Isocyanates: Sampling, Analysis, and Health Effects

138 Pages·2002·3.101 MB·English

by  ASTM International

STP 1408
Isocyanates: Sampling, Analysis,
and Health Effects
Jacques Lesage, Irene DeGraff, and Richard Danchik,
editors
ASTM Stock Number: STP1408
ASTM
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Library of Congress Cataloging-in-Publication Data
Isocyanates : sampling, analysis, and health effects / Jacques Lesage,
Irene DeGraff, and Richard Danchik, editors.
.p cm. -(STP ; 1408)
"ASTM Stock Number: STPI408."
Contains papers presented at a symposium.
Includes bibliographical references and index.
ISBN 0-8031-2879-7
l. Isocyanates--Toxicology---Congresses. .2 Isocyanates--Environmental
aspects--Congresses. .3 Isocyanates--Analysis---Congresses. .4
Environmental sampling---Congresses. .I Lesage, Jacques, t958- II.
DeGraff, Irene, 1948- III. Danchik, Richard, 1943- IV. ASTM special
technical publication ; .8041
RA1247.M45 481 2001
615.9'5142~dc21
2001056056
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detnirP ni Saline, IM
2002
Foreword
This publication, lsocyanates: Sampling, Analysis, and Health Effects, contains papers
presented at the symposium of the same name held in Orlando, Florida, on October 26-27,
2000. The symposium was sponsored by ASTM Committee D22 on Sampling and Analysis
of Atmospheres, and its Subcommittee D22.04 on Workplace Atmospheres, in cooperation
with IRSST (Institut de recherch6 en sante et en securite du travail du Quebec). The sym-
posium co-chairs were Irene D. DeGraff, Supelco, Bellefonte, Pennsylvania, USA and
Jacques Lesage, IRSST, Montreal, Quebec, Canada.
Contents
Isocyanate Measurement Methods--ISO Standardization--RiCHARD .H NWORB
Analysis of Isocyanates with LC-MS/MS--ANDERS ,NITSO TIGRAM ,NERGDNUS
JENNY EKMAN, ROGER LINDAHL, AND JAN-OLOF LEVIN 21
Laboratory Comparison of Sampling Methods for Reactive Isocyanate Vapors
and Aerosols~RoY .J RANDO, HALET G. POOVEY, AND
DINKAR R. MOKADAM 12
Work-Related Asthma from Exposure to Isocyanate Levels Below the
Michigan OSHA Permissible Exposure Limit~MARV OJ ,YLmER
KENNETH D. ROSENMAN, AND JOHN H. PECK 38
Isocyanate Exposures in the United Kingdom~JOHN .J NEDNILAcM 54
Some Limitations in the Use of Urine Biomonitoring for Measuring TDI
ExposuFe~ANNE HARMAN CHAPPELLE, RONALD N. SHIOTSUKA, AND MICHAEL
J. BARTELS 64
Patch Testing for IsoeyanateSmATHENA T. JOLLY, DIETER BRAMANN, AND HANS-
PETER HOFFARTH 75
Antibody Testing: Analysis of the Specificity of Antibody Detection in a Non-
Diisocyanate-Exposed PopulationmWILLIAM .E ,NWORB
SHEREEN GAMALUDDIN, AND AMY L. KENNEDY 80
Field Evaluation of a Gravimetric Sampling Method as a Screening Tool for
the Monitoring of Airborne Isocyanates in Paint-Spray Operations--
WM. WESLEY NORTON AND VENKATRAM DHARMARAJAN 94
Workplace TRIG and Air-Purifying Respiratory Protection--
HALET G. POOVEY AND ROY J. RANDO 011
Use of Air-Purifying Respirators for Substances with Limited or Poor
Warning Properties--STEFANIE M. CORBITT, E. A. HEGER, AND
DAVID G. SARVADI 321
Richard H. Brown L
Isocyanate Measurement Methods - ISO Standardization
Reference: Brown, R.H., "Isocyanate Measurement Methods - ISO
Standardization," Isocyanates: Sampling, Analysis and Health Effects, ASTM STP
,8041 J. Lesage, I. D. DeGraff, and R. S. Danchik, Eds., American Society for Testing
and Materials, West Conshohocken, PA, 2002.
Abstract: Historically, a large number of alternative methods have been devised for the
measurement of airborne isocyanates. Nearly all these methods rely on the
derivatization of the reactive isocyanate groups to products that can be analyzed,
usually by some form of chromatography. The choice of an ideal method relies partly
on the requirements of the regulatory authorities, but there are also technical
considerations concerning the validity and reliability of the various methods and the
cost and availability of instrumentation. It would be comforting if we had a consistent
body of advice from the regulatory authorities concerned. However, NIOSH (USA)
recommends three methods, OSHA (USA) recommends two methods, ASTM (USA)
recommends three methods, NIWL (Sweden) recommends one method and the HSE
(UK) recommends two methods. All of these methods are different, with the exception
of the 1-(2-methoxyphenyl)piperazine (2-MP) and the 1-(2-pyridyl)piperazine (2-PP)
methods, which appear twice.
