The level of contamination was found to be up to 2,000,000 asbestos fibres per gram of soil. The extent of the contamination of the soil beyond the rain water run off line was not determined. A recommendation of the study was to wet down soil around houses before performing any excavations.
A method for determining asbestos fibres in soil was developed for the study. This method involves the suspension of soil in water followed by filtration and preparation for examination using scanning electron microscopy (SEM). The scanning electron microscope allows fibres to be identified by their morphology and chemical composition using energy dispersive X-ray spectroscopy (EDS). The method to determine asbestos fibres in soil has been applied to contaminated soils around rail tracks and building sites. The method is offered as a service by the NIOH and requests for this service should be addressed to Dr J I Phillips, Head of Electron microscopy, NIOH.
Reference
1Phillips JI, Renton K, Murray J, Garton E, Tylee BE, Rees D. Asbestos in and around Soweto dwellings with asbestos cement roofs. Occup Health Southern Africa 2007;13(6):3-7.
2Phillips JI, Renton K, Badenhorst C. Potential health hazard from cleaning asbestos cement roofs: a case report. Occup Health Southern Africa 2006; 12(5):20-22.