Journal of J Occup Health 2007; 49: 482Ð492 Occupational Health
Evaluation of the Control Banding Method—Comparison with Measurement-based Comprehensive Risk Assessment
Haruo HASHIMOTO1, Toshiaki GOTO1, Nobutoyo NAKACHI1, Hidetaka SUZUKI1, Toru TAKEBAYASHI2, Shigeyuki KAJIKI3 and Koji MORI3
1Medicine and Occupational Health, ExxonMobil Yugen Kaisha, 2Department of Preventive Medicine and Public Health, School of Medicine, Keio University and 3Occupational Health Training Center, University of Occupational and Environmental Health, Japan
Abstract: Evaluation of the Control Banding workplace safety by compensating for its insufficient Method—Comparison with Measurement-based exposure information with safe-sided judgment criteria Comprehensive Risk Assessment: Haruo and by requiring experts’ intervention in high-risk cases. HASHIMOTO, et al. Medicine and Occupational Health, Control banding could be widely and effectively utilized ExxonMobil Yugen Kaisha—The control banding in Japan, especially by employers in small enterprises, method, or “control banding”, is a simplified risk provided that the above characteristics are pre- assessment system for chemical handling tasks. This acknowledged and health experts are made available. system is supposed to provide assessment results of To this aim, it is essential to develop new local health reasonable quality without expert involvement. The experts and establish institutional mechanisms for objective of this study was to evaluate the facilitating employers’ access to expert advice. It should appropriateness of control banding judgment on the however be noted that the number of workplaces basis of workplace safety. A common approach for evaluated in this study was small. assessing workplace risk, which is called (J Occup Health 2007; 49: 482Ð492) “comprehensive risk assessment” in this study, is to measure workers’ exposure and compare it with Key words: Control banding, COSHH Essentials, Risk relevant occupational exposure limits. Risk assessment, Exposure, Chemicals, Hazard, Control, assessment was performed with control banding Small enterprises, Expert (COSHH Essentials, UK) at 12 workplaces of a petroleum company in Japan, where health risks had It has been reported that the number of chemicals already been assessed separately through currently used in Japan is more than fifty thousand. This comprehensive risk assessment by experts and control makes the appropriate control of the health risks of these technologies implemented accordingly. The obtained chemicals a current occupational health issue1). While control banding judgments were then examined with occupational health control of chemicals in Japan has been regard to their adequacy by comparing them with existing control technologies. There was majority of performed according to the Industrial Safety and Health cases (seven) where judgments by control banding Law, which defines specific requirements for workplaces, were identified as “over-controlled”; there was no employers are supposed to autonomously perform risk judgments identified as “under-controlled”. Control assessment and management of chemicals that are not banding also requested the seeking of expert advice specified in regulatory clauses, since the number of in the majority of cases (eight). Thus, it was chemicals regulated by the law is limited. With this demonstrated that control banding tends to provide background, the Ministry of Health, Labour and Welfare, safe-sided judgment. A possible interpretation of this Japan, promulgated the “Guideline for risk assessment is that control banding is inherently designed to secure of chemicals and other hazards” in March 2006, which recommends employers to perform risk assessments for all chemicals used by them and to take risk mitigation Received Jun 28, 2007; Accepted Aug 13, 2007 2) Correspondence to: H. Hashimoto, Medicine and Occupational measures as needed . Health, ExxonMobil Yugen Kaisha, 1Ð8Ð15 Kohnan, Minato-Ku, In order to perform an accurate risk assessment of a Tokyo 108-8005, Japan workplace, collection of detailed hazard information and (e-mail: [email protected]) measurements of workers’exposure are commonly Haruo HASHIMOTO, et al.: Evaluation of the Control Banding Method 483 required, and a health expert who has sufficient company in Japan, were assessed with control banding knowledge of chemicals management is usually needed (COSHH Essentials) available on the HSE website6). The to perform them. However, there are often cases where details of each task, its process, duration, the chemical an expert is not readily available, especially among small handled and its amount, are shown in Table 1. and medium enterprises. Thus, a simple risk assessment Characteristics of each task relevant to control banding method is required which does not require expert assessment, such as the chemical species assessed, its involvement. Risk-phrases (R-phrases) and hazard group, scale of use, The control banding method, or “control banding”, is and ability to become airborne, are shown in Table 2. R- a risk assessment system for chemical handling tasks phrases corresponding to a chemical were identified which was originally developed by the HSE (Health and through the chemicals database carried on the homepage Safety Executive, UK) and is now being globally of the European Chemicals Bureau7). When the handled promoted by the ILO (International Labour Organization). chemical was a mixture of multiple chemical species, R- Control banding