Interpretation and use of occupational exposure limits for chronic disease agents

Occupational Medicine - State of the Art Reviews

Volumn 11, Issue 3, 1996, Pages 561-590

  Hewett, Paul ^a  

^a NATIONAL INSTITUTE FOR OCCUPATIONAL SAFETY AND HEALTH   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

CHEMICALLY INDUCED DISORDER; CHRONIC DISEASE; EPIDEMIOLOGY; HEALTH EDUCATION; HUMAN; MAXIMUM ALLOWABLE CONCENTRATION; OCCUPATIONAL DISEASE; OCCUPATIONAL EXPOSURE; OCCUPATIONAL HEALTH; REVIEW; RISK ASSESSMENT; RISK MANAGEMENT; STATISTICAL MODEL;

CHRONIC DISEASE; EPIDEMIOLOGIC METHODS; HEALTH EDUCATION; HUMANS; MAXIMUM ALLOWABLE CONCENTRATION; MODELS, STATISTICAL; OCCUPATIONAL DISEASES; OCCUPATIONAL EXPOSURE; OCCUPATIONAL HEALTH; RISK ASSESSMENT; RISK MANAGEMENT;

EID: 33748967742     PISSN: 0885114X     EISSN: None     Source Type: Journal    
DOI: None     Document Type: Article

References (126)

