1 / 12 253 Avenue du Général Leclerc – 94701 Maisons-Alfort Cedex, France – siren: 180092348
The Director General
Maisons-Alfort, France, 9 February 2009
OPINION
of the French Agency for Environmental and
Occupational Health Safety
Relating to "taking into account the dimensional criteria for the
characterisation of health risks linked to asbestos inhalation"
Afsset Solicited Request No. "2005-001"
Summary
Presentation of the question ... 2
Scientific Context ... 2
Appraisal Organisation ...3
Results from the collective appraisal ... 4
DEFINITION OF THE DIMENSIONAL PARAMETERS USED FOR THIS APPRAISAL AND CURRENT REGULATORY VALUES... 4
IDENTIFICATION AND HAZARD CHARACTERISATION... 4
METROLOGICAL DATA AND ASSESSMENT OF EXPOSURE... 6
CARRYING OUT OF A QUANTITATIVE HEALTH RISK ASSESSMENT... 8
APPRAISAL CONCLUSIONS... 8
Recommendations from the collective appraisal ... 9
I RECOMMENDATIONS ON THE SUBJECT OF REGULATION AND HEALTH RISK MANAGEMENT LINKED TO ASBESTOS... 9
2 / 12
The mission of Afsset, the French Agency for Environmental and Occupational Health Safety, is to help ensure environmental and occupational health safety and assess potential health risks in these areas. It provides competent authorities with all information on risks as well as the expertise and technical support needed to implement legislation, regulations and risk management strategies.
Presentation of the question
On 7 February 2005, the Directorate General for Health (DGS), the Directorate General for Employment (DGT) and the Directorate for Economic Studies and Environmental Evaluation (D4E) requested Afsset go ahead with a health risk assessment relating to short asbestos fibres (FCAs) (length L <5 m, diameter d <3 m, with a ratio L/d 3). An additional engagement letter addressed to the Agency from the Director of Pollution and Risk Prevention (DPPR), the DGS and the DGT, dated 16 May 2007, requested that the field of investigation be extended to include fine asbestos fibres (FFAs) (L 5 m, d <0.2m and L/d 3).
The questions asked by the funding ministries centre around three themes:
Assessing the toxicity of short and fine asbestos fibres (FCAs and FFAs)
Determining the possibility of characterising the particle size distribution of fibres according to exposure scenarios (general public or occupational environment) and the type of asbestos (chrysotile or amphibole);
Assessing the risks to human health linked to FCA exposure (not included in current regulations) and to FFA exposure (not included in current occupational regulation).
The assessment must also allow the relevance of the current regulatory measures in force to be determined; especially the current thresholds (threshold of 5 f/L for the general population; 100 f/L (0.1 f/cm3) in 1 hour for workers) and the lack of data for FCAs (in the
general as well as the occupational environment) and FFAs (in the occupational environment). With the support of the Committee of Specialized Experts (CES) for "Occupational exposure limit values (OEL)", the Agency must reach a decision as to whether it is necessary to establish another OEL by indicating the level(s) and the recommended reference period(s). A more general analysis relating to metrology is requested, especially focusing on existing analytical techniques.
Scientific Context
An international reference method, proposed at the end of the 1960s by the World Health Organization following a consensus based on metrological considerations, defines the characteristics of the fibres to be taken into account when measuring the concentration of fibres in the air. A fibre is defined as any solid particle, natural or artificial, elongated with parallel sides having a diameter less than 3 m, a length greater than or equal to 5 m and a length width ratio greater than 3.
A publication by Dodson et al. (2003)1 discusses this definition and investigates the pathogenicity of asbestos fibres based on their dimensional parameters. This article, which is a critical literature review, analyses and highlights the potential impact asbestos fibres under 5 m in length can have on health. The authors conclude that current data supports the
1 Dodson RF, Atkinson MA, Levin JL. (2003). Asbestos fiber length as related to potential pathogenicity: a critical review. Am J Ind Med. 44(3): 291-297.
hypothesis that asbestos fibres result in a pathological outcome regardless of their length. They therefore suggest that the exclusion of FCAs from the genesis of asbestos-related diseases is questionable. It was following this publication being issued that the ministries made the request to Afsset regarding this issue.
