Lead poisoning of free-living birds in Esperance

By Dr Rupert Woods, Manager, Australian Wildlife Health Network, P.O. Box 20, Mosman NSW

Introduction

Lead intoxication, associated with atmospheric lead carbonate, was the cause of a mass mortality of primarily nectivorous and insectivorous birds (wattle birds, honeyeaters and miners) at Esperance in Western Australia in early December 2006.  The incident raised the importance of wildlife acting as indicators for human health and the critical need for cooperation between the various National and State/Territory agencies involved in responding.  It is concluded that although encouraging and enterprising research and policy initiatives are occurring in wildlife health in Australia, such activities, taking into account Australia’s unique wildlife and organisational structure, could benefit from improved co-ordination, better commitment to collaboration and to integration of wildlife surveillance into the existing arrangements. 

Key words: lead carbonate, wild birds, Esperance, mass mortality.

Case report

Lead intoxication, associated with atmospheric lead carbonate, was the cause of a mass mortality of primarily insectivorous and insectivorous birds (wattle birds, honeyeaters and miners) at Esperance in Western Australia. 

Dead and dying birds were first noticed in early December 2006.  A number of dying birds were seen convulsing prior to death.  The number of deaths during December (2006) - January (2007) was confirmed at 400 - 500.  However, the total number of deaths was subsequently extrapolated to 4000 - 5000.  Initial necropsies were unhelpful with no gross abnormalities detected.  Differential diagnoses included infectious processes and intoxication.  Avian influenza, virulent Newcastle disease and West Nile virus were excluded.  Tests for toxic blue green algae in local ponds were negative and no organo-chlorines, organo-phosphates or pyrethroid pesticides were detected in tissue samples.  Testing of tissue samples and the presence of characteristic lead inclusion bodies in the kidneys of dead birds indicated that at least a proportion of the estimated 4000 - 5000 wild birds died from lead poisoning.  A second episode occurred in early March (2007) when 150 birds mostly purple-crowned lorikeets died.  Tests on tissue samples from ten of these birds were also found to have significant lead levels (11 - 98 mg/kg wet weight).

Results of leaf, flower stamen and bird feather tests also showed high lead and nickel levels.  Large tonnages of lead carbonate mined at Wiluna were being exported via the port at Esperance.  Isotope fingerprinting on samples taken in Esperance matched the lead in the samples of material transported into and out of the town.  Marine sedimentary samples, collected from the seabed directly under the Esperance Port Authority’s discharge pipe, also returned very high lead and nickel levels.  Australian guidelines for sediment lead levels are 50 - 220 mg/kg and the Esperance marine samples showed lead levels between 3,600 - 29,000 mg/kg.  Similarly, guidelines for sediment nickel levels are 21 - 52 mg/kg and the marine sediments had levels of 660 - 5,900 mg/kg.

A full investigation by the Environmental Enforcement Unit (EEU) and a comprehensive health and ecological risk assessment occurred as a result of the findings of lead intoxication.  The investigation included blood testing of Esperance community members and environmental sampling (water, rainwater tanks, soil).  The Western Australian Department of Health advised people not to drink water from rainwater tanks until the tanks had been tested for lead, emptied and cleaned.  It was also recommended that consumption of shellfish and crustaceans taken from the area should be avoided.  Lead carbonate export from the port was suspended.

As a result of this event, a parliamentary inquiry was held by the Western Australian Government (Education and Health Committee 2007).

Discussion

Communication, prior preparation and identification of roles and responsibilities are crucial in any response and to better manage wildlife mortality events, an integrated response plan, where roles and responsibilities are clearly outlined, is required in each of Australia’s States and Territories (including Departments of Agriculture, Health and Conservation).  It is important to identify funding resources in line with jurisdictional responsibilities.  However, there needs to be recognition of the need to manage incidents beyond jurisdictional boundaries and the identification of strategies, responsibilities and sources of resources to deliver.  Laboratory issues particularly associated with funding and prioritization need to be addressed to allow the confirmation of a diagnosis.  There is also a need to better integrate wildlife samples with mainstream agricultural sample management.

To improve the capability of recognizing emerging and emergency wildlife diseases better national surveillance systems are needed, as well as better integration and sharing of information.  Australia needs to recognise more and more the need for meaningful collaboration between organisations and government departments. There is a need for close consultation, collaboration and commitment to develop among environment, human health and agriculture organisations.

Conclusion

The event raises the importance of wildlife acting as indicators for human health and the critical need for cooperation between the various National and State/Territory agencies in responding to incidents such as this.  It is concluded that although encouraging and enterprising research and policy initiatives are occurring in wildlife health in Australia, such activities, taking into account Australia’s unique wildlife and organisational structure, could benefit from continuing to improve co-ordination, better commitment to collaboration and to integration of wildlife surveillance into the existing arrangements. 

References

Education and Health Committee - Report, Inquiry into the cause and extent of lead pollution in the Esperance area - 06-09-2007.url  http://www.parliament.wa.gov.au/web/newwebparl.nsf/iframewebpages/Committees+-+Inquiries  Accessed 18 Mar 2010.