Annals of Occupational Hygiene Advance Access originally published online on December 21, 2006
Annals of Occupational Hygiene 2007 51(2):113-119; doi:10.1093/annhyg/mel077
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Exposure of UK Industrial Plumbers to Asbestos, Part II: Awareness and Responses of Plumbers to Working with Asbestos During a Survey in Parallel with Personal Sampling
Health and Safety Laboratory, Harpur Hill Buxton SK17 9JN, UK
*Author to whom correspondence should be addressed: E-mail: delphine.bard{at}hsl.gov.uk
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ABSTRACT |
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 TOP ABSTRACT INTRODUCTIONAIMS AND STRATEGYMETHODSRESULTSCONCLUSIONSAPPENDIXACKNOWLEDGEMENTSREFERENCES |
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Throughout the European Union, millions tonnes of asbestos were used in the manufacture of products for building and for industrial installations. Today, in the UK, it is estimated that over half a million non-domestic premises alone have asbestos-containing materials in them and it is recognized that those working in building maintenance trades continue to be at significant risk. In part II, the awareness of UK plumbers to when they are working with asbestos was investigated and compared with the monitored levels reported in part I. The plumbers were issued by post with passive samplers, activity logs to monitor a working week and a questionnaire. The activity logs were used to assess whether maintenance workers were knowingly or unknowingly exposed to airborne asbestos fibres during a course of a working week. The questionnaire was designed to gather information on their: age, employment status, current and past perception of the frequency which they work with asbestos and knowledge of the precautions that should be taken to limit exposure and risk. Approximately 20% of workers reported on the sample log that they had worked with asbestos. There was a high correlation (93%) between the sampling log replies that they were knowingly working with asbestos and measured asbestos on the passive sampler. However, some 60% of the samples had >5 µm long asbestos structures found by transmission electron microscopy (TEM) analysis suggesting that the plumbers were aware of about only one-third of their contacts with asbestos materials throughout the week. This increased to just over one half of the plumbers being aware of their contact based on the results for phase contrast microscopy (PCM) countable asbestos fibres. The results from the questionnaire found that over half of the plumbers replying thought that they disturb asbestos only once a year and 90% of them thought they would work with asbestos for <10 h year–1. Their expectations and awareness of work with asbestos were therefore far lower than found during the period of monitoring. The response to an open question on the precautions to be taken, found that 61% of plumbers would avoid disturbance and 59% would use respiratory protection if they did disturb asbestos. However, their awareness of the methods and the need to reduce their risk by control of emissions at source was very low and suggests that further awareness raising and training is needed. The survey was carried out prior to the introduction of the duty to manage and gives a useful baseline to assess the impact of regulatory initiatives.
Keywords: Asbestos • exposure • awareness • maintenance worker
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONAIMS AND STRATEGYMETHODSRESULTSCONCLUSIONSAPPENDIXACKNOWLEDGEMENTSREFERENCES |
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Inhalation of asbestos fibres can lead to fatal diseases such as lung cancer, mesothlioma and asbestosis. There is a long latency period between first exposure to asbestos and the development of the diseases, typically from 15 to 60 years. Past industrial manufacture and use of asbestos-containing products has led to a high incidence of asbestos related diseases and this accounts for a high proportion of all industrially related cancers (Peto et al., 1995, 1999). The present incidence of asbestos related diseases is a result of exposure experienced by workers 30–40 years ago and the annual mortality rates due to past asbestos exposure are predicted to continue to rise over the next 15 years, regardless of any further controls that could be applied now. Although UK and European Union (EU) have taken measures to reduce the risk from asbestos exposure, there are a number of sources that have the potential for continuing exposure and future disease. Large amounts of asbestos are still in place in buildings and epidemiological data suggest that there has been and continues to be a significant risk to demolition and maintenance workers, who may through their work unknowingly disturb asbestos-containing materials (McElvenny et al., 2005). Present exposures may result in asbestos related diseases, which will not emerge until the years 2030–2040 due to the long latency period between first exposure and the development of the diseases.
Maintenance workers might disturb or damage asbestos-containing materials (ACMs) in the course of their work and might be unknowingly exposed to airborne asbestos fibres. Plumbers are one of the highest risk cohorts of workers with a proportional mortality ratio of 4.57 based on 1978–1995 mesothelioma figures.
