title: BTEX in vitro exposure tool using human lung cells: trips and gains.
abstract: Cytotoxicity of benzene, toluene, ethylbenzene and xylenes (BTEX) to human lung cells was explored using three different exposure methods: Method 1 - in normal 96-well plates using DMSO as a carrier vehicle, we exposed (a) human lung carcinoma A549 cells, (b) A549 cells over-expressed with cytochrome P450 2E1 cells, and (c) normal lung fibroblast LL-24 cells to benzene, toluene, ethylbenzene and xylene individually and in a mixture which models car exhaust gases for between 1-88 h. We found that the order of the BTEX potency is benzene<toluene<ethylbenzene=m-xylene with acute BTEX toxicity to A549≈LL-24>CYP2E1 over-expressed A549 cells. A significant difference was found between inter-assay responses for all 24h exposures (P<0.005) suggesting a poor assay repeatability. No sign of potency increase was found from 6 to 72 h exposures. Method 2 - Using sealed vials to expose A549 cells to benzene, toluene and ethylbenzene, we observed a twenty-fold increase in their cytotoxicity, but also with no time-course effect. Method 3 - Using air exposed hanging-drop cell culture, we were able to see both an increase of demonstration of toxicity and a time-course effect from 1 to 12h exposure. We conclude that exposing cells in sealed and unsealed media using DMSO as a carrier vehicle was not suitable for BTEX exposure studies. Hanging-drop air exposure has more potential. It should be noted that if there are any changes in their exposure matrixes, its exposure mass distribution in cells could differ.
authors.affiliation: The University of Queensland, National Research Centre for Environmental Toxicology (Entox), 39 Kessels Rd., Coopers Plains, Brisbane, QLD 4108, Australia; CRC for Contamination Assessment and Remediation of the Environment, Mawson Lakes, Adelaide, SA 5095, Australia.
authors.forename: Faye F
authors.initials: FF
authors.lastname: Liu
authors.affiliation: The University of Queensland, National Research Centre for Environmental Toxicology (Entox), 39 Kessels Rd., Coopers Plains, Brisbane, QLD 4108, Australia; CRC for Contamination Assessment and Remediation of the Environment, Mawson Lakes, Adelaide, SA 5095, Australia.
authors.forename: Cheng
authors.initials: C
authors.lastname: Peng
authors.affiliation: The University of Queensland, National Research Centre for Environmental Toxicology (Entox), 39 Kessels Rd., Coopers Plains, Brisbane, QLD 4108, Australia; CRC for Contamination Assessment and Remediation of the Environment, Mawson Lakes, Adelaide, SA 5095, Australia. Electronic address: j.ng@uq.edu.au.
authors.forename: Jack C
authors.initials: JC
authors.lastname: Ng
mesh_terms: D001554:Benzene / Q000633:toxicity*; D001555:Benzene Derivatives / Q000633:toxicity*; D045744:Cell Line, Tumor; D019392:Cytochrome P-450 CYP2E1 / Q000378:metabolism; D004121:Dimethyl Sulfoxide; D005347:Fibroblasts / Q000187:drug effects; D006801:Humans; D008168:Lung / Q000166:cytology / Q000187:drug effects*; D013997:Time Factors; D014050:Toluene / Q000633:toxicity*; D018675:Toxicity Tests / Q000379:methods*; D001335:Vehicle Emissions; D014992:Xylenes / Q000633:toxicity*
chemical_list: D001555:Benzene Derivatives; D001335:Vehicle Emissions; D014992:Xylenes; D014050:Toluene; D019392:Cytochrome P-450 CYP2E1; D001554:Benzene; C004912:ethylbenzene; D004121:Dimethyl Sulfoxide
keywords: A549; BTEX; Hanging drop; In-vitro air exposure; Media exposure