almost impossible to manage once used by the householder, whilst new organic
contaminants arising from manufacturing and processing practices all end up down
the drain, where the burden of dealing with them falls onto the wastewater systems.
These newer contaminants have arisen from microbeads and nanoparticles in cosmetics to microthreads or cancer-causing nonylphenol ethoxylates (NPE) and
phthalates in synthetic clothing with studies finding NPEs in 63% of the new
clothing items it tested and phthalates in 100% of the samples and to a range of
perfluorinated chemicals (Greenpeace 2012a, b). They also include antimicrobials
and endocrine disruptors from medications and, more recently, potentially toxic
levels of more ‘mainstream’ chemicals, such as caffeine (Davis 2017; Sidhu et al.
2012). There are over 143,000 chemicals registered for use in the European Union
(EU) alone with researchers in the EU identifying over 140,000 chemical contaminants in wastewater sludge (European Commission 2001a, b), whilst in the United
States, research has identified over 80,000 contaminants (US EPA 2009). Given that
Australian consumers buy and use similar products to both the Americans and
Europeans, we could assume broadly similar levels. A recent review has identified
a list of ‘chemicals of concern’, including new organic contaminants (OCs) in
biosolids used for agricultural use (McGrath et al. 2017). These include
perfluorinated chemicals (PFOS and PFOA), polychlorinated alkanes (PCAs),
polychlorinated naphthalenes, organotins, triclosan, antibiotics and pharmaceuticals.
This review (McGrath et al. 2017) specifically noted a number of emerging OCs
(namely PFOS, PFOA and PCAs) for priority research attention as they are ‘environmentally persistent and potentially toxic with unique chemical properties or
presence in large concentrations in biosolids, that make it theoretically possible for
them to enter human and ecological food-chains from biosolid-amended soils’.
Further studies have also noted a high volume of plastics (mirco and nano) in
sewage sludges with concentrations of up to 300 particles per kilogram [dry weight]
(Mahon et al. 2017; Li et al. 2018). Around 35% of microplastics in the oceans are
thought to be fibres from synthetic textiles (Boucher and Friot 2017) released when
washing clothes. Whilst human activities and products release microplastics to
wastewater, wastewater treatment plants are effective at removing microplastics,
retaining them in the solid fraction that may contaminate terrestrial ecosystems when
applied as fertiliser (Prata 2018). It is important to acknowledge the significant
volume of high-quality scientific analysis around the beneficial application of biosolids to land which has been conducted over 35+ years. Much of this research has
determined that the majority of compounds studied do not place human or animal
health at risk under current application rates and procedures (Clarke and Smith 2011;
Fang et al. 2017). Much of this evidence and regulatory assessment has concentrated
on total elemental content or single-step leaching procedures as the basis for its risk
assessment. More recent studies have investigated leaching from soils associated
with repeated applications of biosolids (and biosolids-amended composts) across a
range of soils, even considering convection and diffusion effects from different
application scenarios (Venkatesan and Halden 2015). At least one study has even
considered the effect on soils and leachability from repeated applications of biosolids with a secondary material (such as fly ash), whilst other studies have determined that many persistent organic pollutants are not readily bioavailable to
132
G. Davis
contaminants arising from manufacturing and processing practices all end up down
the drain, where the burden of dealing with them falls onto the wastewater systems.
These newer contaminants have arisen from microbeads and nanoparticles in cosmetics to microthreads or cancer-causing nonylphenol ethoxylates (NPE) and
phthalates in synthetic clothing with studies finding NPEs in 63% of the new
clothing items it tested and phthalates in 100% of the samples and to a range of
perfluorinated chemicals (Greenpeace 2012a, b). They also include antimicrobials
and endocrine disruptors from medications and, more recently, potentially toxic
levels of more ‘mainstream’ chemicals, such as caffeine (Davis 2017; Sidhu et al.
2012). There are over 143,000 chemicals registered for use in the European Union
(EU) alone with researchers in the EU identifying over 140,000 chemical contaminants in wastewater sludge (European Commission 2001a, b), whilst in the United
States, research has identified over 80,000 contaminants (US EPA 2009). Given that
Australian consumers buy and use similar products to both the Americans and
Europeans, we could assume broadly similar levels. A recent review has identified
a list of ‘chemicals of concern’, including new organic contaminants (OCs) in
biosolids used for agricultural use (McGrath et al. 2017). These include
perfluorinated chemicals (PFOS and PFOA), polychlorinated alkanes (PCAs),
polychlorinated naphthalenes, organotins, triclosan, antibiotics and pharmaceuticals.
This review (McGrath et al. 2017) specifically noted a number of emerging OCs
(namely PFOS, PFOA and PCAs) for priority research attention as they are ‘environmentally persistent and potentially toxic with unique chemical properties or
presence in large concentrations in biosolids, that make it theoretically possible for
them to enter human and ecological food-chains from biosolid-amended soils’.
Further studies have also noted a high volume of plastics (mirco and nano) in
sewage sludges with concentrations of up to 300 particles per kilogram [dry weight]
(Mahon et al. 2017; Li et al. 2018). Around 35% of microplastics in the oceans are
thought to be fibres from synthetic textiles (Boucher and Friot 2017) released when
washing clothes. Whilst human activities and products release microplastics to
wastewater, wastewater treatment plants are effective at removing microplastics,
retaining them in the solid fraction that may contaminate terrestrial ecosystems when
applied as fertiliser (Prata 2018). It is important to acknowledge the significant
volume of high-quality scientific analysis around the beneficial application of biosolids to land which has been conducted over 35+ years. Much of this research has
determined that the majority of compounds studied do not place human or animal
health at risk under current application rates and procedures (Clarke and Smith 2011;
Fang et al. 2017). Much of this evidence and regulatory assessment has concentrated
on total elemental content or single-step leaching procedures as the basis for its risk
assessment. More recent studies have investigated leaching from soils associated
with repeated applications of biosolids (and biosolids-amended composts) across a
range of soils, even considering convection and diffusion effects from different
application scenarios (Venkatesan and Halden 2015). At least one study has even
considered the effect on soils and leachability from repeated applications of biosolids with a secondary material (such as fly ash), whilst other studies have determined that many persistent organic pollutants are not readily bioavailable to
132
G. Davis