Emerging Contaminants - Crisis Or Manageable Risk?

Introduction

Advances in analytical techniques over the years have allowed the detection of compounds in water at very low concentrations.[1] This has facilitated identifying many compounds that previously went undetected in treated and untreated waste water, receiving water bodies and also drinking water.[2]

These contaminants are generally referred to as Emerging Contaminants (ECs) or Contaminants of Emerging Concern (CEC). They are not named “emerging” because they are new or recently introduced in the aquatic environment, but merely because previously they were unrecognized.[3]

At present the global scientific community is grappling with the question whether ECs pose any substantial health risks to humans. While the serious empirical exploration is under way, misplaced media hype about them risks creating undue public panic.

Emerging contaminants

Pharmaceuticals and personal care products (PPCP) and endocrine-disrupting compounds (EDC) (including steroids and hormones) are among the most frequently detected anthropogenic contaminants in water (that is, those originating in human activity).[4] ECs have been categorised into natural compounds, synthetic compounds and emerging pathogens.

Natural compounds.Living organisms, including plants and humans and animals, constantly excrete steroid hormones in their active forms into the environment.[5] These enter the aquatic environment through the application of biosolids and animal manure, treated and untreated effluent discharges and sewer overflow events.

Synthetic compounds. Synthetic compounds are bioactive substances. They are used by households, especially cosmetics personal hygiene, and as well as in agriculture and industry. They include pharmaceutically active compounds (PhACs), personal care products (PCPs) and endocrine-disrupting compounds (EDCs). PhACs are chemicals that elicit a pharmaceutical response in humans (including prescribed, over the counter and illicit drugs).[6]

PhACs are an integral element of modern life. PhACs are used in humans and in agriculture in animals. They are used to treat and cure diseases in humans and as veterinary drugs.

However, if not completely metabolised, these compounds are excreted (faeces and urine) and enter the aquatic environment via wastewater treatment discharge[7]. Researchers have shown that up to 90 percent of antibiotics pass through the body without metabolizing. This means they may leave the body almost intact.[8]

EDCs refers to exogenous substances or mixtures that alters the function(s) of the endocrine systems and consequently causes adverse health effects in an intact organism (Department of Water Sanitation (DWS), 2016). EDCs may be natural but a variety of others can originate from synthetic products. EDCs mimic the occurrence of natural hormones. They can block the production of hormones by inhibiting or stimulating the endocrine system. [9]

Emerging and re-emerging waterborne pathogens. New waterborne pathogens are being recognised, and new strains of existing pathogens are being discovered in the aquatic environments. The major sources of these pathogens (including the new strains) include, livestock, storm water, human recreational activities[10] and microbial evolution.[11] The major challenges with these pathogens are lack of understanding of their transmission routes and their Minimum Infective Dose (MID).[12] (The MID concept is traditionally used for bacteria that contaminate foods causing infection in or from the digestive tract. MID is defined as the minimum number of bacteria ingested (the dose) required to produce a pathology in the consumer). Little has been documented on the effectiveness of disinfection or inactivation of these pathogens.

Characteristics of emerging contaminants

1. Limited information and knowledge gaps. The understanding of ECs is still in its infancy. This is because of their recent discovery in the aquatic environment and their recognition as contaminants with potential negative effects on human health.
2. Chronic exposures. Risks associated with exposure over long periods (chronic) to unregulated ECs plus their consumption at low levels are not well understood.[13] Even so, some studies classify most ECs as carcinogenic and endocrine-disrupting.
3. Monitoring. Most ECs do not yet have suggested concentration benchmarks for human health. They are therefore not subjected to routine monitoring programmes and or emission control regimes.[14]
4. Research challenges.Research efforts into gaining a better understanding of ECs are complicated by synergies. Synergism refers to the effect caused when exposure to two or more chemicals at the same time results in health effects that are greater than the sum of the effects of the individual chemicals.[15]
5. Pseudo–persistent or ‘continuously present’ contaminants. These substances are continuously discharged into the aquatic environment. They therefore do not need to be persistently in the environment to cause negative effects. The key factor is that their supply is continually replenished, even if their half-lives are short.[16]^;[17]
6. Removal. Conventional water treatment works and waste water treatment systems have not been designed to remove ECs in water. As a result, ECs have been detected in varying concentrations in both treated wastewater and drinking water.
7. Ubiquity. ECs are ubiquitous (found everywhere) in in the aquatic environment.[18]

Research, sampling and analytical protocols

ECs have enjoyed significant attention from South African research institutions, with studies identifying and documenting a multitude of ECs in different South African water bodies. These include treated waste water, rivers and potable water. For example,Manickum (2011) identified several in treated sewage [19], Rimayi et al. [20] identified 200 ECs in the Jukskei River (Gauteng Province) water and oestrogenic activity detected in distribution points in Pretoria and Cape Town [21].