recommends necessary control phrases assigned to that mixture (example: gasoline) were technologies based on only three characteristics of a used for assessment, and R-phrases assigned to chemical handled: these are “hazard of the chemical”, components of the mixture (example: benzene) were not “scale of use”, and “ability to become airborne”3). Since used. This is because it was assumed that it would not control banding is designed to follow a standardized necessarily be easy for small and medium enterprises, process without direct exposure monitoring, this method the chief target employers of control banding, to obtain is supposed to provide assessment results with reasonable specific information regarding components of a chemical quality under circumstances in which an expert is not mixture. However, the chemical species assessed for task available. Several published studies have investigated # 4 was selected as benzene, and not petroleum products, the appropriateness of risk assessment judgments of since it was well known by workers that the petroleum control banding. These studies have attempted to validate products handled in this task contained appreciable the two exposure models on which the risk decision amounts of benzene (1 to 5%). For respective tasks, the scheme of control banding is grounded3Ð5). It was partially set of above information was input into control banding demonstrated that control banding tends to provide online interface, and then one of the four risk levels— appropriate or safe-sided (over-controlled) judgment in the “control approach criteria” which range from level 1 general. However, the results of these studies are (lowest risk) to level 4 (highest risk)—was judged and insufficient to draw an overall conclusion regarding the presented (Table 2). appropriateness of control banding for workplace safety, because the actual exposures of workplaces controlled in Comprehensive risk assessment accordance with control banding judgment were not The following risk assessments and managements were directly compared with the relevant occupational performed by workplace health experts (a Certified exposure limits. Industrial Hygienist of U.S.A. or equivalent) with more Occupational exposure limits have been common than several years of experience. A series of assessment judgment criteria for workplace safety. In order to steps was used for this risk assessment. First, personal accomplish accurate risk assessment of chemical handling exposure monitoring was performed regarding the most tasks, it is usually considered as a standard approach to hazardous or most representative component of the evaluate the exposure level and to compare it with chemical handled. The monitored chemical species were occupational exposure limit of the chemical; this approach benzene, lubricating oil (monitored as total hydrocarbons) will hereafter be called “comprehensive risk assessment” and n-heptane (Table 1). The exposure monitoring was in this study. In this study, risk assessment was performed carried out with passive samplers (Traceair OVM-1 from with control banding at workplaces where health risk had K&M Environmental Co.) which were then analyzed at already been assessed separately by experienced experts the ExxonMobil Biomedical Sciences Inc. (New Jersey, through comprehensive exposure assessment and control U.S.A.) which is an AIHA (American Industrial Hygiene technologies had been implemented, as needed, Association) accredited industrial hygiene laboratory8). accordingly. Then, the appropriateness of control banding Second, a set of “exposure rating” was defined, in order was examined by comparing the obtained control banding to classify the degree of exposure for workers. This is judgment with the already existing controls. shown in Table 3: there are five levels of exposure rating from A (highest exposure) to E (lowest exposure) which Methods are based on the relative relationship between the Control banding magnitude of exposure and the corresponding The risk levels of 12 chemical handling tasks, which occupational exposure limit of the chemical monitored. are performed in refineries, a petrochemical plant, oil For a task with a duration of more than 15 min (i.e. with terminals and a research laboratory of a petroleum monitoring time more than 15 min), the 8-h time-weighted 484 J Occup Health, Vol. 49, 2007
15 min, ACGIH-
≤
hood
hood
hood
observation, *8: General exhaust ventilation originally equipped, *9:
ne(5%), *5: Major naphtha ingredients: benzene(1.2%), toluene(1.5%),
(ppm) (ppm) *1 Requested? Implemented
15 min, 8 h TWA for task duration >15 min, *2: Reference value: ACGIH-TLV-STEL for task duration
≤
)
l
*4
*5
oil *9 hydrocarbon *9
Sludge
solvent
benzene
Naphtha 2 Benzene 2 <0.00 <0.00 2.5 D I 2 N Ð
Products
3
90 Lubricating 4 Total 2 <0.35 <0.07 100 E II 3 N Ð *8
45 Gasoline 0.01 Benzene 3 0.16 0.02 0.5 D I 2 N Ð *8
10 Acetone 0.05 (Acetone) Ð Ð Ð 750 C III 2 N Ð *7, *8
50 Toluene 0.5 (Toluene) Ð Ð Ð 50 A III 1 Y Ventilation *7, *8
15 Gasoline 8,000 Benzene 33 0.40 0.40 2.5 C I 2 N Ð
480 Oily 1,000 Benzene 6 6.84 6.84 0.5 A I 1 Y RPE-2 *6
480 Oil with 1 (Benzene) Ð Ð Ð 0.5 A I 1 Y Ventilation *7, *8
480 Petroleum 0.75 (Toluene) Ð Ð Ð 50 A III 1 Y Ventilation *7, *8
215 Petroleum 1 n-Heptane 2 6.60 2.96 400 E III 3 N Ð *8
(min) (
Duration Handled Handled Chemical n Av. TWA (ppm) rating *3 Level
drums 10 Naphtha 1,000 Benzene 4 2.08 1.37 2.5 B I 1 Y RPE-1 *6
l
bons; the RV (100 ppm) is a company standard of ExxonMobil Co.