Appraisal Organisation
The appraisal was carried out in compliance with the French Standard NF X 50-110 "Quality in Expert Appraisal - General Guidelines for an Expert Appraisal (May 2003)" with the objective of covering the following points: expertise, independence, transparency and traceability.
Afsset called upon the "Risk Assessment linked to Air Environments" Committee of Specialized Experts (CES) to work on this solicited request. This committee commissioned the "short asbestos fibre and fine asbestos fibre" working group to carry out this appraisal. The working group's appraisal activities were regularly submitted to the CES. The report produced by the working group takes into account the additional observations and aspects passed on by members of the CES. These appraisal activities are therefore a result of work by a group of experts with complementary expertise.
This opinion is the basis of the scientific aspects of the final report from this collective appraisal "Taking into account the dimensional criteria for the characterisation of health risks linked to asbestos inhalation. Reassessment of toxicological, metrological and epidemiological data in the scope of a health risk assessment for the general public and occupational environment" (November 2008) which was adopted by the CES during its meeting of 2 December 2008.
Results from the collective appraisal
DEFINITION OF THE DIMENSIONAL PARAMETERS USED FOR THIS APPRAISAL AND CURRENT REGULATORY VALUES
short asbestos fibres (FCAs): 0.5 m < L< 5 m, d < 3 m and L/d 3 fine asbestos fibres (FFAs): L 5 m, d < 0.2 m and L/d 3
fibres measured through occupational health (FRp, corresponding to fibres defined by the WHO and counted by PCM:
Occupational exposure limit for 1 hour2: 0.1 f/cm3 (100 f/L)
Measurement technique: Phase Contrast Microscopy (PCM)
Dimensions measured: L 5 m, 0.2 m < d < 3 m and L/d 3
For information, the current occupational environment encompasses work involving asbestos removal, activities where contact with materials or products containing asbestos (MPCA) is likely to expose the worker to asbestos fibres in the outside environment (for example: working with asbestos containing asphalt, the transfer of asbestos containing materials) as well as in the indoor environment.
fibres measured in the general environment (FRg, corresponding to fibres defined by the WHO and counted by (ATEM):
Regulatory value3: 5 f/L
Measurement technique: Analytical Transmission Electron Microscopy (ATEM)
Dimensions measured: L 5 m, 0.01 m < d < 3 m and L/d 3
For information, the general indoor environment encompasses residential or non-residential buildings but equally the occupational environment defined by "passive" exposure of workers such as offices, shops, industrial units where, for example, part of the building contains MPCAs still in place. These scenarios do not involve exposure directly linked to an activity in the workplace involving contact with MPCAs.
HAZARD IDENTIFICATION AND CHARACTERISATION EXPERIMENTAL DATA
Analysis from studies carried out on animals indicates a difference in the toxicity of asbestos fibres depending on dimensional criteria.
The results from these studies confirm that "long" fibres have a greater carcinogenic potency compared to "short" fibres. These results have been observed with either no or few tumours resulting from FCAs depending on the protocol and the asbestos mineral type.
A significant increase in the number of tumours was observed in relation to the decrease in the diameter of the fibres (0.25 m < d < 1.5 m) independent of its length, including lengths < 8 m.
In vitro data confirms the major role the dimensional parameters have overall (more
significant effects with an increase in length and decrease in diameter) in the carcinogenic
2 Decree No. 2007-1539 of 26 October 2007 3 Decree No. 2003-462 of 23 May 2003
properties of asbestos fibres. A number of studies indicated cytotoxic or genotoxic effects or affecting mitosis linked to FCAs.
However, many other studies suggest that there are other factors besides dimension that play a part in the carcinogenic properties of asbestos fibres: surface reactivity, chemical composition or interaction with certain molecules, such as aromatic polycyclic hydrocarbons. These factors, which furthermore influence biopersistance, apply to all particle size classes of asbestos fibre.
