Asbestos exposure during home renovation in New South Wales

Asbestos inhalation is established beyond doubt as the cause of the fatal cancer malignant mesothelioma (MM). Recently, there has been an epidemic of asbestos-related diseases in several westernised nations, resulting from past occupational exposure.1,2 Although estimates suggest that more than 125 million people are exposed to asbestos in occupational settings,3 the number of people non-occupationally exposed is not known.

Asbestos is a generic term for a number of different fibrous silicates, which vary in their potency for causing malignancy and include amphiboles (crocidolite or blue asbestos) and amosite (brown asbestos), and serpentine forms such as chrysotile (white asbestos). Health risks associated with amphibole exposure are much greater than those with chrysotile.4 However, all types are currently classified as carcinogenic, and no threshold for exposure has been identified for chrysotile in recent WHO reports,5 although this issue is still controversial.6

Asbestos use has been banned in many industrialised countries since the 1970s, but asbestos-containing materials are still found in many buildings in Australia, including domestic residences.7,8 The housing boom after World War II required new types of construction materials to compensate for a shortage of bricks,9 especially in New South Wales. Thus, asbestos cement sheeting, commonly known as “fibro”, was intensively produced and used during this period. Australian fibro sheeting contained amphibole as well as chrysotile asbestos until the mid 1980s.7

The United States Centers for Disease Control and Prevention (CDC) have warned that asbestos-containing materials can be disturbed during maintenance, renovation or demolition activities, and that precautions should be used to minimise asbestos exposure.10 Australia has the highest per-capita rate of asbestos diseases in the world, and rates of MM continue to climb.11,12 MM secondary to exposure to asbestos-containing materials is an emerging public health problem.13-17 Recently, there has been concern that exposure from disturbance of building products, including through do-it-yourself (DIY) home renovation activities, accounts for an increasing proportion of deaths from MM.16,17 The proportion of cases of MM in Western Australia attributed to home renovation has increased markedly in both men and women over the past 10 years.17 Home renovation is a popular activity in Australia, and asbestos-containing materials may be a source of exposure to householders if respirable asbestos dust is released.

The Federal Government recently approved a national strategic plan to improve asbestos identification and management and remove all asbestos-containing materials from government and commercial buildings by 2030.18 This includes examination of the feasibility of removal of asbestos from residential properties. Over 820 000 dwellings in Australia (about 15% of dwellings constructed before 1987) are reported to have asbestos-containing materials or fibro as a main construction material, but the exact number of homes containing asbestos products is not known.

No studies have assessed the frequency of home renovation in NSW and the number of people taking precautions against asbestos exposure during these activities. In this study, we aimed to describe the proportion of individuals who reported asbestos exposure during both DIY and non-DIY home renovations and their types of exposure.

This study was conducted between January and June 2008 in NSW, and approved by the NSW Electoral Commission and the Prince of Wales Hospital’s Human Research Ethics Committee. A structured questionnaire was mailed to 10 000 adults randomly selected from the NSW electoral roll. This was designed to measure renovation activity, tasks undertaken and family members exposed to asbestos. Each participant was asked to report on up to three episodes of renovation. Up to two follow-up questionnaires were sent to non-responders. The questionnaire is available on request.

A total of 3612 responses were received, giving an overall response rate of 37.5% (Box 1 and Box 2). There were 363 incorrect addresses and two people were reported as deceased; 9635 people received questionnaires. Of the 3212 participants who reported their age, the mean age was 51.3 years (SD, 13.4 years). There were 1955 women and 1610 men, and 47 participants did not report their sex.

Of the 1597 respondents (44.2%) who reported having home renovations, 858 participants (53.7%) were DIY renovators, and 739 (46.3%) were non-DIY renovators. Most of the DIY renovators (527; 61.4%) reported having had asbestos exposure, and 20 respondents (2.7%) in the non-DIY group also reported having exposure. DIY renovators were more likely to be male (491 respondents; 57.2%) than non-DIY renovators (P < 0.05).