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3. 68
4. Many of the concepts and observations in this chapter can be generally applied to irritants, acutely toxic substances, and substances that are not usually considered chronic disease agents but have (TWA) OELs as control limits.
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6. 7,68 However, such complete standards are usually not recommended by nonregulatory risk assessors.
7. OSHA (Occupational Safety and Health Administration): Occupational exposure to benzene: Final rule. Fed Reg 52(176):34460-34578, 1987.
8. The number of measurements collected during a single shift can vary from a single, full-shift measurement to several consecutive, partial-shift measurements as long as the TWA is accurately estimated.
9. Finkel AM: Commentary: Who's exaggerating? Discover May:48-54, 1996.
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14. This refers to the ability to measure accurately concentrations of respirable coal mine dust at or near the REL.
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18. Some industrial hygienists believe that they should not be classified as risk managers but instead as risk assessors. This is because, in most cases, the prerogative to implement or augment controls resides solely with the plant manager. My view is that industrial hygienists should be considered not only part of a company's occupational exposure risk management program but also an integral, critical part. A "risk assessment," as the term is commonly used in government and academia when considering occupational exposures, typically involves the determination, based on an analysis of exposure and health effects data from a cohort, of the probability of an adverse outcome given a specific level of working lifetime average or cumulative exposure. It is difficult, if not impossible, to determine this probability for any specific employee.
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22. Occupational Safety and Health Act of 1970 (OSHAct): Public Law 91-596, 1970.
23. Federal Mine Safety and Health Act of 1977 (FMSHAct): Public Law 91-173, 1977.
24. "Acceptable risk" or "de minimis" risk for occupational risk factors has yet to be quantified.
25. Occupational Safety and Health Administration: Updating permissible exposure limits (PELs) for air contaminants; Meeting. Fed Reg 61:1947-1950, 1996.
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27. Peak exposures or sustained periods of high exposures may be important in the etiology of many occupational chronic diseases. However, exposure histories are nearly always incomplete. Consequently, the epidemiologist by default uses the estimates of long-term exposure in exposure-response analyses.
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33. Esmen NA: A distribution-free double-sampling method for exposure assessment. Appl Occup Environ Hygiene 7:613-621, 1992.
34. 31,36,51,53 After a baseline evaluation periodic evaluations should occur at least yearly. If, after several years, a consistent history of well-controlled exposures or better can be demonstrated, the employer may be justified in reducing the number of measurements collected and/or the frequency of sampling (for example, to once every two or three years, depending on the circumstances).
35. Rappaport SM, Selvin S, Roach SA: A strategy for assessing exposures with reference to multiple limits. Appl Ind Hygiene 3:310-315, 1988.
36. Hawkins NC, Norwood SK, Rock JC (eds): A Strategy for Occupational Exposure Assessment. Fairview, VA, American industrial Hygiene Association, 1991.
37. 29,47,116,121
38. An exposure monitoring program or exposure assessment strategy is composed of two parts: an exposure sampling strategy and a decision logic. The exposure sampling strategy specifies the process for selecting whom to monitor, when to monitor, how many TWA measurements to collect, and how often to repeat this process. The decision logic specifies the procedure for interpreting the exposure data and deciding whether or not the work environment is currently acceptable or unacceptable.
39. 31,48,71
40. Leidel NA, Busch KA, Lynch JR: Occupational Exposure Sampling Strategy Manual. National Institute for Occupational Safety and Health publication no. 77-173 (available from the National Technical Information Service, publication no. PB274792), 1977.
41. The decision logic was simple: If the first measurement is less than half the PEL, conclude that the work environment is acceptable for the exposure group represented by the MRE. If the first measurement is above the PEL, conclude that the work environment is unacceptable and take corrective action. Otherwise, collect additional measurements at specified intervals until either two consecutive measurements are less than half the PEL (and conclude that the exposures are acceptable) or any single measurement is above the PEL (and conclude that exposures are unacceptable and take appropriate actions to reduce exposures).
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45. 7,46 Otherwise, a random sampling strategy should be devised so that there is a high likelihood that the higher exposed employees are represented in the sample.
46. 46
47. Guest IG, Cherrie JW, Gardner RJ, Money CD: Sampling Strategies for Airborne Contaminants in the Workplace. British Occupational Hygiene Society Technical Guide No. 11 (ISBN 0 948237 14 7). Leeds, H and H Scientific Consultants, 1993.
48. Ayer HE: Occupational air sampling strategies. In Hering SV (ed): Air Sampling Instruments for Evaluation of Atmospheric Contaminants. 7th ed. Cincinnati, American Conference of Governmental Industrial Hygienists,1989.
