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Cancer risk assessments for trichloroethylene (TCE) based on linear extrapolation from bioassay results are questionable in light of new data on TCE's likely mechanism of action involving induced cytotoxicity, for which a threshold-type dose-response model may be more appropriate. Previous studies have shown that if a genotoxic mechanism for TCE is assumed, algebraic methods can considerably simplify the use of physiologically based pharmacokinetic (PBPK) models to estimate virtually safe environmental concentrations for humans based on rodent cancer-bioassay data. We show here how such methods can be extended to the case in which TCE is assumed to induce cancer via cytotoxicity, to estimate environmentally safe concentrations based on rodent toxicity data. These methods can be substituted for the numerical methods typically used to calculate PBPK-effective doses when these are defined as peak concentrations. We selected liver and kidney as plausible target tissues, based on an analysis of rodent TCE-bioassay data and on a review of related data bearing on mechanism. Tumor patterns in rodent bioassays are shown to be consistent with our estimates of PBPK-based, effective cytotoxic doses to mice and rats used in these studies. When used with a margin of exposure of 1000, our method yielded maximum concentration levels for TCE of 16 ppb (87 micrograms/m3) for TCE in air respired 24 hr/day, 700 ppb (3.8 mg/m3) for TCE in air respired for relatively brief daily periods (e.g., 0.5 hr while showering/bathing), and 210 micrograms/liter for TCE in drinking water assuming a daily 2-liter ingestion. Cytotoxic effective doses were also estimated for occupational respiratory exposures. These estimates indicate that the current OSHA permissible exposure limit for TCE would produce metabolite concentrations that exceed an acute no observed adverse effect level for hepatotoxicity in mice. On this basis, the OSHA TCE limit is not expected to be protective.

Publisher Summary This chapter presents results for recommended (REL) and permissible (PEL) exposure limits in air for safeguarding health for major organic chemical compounds. The REL value is the recommended exposure limit by the National Institute for Occupational Safety and Health. The PEL value is the permissible exposure limit for maintaining health as provided by Occupational Safety and Health Act. Both REL and PEL values apply to a 40 hour workweek. The last column in the tabulation provides immediately dangerous to life or health values. The tabulation also provides the freezing and boiling point temperatures which are helpful in determining whether the substance is a gas, liquid or solid at ambient conditions. The results are displayed in an easy-to-use table, which is especially applicable for rapid engineering usage. The organic chemicals encompass hydrocarbon, oxygen, nitrogen, halogen, silicon, sulfur and other chemical type compounds.

The Occupational Safety and Health Act, passed by the US Congress in 1970, establishes the authority and basic principles by which health standards are promulgated by the Occupational Safety and Health Administration. These principles have been interpreted and refined by 25 years of case law that has developed as a direct result of rule-making activity. The Act requires OSHA to develop health standards that “ensure to the extent feasible, on the basis of the best available evidence, that no employee will suffer material impairment of health or functional capacity even if such employee has regular exposure to the hazard … for the period of his working life.” Thus, OSHA has a fundamental responsibility under the Act to establish health standards that are based on health evidence and that are designed to minimize risk to each individual who may be exposed to a particular hazard for a working lifetime. The Act and accompanying case law also explicitly require OSHA to consider the technological and economic feasibility in developing new standards. In practice, when promulgating new standards dealing with potential carcinogens, the stringency of the standard is more constrained by feasibility considerations than by the weight of health evidence or magnitude of risk. In one of the more significant legal rulings relevant to standards development, the US Supreme Court has ruled that OSHA, before issuing a new standard, must demonstrate that a significant risk of harm exists among workers exposed to the hazard in question, and that the new standard will substantially reduce that risk. For carcinogenic hazards, this necessitates conducting quantitative risk assessments to meet this legal test. Although OSHA has not defined any risk level as representing a de minimis risk, the Agency has determined as a policy matter that lifetime risks of a magnitude of 1 cancer case per 1,000 workers constitute a significant risk that warrant further reducing exposures, provided that such reduction is both technologically and economically feasible. OSHA evaluates both human epidemiological and experimental animal data in determining the potential carcinogenicity of workplace contaminants, and often relies on scientific organizations such as IARC for evaluating the overall weight of evidence. Quantitative risk assessments are conducted both in-house and by outside experts. During the public comment periods and hearings conducted for each rule-making, OSHA also receives quantitative risk assessments conducted by interested parties, and must evaluate those assessments in reaching regulatory decisions. Because each new standard must be developed under this formal public process, OSHA's risk analysis is subjected to a high degree of scientific scrutiny. Specific to the subject of inorganic carcinogens, OSHA has promulgated comprehensive standards covering three hazardous materials (inorganic arsenic, asbestos, and cadmium), and is developing a proposal to issue a new standard on another substance (hexavalent chromium). Comprehensive health standards include requirements to: comply with permissible exposure limits; conduct exposure monitoring, medical surveillance, and employee training; and develop programs for using respirators and other protective equipment. The permissible exposure limit for a new standard is developed directly from quantitative risk assessment results and feasibility considerations. Epidemiologic studies have provided the data that the Agency has relied upon for quantitative risk assessment for these standards; however, in the cadmium rule-making, animal data also played an important role in evaluating the relative potency of various cadmium compounds. It has been OSHA's experience in conducting risk assessments for both inorganic and organic compounds that risk estimates based on animal data are consistent with, and often lower than, estimates based on epidemiological studies, that is, use of animal data in risk assessment has not been shown in OSHA's experience to systematically overestimate risks to workers. OSHA has been collecting and reviewing scientific information on two other materials, silica and man-made mineral fibres, as part of an ongoing prioritization process to identify future candidates for either rule-making or information dissemination activities.