Chemical handling tasks and their risk assessment results by comprehensive exposure assessment
Task Description Task Chemical Quantity Monitoring RV *2 Exp. HER Risk Control Note
efilling gasoline into a test
Disconnecting and cleaning aDisconnecting 15 Gasoline 1 Benzene 6 0.18 0.18 2.5 D I 2 N Ð strainer (height=30 cm) attached to gasoline transfer piping Filling naphtha into 200 while holding the charging nozzle Shoveling and cleaning residual oily sludge inside a huge crude oil tank Testing benzene-containing petroleum products in laboratory Washing used glass sample bottles of petroleum products in laboratory Drawing off hot motor oil from a test automobile engine Washing disassembled engine parts, with solvent
automobile engine, with small amount of leakage Rinsing laboratory glassware with acetone
toluene
product, while handling the charging nozzle on the lorry roof
from a faucet attached to process
piping
Table 1.
#
1
2
3
4
5
6
7
8R
9
10 Rinsing laboratory glassware with
11 Loading a tank lorry with gasoline
12 Sampling small amount of naphtha
*1: Time weighted average (TWA) exposure: 15 min TWA for task duration TLV-TWA for task duration >15 min, *3: Health effect rating, *4: Major gasoline ingredients: benzene(0.5%), toluene(6%), n-hexa n-hexane(12%), *6: Respiratory protective equipment: RPE-1=half face mask, RPE-2=full face mask, *7: Exposure rating judged by Monitored as total hydrocar Haruo HASHIMOTO, et al.: Evaluation of the Control Banding Method 485
Table 2. Risk assessment results by control banding
Task Chemical evaluated Scale of use Ability to Become Control Approach # Name R-phrase Assigned Hazard Group *1 *2 Airborne *3 Criterion *4
1 Gasoline 45, 65 E M M 4 2 Naphtha 45, 65 E L M 4 3 Crude Oil 45 E L M 4 4Benzene 45, 46, 36/38, 48/23/24/25, 65 E M M 4, S 5 Toluene 38, 48/20, 63, 65, 67 D S M 3, S 6 Lubricating oils 45 E M L 4 7 n-Heptane 38, 50/53, 65, 67 A M M 1, S 8 Gasoline 45, 65 E S M 4 9 Acetone 36, 66, 67 A S M 1, S 10 Toluene 38, 48/20, 63, 65, 67 D S M 3, S 11 Gasoline 45, 65 E L M 4 12 Naphtha 45, 65 E M M 4
*1: A=Least hazardous, E=Most hazardous, *2: S=Small, M=Medium, L=Large, *3: L=Low, M=Medium, H=High, *4: Corresponding control recommendation: 1=General ventilation, 2=Local exhaust ventilation, 3=Enclosure, 4=Seek expert advice, S=Skin and eye precautions.
Table 3. Definition of “exposure rating” relatively large, more than 0.5 l. On the other hand, the exposure level was estimated to be low for task #9, since Exposure rating Definition the amount of chemical handled was low, 0.05 l, and A >RV* ACGIH-TLV-STEL of acetone is exceptionally high, 750 B 50Ð100 % of RV ppm. Consequently, the exposure rating of the 12 tasks C 10Ð50 % of RV was respectively assigned to one of the levels from A to D 1Ð10% of RV E, as shown in Table 1. E No exposure Third, according to the scheme utilized by Booher et al.10), hazard levels of handled chemicals were classified, *Reference value: ACGIH-TLV-TWA for tasks >15 min, based on the EU labeling classification11), into four or ACGIH-TLV-STEL for tasks ≤15 min. levels—from I (most hazardous) to IV (least hazardous)— hereafter called “health effect rating” (HER). The labeling classification of each chemical was assigned in accordance with R-phrases of the chemical. Specifically, average (TWA) exposure was calculated from the benzene was assigned to HER I since it is a “category 1 analyzed airborne concentration; the average 8-h TWA carcinogen”; lubricating oil was assigned to HER II since was then obtained by averaging the relevant sample data. it is a “category 2 carcinogen”; and n-heptane, toluene Then, the exposure rating of this task was assigned based and acetone were assigned to HER III since they are on that average TWA. For a task with a duration of equal “irritant”(Table 1). to or less than 15 min, the average 15-min TWA was Finally, a matrix was constructed as shown in Table 4. calculated similarly, and the exposure rating of the task This matrix defines three risk levels from 1 (highest) to 3 was then assigned. (lowest) for a chemical handling task, based on a The exposure rating of tasks #4, 5, 9 and 10 were combination of the exposure rating and the health effect assigned based on qualitative judgment: the experts rating of the task. The risk levels of the 12 tasks were carefully observed the respective tasks and estimated individually determined by adopting the exposure rating exposure levels with knowledge of past exposure and the health effect rating of each task in this matrix; monitoring results for similar tasks within the worksite. the result is shown in Table 1. For tasks with a determined This type of qualitative judgment has been acknowledged risk level of 1 (highest), a new exposure control as an effective screening method before quantitative technology, such as engineering or administrative control, measurements in the Occupational Exposure Sampling was executed. The actual design or content of the control Strategy Manual by NIOSH9). Specifically, the exposure was determined by the experts. For tasks with risk levels levels were estimated to be relatively high for tasks #4, 5 of 2 or 3, no exposure control technology was newly and 10, since the amount of chemical handled was implemented. 486 J Occup Health, Vol. 49, 2007
