Organophosphate esters and their specific metabolites in chicken eggs from across Australia: Occurrence, profile, and distribution between yolk and albumin fractions

A substantial increase in the usage of organophosphate esters (OPEs) as flame retardants and plasticizers in rubbers, textiles, upholstered furniture, lacquers, plastics, building materials and electronic equipment has resulted in their increasing concentrations in the environment over time. However, little is known about the concentrations and fate of OPEs and their metabolites (mOPEs) in biota, including chicken eggs. The aim of this study was to understand the spatial variation in the concentrations in chicken eggs and the partitioning between yolk and albumin. In total, 153 chicken eggs were purchased across Australia and analysed for 9 OPEs and 11 mOPE. Most of the compounds were found to be deposited in egg yolk, where diphenyl phosphate (DPHP, 3.8 ng/g wet weight, median) and tris(2-chloroisopropyl) phosphate (TCIPP, 1.8 ng/g wet weight, median) were predominant mOPE and OPE, respectively. Moreover, no spatial differences in concentrations of OPEs and mOPEs in eggs purchased from different locations were found in this study. Although comparable levels of ∑OPEs were detected in egg yolk and albumin, much higher concentrations of ∑mOPEs were found in yolk than albumin. Meanwhile, a negative correlation (R² = 0.964, p = 0.018) was found between the molecular mass of analytes and partitioning coefficient of Cyₒₗₖ/Cyₒₗₖ₊ₐₗbᵤₘᵢₙ (defined as chemical concentration in egg yolk divided by the sum of chemical concentrations in both yolk and albumin). These results indicate that n-octanol/water partition coefficients (log KOW) may not be a crucial factor in the distribution of OPEs and mOPEs between egg yolk and albumin, which is important in understanding distribution of emerging organic contaminants in biota.