Written by Professor Karen Dwyer, Nephrologist, Clinical Director, Kidney Health Australia
Chronic kidney disease (CKD) poses a significant health burden to the Australian population, with a prevalence of 1:10 amongst non-Indigenous Australians and 1:5 amongst Indigenous Australians (1). The prevalence of kidney disease in Indigenous Australians increases exponentially with degree of remoteness (1) and in some regions is considered endemic (2). Further, there are several areas outside of Indigenous communities where the prevalence of CKD is greater than for the state as a whole, many of which are in agricultural communities.
Agricultural (3) and Indigenous (4) communities in Australia have an increased prevalence of hypertension, diabetes and obesity, all of which are risk factors for CKD. It is not clear if these risk factors alone account for the upsurge in kidney disease in these communities and unidentified nephrotoxins as contributing factors is an area of intense interest. Historically lead poisoning was implicated in a spike of deaths in 1930’s due to “nephritis” in Queensland (reviewed in (5)). More recently data demonstrated that the drinking water in Aboriginal communities in Western Australia, in which CKD is endemic with a prevalence of 22.8% (1, 2), were contaminated with the putative nephrotoxins nitrate and uranium (2). Further, a number of Australian towns have been affected by water contamination with Perfluoroalkyl substances (PFAS) and Perfluorooctyl Sulfonate (PFOS), which have been linked with altered kidney function (6). The issues faced by towns across Australia, some of which have attracted intense media coverage, include Katherine (NT) (7, 8); Oakey (Queensland) (9); Williamtown (NSW) (10) and Penshurst (Victoria) (11).
Many regions in Australia are dependent on agriculture as the primary industry. As the push for higher and consistent agricultural production has continued so has pesticide and fertiliser use in Australia. A Deloitte report estimated more than A$20.6 billion of Australian crop production was attributed to Crop Protection Products in 2015-16 (12). Crop Protection Products are natural and synthetic chemicals used to control insects, disease and weeds in food crops and plants with herbicides, insecticides and fungicides making up 85% of the product sales (12). This increased use, whilst increasing production, has led to pollution of water courses and underground water aquifers (13).
A study undertaken of 1454 wells in Northeastern Australia reported 3% of well water above the permissible limit for drinking water, however in three specific areas 14-21% of wells showed elevated nitrate concentrations and these corresponded to higher intensive agricultural areas (14). According to the Australian Bureau of Statistics, 5.3million tonnes of fertiliser were applied to 49.1 million hectares of agricultural land in 2014-15. The most common were nitrogen-based fertilisers accounting for 66%, with urea and ammonium phosphate the most common (15). According to Gourley et al (16), even if action were taken to reduce nutrient surpluses, there will be a lag in water-quality improvement as accumulated nitrogen and phosphorus continue to provide a source of nutrients. Practically, this means that degraded water quality will continue to occur despite land-based improvements.
Accurate figures for pesticide usage is difficult to obtain as although the Australian Pesticides and Veterinary Medicines Authority (17) publishes a list of the total number of products, the actual volume used is not stated. Furthermore, although an Australian Agricultural Chemicals Usage Database (18) contains information on the agricultural chemicals used in Australia from 1997 to 2006 by broadacre farmers, data beyond these dates are not available.
The traditional risk factors of diabetes, obesity, and hypertension account for much of the burden of CKD. However, increasingly additional factors operational in local environments such as water contamination and use of agrochemicals require attention. It is likely that no one single factor is responsible for the increased prevalence of kidney disease observed within pockets in Australia, rather multiple factors act in a synergistic fashion in an at-risk population.
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