2. A total of 45 free-range hen and duck egg samples, each sample consisting of six individual eggs, were collected from farms or private houses in Kent, Essex, Norfolk, and Buckinghamshire between November 1994 and April 1996. We have been informed that the purpose of this exercise was to examine the use of free-range eggs as indicators of environmental contamination, rather than to estimate dietary exposure to these compounds through the consumption of free-range eggs. The sampling sites were selected for practical convenience rather than on the basis of concerns about local contamination. We note that these free-range egg samples may not be representative of those on sale throughout the United Kingdom.
Concentrations of dioxins and dioxin-like PCBs
Concentrations of dioxins and dioxin-like PCBs in the combined yolk and white of hen eggs were in the range of 1.1-22 (mean 6.3, median 3.5) ng Toxic Equivalents (TEQ)/kg fat. In the combined yolk and white of duck eggs concentrations were in the range of 1.9-49 (mean 12, median 5.2) ng TEQ/kg fat. We note that in both cases the distribution of values appeared to be skewed. We have been informed that there were no obvious major point sources of contamination in the immediate vicinity of these sampling sites to account for the higher values. We have been told that the most likely source of contamination of free-range eggs by these compounds is via the ingestion of soil and sediment by hens and ducks as they forage for food. However, environmental sampling at the sites of egg collection was not undertaken.
Estimated dietary exposures
We have been provided with estimated dietary exposures for toddlers, schoolchildren, and adults to dioxins and dioxin-like PCBs based on the concentrations of these compounds in free-range eggs in this survey. However, we consider that, because these free-range eggs may not be representative of those on sale throughout the UK, the data from this survey cannot be used to estimate dietary exposures to dioxins and dioxin-like PCBs with any confidence from these sources. Nor can the data from this survey be used to draw any comparisons between free-range eggs and other hen and duck eggs, for which there are few data available.
We consider that this survey of dioxins and dioxin-like PCB in free-range hen and duck eggs cannot be used to estimate the risk to health of consumers of such eggs in the UK.
The concentrations of dioxins and dioxin-like PCBs in free-range hen and duck eggs might be used as an indicator of environmental contamination. A larger, more rigorously designed study would be needed to investigate this.