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54. The Committee allows that the industrial hygienist may select the "most exposed worker" when determining whether an HEG is in compliance with a government standard.
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56. 55
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58. Rappaport SM, Kromhout H,Symanski E: Variation of exposure between workers in homogeneous exposure groups. Am Ind Hyg Assoc J 54:654-662, 1993.
59. Such data include repeat measurements randomly collected from a random sample of workers within each exposure group, which then could be analyzed using ANOVA techniques.
60. Efficiency refers to the ability to come to a decision, right or wrong, with a limited number of measurements.
61. Tuggle RM: Assessment of occupational exposure using one-sided tolerance limits. Am Ind Hyg Assoc J 43:338-346, 1982.
62. Any LTA OEL should have a corresponding TWA OEL to prevent abuse of the LTA OEL concept. For example, it is inappropriate to expose workers to 12 times the LTA OEL for 1 month followed by 11 months of zero exposure.
63. 31 recommended a similar goal: "A [reasonably homogeneous] job-exposure group which is within 0.1-1.0 x exposure limit band but yields results consistently below one-third the exposure limit could be sampled at a reduced frequency, namely once every two months" (p 327).
64. Roach SA, Rappaport SM: But they are not thresholds: A critical analysis of the documentation of threshold limit values. Am J Ind Med 17:727-753, 1990.
65. The effective OEL, or citation value, is the OEL plus an allowance for sampling and analytical error (SAE). SAE is calculated using the total coefficient of variation (CVT) for the sampling and analytical method. For a typical CVT of 0.1 the allowance is easily calculated: SAE = (1.645 • CVT • OEL).
66. Spear RC, Selvin S, Schulman J,Francis M: Benzene exposure in the petroleum refining industry. Appl Ind Hygiene 2:155-163, 1987.
67. Rappaport SM, Lyles RH, Kupper LL: An exposure-assessment strategy accounting for within- and between-worker sources of variability. Ann Occup Hyg 39:469-495, 1995.
68. Occupational Safety and Health Administration: Occupational exposure to asbestos; final rule. Fed Reg 59:40964-41158 (p 41058), 1994.
69. 36 was directed at persuading industrial hygienists to collect sufficient measurements for each homogeneous exposure group (HEG) so that the underlying parameters of the group exposure distribution are reliably estimated. These parameter estimates are then used in various statistical procedures to assess the acceptability of the exposure distribution for the HEG.
70. Cope RF, Pancamo BP, Rinehart WE, Haar GLT: Personnel monitoring for tetraalkyl lead in the workplace. Am Ind Hyg Assoc J 40:372-379, 1979.
71. Rock JC: Occupational air sampling strategies. In Cohen BS, Hering SV (eds): Air Sampling Instruments for Evaluation of Atmospheric Contaminants. 8th ed. Cincinnati, American Conference of Governmental Industrial Hygienists, 1995.
72. Nicas M, Simmons BP, Spear RC: Environmental versus analytical variability in exposure measurements. Am Ind Hyg Assoc J 52:553-557, 1991.
73. The survey notes should be evaluated for unusual occurrences (e.g., spills, temporary control equipment breakdowns) that are unlikely to recur or for systematic changes in the work environment (e.g., increased production level, process changes, decreased efficiency of the control equipment, introduction of new or untrained workers, changes in work practices).
74. 7 OSHA recommended that exposure data more than I year old be given little or no weight in evaluating the current exposure management practices. In the preamble to the 1992 cadmium revised PEL, OSHA stated that when using "historic monitoring" results to meet the "initial monitoring" requirements of the new standard, the employer must meet two conditions: (1) the historic exposure conditions must be similar to current conditions and the measurement method must conform to the requirements of the standard, and (2) monitoring must have been conducted "within 12 months prior to the publication date of this standard" (Fed Reg 57(178):42337, Sept 14, 1992).
75. Ziem GE, Castleman BI: Threshold limit values: Historical perspectives and current practice. J Occup Med 31:910-918, 1989.
76. Castleman BI, Ziem GE: American Conference of Governmental Industrial Hygienists: Low threshold credibility. Am J Ind Med 26:133-143, 1994.
77. American Conference of Governmental Industrial Hygienists: Threshold Limit Values: A more balanced appraisal. Appl Occup Environ Hygiene 5:340-344, 1990.
78. Corn M: Regulations, standards, and occupational hygiene within the U.S.A. in the 1980s. Ann Occup Hyg 27:91-105, 1983.
79. Corn M: Historical perspective on approaches to estimation of inhalation risk by air sampling. Am J Ind Med 21:113-123, 1992.
80. Stokinger HE: Threshold Limit Values. Dangerous Properties of Industrial Materials Report. May/June pp 8-13, 1981.
81. Stokinger HE: Threshold limits and maximum acceptable concentrations: Their definition and interpretation. Am Ind Hyg Assoc J 23:45-47, 1962
82. (see also a nearly identical article in Arch Environ Health 4:115-117, 1962).
83. Stokinger HE: Modus operandi of threshold limits committee of ACGIH. In Transactions of the Twenty-sixth Annual Meeting of the American Conference of Governmental Industrial Hygienists 26:23-29, 1964.
84. Stokinger HE: Industrial air standards - theory and practice. J Occup Med 15:429-431, 1973.
85. Stokinger HE: Intended use and application of the TLVs. In Transactions of the Thirty-third Annual Meeting of the American Conference of Governmental Industrial Hygienists, 33:113-116, 1971.
86. Roach SA, Baier EJ, Ayer HE, Harris RL: Testing compliance with threshold limit values for respirable dusts. Am Ind Hyg Assoc J 28:543-553, 1967.
87. 48,85
