Majumdar, Dipanjali and Dutta, Chirasree and Sen, Subha (2016) Inhalation exposure or body burden? Better way of estimating risk - An application of PBPK model. Environmental Toxicology and Pharmacology, 41. pp. 54-61. ISSN 1382-6689 (Print) and 1872-7077 (Online)

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Abstract

We aim to establish a new way for estimating the risk from internal dose or body burden due to exposure of benzene in human subject utilizing physiologically based pharmacokinetic (PBPK) model. We also intend to verify its applicability on human subjects exposed to different levels of benzene. We estimated personal inhalation exposure of benzene for two occupational groups namely petrol pump workers andcar drivers with respect to a control group, only environmentally exposed.Benzene in personal air was pre-concentrated on charcoal followed by chemical desorption and analysis by gas chromatography equipped with flame ionization detector (GC-FID). We selected urinary trans,trans-muconic acid (t,t-MA) as biomarker of benzene exposure and measured its concentration using solid phase extraction followed by high performance liquid chromatography (HPLC). Our estimated inhalation exposure of benzene was 137.5, 97.9 and 38.7 ug/m3 for petrol pump workers,car drivers and environmentally exposed control groups respectively which resulted in urinary t,t-MA levels of 145.4 ± 55.3, 112.6 ± 63.5 and 60.0 ± 34.9 ug/g of creatinine, for the groups in the same order.We deduced a derivation for estimation of body burden from urinary metabolite concentration using PBPK model. Estimation of the internal dose or body burden of benzene in human subject has been made for the first time by the measurement of t,t-MA as a urinary metabolite using physiologically based pharmacokinetic (PBPK) model as a tool. The weight adjusted total body burden of benzene was estimated to be 17.6, 11.1 and 5.0 �g kg−1of body weight for petrol pump workers, drivers and the environmentally exposed control group, respectively using this method. We computed the carcinogenic risk using boththe estimated internal benzene body burden and external exposure values using conventional method.Our study result shows that internal dose or body burden is not proportional to level of exposure rather have a non-linear relationship. At a higher exposure level such as for occupational exposure of petrol pump workers and drivers, the conventionally estimated risk is higher than risk estimated from internal body burden. Likewise, for environmental exposure the conventional risk estimation predict lower level than estimated in our study. This emphasizes the importance of body burden and to consider it as a key parameter while estimating health risk at varying level of exposure.

Item Type:	Article
Uncontrolled Keywords:	PBPK;Benzene;Body Burden;Health Risk;Occupational Exposurea
Subjects:	Air Pollution Environmental Health
Divisions:	UNSPECIFIED
Depositing User:	Dr Dipanjali Majumdar
Date Deposited:	21 Jan 2016 10:09
Last Modified:	21 Jan 2016 10:09
URI:	http://neeri.csircentral.net/id/eprint/562

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