Numerous limits, linked notably to experimental constraints, nevertheless have an influence on these results and their interpretation regarding the toxic potential of FCAs. The preparation and analysis conditions of the samples, the number of animals used in the protocols, the systematic and simultaneous presence of fibres greater than 5 m in length and fibres shorter than 5 m in length in the samples tested all lead to doubts, which means it is not possible to reach a single diagnosis for carcinogenic effects resulting from FCAs. At the present time, no experimental study enables the precise assessment of the dose-effect relationship for each asbestos fibre particle size class independent of the other particle size classes.
Finally, in view of current knowledge, the existence of a carcinogenic effect from FCAs
cannot be dismissed.
Regarding FFAs, data collected is in agreement and confirms the existence of a
carcinogenic effect caused by this particle size class.
BIOMETROLOGICAL DATA FROM HUMANS
Interpretation of biometrological data from humans is difficult due to the fact that a number of technical parameters can interfere with the result (sampling methods, storage, preparation and analysis of biological samples) as well as intervening factors after fibres inhalation (elimination kinetics or the effect of smoking) has occurred. Taking these remarks into consideration, the study into the pulmonary asbestos fibre burden indicates the constant presence of FCAs and more so of FFAs, in varying proportions depending on the study and type of fibre.
Finally, current biometrological data does not enable a conclusion to be drawn on the
possible role of FCAs in human pathology.
EPIDEMIOLOGICAL DATA
An analysis of epidemiological studies was conducted in the industrial sectors presenting the highest concentrations of FCAs, according to metrological data found in the literature or acquired for this appraisal. This analysis did not indicate an excessive risk of bronchial cancer or mesothelioma in the breaking system maintenance sector or in asbestos-cement (chrysotile) production, but showed an increased risk in the mining sector.
The highest risk excesses were observed in other industrial sectors where workers are exposed to lower amounts of FCAs and thus more long asbestos fibres. The data from the meta-analyses published recently confirm these results.
Furthermore, data from the same meta-analyses underlines the major role that amphibole fibres play compared to chrysotile. Moreover, there appears to be an excess risk of developing cancer following inhalation of chrysotile fibres.
The variable nature of FCA proportions between the industrial sectors, associated with a toxicity that is certainly lower for FCAs compared with long fibres, could therefore lead to a plausible hypothesis to explain the differences in excess risk between the sectors. Nevertheless the doubt that can be attributed to estimated exposure levels, the non-representative nature of the metrological data collected and the presence, even in small quantities, of fibres 5 m in length in sectors where the excess risk is lower, does not allow a formal conclusion to be drawn concerning the absence or presence of a low carcinogenic
effect for FCAs. No validated epidemiological morbidity or mortality data was associated with FCAs.
Finally, the toxicity of FCAs assessed from an epidemiological point of view cannot be dismissed, even though the results indicate a negative or low effect compared with long asbestos fibres.
The US Environmental Protection Agency (EPA) and the National Institute for Occupational Safety and Health (NIOSH) recently carried out work on modelling the dose-effect relationship for bronchial cancer (and mesothelioma by EPA), based on ATEM metrological data. Taking into account the finest fibres has enabled significant improvements in the accuracy of the models estimating the changes in the dose-effect relationship for bronchial cancer and mesothelioma to be made.
With regards to FFAs, recent data, albeit not in high numbers, confirms the existence of a significant carcinogenic effect.
Finally, recent data on the dose-effect relationship for bronchial cancer from low levels of exposure to asbestos obtained for fibres greater than 5 m in length shows that the current model used (linear without threshold) underestimates the relationship for low doses. These
factors are prompting the current OEL in force in France to be lowered, as in the case
of certain other countries such as Switzerland, Germany and Holland which adopted a value of 0.01 f/mL over 8 hours (compared with the current regulatory value in France of 0.1 f/mL over one hour).