88. American Conference of Governmental Industrial Hygienists: Threshold Limit Values for Air-borne Contaminants for 1968, Recommended and Intended Values, 1968.
89. Nearly identical wording has been included in the introduction of every TLV booklet since 1968, including the current 1995-1996 booklet.
90. Stokinger HE: Current problems of setting occupational exposure standards. Arch Environ Health 19:277-280, 1969.
91. In 1969 and 1971 Stokinger lamented the fact that occasionally the "factory inspector" and "legal profession" interpreted high short-term measurements (i.e., partial shift, the common type of measurement prior to the 1970s) as evidence that the TWA TLV had been breached or as "proof or disproof of an existing disease or physical condition." Stokinger noted that such short-term measurements were best compared to ceiling values and the then newly developed short-term limits and not to the TWA TLVs.
92. American Conference of Governmental Industrial Hygienists: 1995-1996 Threshold Limit Values (TLVs) for Chemical Substances and Physical Agents and Biological Exposure Indices (BEIs). ACGIH, Cincinnati, 1995.
93. Stokinger also mentioned that TLVs should not be used as a measure of "relative index of toxicity." The strength of the data for each TLV vary, the site and mode of action vary, and, most importantly, the actual risk depends on the likelihood and severity of exposure. (It also may be assumed that the exposure-response curves for different substances will have different shapes or slopes.)
94. Brief RS , Scala RA: Occupational exposure limits for novel work schedules. Am Ind Hyg Assoc J 36:467-469, 1975.
95. American Conference of Governmental Industrial Hygienists: Documentation of the Threshold Limit Values and Biological Exposure Indices. 6th ed. ACGIH, Cincinnati, 1991.
96. Consider your response if your physician announced that your blood cholesterol was 400 mg/dl but that you should not be concerned because the average across all the patients that day was equal to or less than the goal of 200 mg/dl.
97. Occupational Safety and Health Administration: Occupational exposure to lead; final standard. Fed Reg 43(220):52952-53014, 1978.
98. Paull JM: The origin and basis of threshold limit values. Am J Ind Med 5:227-238, 1984.
99. 91
100. American Conference of Governmental Industrial Hygienists: Documentation of the Threshold Limit Values for Substances in Workroom Air. 3rd ed. ACGIH, Cincinnati, 1971.
101. Within-shift excursion factors make little or no sense if the TWA TLV is truly an upper limit for the long-term, lifetime average exposure of each worker.
102. Silva P: TLVs to protect "nearly all workers." Appl Occup Environ Hygiene 1:49-53, 1986.
103. American Industrial Hygiene Association: Workplace environmental exposure level guides. Am Ind Hyg Assoc J 55:71-72, 1994.
104. American Industrial Hygiene Association: AIHA WEEL Committee Charter, May 11, 1994.
105. U.S. Supreme Court: Industrial Union Department, AFL-CIO v. American Petroleum Institute et al., case nos. 78-911, 78-1036. Supreme Court Reporter 100:2871, 1980.
106. Asbestos, vinyl chloride, inorganic arsenic, lead, benzene, coke oven emissions, cotton dust, 1,2-di-bromo-3-chloropropane, acrylonitrile, ethylene oxide, and formaldehyde.
107. de la Cruz PL, Sarvadi DG: OSHA PELs: Where do we go from here? Am Ind Hyg Assoc J 55:894-900, 1994.
108. Nicholson WJ, Landrigan PJ: Quantitative assessment of lives lost due to delay in the regulation of occupational exposure to benzene. Environ Health Perspect 82:185-188, 1989.
109. Imagine, if you will, the excuses that could be made if speed limits were legally defined as "65 mph and under, 95% of the time" or "65 mph, on average." Enforcement would be difficult indeed.
110. Occupational Safety and Health Administration: OSHA Technical Manual (OTM), Directive TED 1.15, September 22, 1995.
111. Historical measurements will not be comparable to OSHA's full-shift compliance measurements if the measurements represent grab-samples or short-term exposures; were collected from substantially different shifts, processes, operations, or occupations; or process changes have occurred.
112. National Institute for Occupational Safety and Health: NIOSH Recommended Exposure Limit Policy, May 24, 1996.
113. Harris RL: Information, risk, and professional ethics. Am Ind Hyg Assoc J 47:67-71, 1986.
114. Naumann BD, et al.: Performance-based exposure control limits for pharmaceutical active ingredients. Am Ind Hyg Assoc J 57:33-42, 1996.
115. National Institutes of Health: Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel II). NIH publication no. 93-3095, 1993.
116. There is one aspect of cholesterol risk management that does not easily translate to the workplace. The NIH recommends that physicians encourage patients with a record of high cholesterol to reduce their cholesterol level considerably below the target value to balance the excessive exposures. With the exception of coal miners (who can be transferred to low dust areas based on evidence that pneumoconiosis has developed) and lead workers (who are transferred to low lead areas on the basis of excessive blood lead levels), this concept is not usually practiced by occupational health risk managers.
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123. American Industrial Hygiene Association American Industrial Hygiene Association white paper: A generic exposure assessment standard. Am Ind Hyg Assoc J 55:1009-1012, 1994.
124. Occupational Safety and Health Administration: Generic standard for exposure monitoring - Advance notice of proposed rulemaking. Fed Reg 53:37591-37598, 1988.
125. Organization Resources Counselors, Inc.: A Proposed Generic Workplace Exposure Assessment Standard. Washington, DC, Organization Resources Counselors, Inc., 1992.
126. 46