Table 4. Matrix for “Risk level*” assignment in comprehensive exposure assessment
HER** Exposure rating AB C D E
I11223 II 1 1 2 3 3 III 1 2 2 3 3 IV 2 2 3 3 3
*Risk level: 1=Highest risk, 3=Lowest risk, **Health effect rating: I=Most hazardous, IV=Least hazardous
Table 5. Comparison scheme of risk assessment results
Control banding: Comprehensive exp. “Appropriateness” of judgment Control approach criteriona assessment: Risk levelb by control banding
1, 2, or 3 1 Over-controlled c Appropriate c Under-controlled c 1, 2, or 3 2 or 3 Over-controlled 41Not comparable 42 or 3 Over-controlled
a1=General ventilation, 2=Local exhaust ventilation, 3=Enclosure, 4=Seek expert advice, b1=Control requested, 2=Control not requested, 3=Control not requested, cThe actual control executed through comprehensive exposure assessment was compared with the control recommended by the control approach criterion.
The comprehensive risk assessment utilized here, the comprehensive risk assessment is a standard. The which represents a series of risk assessment steps results were classified into four criteria—“over- described above, is a way of quantifying magnitude of controlled”, “appropriate”, “under-controlled” and “not risk from a two-dimensional matrix. These two comparable”, as shown in Table 5. Namely, the control dimensions are the hazard and exposure levels of a approach criterion given by control banding was chemical, the latter being determined by the relative compared with the judgment of the comprehensive risk relationship between the observed exposure and the assessment whether new control technology was occupational exposure limit of the chemical. These two requested or not (i.e. whether the judged risk level was dimensions respectively represent “magnitude of a “1” or “2 or 3”). In cases where the control approach hazard” and “probability of occurrence of that hazard” criterion was level 1, 2 or 3, and also control technology which are key components of “risk” by definition. was requested by the comprehensive risk assessment (i.e. judged risk level was 1), the actual control ececuted was Comparison of control banding and the comprehensive compared with the specific type of the control risk assessment recommended by the control approach criterion. Let us make an assumption that the comprehensive risk assessment method utilized in this study is capable Results of assessing magnitude of risk with reasonable accuracy Risk assessment results by means of control banding and that the control measures actually implemented were are shown in Table 2. The judged control approach just enough in regard to their scale and quality; the basis criteria of 12 tasks ranged from 1 to 4. Each control of this assumption is that this assessment method is based approach criterion, from 1 to 4, represents a specific on direct or indirect exposure measurements, and that control recommendation. These are “general ventilation”, experts are involved throughout the process. The “local exhaust ventilation”, “enclosure”, and “seeking appropriateness of the control banding judgment was expert advice”, respectively. Five tasks which involved examined for 12 tasks, on the basis that risk judgment by chemicals hazardous to the skin and eyes were Haruo HASHIMOTO, et al.: Evaluation of the Control Banding Method 487
Table 6. Repeat risk assessment by comprehensive exposure assessment after implementation of control technologies
# Monitoring TWA *1 RV *2 Exp. HER Risk Note Chemical n Av. TWA Assumed (ppm) rating *3 level (ppm) (ppm)*1 (ppm)
2 (Benzene) Ð Ð Ð <0.14 2.5 D I 2 Assumption based on APF (*4) of a half face mask (10) 3 (Benzene) Ð Ð Ð <0.14 0.5 C I 2 Assumption based on APF (*4) of a full face mask (50) 4 Benzene 9 0.07 0.07 Ð 0.5 C I 2 5 Toluene 2 6.10 6.10 Ð 50 C III 2 10 (Toluene) Ð Ð Ð Ð 50 D III 3 Judged by observation
*1: 8 h time weighted average exposure, *2: Reference value: ACGIH-TLV-STEL for task duration >15 min, ACGIH-TLV-TWA for task duration >15 min, *3: Health effect rating, *4: Assigned protection factor (NIOSH, yielding 1/10 or 1/50 decrease in exposure for a half or full face mask respectively.)
