title: Mathematical model developed for environmental samples: prediction of GC/MS dioxin TEQ from XDS-CALUX bioassay data.
abstract: Remediation of hazardous waste sites requires efficient and cost-effective methods to assess the extent of contamination by toxic substances including dioxin-like chemicals. Traditionally, dioxin-like contamination has been assessed by gas chromatography/high-resolution mass spectrometry (GC/MS) analysis for specific polychlorinated dibenzo-p-dioxins, dibenzofurans, and biphenyl congeners. Toxic equivalency factors for these congeners are then used to estimate the overall dioxin toxic equivalency (TEQ) of complex mixtures found in samples. The XDS-CALUX bioassay estimates contamination by dioxin-like chemicals in a sample extract by measuring expression of a sensitive reporter gene in genetically engineered cells. The output of the XDS-CALUX assay is a CALUX-TEQ value, calibrated based on TCDD standards. Soil samples taken from a variety of hazardous waste sites were measured using the XDS-CALUX bioassay and GC/MS. TEQ and CALUX-TEQ from these methods were compared, and a mathematical model was developed describing the relationship between these two data sets: log(TEQ) = 0.654 x log(CALUX-TEQ) + 0.058-(log(CALUX-TEQ))2. Applying this equation to these samples showed that predicted and GC/MS measured TEQ values strongly correlate (R2 = 0.876) and that TEQ values predicted from CALUX-TEQ were on average nearly identical to the GC/MS-TEQ. The ability of XDS-CALUX bioassay data to predict GC/MS-derived TEQ data should make this procedure useful in risk assessment and management decisions.
authors.affiliation: Xenobiotic Detection Systems, 1601 East Geer Street, Suite S, Durham, North Carolina 27704, USA.
authors.forename: David J
authors.initials: DJ
authors.lastname: Brown
authors.forename: Jean
authors.initials: J
authors.lastname: Orelien
authors.forename: John D
authors.initials: JD
authors.lastname: Gordon
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Chu
authors.forename: Michael D
authors.initials: MD
authors.lastname: Chu
authors.forename: Masafumi
authors.initials: M
authors.lastname: Nakamura
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Handa
authors.forename: Fujio
authors.initials: F
authors.lastname: Kayama
authors.forename: Michael S
authors.initials: MS
authors.lastname: Denison
authors.forename: George C
authors.initials: GC
authors.lastname: Clark
mesh_terms: D001681:Biological Assay / Q000379:methods*; D004147:Dioxins / Q000032:analysis*; D004784:Environmental Monitoring / Q000379:methods*; D008401:Gas Chromatography-Mass Spectrometry; D006256:Hazardous Waste / Q000032:analysis*; D008956:Models, Chemical; D018570:Risk Assessment; D012989:Soil Pollutants / Q000032:analysis*
chemical_list: D004147:Dioxins; D006256:Hazardous Waste; D012989:Soil Pollutants