Laura Quinn

Dioxin-like chemicals in soil and sediment from residential and industrial areas in central South Africa.

Persistent organic pollutants (POPs) are a global concern due to their ubiquitous presence and toxicity. Currently, there is a lack of information regarding POPs from South Africa. Here we report and interpret concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), -dibenzofurans (PCDFs) and co-planar-biphenyls (PCBs) in soils and sediments collected from central South Africa. High resolution gas chromatography-high resolution mass spectrometry (HRGC/HRMS) and the H4IIE-luc bio-assay were used to identify and quantify individual PCDD/F congeners and to report the total concentration of 2,3,7,8-tetrachloro dibenzo-p-dioxin equivalents (TCDD-EQ), respectively. TCDD-EQs determined by use of the bio-assay, and concentrations of WHO(2005)-TEQ (toxic equivalents) determined by chemical analysis, were similar. The limit of detection (LOD) for the bio-assay was 0.82 and 2.8 ng TCDD-EQ kg(-1), dw for sediment and soil, respectively. EQ20 concentrations determined by use of the bio-assay ranged from <LOD to 70 ng TCDD-EQ kg(-1), dw for soil, and from <LOD to 45 ng TCDD-EQ kg(-1), dw for sediment. Concentrations of WHO(2005)-TEQ in soils were generally greater than those in sediments, and soils from the industrial area of Vanderbijlpark and the residential area of Klerksdorp contained the greatest concentrations. Based on the congener-specific HRGC/HRMS analyzes, concentrations of WHO(2005)-TEQ ranged from 0.12 to 32 ng WHO(2005)-TEQ kg(-1), dw in sediments, and between 0.34 and 20 ng WHO(2005)-TEQkg(-1), dw in soils. The sources, processes and threats that govern and are associated with the lesser concentrations in sediment and greater concentrations in soils need further investigation.

Pesticide Use in South Africa One of the Largest Importers of Pesticides in Africa

South Africa is a diverse country, with a diverse environment that is home to more than 49 000 000 people. Pesticide usage is very often necessary to maintain both agricultural productivity as well ...

Polycyclic Aromatic Hydrocarbons (PAHs) in Soil and Sediment from Industrial, Residential, and Agricultural Areas in Central South Africa: An Initial Assessment

Polycyclic aromatic hydrocarbons (PAHs) are of global concern due to their ubiquitous presence, toxicity, and carcinogenicity. No data on PAHs in soils from South Africa have been published, even though it has the largest economy and industrial base in Africa. During this initial assessment, the levels of PAHs were determined in soils and sediments collected from central South Africa, specifically targeting industrial, residential, and agricultural areas. Analysis was performed by gas chromatography/mass spectrometry (GC/MS). The total concentration of PAHs (Σt-PAH) ranged between 44 and 39,000 ng/g, dw and the concentration of carcinogenic PAHs (Σc-PAH) ranged between 19 and 19,000 ng/g, dw. Pyrogenic processes were the most likely sources, with minimal petrogenic contributions. PAH levels were in the same range as levels reported from other countries, and the majority of the sites did not exceed Canadian environmental quality guidelines. Based on assumptions for dermal contact and ingestion of PAH-contaminated soil, we provisionally calculated only a small increase in cancer risk, but additional PAH inhalation could add considerably to this risk. Our data indicates a need for more analysis in industrial and residential areas, and should include air.

Levels of PCBs in wild bird eggs: Considering toxicity through enzyme induction potential and molecular structure

Polychlorinated biphenyls (PCBs) were analysed in wild bird eggs from industrialised areas in South Africa. The concentration, congener profile, feeding guild, potential associated risk and biology were investigated. PCBs were detected in all eggs with 30 congeners present in more than 80% of the samples. Σ(34)PCB concentrations ranged between 0.9 and 296 ng g(-1) wet weight (ww). The metabolic potential of the PCB metabolic groups showed good agreement with the biodegradability of the individual congeners. Phenobarbital-type (PB-type) inducer PCBs were prevalent, indicating the predominance of less toxic PCB congeners. However, non-ortho PCBs which were not included in the current analyses, could affect the toxic potential of the PCBs in the eggs requiring more investigation. Although the current levels of PCBs measured do not indicate a health risk to the birds assessed, the presence of mono-ortho PCBs at appreciable levels motivates for the assessment of dioxin-like chemicals in wild bird eggs.