METROLOGICAL DATA AND ASSESSMENT OF EXPOSURE METROLOGICAL METHODS
In France, measurement of exposure in the occupational environment is based on the PCM technique (Standard XP X 43-269: 2002) whereas environmental exposure is measured using ATEM (indirect method, French standard NFX 43-050: 1996).
The first method presents a certain number of limitations (no identification of the nature of the fibre, does not recognise FCAs and fibres with a diameter < 0.2 m) but its simplicity and low cost has led it to become the international benchmark method in the occupational environment. In contrast, the use of ATEM varies depending on the country (direct method, indirect or use of analytical scanning electron microscopy (ASEM) for example in Germany with the standard VDI-3492).
In all cases, only fibres greater than 5 m in length are currently counted (L 5 m, 0.2 m < d < 3 m, L/d 3 for PCM; L 5 m, d < 3 m, L/d 3 for ATEM). Due to the difference in the sensitivity between the two techniques and the absence of fibre type identification ability for PCM, there is not a reliable modelling method that enables measurements made by
one technique to be compared with the other. Average conversion factors (from PCM to
ATEM) going from 1.7 to 4 have been proposed as a function of fibre type, which can reach 30 in certain instances.
ATEM is the only method that enables the precise identification of asbestos fibres and the different classes of fibres be counted (FCA, FFA, FRg, FRp). This method is undeniably the most appropriate method to carry out particle size distribution analysis of asbestos in air samples.
ASSESSMENT OF EXPOSURE
Literature data relating to particle size distribution of asbestos fibres in the environment remains limited. Thus, the results presented originate mainly from studies carried out as requested by Afsset within the scope of this appraisal. These studies were carried out using ATEM (indirect method, French Standard NFX 43-050: 1996).
GENERAL OUTDOOR ENVIRONMENT. The Research Laboratory on Inhaled Particles (LEPI - ville de Paris) has proceeded to re-analyse samples taken between 1993 and 1995 in the Ile
de France region, taking into account all dimensional classes of fibres. The samples only contained chrysotile. The median and maximum levels are 0.12 and 0.47 f/L respectively for FRg (including FFAs) and 0.32 and 2.73 f/L for FCAs. The regulatory threshold currently set for the general environment is based on the background pollution established from measurements taken in the Ile de France region in 1974 (maximum concentrations of 5 f/L for asbestos fibres defined as having a length greater than 5 m). The background
pollution determined for the Parisian conurbation in the 1990s appeared to be broadly lower than that of the 1970s because the maximum concentrations of fibres with a length
greater than 5 m were divided by 10.
GENERAL INDOOR ENVIRONMENT. A re-analysis of 105 samples taken from a range of buildings was carried out by LEPI (between 1997 and 2004). The dominance of chrysotile fibres was confirmed (> 90%). The concentrations were at the limit of detection at 630.9 f/L for FCAs, 14.0 f/L for FFAs and 16.3 f/L for FRg. On average FCAs represented 71% (asbestos cement materials) to 98% (thermal insulation) of fibres counted, with FFAs representing 1.5% to 16.5%. Results indicate that the concentrations and proportions of
FCAs appear to be influenced by the nature of the materials close to where the samples were taken. From 4% (flocking) to 67% (asbestos cement) of samples only containing FCAs. These differences are a reflection of the variable levels of degradation of
the materials located close to where the samples were taken. These results are affected by the small number of samples taken (n=105) and by their lack of representativeness (retrospective series without random selection from the documented areas).
OCCUPATIONAL ENVIRONMENT. 192 samples, taken by the Institut de recherche Robert-Sauvé en santé et sécurité du travail (IRSST, Quebec) between 1990 and 2006, representative of 7 industrial sectors (asphalt, brake manufacturing, mining, textiles, removal, recycling and asbestos cement) were analysed. More than 45000 fibres were counted (of which 98% were chrysotile) with average and maximum concentrations of 16.3 and 505.2 f/mL respectively for FCAs, 0.4 and 18.4 f/mL for FFAs and 0.5 and 9.3 f/mL for FRp. There was very little
variation in the proportions of FCAs and FFAs in these samples (from 87% to 96% and 2.1% to 5.6% respectively). Within the limits for comparison for data acquired using
different analytical methodologies, historical literature data seems to indicate a more significant variation for the different particle size classes, in particular for FCAs. The per sector data is insufficient to be able to be used to determine the significant distribution variations for FCAs between the sectors.