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AIMS AND STRATEGY |
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The aim of this study was to assess whether industrial plumbers were knowingly or unknowingly exposed to asbestos and obtain a detailed picture of workers' awareness, assumptions and responses to working with asbestos-containing materials (ACMs). This UK baseline study was carried out before the new duty to manage asbestos (Regulation 4) in the control of asbestos at work regulations (HSE, 2002) came into force (May 2004).
As mentioned in Burdett and Bard (2007) (hereafter referred to as Part I), the strategy was to recruit a target group of 100 industrial plumbers through the Institute of Plumbers. This group was issued by post with a passive sampler, a set of instructions, an activity log to monitor a working week and a questionnaire. The samplers returned were analysed for asbestos using analytical transmission electron microscopy (TEM) and along with the activity logs would be used to assess whether maintenance workers were either, knowingly or unknowingly, exposed to airborne asbestos fibres during the course of a working week. A second round of sampling for a further week took place for those who returned the sampler. The questionnaire was also analysed using the TEM results to gain information on plumbers' awareness to asbestos.
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METHODS |
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An initial feedback form was used to define the size of the company and the number of plumbers employed. The questionnaire sent out with the first sampler contained 10 questions of which 1 was an open question rather than a tick box reply (see Appendix). The questions were designed to obtain information in a number of important areas including the duration of employment and age, an assessment of their own ability to detect asbestos-containing materials and to assess their response if they came across asbestos materials. The questionnaire was designed in a tick box answer format, both for ease of analysis and to limit any ambiguity in the interpretation.
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RESULTS |
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In Round 1, a total of 96 passive samplers and questionnaires were sent out to plumbers, who had indicated they were willing to participate in the survey. In Rounds 1 and 2, 50 and 24 samplers with activity logs were returned along with 48 questionnaires completed in Round 1. The TEM analysis of the passive samplers was discussed in Part I.
Questionnaire results
Of the respondents 54% were employees and 46% self-employed, mainly working in small enterprises of whom 90% worked for companies of 
10 employees.
Most of the respondents (86%) were 35–55+ years old and the average working experience per plumber is 23.6 years based on 46 replies.
Most of the plumbers surveyed (79%) thought that they were able to recognize ACMs (12% very well and 67% quite well). Only one plumber answered not at all to this question. This worker started in the profession 3 months ago and was currently under training. The remaining maintenance workers (19%) thought they were not very well able to recognize ACMs.
In answer to the question ‘how do you normally find out if the work involves disturbing asbestos materials?’, 81% of the plumbers selected the statement ‘from experience’. For 56% of the respondents, experience is the first choice for deciding if the work involves disturbing ACMs and for 19% it is the only factor they mentioned. While 69% of the plumbers said they would ask the employer or owner/manager of premises, 19% ranked this method first, 73% replied they would identify asbestos from labels stuck on materials and 12% ranked this method first. Only 6% of the plumbers surveyed replied they did not know what to do.
The question ‘What precautions do you normally take?’ was an open question. The answers were analysed and grouped in 11 categories/good work practices. The most common precautionary measures given were ‘carry out the work avoiding disturbing ACMs or do not work with asbestos’ (61%) and ‘wear respiratory protective equipment (RPE)’ (59%). Of these 20% mentioned overall or protective clothing, 20% gloves and 10% other personal protective equipment (PPE) such as goggles or hat. Only 15% of them thought about wetting, which is an important control measure. Few thought about personal decontamination (7%) and similarly, keep disturbance to a minimum (5%), avoid breaking ACM (2%), clean the work area on completion of the work (2%) or dispose of asbestos waste (5%). Nobody mentioned the use of hand tools in preference to power tools or the use of low dust cleaning method. Some plumbers answered ‘ventilate the area’ (7%).
About half of the respondents (52%) thought they worked with ACMs only once a year, 29% every 6 months and 14% once a month (Fig. 1). None of them answered once a day or once a week. Two plumbers thought they never disturbed ACMs. Furthermore, most of them (90%) over the last year thought they did not work at all with asbestos (30%) or worked <10 h (60%) (Fig. 2). Only 10% of the plumbers answered 10–40 h and none of them ticked the box 40–100 h or >100 h.
