Introduction: Contamination causes undue risks to society, ecosystems, water and soil resources, and threatens the viability of many industries1,2. As well as affecting soil, surface water and groundwater, air pollution has been recognised as one of the planet’s most challenging problems. This contamination of the living environment has been linked to 13.7 million deaths a year by the World Health Organisation, almost a quarter of all human fatalities https://www.who.int/data/gho/data/themes/public-health-and-environment). Even more concerning are the nonlethal side effects of global contamination, e.g. the decline in human IQ, the collapse of male fertility, the increase in child developmental and mental disorders etc. which, on a daily basis, adds millions of dollars to medical costs and indeed impacts the quality of human life. Describing contamination’s impact by deaths alone understates the problem. It is the lifelong disabilities and suffering of a growing percentage of the population which is also a core issue. There are hardly any measures in place to minimise these impacts other than some regulatory measures that rarely include all toxins in circulation around the planet.
The extent and severity of air pollution depends on many factors – including population, industrial activities, and measures in place to minimise contamination – and thus varies considerably among and within countries. Although more than $US$2 billion is spent annually to manage or remediate contaminated land and water bodies in Australia, limited funds have been allocated towards the management or remediation of air. Globally, environmental management costs exceed $US750 billion per annum with US $65 to $85 billion of this used for clean-up costs. However, these costs do not include the medical costs linked to many debilitating human health issues confronted in most if not all countries globally.
Globally, it is estimated that there are more than 10 million potentially contaminated sites. Despite growing awareness of the risks of exposure to contaminants, activities that contribute to contamination of our environment are on the increase in many countries as populations grow and industrialisation increases. One reason for this is a lack of adherence to regulatory policies, especially in developing countries, many of which are chronically under-resourced. What is needed are global protocols for restricting the use of toxic chemicals and a global 'contamination IPCC' to oversee and reduce universal contamination. Take a metaphor of IPCC that the climate talk and action has been much visible as a result of forming Intergovernmental Panel on Climate Change (IPCC) in 1988.
The proportion of contaminated sites that are successfully remediated is disconcertingly small. Uncertainties about the nature and extent of contamination can be a major constraint to sustainable development in both urban and rural areas, thereby increasing pressure on the use of limited uncontaminated land. Moreover, many techniques available for in situ or ex situ remediation are prohibitively expensive and thus poorly adopted.1
Unlike point source contamination associated with industrial activities, diffuse pollution, such as that encountered in broadacre or agricultural farmlands, poses a different challenge. Although the risk of direct exposure from soil to person is low, the bioaccumulation of contaminants into crops and subsequent exposure via food consumption poses a major risk to humans and also damages local and international trade. Added to these are the inherent dangers of chemical mixtures, even from innocuous substances. The dangers of chemical mixtures are rarely considered by regulatory jurisdictions and indeed industries linked to contaminants. Also, the absence of information about the toxicity of new and existing chemicals further constrains management of environmental contamination.
Although generally present in low concentrations, diffuse contamination is often difficult and expensive to remediate because it can be spread over very large areas.
Exposure risks: The risks associated with exposure to contaminants vary considerably depending on the source and pollutant matrix. While 4 million deaths per year are linked to soil, water or food contamination, a recent World Health Organization report estimates air pollution poses a much higher risk than other forms of pollution, killing an estimated 6 million people every year. UK estimates suggest that air pollution will make 2.4 million people ill in England between now and 2035 and the healthcare and social costs of air pollution could reach US $23 billion by 2035.3 Air pollution is now seen as the invisible killer. Air pollution is caused almost entirely due to the use of fossil fuels and is expected to decline as they are phased out. Furthermore, environmental management is constrained by the highly leachable nature of soils in countries with sub-humid to humid tropical conditions (compared to soils in USA and Europe), and this limits application of technologies developed elsewhere. To make sound risk and remediation decisions, we need to refine the way we assess risks from contaminants. We need improved data and protocols that provide reliable prediction of exposures and the associated human/eco-impacts. We also need improved monitoring and assessment procedures and instrumentation for contaminants to deliver reliable, accurate data on contaminant presence and fate.