Table 7. Comparison of risk assessment results and appropriateness of control banding judgment
Task # Control banding: Comprehensive exp. assessment: Control approach Risk level Appropriateness of control criterion Risk level Control done? banding judgment
14 2N Over-Controlled 24 1Y Not Comparable 34 1Y Not Comparable 44 1Y Not Comparable 53 1Y, Ventilation hood Over-Controlled 64 3N Over-Controlled 71 3N*Appropriate 84 2N Over-Controlled 91 2N*Appropriate 10 3 1 Y, Ventilation hood Over-Controlled 11 4 2 N Over-Controlled 12 4 2 N Over-Controlled
*General exhaust ventilation was originally equipped.
additionally classified “S” criterion. The control approach In order to evaluate the effectiveness of the controls criterion having the largest number of tasks (eight tasks) executed, a repeat risk assessment was performed for the is criterion 4. This represents the highest risk level and tasks after implementation of the controls; the results are requests expert advice. shown in Table 6. For tasks #2 and 3, exposure levels at Risk assessment results by means of comprehensive breathing zones were estimated based on an assumption risk assessment are shown in Table 1. The exposure rating that a half-face or full-face air-purifying mask yields a 1/ and the health effect rating of the 12 tasks ranged from A 10 or 1/50 decrease in exposure, respectively, compared to E, and I to III respectively. The risk levels determined with the original exposures previously measured (shown from the combination of these two dimensions ranged in Table 1), since the assigned protection factors defined from 1 to 3. Among them, there were five tasks with risk by NIOSH for half-face and full-face masks are 10 and level 1, to which engineering or administrative controls 50, respectively12). For tasks #4 and 5, exposure were then executed: local exhaust ventilation (laboratory monitoring was carried out. For task #10, the expert enclosing hoods) was installed for tasks #4, 5 and 10, carefully observed the task and qualitatively assessed the and respiratory protective equipment was provided for exposure level. Consequently, the risk levels of these tasks #2 and 3. tasks went down to either level 2 or 3 after implementation 488 J Occup Health, Vol. 49, 2007 of controls: effectiveness of the controls was thus verified. protection is explicitly recommended for skin/eye The comparison of the results of the risk assessments hazardous chemicals without omission. performed with control banding and those with the (d)It should be cautioned that the risk assessment outcome comprehensive risk assessment are shown in Table 7. For can be different depending on what species of tasks #2, 3 and 4, while control banding assigned them chemicals is selected as assessment objects for a to control approach criterion 4 (requesting expert advice), chemical mixture. For example, the risk assessment the comprehensive risk assessment determined their risk of task #1 was performed for gasoline, a common as level 1 and controls were executed, accordingly. name of the mixture. If it were performed for toluene, Control banding judgment was classified as “not a gasoline component with typical concentration of comparable” for these tasks, since it was impossible to several percent, a risk phrase of R-38 would be forecast the actual control advice to be provided by the additionally identified (in the same way as task #5 in expert requested by control banding. For tasks #1, 6, 8, Table 2) and control approach criteria “S” would be 11 and 12, while control banding assigned them to control supplemented accordingly. Control banding requires approach criterion 4 (requesting expert advice), the that all components of a chemical mixture should be comprehensive risk assessment determined their risks as evaluated and the highest (most demanding) control levels 2 or 3, and therefore did not request controls. approach criterion among all criteria presented should Control banding judgment was classified as “over- be followed. However, such a comprehensive controlled” for these tasks, since intervention of an expert approach is often not realizable, a typical obstacle was deemed to be unnecessary. For tasks #5 and 10, being that there are MSDS’s with insufficient control banding assigned them to control approach component information. There is also an issue of cut- criterion 3, and requested “enclosure” of workplaces. off criterion of mixture components, the percent Local exhaust ventilation had actually been installed at composition above which a chemical species is defined these workplaces according to the comprehensive risk as a component. For example, the handling of a assessment results, and it was later confirmed that chemical species with a concentration in the range of exposure risk had been successfully mitigated. Thus, 0.1% to 1.0% in a mixture may be controversial. control banding judgment was classified as “over- While this issue can also be problematic for controlled” for these tasks, since “enclosure” was not comprehensive risk assessment, extra caution should necessarily needed. For tasks #7 and 9, control banding be taken in case of control banding assessments when assigned them to control approach criterion 1, and experts are not involed. requested general ventilation. The comprehensive risk (e) The risk of a task can not be re-assessed after the assessment had not requested control technologies. implementation of control technology since facility However, both workplaces were already equipped with information is not incorporated into control banding general ventilation systems for these tasks, and the assessment steps. In contrast, re-assessment can be comprehensive risk assessment was performed with readily performed by means of the comprehensive risk general ventilation functioning; tasks #7 and 9 were assessment. carried out in a research and testing laboratory room, (f) The COSHH on-line interface is very user-friendly. respectively. Thus, control banding judgment was classified as “appropriate” for these tasks, since the Comparison of this study with preceding studies