The Epidemiology of Lead Poisoning Notifications in New South Wales, Australia, 1996-2016

Abstract

Background/Aim: Elevated blood lead levels have been notifiable in New South Wales (NSW), Australia since 1996. In that time the notifiable blood lead level has been reduced twice, from 15µg/dL to 10µg/dL in 2012 and to 5µg/dL in 2016. We evaluated the impact of this change on notification rates in NSW, and assessed the characteristics and quality of surveillance data. Methods: We analysed notification data for 1996-2016 by geographical area, age, sex, exposure status and occupation, and described trends in blood lead levels. We calculated notification rates and compared these over time and between geographic regions. We also described the characteristics of the surveillance dataset and made recommendations for improvement. We used Stata version 14.1 for all analyses. Results: There were 9724 notifications between 1996–2016, with an average annual notification rate of 6.8 per 100,000. In 2016 the notification rate of 12.9 per 100,000 was double the average rate for the preceding five years. When only notifications of blood lead levels above 15µg/dL were considered, the notification rate for 2016 was 1.94 per 100,000, the lowest rate during the 21-year study period. Notification rates in rural regions where lead mining has occurred, and where there is systematic screening, were more than 10 times higher than in other regions. Key limitations of the data included the lack of a single comprehensive data source, high rates of missing data, and the presence of free-text responses. These limitations made it difficult to analyse notifications rates, particularly by risk and exposure history. Conclusions: Changes to the case definition increased notification rates of elevated blood lead, however when considering only notifications above 15µg/dL rates are at their lowest since lead poisoning became notifiable. It is important to improve data completeness in the lead surveillance system to enhance understanding of the epidemiology of elevated blood lead levels in NSW and factors which lead to increased risk.