Is our drinking water safe from asbestos contamination? It’s a question that may not be so strange to ask in 21st century Britain, even though the most dangerous blue and brown asbestos types were banned in the UK more than thirty years ago. It’s also a question that could be a cause for concern in south east England where nearly a third of the drinking water supplied to the Surrey village of Cranleigh is conveyed through pipes made with asbestos cement.
Professional building trade associations, and the Health and Safety Executive (HSE) continue their campaigns of asbestos awareness to warn about the dangers of exposure. Asbestos containing materials can still be present in any public, commercial or residential building constructed in the UK up to the end of 1999, when imports of white asbestos were finally banned.
It is well-documented that in the years of post WW2 reconstruction, asbestos fibres were widely used throughout the building industry as insulation and material strengthener. During Britain’s peak use in engineering and construction, asbestos imports climbed from just under 170,000 tonnes in 1960 to 183,000 tonnes in 1973 alone. The annual numbers of mesothelioma fatalities significantly rose from the late 1960s onwards as exposures with an increased background or “environmental” risk in a wide variety of settings also occurred.
A considerable number of construction materials were made with a mixture of cement and 10 -15 per cent or even more of asbestos, such as insulation board (AIB), millboard, corrugated roof sheets and in particular, cement pipes. Manufacturers were able to cast cement pipes that were unusually lightweight while retaining the required strength and thickness of diameter.
Higher than average number of pipes made from asbestos
The Drinking Water Inspectorate (DWI), which checks that water companies in England and Wales meet the standards set down in law to supply safe drinking water say there is “no reason for concern” in Cranleigh. The DWI refer to evidence from the World Health Organisation , which concluded that “there is no requirement to set a standard for asbestos in drinking water.”
At the same time, Thames Water say they are “vigorously testing” the water quality, while pointing out that “asbestos cement pipes have been widely used” for drinking water distribution and “there are thousands of kilometres to be found all over the world”. However, the authorities in Cranleigh are not convinced by the lack of tangible evidence to support the assurances that the water is safe. A community spokesman highlights that the drinking water in their area is supplied with a higher than average number of pipes made from asbestos, nearly a third (29 per cent) compared to 2 per cent for the south east of England.
The question of whether there is an increased health risk can depend on different individual factors. Since the late 1970s and early 80s, studies have indicated that a water supply did contain asbestos fibres. In some cases, it was found that there was an increase in the number of asbestos fibres present in drinking water, particularly when the pipes were first installed, although levels would later quickly subside. However, US research carried out in areas where asbestos cement pipes had been extensively used, found no consistent patterns of cancer associated with consumption of asbestos from drinking water.
Asbestos fibres in drinking water were mostly within safe proportions
Fibre size and surface characteristics are also important factors in evaluating health risk. Asbestos fibres greater than 8 µm (micrometres – thousands of an inch) in length and less than 0.25 µm in diameter are regarded as posing the greatest threat while very short fibres of less than 1 µm are considered to be of low risk. Results from studies conducted in Europe, US and Canada found that asbestos fibres in drinking water were mostly within safe diameter categories and in proportions of 1 to 1.1 million fibres per litre.
The presence of asbestos in any building or environment is rightly seen as a cause of concern, despite the assurances in some quarters that there no risk or possibly only a “low risk”. In May 2011, the government confirmed medical opinion that white asbestos is a Class 1 cancer-causing agent without a confirmed threshold level, below which, exposure is not a risk to human health. In 2013, an European Parliament report called for the removal of asbestos from all public buildings by 2028, which could finally signal the end of so-called “low risk” chrysotile white asbestos being simply “contained and managed” in thousands of properties around the UK.
In their 1993 edition of the “Guidelines for Drinking Water Quality”, the World Health Organisation (WHO) stated that there was “ little convincing evidence” of cancer causing properties in asbestos consumed in studies of populations with drinking water supplies containing high concentrations.”
In addition, the WHO Drinking Water Committee did not regard revision as necessary when considering the presence of asbestos in drinking water. While asbestos cement pipes have been widely used for drinking water distribution worldwide, including many European countries, few if any countries continue to install asbestos cement piping. Apart from the issues of direct exposure through handling, the health of consumers receiving the water was considered safe for drinking.