Occurrence and Impact of Emerging Contaminants in Nigeria's Freshwater Resources

Introduction

Water is essential to life and it is needed to sustain livelihoods and the environment. This has been manifested by the United Nations Development Agenda, and access to good quality water is at the heart of the attainment of majority of the 17 Sustainable Development Goals (SDGs) particularly, Goals 3, 6 and 14. SDG Goal 3 seeks to “Ensure healthy lives and promote well-being for all at all ages”; SDG Goal 6 seeks to “Ensure availability and sustainable management of water and sanitation for all” and focuses on ensuring safe drinking water, minimizing the release of hazardous chemicals and materials, and improving wastewater management and the safe reuse of wastewater and SDG Goal 14 seeks to “Conserve and sustainably use the oceans, seas and marine resources for sustainable development”. The presence of Emerging Contaminants (ECs) in freshwater presents a major challenge to the attainment of these and the other 14 SDG goals, as they pose serious threats to human life and ecosystems.

ECs are contaminants that are found in drinking water or aquatic environments that have not been previously identified as contaminants. The U.S Geological Survey has defined them as ‘any synthetic or naturally occurring chemical that is not commonly monitored in the environment but has the potential to enter the environment and cause known or suspected adverse ecological and/or human health effects (Raghav et al., 2013). The group of compounds classified as Emerging Contaminants are very diverse in terms of their toxicity, behavior in the environment, treatment required and monitoring technique used to identify them. They include Pharmaceuticals and Personal Care Products (PPCPs), Endocrine Disrupting Chemicals (EDCs), polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), polycyclic aromatic hydrocarbons (PAHs), polychlorinated dibenzofurans (PCDFs), dibenzo-p-dioxins (PCDDs), steroids, hormones, surfactants and surfactant metabolites, flame retardants, pesticides, industrial additives, nanomaterials and gasoline additives (Inam et al., 2015; Stefanakis & Becker, 2016). The use and production of synthetic organic chemicals for use in various industries, households and agriculture has led to an increase in the occurrence and concentration of these compounds, in wastewater effluents and consequently the environment. Most ECs have only recently been recognized as contaminants, as a result of evidence linking them with various adverse effects observed in the environment, aquatic life and human health. They are usually bioactive, bioaccumulative, with a widespread occurrence and persistence in the environment (Stefanakis & Human, 2015). Globally, it is estimated that approximately 2 million tons of wastewater per day are disposed of within receiving waters, these include various chemicals and industrial, human and agricultural waste products (UNESCO, 2003). The presence of ECs in wastewater is a source of concern, as they are used and released in the environment constantly, contaminating surface water and groundwater resources used for potable water. They pose a threat even at low concentrations and make cause chronic toxicity (Carlsson et al., 2009), endocrine disruption in humans and aquatic life (Bolong et al., 2009) and may result in the development of antibiotic resistance genes (Lubick, 2011).