exposure risk was appropriately controlled with general Control banding judges control approach criteria based ventilation. In summary, judgments by control banding on three factors: “hazard of a chemical”, “scale of use”, were “over-controlled” for the majority of tasks, seven; and “ability to become airborne”. It can be interpreted three tasks were “not comparable”, and two were that the judgment scheme of control banding has its “appropriate”; no task was “under-controlled”. grounds on two exposure models3). The first model is: “the exposure level is uniformly predicted, given ‘scale Discussion of use’, ‘ability to become airborne’, and ‘control Characteristics of control banding approach criterion’”. Here, the exposure level is called The following characteristics of control banding can an “exposure band”, and it represents a range of exposure be pointed out based on the results obtained. and not a single value. The second model is: “the safe (a) There is an enhanced tendency to provide safe-sided exposure limit of a chemical is defined in correspondence judgment. to the respective hazard group (‘A’ to ‘D’) to which the (b)There is an enhanced tendency to recommend seeking chemical belongs, and is not directly related to each expert advice; these cases are represented by control chemical species”. This exposure limit represents a range approach criterion 4. of exposure and not a single value, and it actually The following characteristics were also identified. coincides with the “exposure band”. When performing (c) It is valuable in practice that the need for skin/eye risk assessment regarding a chemical handling task, one Haruo HASHIMOTO, et al.: Evaluation of the Control Banding Method 489 first identifies the hazard group to which the chemical unsafe for workers. belongs. This then provides the target safe exposure limit Brooke compared the occupational exposure limits of (i.e. “exposure band”) of the chemical. With this the UK with exposure bands for 111 chemicals. His study “exposure band”, along with “scale of use” and “ability represents a validation attempt for the second exposure to become airborne” of the chemical, one can determine model of control banding, and it identified only 2 cases the “control approach criterion” through back-tracking out of 111 chemicals where the occupational exposure the logic of the first exposure model; this is the risk limit was lower than the exposure band5). This means judgment scheme of control banding. Chemicals in that the exposure bands have been designed to be more hazard group “E” do not have a corresponding exposure conservative than the occupational exposure limits for band, and they are always assigned to control approach most of chemicals. Thus, it was demonstrated that the criterion 4. judgment scheme of control banding is tuned to provide Tischer et al. researched existing databases of 18 safe-sided decisions. different industry operations in Germany regarding their The studies referred to above attempted to validate the work conditions and monitored exposure levels3). They appropriateness of the two exposure models of control identified the exposure band of each chemical handling banding. It was partially demonstrated that control task based on the first exposure model of control banding, banding tends to provide appropriate or safe-sided (over- and then compared the obtained exposure band with the controlled) judgment in general. However, these results measured exposure. They found that actual exposure are insufficient to draw overall conclusions regarding the levels were equivalent to or lower than corresponding appropriateness of control banding from the point of view exposure bands for most of the tasks, which suggested of workplace safety. This is because the actual workplace that the first exposure model was tuned to an appropriate exposures and occupational exposure limits were level or a rather safe-sided level. compared only indirectly, and not directly, within the Jones et al. compared exposure bands to measured studies. Here, let us suppose a chemical handling task exposures with regard to solvent vapor degreasing and which is controlled under a control approach criterion powder bag filling operations, utilizing monitoring data provided by control banding judgment. When we follow accumulated by the National Institute for Occupational the general conclusion reached by Tischer and Brooke, Safety and Health (NIOSH)4). Their study also represents we can assume that the exposure of this task is either a validation attempt for the first exposure model of control equal to or lower than the exposure band, and that this banding. They defined an “over-controlled” error as an exposure band is lower than the occupational exposure instance where conditions of chemical use prompted limit of the chemical. This results in a situation where control banding to recommend newly implementing a the exposure is lower than the occupational exposure control technology, although the monitored airborne limit, and hence, we can conclude that the workplace is concentration was within or below the chemical’s surely safe and that control banding judgment is safe- exposure band in the absence of any control technology. sided. On the other hand, Jones et al. identified a This error was observed for as much as 61% of relevant significant number of “under-controlled” cases where vapor degreasing operations. They also defined an workplace exposures exceeded the relevant exposure “under-controlled” error in which the monitored airborne bands. For these cases, even after taking account of concentration exceeded the upper limit of the chemical’s Brooke’s general conclusion, it is difficult to predict exposure band although there was a control technology whether or not workplace exposure is lower than the implemented according to control banding exposure band in general. Thus, it can be summarized recommendation. This error was observed for as much that verifying the appropriateness of respective exposure as 78% of the vapor degreasing operations, and for as models has limited