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In general, the plumbers surveyed thought they worked more with ACMs 5 years ago and even more 20 years ago (Figs 3 and 4). However, the majority of them believed they may have disturbed ACMs only once a month or less 5 years ago and 20 years ago. Also, 8% thought they worked with ACMs once a week 5 years ago, compared with 17% 20 years ago and 3% once a day 5 years ago, compared with 11% 20 years ago.
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Sampling log results
The sample logs also contained a number of questions about whether they were working with asbestos and the types of materials being disturbed during the sampling period.
In Round 1, a total of 456 jobs were carried out over the period sampled giving an average of 9.1 jobs for each plumber per week. In Round 2, a total of 235 jobs were carried out over the sampling period, giving an average of 9.8 jobs per week. Although the plumbers contacted were all listed as industrial plumbers, 75% of Round 1 jobs and 64% of Round 2 jobs were carried out in domestic premises (72% overall).
A number of plumbers replied yes to the question on the sample log about whether they were knowingly working with ACMs (Table 1). The results from both rounds were similar. Two replies in Round 2 were answered as ‘yes?’; these have been listed as ‘may be’. Some plumbers also answered ‘no’ but included details of the material being disturbed and gave times for the length of the disturbance. This would mean that some 16 workers (22%) were thought to be working with asbestos.
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In Round 1, a total time of 10 h 50 min was reported as spent working with ACMs. In Round 2, 7 h 20 min were reported as work with ACMs to give a total time of 18 h 10 min. This works out to on average of
0.5% of the working time involved work with asbestos. The maximum time reported as work with ACMs was 630 min and was spent on asbestos packings and loose insulating sprays. Under the UK asbestos licensing regulations (ASLIC, 1987), this work should have been carried out by licensed removal contractors; although, it is not clear whether these materials were merely in the vicinity of the work or directly disturbed. From the sample logs, it appeared that the most common type of ACM disturbed during sampling was cement products (30%) followed by pipe and boiler lagging (19%) (Table 2). One plumber replied that he had worked with an asbestos heat shield mat and another that he had worked with an asbestos sheet. The use of flame resistant mats when using a blowlamp is presumably widespread practice to prevent damage to the nearby surfaces but whether these contain or may contain asbestos is an interesting point. Past observations suggest that these mats were commonly made of chrysotile and their use could account for the large numbers of samples containing chrysotile.
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Comparison between sample log data and the TEM results
In Round 1, of the 10 participants reporting ‘yes’ for work with ACMs, 7 had measurable phase contrast microscopy equivalent (PCME) asbestos fibre concentrations and 9 had measurable >5 µm long asbestos structure concentrations (Table 3). Of the total of 19 workers who possibly thought/suspected/knew they had worked with asbestos over the two rounds, 16 had >5 µm long asbestos structures on their badges (84%). This represented quite a good positive identification of when asbestos was present, which increased to 93% when only the ‘yes’ responses were used.
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However, when the ‘no work with asbestos’ replies were analysed over the two rounds, >5 µm asbestos structures were detected in 53% of the cases and 31% had PCME asbestos fibres. This meant that while there were few false positives there were many false negatives.
The average estimated asbestos concentrations for these two groups of workers are summarized in Table 4. This gives the surprising result that the asbestos exposure of workers who thought they were not working with asbestos, on average, was higher, than the exposure of those who knew they were. Overall, the passive sampler monitoring demonstrated that there was a greater exposure to asbestos than the plumbers were aware of. This result is of concern, although it could be explained by the precautions taken by those knowingly working with asbestos.
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Further insight into plumbers' views and experience of working with asbestos can be obtained by comparing their questionnaire responses with the TEM results and the sample log data. Answers to questions 7 and 8 of the questionnaire (Figs 3 and 4, respectively) regarding frequency and duration of contact with ACMs suggest that
2% of the plumbers surveyed as working with ACMs during the sampling week. In fact the sampling logs indicated that 22% of plumbers were working with asbestos and the TEM results showed an even higher frequency of contact. Over the two rounds, 41% of the samplers were found to contain at least one PCME asbestos fibre and 61% contained at least one >5 µm long asbestos structure (see Table 5). In terms of exceeding the limit of quantification (>3 asbestos fibres counted in the area examined), 15% of the badges were found to contain PCME asbestos fibres, 35% contained >5 µm long asbestos structures.
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The durations of work with ACMs from the questionnaire disagree with the values from the sampling suggesting a degree of caution must be applied to all questionnaire responses and their interpretation.