Objective This study aims to compare liver function indices (aspartate aminotransferase [AST], alanine aminotransferase [ALT], and gamma glutamyl transferase [GGT]) among males who work with lead, organic solvents, or both lead and organic solvents, under the permissible exposure limit (PEL). Methods A total of 593 (out of 2,218) male workers who agreed to share their personal health information for medical research were selected for this study. Those excluded were hepatitis B carriers, individuals exposed to occupational risk factors other than lead and organic solvents, and individuals without liver function results. The 593 were divided into five groups: a lead-exposed group, an organic solvent-exposed group exposed to trichloroethylene (TCE co-exposed solvent group), an organic solvent-exposed group not exposed to trichloroethylene (TCE non-exposed solvent group), a lead and organic solvent-exposed group (mixed exposure group), and a non-exposed group (control group). We performed a one way-analysis of variance (one way-ANOVA) test to compare the geometric means of liver function indices among the groups, using a general linear model (GLM) to adjust for age, work duration, body mass index (BMI), smoking, and alcohol intake. In addition, we performed a binary logistic regression analysis to compare the odds ratios among groups with an abnormal liver function index, according to a cut-off value. Results The ALT and AST of the mixed exposure group were higher than those of the other groups. The GGT of the mixed exposure group was higher than the TCE co-exposed solvent group, but there was no difference among the control group, TCE non-exposed solvent group, lead-exposed group, and mixed exposure group. The same result was evident after adjusting by GLM for age, work duration, BMI, smoking, and alcohol intake, except that ALT from the mixed exposure group showed no difference from the TCE co-exposed solvent group. When the cut-off values of the AST, ALT, and GGT were 40 IU/L, 42 IU/L, and 63 IU/L, respectively, a logistic regression analysis showed no differences in the odds ratios of those who had an abnormal liver function index among the groups. However, if the cut-off values of the AST, ALT, and GGT were 30 IU/L, 30 IU/L, and 40 IU/L, respectively, the odds ratio of the AST in the mixed exposure group was 4.39 (95% CI 1.86-10.40) times higher than the control. Conclusion This study indicates that a mixed exposure to lead and organic solvents is dangerous, even if each single exposure is safe under the permissible exposure limit. Therefore, to ensure occupational health and safety in industry, a continuous efforts to study the effects from exposure to mixed chemicals is needed.

The major occupational concern from bio-decontamination of equipment using vapor phase hydrogen peroxide (VHP) generation systems is potential operator exposure outside the protective barrier from possible VHP leaks or accidental releases from the sealed piece of equipment during decontamination. For this reason, different real time monitoring techniques were evaluated to determine their ability to accurately measure VHP at concentrations ranging from 0.5 ppm to 5 ppm. The results of this laboratory evaluation suggest that two of the four methods evaluated (the ion mobility spectrometer [IMS] and Polytron) will approximate the National Institute for Occupational Safety and Health +/- 25% accuracy requirements for measuring the concentration of VHP at and near the Occupational Safety and Health Administration permissible exposure limit of 1.0 ppm. Over the range of 0.5 ppm to 5.1 ppm VHP, the IMS had an approximate pooled method accuracy of +/- 21%, while the Polytron had a pooled method accuracy of +/- 22%. However, both instruments had false readings when exposed to nominal concentrations of methanol, bleach, and sulfur dioxide. The two additional VHP monitoring techniques evaluated (the single point monitor [SPM] and Draeger tube) were unable to accurately measure the concentration of VHP when the relative humidity was below 20%.

