Determination of Polychlorinated Dibenzo Dioxin Levels in Fresh Milk from the Dairy Factories of Southwest Iran

Abstract

Background: Currently, release of highly toxic polychlorinated dibenzo-p-dioxins (PCDDs) from combustion processes and industrial activities in the environment, their persistence and bioaccumulation in human attracted more attention and dairy products are among the most important sources of human exposure. This study was aimed to determine the most toxic congeners of dioxins in fresh cow’s milk samples collected from the Southwest of Iran. Materials and Methods: 15 composite samples of pasteurized milk from the each of 3 major dairy factories of Khuzestan Province in spring, summer and autumn from July 2011 to March 2012 (3 seasons) were collected. After precipitation of the proteins, fat phase was reduced and extracted with hexane and ether. After dehydration, furans existed in fat percolated with hexane through a column chromatography which contained silica gel/silver nitrate, silica gel, silica gel/sulfuric acid respectively and with percolating output through another column contained activated charcoal and silica gel and washing the lower column with a mixture of dichloromethane-hexane and toluene, concentrated and dissolved in mobile phase and analyzed using HPLC: 150 mm × 4.6 mm ID, 5 μm cosmosil 5 NPE column equipped with a UV detector at 254 and 267 nm, mobile phase:methanol/water (80:20, v/v) at flow rate of 1 ml/min. Results: All samples were found to be contaminated with dioxins comparatively. The concentration of 2, 3, 7, 8 TCDD and 1, 2, 3, 7, 8 PCDD in lipid content (2-3%) were detected in the range of 0.96-3.17 TEQ pg/g and 0.59-2.87 TEQ pg/g respectively. The mean concentrations of dioxins during summer were higher for all factories than other seasons and the lowest content were obtained during winter.