The information generated from these studies is, however, fragmented and inaccessible to the general public, since there is no centralised and openly available national database. Most of EC research is published in scientific journals. Accessibility to journals is rarely available to the general public, instead being largely restricted to academics with institutional affiliations who have subscriptions to the journals in question.

In addition, the sampling schemes and analytical procedures used in generating information about ECs are not standardized. While some of the results were generated using grab samples others were generated using composite sampling methods. In this instance, Moodley et al.[22] recognize that “grab sampling” is the widely used method in sampling waste water or surface water.[23] Yet they find grab sampling an unsuitable method or procedure for ECs. Tran et al. instead recommend composite sampling methods.

The discounting of grab sampling is because it is limited in that it provides only a snapshot of prevailing conditions at any specific time. If procedures are not standardised, differences in findings can be attributed to differences in methods rather than reflecting real regional and point conditions.

Public awareness

EC reports usually indicate that their concentrations in water supplies are in minute quantitiesor orders of magnitude below known acute toxicity levels[24]. But public perceptions and concerns regarding the presence of ECs in water supplies cannot be discounted. Since 2015, the South African print media have published several articles on the presence of ECs in water resources (including potable water). News media are accessible sources of information to the public. Yet some reports tend to be sensational. Thus, media coverage appears to have over-emphasised the presence of certain ECs in water. Undue preoccupation with certain emerging contaminants risks overlooking the presence of a multitude of contaminants already identified in South African water bodies. The result may be undue and misdirected public alarm.

Recognition by the water sector

The South Africa water sector on the whole recognises the presence of ECs in water bodies, as well as the need to monitor, manage and regulate these contaminants. Yet the sector also acknowledges that the Department of Human Settlement, Water (DHSWS) and Sanitation currently does not have a formalised strategy for dealing with ECs.[25] Most policy documents addressing ECs thus only establish the need for further research, financial support, capacity-building and inter-laboratory collaborations and partnerships. These are seen as means for eventually filling knowledge gaps and in due course addressing ECs in South African water resources. At present available documentation and strategies for ECs offer no time frame for addressing any of proposed actions.

Chapter 14 of the National Water Act (36 of 1998)[26] contains provisions for monitoring, assessment and information dissemination for water resources including water quality. Given the inconsistencies in the monitoring, assessment and reporting of EC data, it is imperative that the DHSWS consider incorporating ECs in their monitoring systems as part of its data dissemination platforms. This would help provide consistent information generated through standardised approaches.

Lessons from the European Union’s NORMAN Network

The European Union in 2005 established and funded a multinational NORMAN Network. [27] NORMAN is an acronym for network of reference laboratories, research centres and related organisations for monitoring of emerging environmental substances.[28] The network enhances the exchange of information on emerging environmental substances, and encourages validation and harmonisation of common measurement methods and monitoring tools so that the requirements of risk assessors and risk managers can be better met. It specifically seeks both to promote and to benefit from the synergies between research teams from different countries in the field of emerging substances.

The NORMAN Network was established on the following principles:

1. It is to be an independent, transparent, and open network, working for a sustainable environment without harmful substances.
2. It serves as a watchdog and alarm bell for emerging environmental threats.
3. It functions as a bridge between science and policy.
4. It offers a platform for innovative bottom-up initiatives to explore new monitoring challenges.

Since its inception, the NORMAN Network has achieved (i) wide exchange of water quality data generated through standardised protocols; (ii) provision of more transparent information and monitoring data; (iii) establishment of an independent and competent forum for technical and scientific issues on ECs.

In addition, the NORMAN Network has created a successful interface between scientific research and policy. Through a collaborative approach, the Network has gained a stronger voice (70 members from 20 countries) in addressing emerging water quality issues with the European Commission and other public institutions.

The South and Southern African water sector may learn from the NORMAN Network. A similar or related undertaking could have significant benefits. These include building a reliable and centralised EC national or regional database, standardising sampling and analytical protocols, and strengthening inter-laboratory partnerships and laboratory staff training and accreditation.

Conclusion

The presence of emerging contaminants in South African water resources is well supported by research. The South African water sector generally recognises the need to manage, monitor and regulate ECs and also to conduct more research to develop a better understanding of these pollutants and any acute or chronic effects on human health.

While the water sector and policy documents suggest the need to address ECs, there are no set or proposed timeframes for implementation of any of the suggested strategies. Based on lessons from the European Union’s NORMAN Network, a collaborative approach to ECs may be necessary for the South African and regional water sector. Collaborations and partnerships may help in data dissemination, strengthen and inform debate and underscore the need for regulatory frameworks and compliance.

Nhlanhla Mnisi
Researcher
nhlanhla@hsf.org.za

[1]Fatta-Kassinos & Ledin, 2010, URL: https://www.ncbi.nlm.nih.gov/pubmed/20685017