologici di queste sostanze vengono discussi, con l'obiettivo di guidare gli igienisti industriali e i medici del lavoro nella scelta del miglior approccio per la valutazione dell’esposizione lavorativa.
Keywords
Biological monitoring, biological variability, environmental monitoring, toxicokinetic modelingArticoli correlati che potrebbero interessarti
Journal of Occupational and Environmental Hygiene. Vol. 12, Iss. 2, February 2015