Linda L. Sibali

Bio: Linda L. Sibali is an academic researcher from University of South Africa. The author has contributed to research in topics: Alkylphenol & Photocatalysis. The author has an hindex of 10, co-authored 19 publications receiving 228 citations. Previous affiliations of Linda L. Sibali include RAND Corporation & Cape Peninsula University of Technology.

Distribution, exposure pathways, sources and toxicity of nonylphenol and nonylphenol ethoxylates in the environment

Abstract: Alkylphenols (APs) are ultimate breakdown products of alkylphenol polyethoxylate (APEs) that are used in cleaning and industrial processes. The most commonly used APEs in the market are the nonylphenol ethoxylates (NPEs) and octylphenol ethoxylates (OPEs). As a result of their widespread use and their lipophilic nature, these compounds are ubiquitous in the environment and are currently of concern because of their toxicity, oestrogenic properties and widespread contamination. This review summarizes the concentrations of NPE and NP in different environmental media. The sources of NPE in the environment and toxicity are reviewed. Their distribution patterns in the environment as well as exposure pathways are discussed with a view to provide better understanding of these emerging environmental contaminants. It is envisaged that this review will heighten the importance of identifying emerging issues and data gaps, and generate a future research agenda on APEs. Keywords : nonylphenols, nonylphenol ethoxylates, concentrations, exposure pathway, sources, toxicity

Determination of selected organochlorine pesticide (OCP) compounds from the Jukskei River catchment area in Gauteng, South Africa

Abstract: Organochlorine pesticides (OCPs) are continually detected in the environment due to their increasing applications in agriculture and industry. The presence of OCPs in the environment is not desirable since they are well known to have negative impact in humans, animals and birds. Thus, there has been a continual demand to monitor the presence of OCPs within the environment. Liquid-liquid extraction (LLE) and Soxhlet extraction (SE) methods (using dichloromethane as the extracting solvent,) were optimised and evaluated for the determination of these compounds in surface water (unfiltered and filtered) and sediment samples. The crude extracts obtained were subjected to column chromatography for clean-up. Thereafter, 1 µl of the cleaned extracts were injected into the GC equipped with ECD. Percentage recoveries obtained for OCPs ranged from 98.90±7.32 (2,4'-DDE) - 124.1±8.23 endosulfan II (ENDO II) % and from 98.99±5.30 (2,4'-DDE) - 121.1±0.38 (4,4'-DDE) % in spiked triply distilled water and sediment samples respectively. The levels of OCPs obtained in unfiltered environmental water samples ranged from 0.631±0.03 (γ-HCH) - 1 540±0.19 ng·ml-1 (4,4'-DDT) while levels in filtered water samples ranged from 0.895±0.01 (γ-HCH) - 9 089±0.08 ng·ml-1 (HEPTA). Levels of analysed OCPs obtained in sediments ranged from 0.266±0.01 (δ-HCH) - 22 914±2.85 ng·gdw-1 (2,4'-DDE). Analytes adsorbed on the sample bottles used for water samples collection gave levels which ranged from 0.01±0.01 - 1.06±0.02 ng·ml-1 for OCPs. The levels obtained from the catchment were significantly higher than the water criteria values recommended by USEPA and DWAF for the protection of the aquatic environment. Levels obtained were also higher than those of other studies conducted so far in South African aquatic environments. There is, therefore, a definite pollution of the Jukskei River catchment by the OCPs studied.

Alkylphenol ethoxylates and brominated flame retardants in water, fish (carp) and sediment samples from the Vaal River, South Africa.

Abstract: Alkylphenol ethoxylates (APEs) and brominated flame retardants (BFRs) are known to be bio-accumulative, persistent, and endocrine disruptors and can cause adverse health effects in animals and humans. In this study, environmental samples were collected from sites along the Vaal River, South Africa in order to determine the concentrations of APEs and BFRs in water, sediment, and fish samples. The highest concentrations of these pollutants were observed from discharge of the Rietspruit WWTW. Measurable levels of both APEs and BFRs were observed with APEs exhibiting higher concentrations than BFRs in all the matrices. The concentrations observed for APEs and BFRs were as follows: 1.00–3.85 μg/L APEs, 0.09–0.26 μg/L PBDEs, ND- 0.14 PBBs and 0.51–1.77 μg/L HBCD for water samples; 47–63 ng/g lipid APEs, 3.24–12.4 ng/g lipid PBB, 4.63–33 ng/g lipid PBDEs and 10–13 ng/g lipid HBCD for fish; and 40–184 ng/g (wet weight (ww)) APEs, 2.93–5.9 ng/g (ww) PBB, 10–24 ng/g (ww) PBDEs, and 15–52 ng/g (ww) HBCD for sediment samples. The concentrations of APEs and BFRs in water samples were found to be in the range with the results reported in the literature while the concentration in fish and sediment were lower than the concentrations reported in other studies.