effectiveness in evaluating control much as 48% of the bag filling operations. Based on banding system. these results, Jones et al. concluded that their analysis The most appropriate approach would therefore be to did not support the view that control banding would be compare the measured exposure of a chemical, used in a able to accurately identify appropriate control workplace where the risk assessment had been performed technologies and that the recommended control with control banding and the control technology advised technologies were capable of adequately controlling by it implemented, with the occupational exposure limit exposures. This is a different conclusion from that of of the chemical, in order to verify control banding system Tischer et al4). Caution should be noted for the “under- on the basis of actual workplace safety. However, there controlled” errors in Jones’ study, since the monitored is a concern in terms of workers’ safety if we first assess exposure levels had not been compared with the a workplace with control banding, then implement control occupational exposure limits of the chemicals concerned. technology accordingly, and lastly monitor exposure of Therefore, an “under-controlled” error does not the workplace to examine its environment (i.e. a necessarily suggest a workplace condition deemed to be prospective study). In our study, risk assessment was 490 J Occup Health, Vol. 49, 2007 performed with control banding at workplaces where the the reason for the imperfection of their validation as being risk had already been assessed by means of a due to the fact that while all combinations of task comprehensive exposure assessment (that is, exposures conditions amounted to a total of 54 exposure scenarios were monitored and compared with occupational in control banding, their study covered only 8 scenarios exposure limits) and control technologies had been and further tended to concentrate on “medium scale” and implemented as needed according to experts’ professional “medium volatility/dustiness” conditions. Jones’s study judgment. Then, the appropriateness of control banding contains a large database as well. The numbers of was evaluated by comparing the obtained control banding workplaces evaluated were 33 for vapor degreasing and judgment with existing control technologies (i.e. a 22 for bag filling operations, and the numbers of chemical retrospective study). species measured were 7 and 19, respectively, while the The findings of this study demonstrate that control number of exposure measurements was about 710 4). banding tends to make safe-sided judgments. Namely, The above two studies suggest that substantially large- control banding requested additional exposure protection scale investigation will be necessary to evaluate control measures for workplaces where the actual exposures were banding system with accuracy and objectiveness. Thus, lower than the relevant occupational exposure limits. since the scope of tasks and chemicals evaluated in our Such cases were observed in more than half of the tasks study was limited, it is appropriate to acknowledge this evaluated. Thus, this study confirms that control banding work as a pilot study which compared control banding judgment is safe-sided in reality on the basis of workplace with actual workplace management performed by means safety. of comprehensive risk assessment, and it should be It was also observed in this study that there were a cautioned that the generalizability of this study will be number of cases where control banding requested expert limited. consultation (i.e. control approach criterion 4). This is because many tasks involved petroleum products such Utilization of control banding in Japan as gasoline or naphtha which contain benzene It is desirable that health risk assessment of chemicals (carcinogen, R45). In the Jones’ paper, “control approach be performed by experts having an appropriate level of criterion 4” was assigned to 13 chemicals among 26 expert knowledge, since health risk is not often readily chemical substances (liquid or powder) evaluated4); the perceivable by workers and specialized knowledge such frequency of “control approach criterion 4” was not as toxicology is usually required for health risk specifically discussed in the other studies referred to assessment and management. However, the availability earlier. In addition, all chemicals assigned to hazard group of experts is significantly different in practice from one E and some of the chemicals assigned to hazard groups enterprise to another. Therefore, an employer will C and D are judged as “control approach criterion 4” implement control technology complying with an expert’s within the decision scheme of control banding6). On the risk assessment result, as long as an expert is available whole, we can predict that there will be, in general, and the quality of the collected hazard information is moderately frequent occurrence of control banding good. In contrast, an employer will rather carry out safe- judgment requesting expert consultation. sided (over-controlled) control technology if an expert is unavailable or the quality of the hazard information is Position and limitation of this study poor, considering uncertainty factors within the risk It must be noted that the scope of tasks evaluated in assessment system employed13). An example of such this study was limited. The number of tasks was 12, and choices between the two is the comprehensive risk the task processes were mainly liquid transfer and assessment and control banding investigated in this study. washing within one petroleum company. More than half These two methods can represent, in short, choices of a of the chemicals handled in these tasks were benzene- “tailored method with accuracy” or a “safe-sided method containing petroleum materials, such as gasoline or compensating for scarcity of information”. It can be naphtha. In addition, most of the chemicals evaluated interpreted that control banding is inherently designed to are classified as “medium” for their “ability to become compensate