Clean up: The cost of clean-up continues to rise given the challenges of remediating both surface and subsurface contamination. Soil is now seen as a complex heterogeneous system that, once contaminated (especially when coupled with groundwater), is not easily remediated. Furthermore, drastic risk control (e.g. cleaning up sites to background concentrations or to the levels suitable for sensitive land use) is rarely technically or economically feasible. It is thus desirable to apply remedial approaches that reduce the risk of contamination while allowing the soil to remain on site. This approach to site remediation, which is gaining increasing acceptance, is commonly known as risk-based land management.
While clean-up is desirable it does not address and will never solve the overall contamination problem. It treats only one of the symptoms. What is needed is a global treaty to reduce Earth system contamination at source – i.e. to prevent pollution occurring in the first place by not releasing any more untested chemicals, maintaining a global inventory of what is released, and pinpointing major sources of toxicity (e.g. plastics in the home).
While the act of contaminating the environment may itself expend low energy and cost, the complex nature of contaminants – coupled with the heterogeneity of media in which contamination resides, risks and multiple receptors – means that the act of cleaning up is complex and cost- and energy-intensive. Given our planet’s large number of contaminated sites, the fragmented approach along national lines and the slow pace of remediation, it will take many generations to clean up the Earth, and we will never achieve the pristine conditions that existed prior to human civilisation.
Can we clean up the earth? This paper has provided an overview of the extent of global contamination, its risks and impacts, the challenges to remediation, and why a clean Earth is humanity’s next great challenge. The paper has also proposed that an international ‘contamination IPCC’ is necessary to meet this challenge. An international body of this type could champion a coordinated approach to the following issues.
Global issues that need to be considered:
(a) The development of a comprehensive database and international chemical inventory and improved exposure pathway models that would assist with risk assessment of contaminated sites and air pollution.
(b) The prioritisation of action for target contaminants/circumstances, especially for recalcitrant contaminants and mixtures in complex environments or where high risks are posed.
(c) The development of specific remediation techniques relevant to region- or country-specific conditions, and demonstration of those techniques at national scale to encourage uptake.
(d) The development of a database that provides the basis for a decision-support system on techniques for remediation or management of contaminated sites.
(e) The availability of highly qualified environmental management and risk assessment graduates.
(f) Environmental legislators with expertise in assessment and management of site contamination.
(g) Trained professionals who can assist with the social implications of contaminants.
(h) A global industry training program to raise industry awareness of the effects of global poisoning (which they ignore) and build a culture of stewardship for dangerous products.
Capacity building: Addressing the issues outlined above will also require a significant effort to build sufficient skilled capacity around the globe. There is strong demand for trained graduates with expertise in not only environmental management but also legal and social issues relating to contaminated soils.
Conclusion: The large number of contaminated sites together with increasing evidence of health effects from the consumption of foods grown on contaminated sites or farms with low level of contamination suggests that there would be considerable benefit in assembling a focussed group of international leaders in the field – through mechanisms such as the globalCARE™ initiative – to tackle these problems on a global scale. Members of this group should have skills to develop technology for (a) assessment of risks, and (b) management or remediation of degraded environments contaminated from both point and dispersed sources. A well-resourced international group such as this, together with a global treaty to reduce contamination at its source, may be able to reverse the trend and in time may well be able clean up the earth.
References
1. Naidu, R. (2013). Recent Advances in Contaminated Site Remediation. Water, Air, and Soil Pollution. 224(12), 1705.
2. Naidu, R. et al. (2021). Chemical pollution: A growing peril and potential catastrophic risk to humanity. Environment International. 156, 106616.
3. Kass, D. (2018). Air pollution kills six million people every year: it's time for us to wake up to this grave threat. The Telegraph, 27 September 2018. www.telegraph.co.uk/news/2018/09/27/air-pollution-kills-six-million-people-every-year-time-us-wake/