SPECIFIC CASE FOR THE HAUTE-CORSE DATA.
Haute-Corse is characterized by the presence of natural deposits of asbestos containing rocks.
OUTSIDE ENVIRONMENT. 215 samples taken in 2001/2002 (126 taken close to ground work, 89 with no ground work present) were re-analysed, taking into account particle size distribution. Two types of asbestos fibres were identified (chrysotile and tremolite). The total fibre concentration varied from the detection limit (0.94 f/L) to 51 f/L (average 3.7 f/L) for tremolite, and from the detection limit (0.94 f/L) to 401 f/L (average 19 f/L) for chrysotile. The
amount of FCAs varied largely as a function of sampling site and the type of asbestos fibre, with values reaching 90% for sites mainly containing chrysotile and between 50% and
90% for other sites largely contaminated with tremolite.
INDOOR ENVIRONMENT. Data from buildings (58 samples between 2006 and 2007) indicate average concentrations of 0.54 to 14.4 f/L for FRg, depending on the site, demonstrating
pollution which is of a higher value than current regulations (5 f/L) for certain sites. The
average FCA concentrations vary from 1.03 to 23.7 f/L depending on the site. The fibres identified indoors are the same as those found outside in the zones with asbestos deposits and certain scenarios demonstrate pollution being confined to the interior of the
CARRYING OUT OF A QUANTITATIVE HEALTH RISK ASSESSMENT
In 1986 the EPA proposed a unitary excess risk of 2.3 10-1 per f/mL (all types of asbestos)
uniquely for fibres with a length to 5 m and measured by PCM. This model was used as a base by Inserm in 1997 in its collective appraisal.
In 2003 the EPA produced new exposure indices for health risk assessments, based on ATEM metrological data, and relating specifically to fibres L > 10 m and d < 0.4 m. Nevertheless, the limits of these estimations based on a single fibre class were highlighted.
Finally, it is not possible, with current knowledge, to develop a quantitative health risk assessment linked to the particle size distribution of all asbestos fibres due to:
the absence of dose-effect relationship information for each asbestos fibre particle size
class, independent of other particle size classes;
the fact that the current unitary risk excesses were defined for fibres with a length to 5 m and based on measurements taken by PCM in occupational cohorts exposed to high concentrations;
the variety in particle size distribution of asbestos fibres depending on the mineral variety, the type of environment, the type of MPCA close by and, to a lesser extent, the industrial sector.
APPRAISAL CONCLUSIONS
The experts therefore went for a qualitative approach to put forward the dimensional criteria to be considered in asbestos fibre measurement.
With regards to FFAs, the results from the appraisal confirm the interest in measuring FFAs
within the scope of the general environment regulations and the experts are in agreement about the need to recommend that this particle size class be considered in occupational environment regulations.
In view of the appraisal carried out for FCAs and despite numerous uncertainties requiring the need to obtain additional data, it must be highlighted that the dangerous nature of FCAs is not exclusive and that this particle size class is systematically present, and in significant proportions, according to metrological data.
For the general environment, FCAs could be used in regulations as an indicator to demonstrate the level of degradation of MPCA and asbestos exposure to the population. For the occupational environment, considering FCAs in epidemiological studies could lead to an improvement in knowledge on the dose-effect relationship and ultimately to a reduction in the inaccuracies of models used for quantitative assessment of health risks.
Recommendations from the collective appraisal
IRECOMMENDATIONS ON THE SUBJECT OF REGULATION AND HEALTH RISK MANAGEMENT LINKED
TO ASBESTOS
In view of the results from the collective appraisal, Afsset considers that a revision of the
current regulations is justified and proposes to make changes based on the following considerations, in terms of health risk management, linked to asbestos:
1 Regarding metrology:
Propose a revision of the standard general and occupational environment metrology methods supplementing them with new counting rules and an adapted sampling strategy, in particular:
o Using ATEM, not only for relative regulation of the general environment, but also for the occupational environment.