Investigation of the higher asbestos fibre levels (PCME fibre concentration approaching or exceeding 0.1 f ml–1) showed that the plumbers were not always aware that asbestos was being disturbed as there was an equal number of plumbers showing high exposure levels, who reported ‘yes’ for work with ACMs compared with ‘no’.
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CONCLUSIONS |
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TOPABSTRACTINTRODUCTIONAIMS AND STRATEGYMETHODSRESULTSCONCLUSIONSAPPENDIXACKNOWLEDGEMENTSREFERENCES |
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A questionnaire, when carried out in parallel with a monitoring strategy provides a more comprehensive assessment of worker awareness, assumptions and responses to working with ACMs.
The passive sampler and the analytical method appeared to have a high correlation rate (93%) with the plumbers who replied ‘yes’ to working with ACM's. The one instance where asbestos was not found was for 10 min work with a cement sheet, which may or may not have contained asbestos and does not readily release fibres.
The results of the TEM analysis of the passive samplers showed that the percentage of workers exposed to >5 µm asbestos structures was 62% in Round 1 and 58% in Round 2; the values for PCME asbestos fibres were 46 and 29%, respectively. The number of workers reporting work with ACMs on the sample logs was 20% suggesting they were underestimating or unaware of many of their contacts with ACMs during sampling.
The questionnaire suggested that over half of the respondents would expect to disturb ACMs only once a year and 90% thought they would work with ACMs less than 10 h per year. This showed their overall awareness and expectations of working with ACMs a substantial underestimate compared with the TEM and sample log results.
Although 60% of the plumbers said they would avoid disturbing asbestos or wear respiratory protection only a small percent of them mentioned the use of control methods in the questionnaire.
Using best estimates, the average PCME asbestos concentrations of the plumbers who indicated they had worked with ACMs was 0.05 f ml–1. The plumbers who had not worked with asbestos had an average PCME asbestos concentration of 0.06 f ml–1, showing their exposure was not modified by their awareness that ACMs were or were not being disturbed. Although open to interpretation the implication is that many plumbers were unaware they were disturbing ACMs and applied no controls.
This survey of industrial plumbers will act as a baseline to assess the effect of the introduction of the duty to manage asbestos (Regulation 4, Control of Asbestos at Work Regulations, 2002) in premises.
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APPENDIX |
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TOPABSTRACTINTRODUCTIONAIMS AND STRATEGYMETHODSRESULTSCONCLUSIONSAPPENDIXACKNOWLEDGEMENTSREFERENCES |
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ACKNOWLEDGEMENTS |
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TOPABSTRACTINTRODUCTIONAIMS AND STRATEGYMETHODSRESULTSCONCLUSIONSAPPENDIXACKNOWLEDGEMENTSREFERENCES |
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The authors thank the Institute of Plumbers for their help and the many plumbers who took part in the survey.
Received February 27, 2006; in final form November 3, 2006
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REFERENCES |
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TOPABSTRACTINTRODUCTIONAIMS AND STRATEGYMETHODSRESULTSCONCLUSIONSAPPENDIXACKNOWLEDGEMENTSREFERENCES |
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Burdett G and Bard D. (2007) Exposure of UK industrial plumbers to asbestos. Part I – Monitoring of exposure using personal passive samplers. Ann Occ Hyg 51: [this issue].
Health and Safety Executive (HSE). (2002) Control of asbestos at work regulations (CAWR)—Work with insulation, asbestos coating and asbestos insulating board. (The Stationary Office., London) 4th edn. ISBN 0 7176 2563 X.
Health and Safety executive (HSE). (2002) Control of asbestos at work regulations (CAWR)—Work with asbestos, which does not require a licence. (The Stationary Office., London) 4th edn. ISBN 0 7176 2562 1.
McElvenny DM, Darnton AJ, Price MJ, Hodgson JT. (2005) Mesothelioma mortality in Great Britain from 1968 to 2001. Occup Med (Lond) 55:79–87.
Peto J, Hodgson JT, Mathews FE, Jones JR. (1995) Continuing increase in mesothelioma mortality in Britain. Lancet 345:535–9.[CrossRef][Web of Science][Medline]
Peto J, Decarli A, La Vecchia C, Levi F, Negri E. (1999) The European mesothelioma epidemic. Br J Cancer 79:666–72.[CrossRef][Web of Science][Medline]
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