for insufficient exposure information by a airborne”, and the number of exposure measurement data safe-sided judgment and to secure the safety of high-risk utilized was rather small—about 70. workplaces by requesting expert intervention. Tischer et al. mention in their study that they were Control banding could be effectively utilized for risk able to validate the appropriateness of COSHH Essentials assessment of chemicals in Japan, provided that its safe- scheme only partially, despite the fact that they evaluated sided characteristics are pre-acknowledged by users and as many as 18 kinds of tasks within a wide variety of that channels for expert intervention are secured. This industries such as textile, printing, chemical and furniture system could also be utilized for screening purposes manufacturing, and that the number of exposure data before performing more accurate risk assessments such utilized was substantial—about 9603). They attributed as the comprehensive risk assessment. In such cases, the Haruo HASHIMOTO, et al.: Evaluation of the Control Banding Method 491 degree of safety of a workplace would be expected to be reasonably high if control banding had judged the present Conclusion status of the workplace as “safe”. The appropriateness of control banding system was Money et al., as members of the COSHH Essentials evaluated based on workplace safety by assessing risks working group of the HSE, reported that control banding of chemical handling tasks with control banding and then is designed as inherently conservative and that it needs comparing the results with a practical risk assessment to be operated in a “screening mode” which presupposes outcome performed with the comprehensive risk seeking access to experts as needed14). They admitted assessment. It was demonstrated that control banding that there have been criticisms regarding artifacts of tends to provide a safe-sided judgment. A possible control banding methodology and cases where control interpretation of this is that control banding is inherently banding “advice” is overly protective for some tasks when designed to secure workplace safety by compensating for compared with recommendations derived from empirical insufficient exposure information with safe-sided occupational hygiene approaches. However, they stressed judgment criteria and by requiring expert advice in high- that the most important consideration is the extent to risk cases. Control banding could be widely and which reasonable risk control advice can be accessed and effectively utilized by employers in Japan, provided that implemented by users in practice. They also mentioned the above characteristics are pre-acknowledged by users. that control banding has a far greater likelihood of meeting To this aim, it will be essential to establish institutional users’ needs in a context where risk assessment experts mechanisms which facilitate development and utilization can not readily be accessed. Their opinion can be of new local health experts. However, it should be noted interpreted as actively supporting the conclusion of this that the scope of tasks and chemicals evaluated in this study, that the control banding judgment is safe-sided, study was limited. and that control banding has potential for future utilization including screening use in Japan. Acknowledgments: This study was supported by the When control banding provides a truly safe-sided (over- Labor Science Research Fund (the Program for controlling) judgment, the employer will bear a wasteful Comprehensive Occupational Safety and Health burden if they obediently implement control technology Research) under supervision of the Ministry of Health, according to the judgment. In reality, it is predictable Labour and Welfare, Japan: subject number of H16- that there will be frequent cases where employers actively roudou-6. seek expert advice after suspecting the accuracy of the References judgment in attempts to avoid potential waste of resources. Also, there can be other cases where employers 1) Mori K: Gendai sangyou-hoken no kadai to korekara. neglect seemingly over-controlling judgment at their own [The issues and the perspectives of today’s occupational discretion because they are cautious about the excessive health; JP]. Hataraku Hitono Anzen to Kenko 5, 50Ð 55 (2004) (in Japanese) cost burden. Considering such situations, and also 2) Guidelines for risk assessment of chemicals and other considering the fact that control banding often advises hazards. Tokyo: Ministry of Health, Labor and Welfare control approach criteria 4, it can be concluded that the Japan, 2006. necessity of providing health experts for control banding 3) Tischer M, Bredendiek-Kamper S and Poppek U: is substantially high in reality, although the control Evaluation of the HSE COSHH Essentials exposure banding system is often perceived as not requiring experts. predictive model on the basis of BAuA studies and The COSHH Essentials on-line interface actually existing substances exposure data. Ann Occup Hyg 47, recommends users to consult certified occupational 557Ð569 (2003) hygienists when it assigns a case as control approach 4) Jones RM and Nicas M: Evaluation of the COSHH criteria 4; on-line linkage to the British Occupational Essentials foe vapor degreasing and bag filling Hygiene Society is also provided6). The existence of operations. Ann Occup Hyg 50, 137Ð147 (2006) 5) Brooke I: A UK scheme to help small firms control established occupational hygienists is thus one of the key health risks from chemicals: toxicological infrastructures for smooth functioning of control banding considerations. Ann Occup Hyg 42, 377Ð390 (1998) system. Therefore, in order to aim for encouraging 6) Health and Safety Executive. UK: COSHH Essentials, utilization of control banding in Japan, it would be Easy steps to control health risks from chemicals. essential to establish institutional and social mechanisms (online), available from
Programs, Laboratory Accreditation Programs, labeling, Annex VI, General classification and labeling Accredited Labs. (online), available from