Occurrence of CCA-treated timber in caterers’ fuelwood stocks in the Cape Town region

Abstract

Wood used as fuel under conditions of urban poverty is a source of air pollution. Fuelwood is harvested from peri-urban green areas or sourced as waste from industry or commerce, and used in the informal economy, both by households and by productive activities such as roadside catering. End-of-life timber may have previously been treated for protection, sometimes by impregnation with chromated copper arsenate (CCA). Combustion of CCA-treated timber could magnify the health and environmental risks associated with air pollution, as a result of the release of arsenic and chromium in toxic and carcinogenic forms. Fuelwood supplies of roadside caterers in the urban settlements of Nyanga and Khayelitsha were randomly sampled and 86 collected specimens were prepared for analysis. A further 12 samples were taken, based on their appearance, from households and caterers in settlements near Stellenbosch, Worcester and Paarl. Shavings from the timber specimens were microwave digested using nitric acid and analysed using inductively coupled plasma analysis. All samples collected in the first round showed low concentrations of Cr, Cu and As, believed to be representative of natural backgrounds. Of the 12 peri-urban samples collected in the second round, 8 showed higher levels, typical of treatment to H2-H5 standards. Once it was clear that appearance was a fair indicator of treatment, a further set of 18 suspect pieces from caterers' supplies in Langa, Nyanga, Khayelitsha and Kayamandi were tested, of which at least 1 sample from each area was found to be treated. CCA-treated timber was found infrequently in fuel supplies of urban caterers, and more frequently in periurban areas. Further research and interventions to limit health and environmental risks are recommended.

Investigation of Arsenic Airborne in Particulate Matter around Caterers’ Wood Fires in the Cape Town Region

“…At least one wood sample collected from those fires was identified to have been CCA-treated. This was confirmed after comparing the results with the blank sample (Niyobuhungiro, 2012).…”

“…Fuel wood burning has been widely recognized as a significant contributor to ill-health through inhalation of such particulate matter in many developing countries (WHO, 2005). Our recent work has reported evidence that waste timber, previously treated with the insecticide CCA (chromated copper arsenate) is being used by informally operating street caterers in urban and peri-urban settings in the Cape Town region (Niyobuhungiro et al, 2012). The combustion of such wood, which may contain each of the elements Cr, Cu and As in the range of 500-6000 mg/kg, has previously been shown to lead to preferential volatilization of arsenic (Rogers et al, 2007).…”

Exposure to CCA-treated wood amongst food caterers and residents in informal areas of Cape Town

“…A previous investigation indicated that CCA-treated wood used as fuel for open fires in street catering could be a significant potential public health problem in Cape Town. 1 In the latter study, CCA-treated wood samples were found in wood used for informal catering activities with the occurrence of treated wood being more prevalent in urban townships than in peri-urban areas of Cape Town. The wood was sourced from commercial and industrial sources.…”

“…The aim of this study was to compare the exposure to CCA-treated wood and the urinary levels of Cr, Cu and As amongst informal food caterers and household residents in an urban area and a peri-urban area in the Western Cape Province in South Africa, following on from a previous study. 1 The relationship between the usage of CCA-treated wood and urinary levels of Cr and Cu will be examined in another paper.…”

Arsenic residues in soil at cattle dip tanks in the Vhembe district, Limpopo Province, South Africa

“…23 Present-day research on arsenic contamination in South Africa includes the search for arsenic-resistant bacterial genes in mining ash and the pollution levels in treated wood. [24][25][26][27] However, research in the field of arsenic contamination of soil at dip tanks -the focus of our study -has been limited. However, one study, conducted by Moremedi and Okonkwo 28 at Ka-Xikundu village close to the Luvuvhu River, also in the Vhembe district, reported high arsenic levels (above >1000 mg/kg) close to a dip site at the surface, and at 50-mm and 100-mm depths, and a significantly lower concentration of about 0.15 mg/ kg at a control site some distance away.…”