Polycyclic aromatic hydrocarbons (PAHs) in sediments from a typical urban impacted river: application of a comprehensive risk assessment

Soweto and Lenasia, the most densely populated area of South Africa, is simultaneously a thriving metropolis, with a fair share of people still living in squalor conditions directly dependant on the natural resources. Because of industrialisation the populace and environment in this urban area are exposed to various pollutants. The aquatic environment was selected as a proxy to study the effect of industrial pollution in this area. The concentrations, source identification, and various environmental risks of polycyclic aromatic hydrocarbons (PAHs) were determined in sediments of the upper reaches of the Klip River. Composite sediment samples collected in low-flow conditions in 2013 and 2014 ranged from 270–5400 ng/g. The PAHs in this aquatic ecosystem were dominated by 4-ring congeners and could be attributed to combustion of organic fuels by chemical mass balance. Heavy traffic and industrial complexes in the northern part of the study area were responsible for the PAH fingerprints. Probable adverse effects such as toxicity to benthic biota were proven after comparison with international sediment quality guidelines (SQG) both survey years. Toxic equivalence quotients (TEQs) calculated for the sediments using fish potency factors (FPFs) were up to 30 times greater than the Canadian guideline for dioxin-like compounds, indicating high probability of carcinogenic effect to fish mediated through the aryl-hydrocarbon receptor. Finally, sediments in the area posed moderate to high ecological risk, which corroborates the other toxicity assessments. The advantage of investigating multiple risk endpoints, is the comprehensive results obtained that allows for a more realistic representation of the study area. Consequently more aspects are kept into account that results in better conclusions.

Response to: Roberts, D.R., et al. on Bouwman, H. et al. Hallogenated pollutants in terrestrial and aquatic bird eggs: converging patterns of pollutant profiles, and impacts and risks from high levels. Env. Res. (2013) 〈http://dx.doi.org/10.1016/j.envres.2013.06.003i〉.

Roberts et al. present five lines of argument in an attempt to weaken the findings and conclusions of our article (Bouwman et al., 2013). We respond to each. (1) Roberts et al. argue that we presented no data to show that there were “fewer piscovore bird populations present” in the malaria controlled area. First, let us correct their sentence – we searched for all “aquatic bird colonies”, a suite of species different and larger than only piscivore birds. Secondly, we did not find “fewer” colonies. We found no breeding aquatic bird colonies after many days of fruitless searching with the help of a professional local bird guide. The datum we presented therefore effectively represents zero and we mentioned this a couple of times in the article. We did find a colony of (terrestrial, not aquatic) Cattle Egrets in the malaria controlled area, and aquatic bird breeding colonies west of Thohoyandou, demonstrating a high probability of finding such if they were present. Furthermore, in 2008, we flew the entire length of the Luvuvhu River inside the Kruger National Park (KNP) by helicopter (for a different project), and also found no breeding colonies inside this world-renowned nature reserve. (The KNP is downstream of our sampling sites.) The lack of breeding colonies was further corroborated by a search on foot of the entire KNP part of the river by an independent team specifically tasked to survey all fish-eating birds in the KNP part of the Luvuvhu River (Botha, 2012). In 2012 they recorded eight African Fish Eagles, five Goliath Herons, one Saddle Billed Stork, four Giant King Fishers, and up to 16 Pels Fishing Owls. However, no Grey Herons were seen over a distance of 23.5 km. It should be noted though, that flooding may have played a role in the 2012 survey. From 2008 to 2011 no more than three Grey Herons were counted in any year, and slightly higher numbers of the other species. An additional request for information for this letter confirmed no breeding or roosting colonies of any aquatic bird along the Luvuvhu River in the KNP, but there is one small breeding colony of Openbilled Storks to the south on a floodplain, and another small colony of cormorants and darters on a pan north of the river. Therefore, in the malaria controlled area, there were no breeding aquatic bird colonies, but there were on either side. There were no prior data we could trace on breeding bird colonies in this remote and rural malaria controlled area outside the KNP. Such data are not regularly collected in South Africa as is the case in many other countries. We could only infer from the study by Laporte (1982) that found Great Blue Herons in Canada having abandoned the colony where DDT concentrations in eggs were the highest, only somewhat higher then we found for the Grey Heron here. It should also be kept in mind that malaria control in this area using DDT has been practiced for more than 60 years. Therefore, any bird breeding data should be older than 60 years – clearly a bit much to expect. We have qualified our statement in the text on this issue as “apparent absence”, and believe this more than answers any objection. (2) Roberts et al. takes issue with part of a sentence in our article that the sparrows with the exceedingly high DDT concentrations “....have developed tolerance to DDT.....”. Our sentence is doubly qualified and parts should not be taken out of context. Keeping in mind that we also referred to the very high DDT concentrations in chickens, we said: