1、raising standards worldwide NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW BSI Standards Publication PD 6699-3:2010 PUBLISHED DOCUMENT Nanotechnologies Part 3: Guide to assessing airborne exposure in occupational settings relevant to nanomaterials This publication is not to b
2、e regarded as a British Standard.PD 6699-3:2010 PUBLISHED DOCUMENT Publishing and copyright information The BSI copyright notice displayed in this document indicates when the document was last issued. BSI 2010 ISBN 978 0 580 68479 1 ICS 13.100; 71.100.99 The following BSI reference relates to the wo
3、rk on this standard: Committee reference NT/1 Publication history First published, November 2010 Amendments issued since publication Date Text affected BSI 2010 i PD 6699-3:2010 PUBLISHED DOCUMENTContents Foreword ii 0 Introduction 1 1 Scope 1 2 Terms and definitions 2 3 Abbreviations 2 4 Exposure a
4、ssessment generic 2 5 Measurement in occupational settings relevant to nanotechnologies 7 6 Strategy for exposure assessment 9 7 Instruments and techniques available for monitoring exposure 13 Annexes Annex A (informative) Selection of instruments 20 Bibliography 25 List of figures Figure 1 The risk
5、 assessment paradigm relating hazard, exposure and risk 3 Figure 2 Predicted total and regional deposition of particles in the human respiratory tract related to particle size, using ICRP 66 model 4 Figure 3 Health-related sampling conventions for workplace aerosols (ISO 7708:1995) 5 Figure 4 Types
6、of nanomaterials 9 Figure 5 Exposure assessment process diagram 10 Figure 6 FMPS size distributions 17 List of tables Table 1 Plausible examples of exposure scenarios and the possible aerosol release 8 Table 2 Available instruments and techniques for monitoring nanomaterial exposure (from PD ISO/TR
7、27628:2007) 14 Table A.1 Tables applicable to particle types 20 Table A.2 Method assessment for discrete, approximately spherical nanoparticles Category A 21 Table A.3 Method assessment for discrete HARN Category B 22 Table A.4 Method assessment for agglomerated nano-particle Category D and heteroge
8、neous agglomerates containing nano-objects Category G 23 Table A.5 Method assessment for agglomerated HARN Category D and heterogeneous containing HARN Category G 24 Summary of pages This document comprises a front cover, an inside front cover, pages i to ii, pages 1 to 28, an inside back cover and
9、a back cover.PD 6699-3:2010 ii BSI 2010 PUBLISHED DOCUMENTForeword Publishing information This Published Document is published by BSI and came into effect on 30 November 2010. The initial drafting of this Published Document was produced in association with BIS as part of their ongoing programme of s
10、upport for standardization. PD 6699, Nanotechnologies, now comprises the following parts: Part 1: Good practice guide for specifying manufactured nanomaterials; Part 2: Guide to safe handling and disposal of manufactured nanomaterials; Part 3: Guide to assessing airborne exposure in occupational set
11、tings relevant to nanomaterials. Use of this document As a guide, this Published Document takes the form of guidance and recommendations. It should not be quoted as if it were a specification and particular care should be taken to ensure that claims of compliance are not misleading. It has been assu
12、med in the preparation of this Published Document that the execution of its provisions will be entrusted to appropriately qualified and experienced people, for whose use it has been produced. Presentational conventions The provisions in this Published Document are presented in roman (i.e. upright) t
13、ype. Its recommendations are expressed in sentences in which the principal auxiliary verb is “should”. The word “should” is used to express recommendations of this Published Document. The word “may” is used in the text to express permissibility, e.g. as an alternative to the primary recommendation o
14、f the clause. The word “can” is used to express possibility, e.g. a consequence of an action or an event. This PD discusses several products that are trade marked. In each case, information is given for the convenience of users of this standard and does not constitute an endorsement by BSI of the pr
15、oducts named. Contractual and legal considerations This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. This Published Document is not to be regarded as a British Standard. BSI 2010 1 PD 6699-3:2010 PUBLISHED DOCU
16、MENT0 Introduction By almost any measure, the growth of nanotechnology as a scientific and technological activity over the last ten years has been enormous. Indicators include almost exponential growth in scientific papers published, patent applications lodged, investments by national authorities an
17、d private industry, number of people employed in the area and revenue generated. This has led to the development and production of many new forms of materials at the nanoscale, with a range of divergent properties when compared to the same materials at a larger scale. Well-known examples include mat
18、erials like carbon nanotubes (CNT), which have greatly enhanced strength and conductivity when compared to other forms of carbon, and quantum dots, which emit light at frequencies which depend on their particle size. These new nanomaterials are synthesized in a wide range of production processes and
19、, in turn, lead to a wide range of applications and processes in which they can be used. Against this background, concerns have been expressed about the potential risk to the health of individuals involved in the manufacture and use of these materials and to the environment (RS/RAEng 2004 1). A full
20、 understanding of the potential risks of such materials when manufactured or used requires an understanding of the intrinsic toxicity of the materials and the extent to which people (or the environment) are exposed. Since publication of the Royal Society/Royal Academy of Engineering report 1 in 2004
21、, there has been a large increase in research activity focused on identifying, categorizing and quantifying the potential risks associated with a wide range of new nanomaterials 2. The focus has been largely on the toxicological aspects, with, to date, less effort on understanding and quantifying ex
22、posure. However, recent studies are contributing to increased understanding of the instruments used and their limitations, and how these can be used in combination to provide better quantification of exposure 3,4. As yet, though, there is no consensus on which methods are appropriate for each situat
23、ion, how they are to be applied in detail, and what the limitations of these methods might be.1 Scope This Published Document gives guidance on the development and implementation of plans and strategies for the assessment of exposure by inhalation of nanomaterials, based on an understanding of the n
24、ature of the exposure and the capabilities and limitations of exposure measurement instrumentation. It is applicable to all workplace settings in which nano-objects, including nanoparticles and nanotubes, are manufactured, processed or used. Sources of other data and information are also provided. T
25、he Published Document describes a structured, step-by-step approach to exposure assessment which takes into account the purpose, the type of information needed, and the usefulness and limitations of the various approaches for exposure assessment for different types of nanomaterials, and provides a r
26、ationale for method selection. This Published Document is intended to compliment the development and take-up of new nanotechnology-based materials in UK industry by providing manufacturers and users of these materials with effective strategies for assessing worker exposure to airborne nanomaterials.
27、PD 6699-3:2010 2 BSI 2010 PUBLISHED DOCUMENT Given the emergent nature of the knowledge base in this area, the guide is targeted at the professional user who already has some knowledge and experience of exposure assessment and occupational hygiene practice.2 Terms and definitions For the purposes of
28、 this Published Document, the terms and definitions given in PAS 136 apply. NOTE The term “nanomaterials” includes nano-objects and aggregates and agglomerates of nano-objects, including where they are embedded within a matrix. 3 Abbreviations APS Aerodynamic particle sizer CNT Carbon nanotube CPC C
29、ondensation particle counter DMA Differential mobility analyser EDX Energy dispersive x-ray analysis ELPI Electrical low pressure impactor FMPS Fast mobility particle counter HARN High aspect ratio nano-objects ICP-MS Inductively coupled plasma mass spectroscopy ICPM-OES Inductively coupled plasma o
30、ptical emission spectrometry OPC Optical particle counter NEAT Nanoparticle emission assessment technique NIOSH National Institute for Occupational Safety and Health NM Nanomaterial NP Nanoparticle PCOM Phase contrast optical microscopy SEM Scanning electron microscope SMPS Scanning mobility particl
31、e sizer TEM Transmission electron microscope4 Exposure assessment generic4.1 Defining exposure The risk to the health of an individual or a population arising from exposure to a chemical agent is generally considered to be a function of the intrinsic harmfulness of the chemical (its toxicity) and th
32、e dose (amount) which accumulates in the specific biological compartment (e.g. the lungs). In an occupational context it is difficult to quantify the dose, specifically in the case of insoluble particulates. In order to quantify and manage the risks, it is usual to use exposure as a proxy for dose.
33、Knowledge of plausible exposure levels and duration BSI 2010 3 PD 6699-3:2010 PUBLISHED DOCUMENT enables realistic interpretation of dose-response relationships. Knowledge and control of exposure is critical in risk assessment and management, as indicated in Figure 1. Figure 1 The risk assessment pa
34、radigm relating hazard, exposure and risk Critical questions in relation to exposure are: how much, how long and how many people are exposed? Thus, exposure is usually measured (quantified or assessed) in terms of its intensity (concentration) and duration (or frequency). Control of exposure (to zer
35、o) effectively removes the risks from the toxic agent. Without exposure there is no risk.4.2 Routes of exposure The main routes by which workers can be exposed to particles are inhalation, ingestion and dermal penetration. a) Inhalation is considered to be the primary route by which particles suspen
36、ded in air can enter the bodies of workers. Once inhaled, particles deposit in all regions of the respiratory tract. The site and extent to which particles deposit in the respiratory tract are dependent on particle size, expressed in terms of aerodynamic diameter (for particles greater than approxim
37、ately 300 nm) or thermodynamic diameter for particles less than 300 nm) 1) . Figure 2 shows the fractional deposition of inhaled particles in the nasopharyngeal, tracheo-bronchial and alveolar regions of the human respiratory tract for nasal breathing at rest, using the predictive mathematical model
38、 of the International Commission for Radiation Protection 5. There is an increasing total deposition as particle size decreases below around 300 nm. 1)The “aerodynamic particle diameter” is the diameter of a sphere with a density of 10 3kgm -3and the same terminal settling velocity in air as the par
39、ticle of interest. The “thermodynamic particle diameter” is the diameter of a spherical particle that has the same diffusion coefficient in air as the particle of interest.PD 6699-3:2010 4 BSI 2010 PUBLISHED DOCUMENTFigure 2 Predicted total and regional deposition of particles in the human respirato
40、ry tract related to particle size, using ICRP 66 model KeyTotal depositionHead regionTracheobronchialAlveolar b) Ingestion exposure to particles in general can arise from hand-to-mouth contact by sucking or licking a contaminated surface, or by eating contaminated food. It might also be caused by sw
41、allowing mucus containing deposited particles which has been cleared from the lung. Occupational ingestion exposure to nanomaterials has not yet been studied to any extent. c) Dermal exposure is of increasing concern in workplaces 6. Workers can be exposed via the skin by handling or touching materi
42、als or surfaces coated with nanomaterials. One of the challenges in managing the risks arising from dermal exposure is that protective equipment designed to prevent exposure, such as gloves, can in itself act as a reservoir of contaminant, potentially exacerbating the exposure. Currently, there is l
43、ittle evidence that insoluble NP depositing on the skin can penetrate the epidermis 7,8. However, only a few studies have been published thus far. Local effects, such as sensitization and dermatitis, have not been investigated for NP and so cannot be ruled out. This Published Document focuses on exp
44、osure by inhalation.4.3 Exposure metrics In early studies which considered the health effects of inhaled particles, dust (particle) samples were collected by drawing air through a filter or other medium and subsequently analysed off-line to estimate exposure, expressed as a concentration in air. For
45、 example, in the coal industry the samples were analysed by counting particles collected on the filter under a light microscope 9. This resulted in an estimate of exposure BSI 2010 5 PD 6699-3:2010 PUBLISHED DOCUMENT in terms of particle number concentration, expressed as number of particles per cc
46、or per m 3of air. Epidemiological studies in that industry later demonstrated a strong correlation between pneumoconiosis and mass concentration, typically expressed as mgm -3 . Assessment in terms of mass was less demanding and more accurate than manual counting under a microscope and so was the pr
47、eferred choice. The use of workplace exposure limits (WEL), based on mass concentrations, has become the norm for measuring or regulating exposure for most hazardous chemicals and particles 10. A further refinement of this approach involves sampling of particles based on collection of a biologically
48、 relevant aerosol fraction. In this context, biological relevance is characterized by the region of the respiratory tract to which a particle can potentially penetrate and determined as a function of particle size, measured in terms of aerodynamic diameter. Such fractions are defined as follows (ISO
49、 7708). The inhalable convention: the mass fraction of total airborne particles that enters the nose or mouth during breathing. The thoracic convention: the mass fraction of inhaled particles that penetrate the larynx, with 50% penetration at 11.64 m (equivalent to 10 m when expressed as a fraction of total aerosol). The respirable convention: the fraction of inhaled particles that penetrate to the alveolar region of the lung, with 50% penetration at 4.25 m (equivalent to 4 m when expres