ATEM is clearly the most appropriate method to be able to analyse the whole range of particle size distribution of asbestos in air samples. Nevertheless, this method will need to be adapted so that it can be used in the occupational environment, notably in terms of determining the desired length of sampling time as a function of analytical sensitivity, and the output of sampling pumps used. Likewise in the general environment, considering FCAs will require adapting the standard currently in force.
For the counting results, where additional results are expected, Afsset recommends that the sum of the relative concentrations of the different asbestos mineral varieties, regardless of the type, be compared to the retained management value. Indeed there is an excess risk of cancer linked to the inhalation of all the different mineral varieties of asbestos.
2 Regarding the general environment:
Carry out measurements systematically taking into consideration the whole particle size
distribution range for asbestos fibres.
The dimensional criteria used in the analyses carried out by LEPI within the scope of this work, and which proved to be useful, can be retained (L > 0.5 m; d < 3 m with a ratio L/d 3).
2.1 General indoor environment
When the regulatory visual examination diagnoses degradation of a material, extend dust accumulation measurements to all MPCAs, especially asbestos flooring slabs, asbestos cement etc.
Express two distinct results, one for fibres with a length greater than or equal to 5 m (corresponding to fibres as defined by the WHO and thus including FFAs) and the other for fibres with a length less than 5 m (FCA).
Establish two management values: one for fibres with a length greater than or equal to 5 m (corresponding to fibres as defined by the WHO and thus including FFAs) and the other for fibres with a length less than 5 m (FCA).
Given the uncertainty regarding the toxicity of FCAs and the interpretation limitations of the models for low exposure doses of long asbestos fibres, Afsset recommends managing the risk with logical action for exposure. So that locations with the highest exposure levels are given priority, Afsset confirms the importance of having a regulation based on the condition of materials (level of degradation). Afsset recommends the regulatory value for long asbestos fibres be lowered and the addition of a ceiling value for FCAs, to reduce the exposure of the population to these fibres.
In addition, Afsset draws attention to risk management with the need to define a management value for FCAs, not resulting from a multiplication from asbestos removal sites with a health risk scenarios source hypothetically linked to the presence of FCAs.
The establishment of these two values would support the current known data on indoor and outdoor pollution of buildings (centralised data from the Directorate General for Health on fibres with a length greater than or equal to 5 m or from data generated by this appraisal), whilst waiting for additional data on the overall particle size distribution of asbestos fibres to be available. It would be desirable to consider the implementation of an action plan for the gradual introduction of these two management values.
o For the management value relating to fibres with a length greater than or equal to 5 m, update the current regulatory value, taking into account the data acquired during the appraisal of the background pollution in the Parisian conurbation.
Afsset recognises that the data collected during the appraisal, from samples taken during the 1990s, is not representative of the current situation in France. The estimates available (EPA, 1986) suggest, within the limits of interpretation linked to the uncertainty of the model, that for an individual excess risk of death by lung cancer or mesothelioma in the general public equivalent to 10-5
or 10-6, the calculated concentrations for asbestos fibres with a length greater
than 5 m (without distinction between the mineral variety) are equivalent or below the background pollution in the Parisian conurbation.
o For the management value relating to fibres with a length lower than 5 m, multiply by a factor at least equal to 10 times the management value, which will be deducted for fibres with a length greater than or equal to 5 m.
The results from air samples taken close to MPCAs from inside buildings indicate that the average value for FCAs was in the order of 90%. This means that for a fibre with a length greater than 5 m, approximately 10 FCAs are detected.
Commence the management process (identification, diagnosis, MPCA degradation, site activity, hierarchy of sites visited, pollution measurement, type of asbestos found etc.) in light of the appraisal carried out, and make the required changes in terms of metrology, management values and extending the diagnosis to other MPCAs.