Continuous exposure to hazardous materials will put the employees at risk of harmful effects from those materials. So it is necessary to establish a permissible level of exposure. All the guidelines for permissible levels of exposure are derived from the original work of the American Conference of Government Industrial Hygienists (ACGIH) who developed a concept they call threshold limit values (TLV). A TLV, which is a proprietary term, refers to the airborne concentration of a substance and represents conditions under which it is believed that nearly all workers may be repeatedly exposed to that substance day after day without adverse effect. The amount and nature of the information available for establishing a TLV also varies from substance to substance. Consequently, the precision of the estimated TLV is also subject to variation. The Occupational Safety and Health Administration–Permissible Exposure limit (OSHA-PEL) defines the average concentration permissible to a worker for a normal eight-hour workday and a forty-hour work week to which all workers may be repeatedly exposed, day after day, without adverse effect. The PEL or TLV concept is widely used throughout the world in spite of some well-founded objections, largely because there is no feasible alternative. The most significant objection pertains to the use of the averaging technique. It is argued that the effects on the body are not necessarily the same when they result from constant uniform exposure to low concentrations as they would be when they result from intermittent exposure to higher concentrations over the same period.

The work described in this report was carried out at a national laboratory of the Department of Energy, during the time that the author was engaged in a Department of Energy Industrial Hygiene Graduate Fellowship. The national laboratory had a respiratory protection program with approximately 50 employees participating. The program was in place to protect employees from over-exposure to airborne contaminants while engineering and work practice controls were being installed and implemented. It was also in place to protect workers in situations where engineering and work control practices were not feasible, such as during maintenance and repair work, as well as in situations where engineering and work practice controls were not enough to lower the exposure to or below the Permissible Exposure Limit (PEL) as set by the Occupational Safety and Health Association (OSHA) as an eight-hour time weighted average (TWA) or an excursion limit. Respirators were also used for emergencies by the emergency response team.

In early 1993, the Navy conducted testing at Norfolk Naval Shipyard to determine if personnel working with marine coatings containing lead, cadmium or chromium or other heavy metals were exposed to concentrations above the Occupational Safety Health Administration (OSHA) established permissible exposure limit (PEL). Based on these tests the Navy concluded that minute amounts of the heavy metals could result in exposures above the PEL. Additionally, the Navy concluded it could not predict exposure based on the concentration of the metal in The coating. In September 1993, four San Diego Master Ship Repair contractors commenced research, testing, and analysis to develop a Technical Document that outlines cost effective procedures to reduce exposure to lead, cadmium, chromium and other heavy metals while remaining compliant with OSHA and EPA Regulations. This project provides a comprehensive technical document the inexperienced and experienced contractor may use in the abatement of heavy metal containing marine coatings. Funding for this project was provided as a cooperative effort by The National Shipbuilding Research Program (NSRP) and by Continental Maritime of San Diego, Inc., National Steel and Shipbuilding Company, Pacific Ship Repair and Fabrication, Inc., and Southwest Marine, Inc. NSRP and these shipyards saw the need for shipyards to be proactive in the area of heavy metal coating systems abatement as current regulations were not "user friendly" in shipboard applications.

A standard is a general term incorporating both regulations and guidelines and can be defined as a set of specifications or rules to promote the safety of an individual or group of people. Absolute assurances are rarely if ever attainable and specifying permissible exposure limits for different hazards depends on the degree of risk that is scientifically and socially acceptable.1 Among the many factors that go into the development of an exposure standard, the selection of a good scientific biological effects data base plays, quite obviously, the most important role.

Silicosis is still a major threat for workers in developing countries Technological advances over the past half century, including wet drilling and improved ventilation, have contributed to substantially reducing the occurrence of silicosis among miners and other dust exposed workers. Hundreds of cases are, however, still identified each year in Europe and the USA,1,2 and silicosis is a major threat for workers in developing countries. Low salaries and less restricting and/or less enforced occupational hygiene standards have attracted many environmentally and occupationally demanding productions,3 and facilitated mining initiatives in developing countries.4 On the other hand, the “reappearance” of silicosis in wealthy western countries has resulted from the extension of occupational health surveillance to previously under scrutinised small or family owned businesses, and the immigration and illegal employment of non-unionised workforce from developing countries. Furthermore, the progressive clearing of the dark and thick cloud of silicosis cases, has been accompanied by the emergence of other diseases such as lung cancer, kidney failure, and immune system disorders,1 which has rekindled the interest in silica research. “The interaction between physical and biological entities is complex” As in many other fields of science, it seems that the more we progress in knowledge, the more we realise the complexity of the interaction between physical and biological entities. Such a complexity is viewed differently from different perspectives, as reflected by the diverse philosophy underlying the OSHA dust permissible exposure limit, which is flexible depending on the silica content in respirable dust (5 mg/m3 in the absence …