In answer to the question “does your current home contain asbestos?”, 584 respondents (16.2%) reported that it did, and 1020 respondents (28.2%) did not know. Of the respondents who reported that their current homes contained asbestos, 252 (43.2%) were DIY renovators. Of the total 858 DIY renovators, 337 respondents (39.3%) reported that their partner had been exposed to asbestos during renovations, and 196 participants (22.8%) reported that their children had been exposed as well as their partner. Non-DIY renovators were less likely to report exposure to asbestos or that their partner or children had been exposed to asbestos than DIY renovators (P < 0.05). A small proportion of the total group (515 respondents; 14.3%) had plans to renovate their homes in the next 5 years. These plans were more common among the DIY renovators (215 respondents; 25.1%) than non-DIY renovators (110; 14.9%) and those who had never renovated (190; 9.4%; P < 0.05). A small proportion of the total group were living in a house containing asbestos and planning renovations (139; 3.8%). Once more, respondents differed in their renovation plans for homes containing asbestos, with more DIY renovators (76; 8.9%) planning to renovate than non-DIY renovators (27; 3.7%) and those who had never renovated (36; 1.8%; P < 0.05).

Among the DIY renovators, self-reported exposure to asbestos cement fibro sheeting was the most common type of exposure (508/527; 96.4%), followed by exposure to asbestos insulation (73/527; 13.9%) and to other materials, such as those used in bathroom, roofing and fencing work (48/527; 9.1%) (Box 2).

Our study provides the first detailed survey of self-reported exposure to asbestos in home renovation in NSW. We found that reported DIY asbestos exposure was common. As would be expected, women were less likely to report DIY asbestos exposure than men. During home renovations, 22.8% reported their partner and children had also been exposed to asbestos. Only 12.0% of the DIY renovators reported using respiratory protection regularly, while 28.4% used this occasionally. About 14% of respondents planned to renovate within the next 5 years.

Ideally, our study would have measured actual rather than reported exposure, but this was not possible in this epidemiological survey. Assessing past exposures is difficult. In the occupational context, many approaches exist: detailed occupational histories, job exposure matrices, expert assessments and exposure databases, among others. However, it is acknowledged that the variability between studies is significant and that overall the validity of exposure estimation methods is poor.19 Validity is likely to be even more questionable for non-occupational exposures, although this issue deserves more research. It is likely that overall exposures from reported asbestos contact will be low. Measurement of airborne asbestos fibre levels during renovation of asbestos cement-clad buildings have shown levels between 0.1 and 0.2 fibres per mL, reducing when appropriate precautions are used,20 but few Australian data are available.7 The exact risk at low levels of exposure (particularly with mixed types of fibres) has not been quantified.

One limitation of our study was the relatively low response rate. Although we designed the study to allow adequate power, and contacted non-responders with reminders, the participation rate was only 37.5%. However, this response rate is comparable to that of other studies,21 and included the largest number of respondents yet surveyed about non-occupational exposure to asbestos in Australia. We have no reason to assume that responders were more likely to have been exposed to asbestos or to live in homes containing asbestos than non-responders. Some aspects of the survey returns suggest that our results are representative of the NSW population; for example, similar smoking rates to those reported elsewhere,22 and the higher rate of DIY activity in men. However, our participants were younger than usual NSW residents,23 possibly reflecting a greater interest in asbestos hazards among younger people. Declining response rates in epidemiological studies are a recognised problem,24,25 and are affected by questionnaire design and mailing strategies.26 Our questionnaire design took into account the current available information on asbestos exposures in NSW,27 but is the first such questionnaire to be trialled in this population.

The issue of the role of low-dose exposure in the pathogenesis of MM remains controversial, and is outside the scope of this report. Current unresolved questions include the magnitude of the risk with low-dose exposure, contamination of chrysotile with amphibole asbestos, and whether a threshold level exists below which carcinogenesis does not occur.4,6,14-16 Compared with occupational exposure, domestic exposure to asbestos is likely to be low28,29 and also to be underestimated, as asbestos can be difficult to identify — knowledge about the frequency with which it is used is generally low even in construction workers who would be expected to be aware of these hazards.8 To our knowledge, an assessment of the awareness of asbestos in domestic dwellings and accuracy of people’s perception of any potential hazard has not been reported.

This study documents significant potential exposure to asbestos during DIY home renovation in NSW. Self-reported asbestos exposure during DIY renovations is common, as is reported exposure of family members, and even basic precautions regarding protection against asbestos inhalation are not used in many DIY renovations. Although recommendations have been made for asbestos removal in the commercial sector, active steps also need to be taken to prevent future possible disease in the residential sector as well. Whether exposure during home renovation will result in disease in the future remains to be seen; however, this entirely preventable exposure needs to be addressed.