Technical Report No. 9
Dr Fiona Harden, Dr Jochen Müller, Leisa Toms
Department of the Environment and Heritage, May 2004
ISBN 0 642 55001 8
About the report
This study was a component of the National Dioxins Program that was tasked to quantify and assess the concentrations and relative chemical compositions of dioxin-like chemicals in blood serum of the Australian population.
The results of this study provide a measure of the levels of dioxin-like compounds, polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs), in pooled blood serum collected throughout Australia in 2003. Serum samples were collected using Sullivan and Nicolaides Pathology (SNP), a pathology company based in Brisbane but with an extensive national network. De-identified samples were selected from surplus pathology samples according to stratification criteria that were provided to Sullivan and Nicolaides staff. These stratification criteria were as follows:
Regional Stratification: 5 regions representing the regional and population distribution of Australians
- Southeast urban
- South urban
- Northeast urban
- West urban
- Rural region encompassing all rural regions of Australia
Age Stratification: 5 age groups
- <16 years
- 16-30 years
- 31-45 years
- 46-60 years
- > 60 years
In total 9,090 samples from the 50 strata were collected and pooled to give 96 pools according to the above criteria. An additional 204 samples, representing four pools, were also assessed as part of a pilot study to determine the suitability of the use of surplus pathology samples for this study.
All pooled samples were sent to ERGO- Forschungsgesellschaft mbH, Hamburg, and ten duplicate samples were sent to Health Canada, Ottawa, Canada for inter-laboratory comparison. Both are laboratories accredited for analytical dioxin analysis.
Dioxin-like compounds were detected in all strata. Overall the levels in the Australian population are very low by international standards and comparable with, although lower than, those observed in the New Zealand population (Buckland et al, 2001). It should be noted that the samples analysed for the New Zealand study were collected in 1996-97, and given that the measured levels of these compounds in humans are continuing to decrease over time, this may account for some of difference. The mean and median levels expressed as upper bound TEQ values for all pooled samples were 10.9 and 8.3 pg TEQ g-1 lipid, respectively. For males, and females the mean levels were 10.4 and 11.5 pg TEQ g-1 lipid, respectively.
A direct relationship of increasing dioxin- like compound levels with increasing age was observed and could be described by the following equation:
Levels in blood expressed as pg TEQ g-1 lipid = 3.3 exp0.0251age (r2 = 0.87)
This relationship was found to hold from approximately 25 years of age until at least the eighth decade and, thus, during these years it is possible to estimate the level of dioxin-like compounds in an individual.s blood serum.
No systematic differences were observed in the levels of dioxin-like compounds in samples collected from males and females. However, slightly higher levels of dioxin-like compounds were observed in females in the >60 years age group. This result could not be explained on the basis of differences in the mean age between males and females in this group.
The levels of dioxin-like compounds across the five regions were remarkably similar within each age range. Some general trends were noted and include the following:
- the levels of dioxin-like compounds across all regions and within each age range appear to be very similar
- Despite the similarity in levels, for all strata except the <16 years females, the samples from the Southeast region exhibit slightly higher levels of dioxin-like compounds
- For <16 years females the highest levels of dioxin-like compounds were found in the Rural region.
It should be noted that because de-identified samples were used in this study, determination of regional differences was complicated. The use of such samples did not allow any assessment of the length of time an individual had resided in a particular area prior to their sample being collected or recording of either food intake or possible exposure to environmental contaminants in that region.
In summary, the levels of dioxin-like compounds in the Australian population are low by international standards and are very similar across all regions of Australia within each designated age ranges. The levels of these chemicals increase with age and can be estimated if the age of an individual is known.