A1653 CYP2E1 activity in Mexican workers occupationally exposed to low levels of toluene

Monday, March 19, 2012: 14:15
Xcaret 2 (Cancun Center)
Octavio Jimenez Garza, Health Sciences, Universidad De Guanajuato Campus León, León, Mexico
Sergio Márquez-gamiño, Health Sciences, Universidad de Guanajuato Campus León, León, Mexico
Arnulfo Albores, External Section of Toxicology, CINVESTAV-IPN, México D.F., Mexico
Cipriana Caudillo-cisneros, Health Sciences, Universidad de Guanajuato Campus León, León, Mexico
Mariella Carrieri, Dipartimento di Medicina Ambientale e Sanità Pubblica, Università di Padova, Padova, Italy
Giovanni Battista Bartolucci, Dipartimento di Medicina Ambientale e Sanità Pubblica, Università di Padova, Padova, Italy
Maurizio Manno, Preventive Medical Sciences, Università degli Studi di Napoli Federico II, Naples, Italy
Handouts
  • ICOH 2012 Presentation.pdf (191.6 kB)
  • Introduction
    CYP2E1, an inducible enzyme present in different human tissues, metabolizes several potentially toxic substances including many volatile organic compounds (VOCs). One indirect way to monitor exposure to VOCs may be, therefore, the assessment of CYP2E1 activity in vivo using the chlorzoxazone (CHZ) test. Goal: To compare CYP2E1 activity in two groups of workers: one with a known occupational exposure to VOCs (exposed group) and the other employed in administrative tasks at two universities (reference group) from the city of León, Guanajuato, México

    Methods
    1) Passive diffusion monitors were used to evaluate individual levels of exposure to toluene, benzene and ethylbenzene in 48 persons (24 tannery workers and 24 administrative controls) during a 8 hour work shift; 2) After 12 h fasting 500 mg CHZ, a selective probe for assessing CYP2E1 activity in vivo, was orally administered and, after two hours, a venous blood sample was collected for HPLC plasmatic quantitative determination of CHZ and its mean metabolite 6-hydroxyclorzoxazone

    Results
    Toluene mean exposure levels were higher in the exposed group (2.86 + 2.0 ppm vs. 0.05 + 0.005 ppm; p<0.001). Also, in this group CYP2E1 activity was lower (p<0.05) and it decreased as the accumulated months of labor exposure increased (negative correlation, p< 0.05)

    Discussion
    These results are in line with previous findings obtained from shoemakers exposed to various solvents but, interestingly, they are partly in contrast with those of another study in printers.In spite of the relatively low levels of toluene exposure found for tannery workers, an effect on CYP2E1 activity was evident. Although the mechanism of this interaction is still unknown, CYP2E1 inhibition per se might represent a health risk, considering that these workers may be less protected against other CYP2E1 substrates present in the labor setting or derived from an intentional exposure.