Investigating Arsenic Contamination in Historic Buildings

Investigating Arsenic Contamination in Historic Buildings: An Aspect of Site Hazard Assessment – An Essential Service

"Native arsenic" by Aram Dulyan  

EBS Ltd has been successfully carrying out independent inspections of buildings and building sites to protect operatives, visitors and occupants from exposing themselves to hidden hazards and potential dangers.

For those contemplating renovation work on an old building, starting work on a new site or proposing an on-site inspection, this preliminary Site Hazard Assessment service could prove to be a vital first step.

The Site Hazard Assessment service will include any or all of the following, tailored to your particular project:

• Testing for Arsenic in historic paintwork, insecticide & pesticides treated wood
• Testing for Anthrax in animal hair hidden within lath & plaster
• Mould levels, including identification for pathogenic & toxic moulds
• Lead levels in paint work
• Hazardous dust assessment & fibrous materials (other than asbestos) – samples collected as necessary
• Electrical components for possible PCB or mercury presence – visual assessment
• Timber treatment chemical assessment

This article describes issues relating to Arsenic

EBS Ltd carries out a preliminary diagnostic, non-destructive, environmental inspection for possible Arsenic contamination.  Arsenic was widely used for treatment of wood (CCA) and historic paintwork that may be incorporated within the plaster of ceilings and walls in old buildings.

Samples are carefully collected and forwarded to an accredited laboratory for elemental analysis to provide information on the possible presence of Arsenic. Paint coatings may also be gathered to detect whether they contain harmful, toxic metals.

Arsenic has been found to be present in old plaster.  The reasons are not entirely clear but it is known that the leather making industry used to soak animal skins in a lime and arsenic slurry to soften them and remove hair.  Arsenic may therefore be associated with any animal hair within plaster.

It is known that arsenic compounds were used as pigments in green paints and wallpapers.

Arsenic may also have been added to plaster to make it set quicker and used as a preservative in timber materials.

Arsenic was widely used in insecticides and pesticides and for treatment of wood, chromated copper arsenate (CCA).

Workplace Exposure Limit

Analysis of various plaster samples has revealed that some contain low levels of arsenic, between 4 mg/kg and 13 mg/kg.  Whilst there does not appear to be any formal guidance regarding what would constitute a safe limit in plaster, arsenic and arsenic compounds have been assigned a Workplace Exposure Limit of 0.1 mg/m3.  This concentration relates to exposure to an airborne concentration averaged over an 8-hour period.  As well as being toxic, arsenic compounds are held to be carcinogenic.

Arsenic levels detected in some plaster samples may be lower than the UK Soil Guidance Level of 32 mg/kg for soil in residential properties. Nevertheless it is clear that inhalation of plaster dust containing such levels, would present a real risk to health.  In situations where significant disturbance of the plaster is taking place, the airborne hazard would be increased, therefore appropriate control measures should be put in place to control dust generation and protect personnel.

As well as inhalation of plaster dust, there is the risk of potential ingestion if good health and safety and personal hygiene practices are not adhered to.  For example arsenic may transfer from dirty hands to food etc.

A systematic risk assessment should be carried out to assess possible exposure to arsenic for all activities involving work on plaster and the requirements of the COSHH Regulations should be followed.

For further information and advice, please contact us.