Phthalate esters (PEs) are by far the most produced and extensively used synthetic organic chemicals with notable applications in many industrial products such as vinyl upholstery, adhesives, food containers, packaging materials, printing inks, adhesives, cosmetics, paints, pharmaceuticals munitions, and insecticides among other. PEs have long been recognised as ubiquitous organic pollutants of prime environmental concern, with urbanisation amongst the main cause and source of these compounds. Due to their notoriety, these compounds are known to pose devastating effects to living organisms including humans. The presence of PEs and their metabolites in the aquatic ecosystems is of concern primarily due to their endocrine disrupting and carcinogenicity properties. Several research studies have reported prevalence, exposure pathways, toxicity, and impacts of PEs in aquatic ecosystems and humans. Their principal routes of exposure could be direct or indirect, of which the direct route include contact, eating, and drinking contaminated foods, and the indirect route constitute aerosols, leaching and other forms of environmental contamination. PEs find way into water systems through means such as effluent discharges, urban and agricultural land runoff, leaching from waste dumps and other diffuse sources. High-end instrumentation and improved methodologies on the other hand have resulted in increased ability to measure trace levels (μg/L) of PEs and their metabolites in different matrices and ecological compartments of water or aquatic ecosystems such as lakes, oceans, rivers, sediments, wetlands and drinking water samples. In light of the above, this article provides an informed and focused information on the prevalence of phthalate esters in aquatic systems and related effects on living organisms and humans. Furthermore, techniques that have enabled the extraction and analysis of these PEs in aquatic samples are also explained. Future research outlooks and needs are also highlighted in this manuscript. This information will be used to better understand their temporal and spatial distributions in the aquatic systems and aid in devising prudent means to curtail their ecological footprints.

Herein, the catchment-wide temporal dynamics and potential ecotoxicological risk of phthalic acid esters (PAEs) in aquatic ecosystems were assessed. Specifically, water samples were collected for a period of six consecutive months from seven selected sites, i.e., covering both dry and wet seasons for seasonal variabilities. The appraised PAEs comprised dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DBP), benzylbutyl phthalate (BBP), diphenyl phthalate (DPP), di-n-hexyl phthalate (DHP), bis(2-ethylhexyl) phthalate (DEHP), di-n-octyl phthalate (DOP), diisodecyl phthalate (DiDP) and diisononyl phthalate (DiNP)) in municipal wastewater effluents, rivers and dam. Their concentrations were quantified using a gas chromatography–flame ionisation detector (GC–FID) via the liquid–liquid extraction mode. The appraised PAEs were ubiquitous in the selected sampling points, with DBP being the most abundant PAE homologue throughout the assessed localities. In particular, quantifiable concentrations were 18.9, 37.9 and 11.5 μg/L for DBP in wastewater effluents, rivers and the dam catchment, respectively, and for overall Σ₁₀PAEs of minimum, mean and maximum of 0.492, 3.6 ± 9.82 and 63.2 μg/L, respectively. In addition, PAE concentrations in the effluents, rivers, and dam samples showed no significant differences with p < 0.05. The overall prominent sequence for ∑PAEs registered: 53.3 > 10.1 > 10.0 > 9.8 > 4.3 > 2.5 > 1.8 > 1.7 > 1.1 > 0.9% for DBP > DEHP > DiDP > DOP > DHP > DPP > BBP > DMP > DEP > DiNP, respectively. The ecotoxicological risk assessment (risk quotient method) showed that DBP and DiDP posed high risk (RQ ≥ 1), and DOP, DEHP, DHP, DiNP and BBP posed median risk to aquatic organisms (0.1 ≤ RQ < 1), while the risk from DMP and DEP was minimal (RQ < 0.1). Additionally, DBP, DEHP, DOP, DPP and DiDP were higher than the water criterion (3 μg/L) of PAEs recommended by the United States Environmental Protection Agency (USEPA) for the protection of aquatic life. Findings from this study should go a long way in guiding regulators, custodians and catchment management forums, along with interested and affected parties, regarding the status and potential ecotoxicological effects of PAEs in the receiving environment.