Can the International Standardization Organization help? Actually, ISO is
preparing four technical specifications. First, it is preparing a method based on the 2-
MP reagent (ISO/FDIS 16207). Second, it is preparing a method based on the 9-(1-
methyl-anthracenyl)piperazine reagent (New Work Item). Two further methods, based
on the dibutylamine method and the Iso-Chek method have been agreed as potential
TM
new work items but have not been balloted yet. So many alternative methods would
seem inconsistent with the ISO objective of variety reduction. The reason is that, in
addition to having different areas of application, all existing methods have some
disadvantages. Thus, a fifth (guidance) standard is being developed which will explain
in more detail the advantages and disadvantages of each method and it is hoped, will
point to the development of a genuinely universal method.
Keywords: isocyanates, air quality, measurement methods, standardization
1Health and Safety Laboratory, Broad Lane, Sheffield $3 7HQ, UK.
thgirypoC (cid:14)9 1002 yb MTSA International www.astm.org
2 :SETANAYCOSI ,GNILPMAS ,SISYLANA DNA HTLAEH STCEFFE
Introduction
"WARNING Isocyanates result in more cases of occupational asthma than any
-
other group of chemicals. You should only use isocyanates if there are no reasonable
substitutes available, ff you do use them, you must take strict precautions.
Occupational asthma is a very serious condition triggered by breathing in isocyanate
vapor or aerosols. High exposures can occur during heating and spraying. Following
this guidance closely will help you reduce the risks."
The above is a quotation from the Health and Safety Executive (HSE) Guidance
Note EH16 1 on Isocyanates, Health Hazards and Precautionary Measures. This
indicates the seriousness of potential industrial exposure to isocyanates. Such
exposures are generally considered to be most significant by the airborne route, since
isocyanates are recognized as being potent allergenic respiratory sensitizers. Some
authors 2 believe that the dermal route is also significant as contributing to respiratory
sensitization, but the majority of studies on isocyanate exposure have concentrated on
the measurement of airborne exposure.
The nature of the isocyanate species involved is complex, Guidance Note EH 16
citing twelve industrial processes where exposure may occur, including the manufacture
and use of polyurethanes and other isocyanate-derived polymers, and processes where
these polymers may be subjected to thermal stress, e.g. flame bonding or soldering.
Historically, interest centered initially on the monomeric diisocyanates (Table 1), as
these were the building blocks of the commonly occurring polyurethanes.
Table 1 - Monomeric Isocyanates
Abbreviation Chemical Name Formula
TDI Toluene diisocyanate CH3-Ph-(NCO)2
MDI Methylene bis (4-phenylisocyanate) OCN-Ph-CH2-Ph-NCO
HMDI Methylene bis (4-cyclohexylisocyanate) OCN-C6H10-CH2-C6HI0-NCO
HDI Hexamethylene diisocyanate OCN-(CH2)6-NCO
However, more recently, prepolymers or oligomers of the isocyanates
(collectively polyisocyanates, Table 2) have been used as they exhibit much lower
vapor pressures than the monomers, and hence should be associated with lower
exposures.
In addition, a number of other compounds containing isocyanate functional
groups have become of interest, particularly in relation to the thermal degradation of
isocyanate-derived polymers (Table 3). Under certain conditions, the isocyanate
polymers can depolymerize, or result in the formation of amines or mixed
amine/isocyanates. Low molecular weight isocyanates, such as methyl isocyanate or
isocyanic acid may also be produced.
