New artificial chemicals are produced in large amounts to meet the increasing industrial demands. The rapid discovery and production of these chemicals may hinder their monitoring in the environment through development of appropriate analytical techniques and development of analytical methods. Consequently, these chemicals of emerging concern (CECs) may enter the environment and cause known or suspected adverse ecological and/or human health effects. Current practices and technologies for water and wastewater treatment in Africa are mainly conventional and are insufficient to ensure safe water for use and basic sanitation (Orata, 2018). The situation therefore is a “recipe” for various contaminants and pollutants present in a wide range of water bodies, some of which are sources of drinking water.
Over the past decade, the rapid development in analytical instrument sensitivity has led to wide detection of up to pg/L levels of pollutants in the environment. Some of these detected pollutants may have not been monitored before or may just have been discovered. Therefore, the CEC terminology acknowledges the existence of harmful environmental agents whose identities, occurrences, hazards, and effects are not sufficiently understood (Halden, 2015). There is a need to understand how CECs interact in and with the environment. CECs are insufficiently regulated, and even some chemicals which were reported much earlier such as dichlorodiphenyltrichloroethane (DDT) can still be considered as CECs because of the continuing interest that they attract among researchers.
Types of Chemicals of Emerging Concern
Chemicals of Emerging Concern (CECs) can be classified into many known micro-pollutant classes that include, pesticides, nanoparticles, pharmaceuticals (Gonzalez-Naranjo et al., 2013), personal care products, poly and per- fluorinated substances, trace and radioelements, industrial chemicals, combustion products, chlorinated solvents, biocides, flame retardants and even rare metal complexes among others. The presence of CECs in the environment can be from diverse sources which can be categorized as synthetic or naturally occurring.
Within Lake Victoria catchment area, the CECs that have been determined in various environmental matrices include endocrine disrupting chemicals (EDCs), poly and per-fluorinated substances (PFASs), personal care products, pharmaceutically active compounds (PhACs), persistent organic pollutants such as pesticides, poly-aromatic hydrocarbons (PAHs) among others. However, a large number of CECs such as, trichloroacetic acid (TCAA), nitrosodimethylamine, methyltert-butyl ether, trichloroethylene, perchlorate, 1,4-dioxane, prions, triclocarban, triclosan and nanomaterials have not been determined within the Lake Victoria catchment.
Endocrine disrupting chemicals are among the most common CECs that are common in wastewater (Liu et al., 2011; Manickum et al., 2011; Xu et al., 2012) especially from industrial effluents. These EDCs are bioactive at very low concentrations and alter function(s) of the endocrine system of an organism and consequently harming it (Pothitou & Voutsa, 2008). Some of the most common EDCs are Bisphenol A, Nonylphenol, Nonylphenol Ethoxylates, Octyphenol, and 17α- ethynylestradiol (EE2) which is a bioactive PhACs that is present in birth control pills (Von Saal et al., 2012).
The sources of various classes of CECs are varied and largely depend on the type of anthropogenic activities that take place in respective areas, as well as exposure routes for the CECs in to different environmental matrices. Example, in the case of PhACs, Kumar et al., (2010) reported that the emission of pharmaceuticals per person measured in wastewater in residential areas is about 10% of the emission measured in hospital wastewater. In modern urban centres, wastewater from various sources such as hospitals, households, agricultural and industrial premises is a CECs exposure media that contain micro-pollutants. The wastewater is often channeled to WWTPs, which acts as an exposure route (Orata, 2018). The CECs are subsequently released to other aquatic ecosystems as effluent and also often as sludge (Orata, 2018).
Assessment of the occurrence and fate of CECs within the Lake Victoria aquatic resources is critical, considering the economic importance of Lake Victoria resources. This chapter mainly focuses on surface and waste water because of its relevance as fate of most pollutants and their role as intermediate in abiota and biota interactions. This chapter evaluates the occurrence, concentrations and fate of CECs in various surface water and wastewater within the Lake Victoria catchment area of Kenya. Reports on the occurrence of CECs in other environmental matrices are also discussed in this chapter.