Risk Assessment of Personal Care Products, Pharmaceuticals, and Stimulants in Mgeni and Msunduzi Rivers, KwaZulu-Natal, South Africa

Abstract

In this work, environmental occurrence and risk assessment of pharmaceuticals, personal care products (PPCPs), and stimulants are presented. A quantitative technique is described for ultrasonic-assisted solid-phase extraction (SPE) followed by GC-MS after derivatization of PPCPs; propylparaben, triclosan, carbamazepine, chloramphenicol, and stimulant caffeine. Ultrasonic-assisted extraction together with centrifugation were used to extract sediment samples collected from the Mgeni and Msunduzi rivers. An SPE procedure was used for cleanup and to concentrate selected compounds from diluted aqueous extracts. The final extracts were derivatized and analyzed with GC-MS in selected ion monitoring (SIM) mode. The recoveries of the analytes ranged from 66 to 108%. The method detection limits were (0.08–1.82 ng g−1 for solid and 0.08–10 μg L−1 for liquid) and quantification limits (0.42–5.51 ng g−1 for solid and 0.25–25 μg L−1 for liquid). The optimized method was applied in the evaluation of two rivers over 3 months in KwaZulu-Natal, South Africa. All targeted compounds were present in the environment at concentration levels between not detected to 174 ng g−1 and not detected to 30 μg L−1 for solids and aqueous environmental samples, respectively. A comparison of predicted no environmental effect concentration (PNECs) with measured environmental concentration (MECs) showed that these PPCPs present a high ecological risk to the receiving environment (agricultural lands and households). Our work is close to reality because we used MECs as opposed to using predicted environmental concentration (PECs) values, which are normally calculated from consumption, production of compound per year, and various estimated factors.

A journey of 10 years in analytical method development and environmental monitoring of pharmaceuticals in South African waters

“…35 In fact, some studies have found the concentrations of carbamazepine in surface water to be minimal with its quantities not exceeded the method quantitation limits. 35,37,46,64 This observation could be associated with the transformation of carbamazepine into other compounds as indicated elsewhere. 45 However, some of these studies did not investigate the occurrence of the transformation products in the same samples.…”

“…45 Other reported applications for Oasis HLB sorbents include their use in the simultaneous extraction of pharmaceuticals, personal care products and stimulants in aqueous samples. 46 Despite its success in sample preparation, Oasis HLB seems to be more suitable for a wide range of analytes. In this regard, the selectivity concerns become prominent when it is used for fewer analytes with similar physico-chemical properties.…”

“…GC instruments have been used with SPE and disposable PDMS sorptive sampler for analysis of pharmaceuticals in surface water. 46,51,68 Limits of detections attained when analyzing a wide range of pharmaceuticals using the SPE-GC-MS system ranged from 0.041 to 1.614 µg L −1 . 51 While these detection limits are sufficient for the analysis of pharmaceuticals in South African surface water, GC-based methods are mostly time-consuming.…”

“…This drug has been detected alongside its metabolite, 10,11-dihydro-11-hydroxycarbamazepine, in South African-based WWTPs. 45 One study indicated that in WWTPs located in KwaZulu-Natal, carbamazepine concentrations did not exceed the method quantitation limit of 2.9 µg L −1 , 46 while there was no detection in Daspoort WWTP (Pretoria, Gauteng). 64,90 However, a different scenario was presented in the same province indicating high levels of this drug in both influents and effluents of five WWTPs (Northern, Umbilo, Umhlathuzana, Amanzimtoti and Darvill) located in KwaZulu-Natal.…”

The potential ecological risk of veterinary pharmaceuticals from swine wastewater on freshwater aquatic environment

“…The averages of the concentration of the veterinary pharmaceuticals (ivermectin, salicylic acid, and tetracycline) in the surface water (Table 4 ) were used as our MEC SW . The MEC can be used in place of the predicted environmental concentration (Gumbi et al, 2022 ). The no observed effect concentration (NOEC) data used in this study were generated using the ToxRat software for 24‐ to 72‐h EC 50 P. subcapitata and 24‐ to 48‐h LC 50 D. magna , but the NOEC for T. thermophila was not calculated from the ToxRat software.…”