NWORB NO OSI NOITAZIDRADNATS 3
Table 2 - Polyisocyanates
Abbreviation Chemical Name Formula
poly-HDI HDI biuret (trimer) NCO 6)2HC(- -N-CONH-(CH2)6 -NCO2
poly-MDI Poly-(methylene bis OCN-Ph-CH2-(Ph-CH2),-Ph-NCO
(4-phenylisocyanate))
TDI 2TDI + Ethylene glycol CH2-O-CO-NH-Tol-NCO
prepolymer I
CH2-O-CO-NH-Tol-NCO
Table 3 - Thermal Degradation Products
Abbreviation Chemical Name Formula
MDA Methylene dianiline H2N-Ph-CH2-Ph-NH2
MDI/MDA 4-Isocyanatophenyl- OCN-Ph-CH2-Ph-NH2
aminoisocyanate 4-aminophenylmethane
MIC Methyl isocyanate CH3 NCO
ICA Isocyanic acid HNCO
Limit Values
Notwithstanding the wide variety of isocyanate species that may be causative
agents for occupational asthma, National regulatory bodies have taken different views
on setting occupational exposure levels. In the USA, the Occupational Safety and
Health Administration (OSHA) has set Threshold Limit Values (TLVs) only for
monomeric isocyanates (Table 4). In addition, guidance values are promulgated by the
American Conference of Governmental Industrial Hygienists (ACGIH). This
professional society originally recommended values forTDI and MDI (at 0.02 ppm)
which were the same as the OSHA limits, but in 1986 3, the values were changed to
0.005 ppm. By this time, HDI and methylene bis(4-cyclohexylisocyanate) had also
been added. The value for methyl isocyanate, adopted in 1977, remained at 0.02 ppm
and is also an OSHA regulated limit. The UK and most other countries followed the
USA lead, at least initially. Thus, the UK reprinted the ACGIH list in its entirety in
1965 4, but in 1984 5, the HSE introduced new limits, calculated as extrapolations
of the monomer limit values, but expressed as total isocyanate functional groups. This
was in response to the introduction of polyisocyanates (see above) and a single limit,
expressed in mg NCO/m 3 was adopted for all isocyanate species, based on then current
toxicological evidence. Australia has also adopted the UK approach, and other
European countries an intermediate one (Table 5).
4 ISOCYANATES: SAMPLING, ANALYSIS, AND HEALTH STCEFFE
Table 4 - USA (ACGIH) Limit Values
Compound Limit Values Comments
HDI 0.005 ppm TWA 1 As monomer
0.034 mg/m 3 TWA
MDI 0.005 ppm TWA l As monomer
0.051 mg/m 3 TWA
HMDI 0.005 ppm TWA As monomer
0.054 mg/m 3 TWA
TDI 0.005 ppm TWA As monomer
0.036 mg/m 3 TWA
MIC 0.02 ppm TWA 1
0.047 mg/m 3 TWA
JOSHA limit is 0.02 ppm
Table 5 - Non-USA Limit Values
Country Limit Values Comments
UK 0.02 mg/m 3 TWA as NCO groups
0.07 mg/m 3 STEL
Australia 0.02 mg/m 3 TWA as NCO groups
0.07 mg/m 3 STEL
Sweden 0.005 ppm TWA as ppm;
0.01 ppm STEL Polyisocyanate not quantified
Finland 0.035 mg/m 3 STEL as NCO groups;
Isocyanate form not specified
Measurement Methodologies
Historically, a large number of alternative methods have been devised for the
measurement of airborne isocyanates. Nearly all these methods rely on the
derivatization of the reactive isocyanate groups to products that can be analyzed,
usually by some form of chromatography. The detection systems have become
increasingly complex: from ultraviolet (UV) adsorption, through to electrochemical
(EC) and fluorescence (fluor) detection. The latest methods are now more likely to
utilize mass spectometry (MS) or even MS/MS. Table 6 gives a summary of the more
important developments, in roughly historical order, with their principles of operation,
advantages and disadvantages and significant literature references.
The choice of an ideal method relies partly on the requirements of the regulatory
NWORB NO OSI NOITAZIDRADNATS 5
authorities, but there are also technical considerations concerning the validity and
reliability of the various methods and the cost and availability of instrumentation.
These are dealt with elsewhere 24.
Table 6 - Isocyanate Measurement Methods
Method Principle Advantages Disadvantages References
Marcali Acid impinged On-site Only aromatic Marcali, 1957
diazotization colorimetric isocyanates. 6
with nitrous acid analysis. Amine
and N-2- Similar response interference
arninoethyl-1- for polymeric messy and
naphthylamine isocyanates inconvenient.
Reagent
potentially
carcinogenic
Ethanol Impinger, forms Separation of Only aromatic Bagon &
urethane isocyanates isocyanates (UV Pumell, 1980
analyzable by (mainly detection) 7
HPLC monomers)
Nitro reagent Impinged glass Separation of Less sensitive Dunlap,
N-(4- wool tube, forms isocyanates than ethanol for Sandridge &
nitrobenzyl)-n- urea analyzable (mainly aromatic Keller, 1976
propylamine by HPLC monomers), isocyanates 8
Equal sensitivity Reagent unstable
for aliphatic and HPLC column
aromatic degradation
isocyanates
MAMA Impinger/filter, Can quantify Variable Sango &
9-(N-methyl- forms urea polyisocyanates, fluorescent yield Zimerson, 1980
aminomethyl) analyzable by Near universal per NCO 9
anthracene HPLC. UV response
Isocyanates factor
identified by
detector ratio
(fluor/UV)
2-MP Impinged filter, Can quantify Analysis is more Warwick,
1-(2- forms urea polyisocyanates complex. Bagon &
methoxyphenyl) analyzable by EC detector Purnell, 1981
piperazine HPLC. unstable (monomer)
Isocyanates Bagon,
identified by Warwick and
detector ratio Brown, 1984
(EC/UV) (total) 10,11