Emerging contaminants – a trendy catch phrase or an issue worth pursuing in New Zealand aquatic environments?
A recent study by NIWA has identified levels of some emerging contaminants around the Auckland marine environment that are similar to those measured in other industrialised countries.
What are emerging contaminants?
Most human activities involve the use of either naturally-occurring or manmade (anthropogenic) chemicals. These can be resilient to degradation, accumulate in different environmental areas, and have toxic effects on living organisms. Historically the use of chemicals that have known toxic effects, and are resistant to environmental degradation has been discontinued and their environmental fate monitored. The pesticide DDT is a good example.
Emerging contaminants (ECs) are chemicals that are not commonly monitored but have the potential to cause adverse ecological and/or human health effects. They may be new or existing but previously undetected contaminants. ECs are predominantly organic chemicals – coined EOCs – and typically classified according to their effects, (i.e. chemicals that may affect hormone status, referred to as endocrine disrupting chemicals (EDCs), or by their use, i.e. pharmaceuticals and personal care products (PPCPs) or new generation pesticides).
EDCs include industrial products like flame retardants, plasticisers and surfactants, along with naturally-occurring steroid estrogens. PPCPs include prescription and over-the-counter medicines, disinfectants and veterinary medicines.
ECs do not include those pollutants that have been well studied and regulated, such as many organochlorine pesticides (OCPs), polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), dioxins and furans, and heavy metals.
The main sources of ECs are:
- municipal sewage treatment plant (STP) effluent and biosolids
- landfill leachate
- urban stormwater
- agricultural and horticultural runoff.
What is the concern?
The major concern with ECs is that they are not regulated. As a result, environmental concentrations and effects are largely unknown. Furthermore, the world population is rapidly expanding – particularly in urban areas – which results in more pressure on important resources such as drinking water and food supplies. As demand increases, the manufacture and use of many ECs is increasing, along with the numbers of individual compounds. A fitting example is nanoparticles, which are finding a multitude of uses, but little is known about their potentially harmful effects.
What has been done?
The problem of ECs is being addressed with increasing urgency in industrialised countries around the world. Advancements in analytical methodologies have made measurement of ECs feasible, allowing information to be gathered on the concentration and fate of these chemicals in the environment.
Within New Zealand, there is also a growing urgency among scientists, local and Regional Councils, and stakeholders to address these issues. NIWA's contribution to the advancement of knowledge has been diverse, including a literature study and field survey of ECs in Auckland's marine receiving environment, involvement in national strategy meetings and development of in-house capability for the measurement and effects of selected ECs.
The field survey of ECs – including surfactants, flame retardants, plasticisers, estrogens, antifouling agents and pesticides – was carried out in 13 marine receiving environments around Auckland. The survey showed that concentrations of ECs in certain locations were similar to those observed in other industrialised countries worldwide. The study highlighted hotspots of contamination. Auckland is New Zealand's largest city with significant industry and a population density similar to New York or Sydney, so these findings were not unexpected. However, other major cities around New Zealand have not been assessed for their burden of emerging contaminants.
The suite of ECs in this study was subsequently expanded, through collaboration with a Spanish research group, to include pharmaceutical active compounds (PhACs). Results show that around half those analysed are reaching the marine receiving environment around Auckland.
New Zealand has a unique physical environment, with rare and potentially vulnerable indigenous fauna and flora. The effects of ECs on people and our unique environment and ecosystems are still barely understood. There is a clear need for a national strategy to manage the risk of EOCs to the New Zealand environment.