Determination of selected phthalate esters compounds in water and sediments by capillary gas chromatography and flame ionization detector

Abstract: The presence of phthalate esters (PAEs) in the environment is not desirable and therefore, needs to be monitored. This study reports the first data on the concentration levels of PAEs in water and sediments of the Jukskei River catchment area, South Africa. The study was conducted during the summer and winter seasons of 2005. Liquid-liquid extraction (LLE) and Soxhlet extraction (SE) methods were optimized, evaluated and used to determine PAEs of interest in water (unfiltered and filtered) and sediments samples, respectively. Mean percentage recoveries in spiked doubly distilled water ranged from 100 ± 5.32 dimethyl phthalate (DMP) – 122 ± 0.46 di-2-ethylhexyl phthalate (DEHP) and 91.6 ± 1.93 diethyl phthalate (DEP) – 117 ± 4.80 dibutyl phthalate (DBP) in sediments. The concentration levels of PAEs studied in unfiltered environmental water samples were in the range of 0.04(± 0.00) (DMP) − 9.76(± 00.1) ng mL−1(DEHP) for PAEs and from 0.09 (± 0.01) (DMP) – 4.38 (± 0.06) ng mL−1(DEHP) for filtered environmen...

Pharmaceuticals, endocrine disruptors, personal care products, nanomaterials and perfluorinated pollutants: a review

Abstract: The presence of emerging micropollutants such as pharmaceuticals, endocrine disruptors, personal care products, nanomaterials and perfluorinated substances in the environment remains a great threat to the health and safety of humans and aquatic species. These micropollutants enter the environment via anthropogenic activities and have been detected in surface water, groundwater and even drinking water at nanogram per litre to microgram per litre concentration. To date, limited information exists on the fate, behaviours, and pathways of these micropollutants in the environment. The potential ecotoxicological effects on the receptors due to exposure to individual or mixture of these chemicals still remain unknown. This review provides an overview on pharmaceuticals, endocrine disrupting compounds, personal care products, nanomaterials and perfluorinated pollutants, with emphasis on their occurrences, effects, environmental fates, and potential risk of exposure in water, soil or sediment. Based on the literature survey, it was found that in spite of an extensive research and different developmental efforts on the challenges of emerging micropollutants, the solution to the problem of emerging micropollutants in the environment is far from being solved. The needs for behavioural change among citizens, strong political will and policy formulation on the part of government are identified as possible panacea for combating the growing influence of these potential damaging substances. Suggestions on proactive and precautionary measures that must be taken to protect the environment as well as guarantee the health and safety of humans and aquatic species are provided. Future research should concentrate on the development of a risk based screening models and framework that can predict the sources, fate and behaviours of emerging contaminants in the environment is recommended.

Hexabromocyclododecanes and tetrabromobisphenol-A in indoor air and dust in Birmingham, UK : implications for human exposure

Abstract: Hexabromocyclododecanes (alpha-, beta-, and gamma-HBCDs) and tetrabromobisphenol-A (TBBP-A) were determined in indoor air from homes (n=33; median concentrations sigma HBCDs = 180 pg m(-3); TBBP-A = 15 pg m(-3)), offices (n=25; 170; 11), public microenvironments (n=4; 900; 27) and outdoor air (n=5; 37; 1). HBCDs and TBBP-A were also determined in dust from homes (n=45; median concentrations sigma HBCDs = 1300 ng g(-1); TBBP-A = 62 ng g(-1)), offices (n=28; 760; 36), cars (n=20; 13,000; 2), and public microenvironments (n=4; 2700; 230). While sigma HBCDs in car dust significantly exceeded (p < 0.05) those in homes and offices, TBBP-A in car dust was significantly lower (p < 0.05) than that in homes and offices. No significant differences were observed between sigma HBCDs and TBBP-A in air or dust from homes and offices. Compared to dietary and inhalation exposures, dust ingestion constitutes an important pathway of exposure to HBCDs and TBBP-A for the UK population. Specifically, using average dust ingestion rates and concentrations in dust, dust ingestion constitutes for adults 34% (TBBP-A) and 24% (HBCDs) of overall exposure, and for toddlers 90% (TBBP-A) and 63% (HBCDs). Inhalation appears a minor exposure pathway to both HBCDs and TBBP-A. On average, dust is 33% alpha-, 11% beta-, and 56% gamma-HBCD, while air is 22% alpha-, 11% beta-, and 65% gamma-HBCD.