2.2 General outdoor environment
Define the background pollution and the asbestos fibre particle size distribution more accurately in the general outdoor environment, notably since the asbestos ban in France (1997).
Improve the characterisation of pollution scenarios close to natural deposits, or close to potentially contaminated sites.
3 Regarding the occupational environment:
Carry out measurements systematically taking into account fibres with a length greater
than or equal to 5 m, thus including FFAs (L 5 m, d < 3 m).
Keep levels of exposure as low as possible through better adapted individual and group protection.
An additional appraisal by Afsset's "Occupational exposure limit values" CES will formulate an asbestos OEL proposal, as well as an associated metrology method. Due to the systematic presence of asbestos fibres with a length greater than 5 m in professional activities linked to asbestos in the work place, the OEL remaining in place will cover the current health risk linked to FCAs. Therefore, Afsset is not proposing to include FCAs in the regulations concerning the occupational environment It is desirable, in a protective approach, that this OEL includes FFAs as well as fibres with a length greater than or equal to 5 m measured by ATEM.
Ensure effective traceability of occupational exposure for individuals (medical file).
With regards to removal techniques:
o
ensure that the company has assessed the risks to workers and the environment before deciding to start asbestos removal. The systematic implementation of test sites enables removal techniques to be adapted to the type of material found and the layout of the site.o
follow the recommendations given by INRS4regarding the removal or containment of asbestos or asbestos containing materials;o
avoid abrasive techniques or cryogenics as these give off a priori the most FCAs and/or FFAs;o
for MPCA removal, treat the material by the most thorough impregnation as possible, to reduce the level of fibres released;o
centralise results for dust removal measurements from asbestos removal companies on a common database so that different techniques can be compared, then recommendations carried out.Reassess group and personal protective equipment for efficacy with regards to FFAs and FCAs, using ATEM metrology methods.
Improve personnel training for those taking samples, especially in terms of sampling strategy and the taking of asbestos fibres samples.
4 Inform and communicate to the public how the measurements have been interpreted for different exposure scenarios.
The roll out of recommendations and the inclusion of new reference values for FCAs highlight the need for information and mindful communication by the relevant parties.
II RECOMMENDATIONS ON THE SUBJECT OF KNOWLEDGE ACQUISITION
Afsset equally recommends acquiring or updating knowledge with regards to the influence of dimensional criteria of fibres in the assessment of health risks linked to asbestos:
1 In the area of toxicology
Obtain new experimental data on FCAs considering:
o
the limits detailed in the report (sample preparation, residual presence of long fibres);o
contradictory results from studies on the biopersistance of FCAs compared with long fibres.Instigate fundamental research on the action mechanisms of fibres, including their genotoxicity, by developing new approaches especially those that will support the evolution of cellular and/or molecular biology techniques.
Following a feasibility study, carry out a meta-analysis of experimental data to investigate a possible dose-effect relationship depending on the proportions of the different particle size classes.
2 In the field of biometrology
Specify the particle size distribution of asbestos fibres which remain in the biological samples (lung, pleura). The particle size distribution must be obtained via ATEM in specific research protocols.
3 In the field of epidemiology
Initiate a study with the aim of bringing together the data from the appraisal relating to the particle size distribution of asbestos fibres from different industrial sectors with cohort study data for the same sectors and collected, for example, by NIOSH or other institutes. This study would potentially reduce inaccuracies in the models that include uniquely fibres with a length greater than or equal to 5 m measured by PCM.
4 In the field of exposure assessment
Obtain data on the particle size distribution of asbestos fibres for:
o
the occupational environment (MPCA removal sites, building maintenance, waste handling based on MPCA, in particular asbestos cement or flooring slabs etc.);o
the general outdoor environment with the view of having samples more representative of the national situation and that are more recent (notably following the ban on asbestos);o
the release of fibres from MPCA for the general indoor environment.Organise the centralisation of metrological data, not only on a general environment level, but also for the occupational environment so that they can be analysed and distributed. Finally, with regards to the numerous unknowns identified, Afsset recommends a thorough investigation into this subject.
The Director General