The study of human exposure to radiofrequency/microwave (RF/MW) radiation has been the subject of widespread investigation and analysis. It is known that electromagnetic radiation has a biological effect on human tissue. An attempt has been made by researchers to quantify the effects of radiation exposure on the human body and to set guidelines for safe exposure levels. A review of the pertinent findings is presented along with the American National Standards Institute (ANSI) recommended safety standard and the United States Air Force permissible exposure limit for RF/MW radiation. An overview of research conducted in the Soviet Union and Eastern Europe is also included in this report.

A pilot study was carried out in the cell houses of three chlor alkali plants to assess level of exposure to mercury vapors among workers by air and biological monitoring. Overall airborne mercury concentrations (mg/m3) were found to range from 0.05 to 0.42 (mean, 0.21, n = 68), 0.03 to 0.16 (mean, .08, n = 49), and 0.02 to 0.17 (mean, 0.04, n = 26), whereas urinary mercury levels (mg/liter) of the exposed workers of the respective plants ranged from 0.076 to 0.592 (mean, 0.207, SD, 0.107, n = 19), 0.015 to 0.220 (mean, 0.070, SD, 0.054, n = 16), and 0.013 to 0.275 (mean, 0.06, SD, 0.054, n = 23). Unattended mercury spillage on the floor and improper sealing of the lids of the end boxes of electrolysis cells were found to be main factors attributing to prevalence of mercury vapors in excess of the permissible exposure limit of 0.05 mg/m3. Based on the deficiencies observed, appropriate control measures have been suggested to reduce airborne mercury vapor concentrations in the work environment. © 1993 Academic Press, Inc.

The lithium/sulfur dioxide battery is a high-energy system capable of delivering 320 Wh/kg (520 Wh/liter). The active cathode material is a gas, SO2, which is present at a pressure of ~30 psi at room temperature. All cells, therefore, contain a vent mechanism in the case. Sulfur dioxide is a poisonous gas with an Occupational Safety and Health Administration (OSHA) permissible exposure limit of 5 ppm in an 8-h day. Exposure of 100–500 ppm can pose immediate danger to life and health.1,2 The electrolyte solvent, acetonitrile, is a moderately toxic, flammable liquid having a boiling point of 81°C. The lowest published toxic concentration for inhalation by humans is 160 ppm for 4 h.1

The current permissible exposure limit is inadequate to protect workers Silicosis (Latin, silex , flint) is perhaps the oldest occupational disease, probably existing in the paleolithic period. Hippocrates and Pliny refer to the disorder. Some of the most tragic and wanton examples of occupational disease were due to silicosis, for example, how table blade grinding in Sheffield (1886) robbed workers of 25 years of life, or the Gauley Bridge disaster in West Virginia (1931). Perusing a recent standard pulmonary medicine textbook would suggest that simple silicosis is no longer a problem as it is “not associated with impairment or disability and even without effect on longevity in many although not all”.1 Case closed, the silicosis story is over, or is it? In this issue of Occupational and Environmental Medicine , t’ Mannetje and co-workers answer this question with an elegant and resounding “no”!2 In a carefully designed pooled analysis a clear exposure-response relation for silicosis and mortality is shown. Increased mortality is also seen at exposure levels below the current US Occupational Health and Safety Administration’s permissible exposure limit (PEL) of 0.10 mg/m3 for respirable crystalline silica. This conclusion is the culmination of considerable new knowledge concerning dose-response relations and methodological developments in the past few decades. New knowledge has accumulated concerning associations between silica exposure and …

The electronics industry is expanding the use of gallium arsenide in the production of optoelectronic devices and integrated circuits. Workers in the electronics industry using gallium arsenide are exposed to hazardous substances such as arsenic, arsine, and various acids. Arsenic requires stringent controls to minimize exposures (the current OSHA PEL for arsenic is 10 micrograms/m3 and the NIOSH REL is 2 micrograms/m3 ceiling). Inorganic arsenic is strongly implicated in respiratory tract and skin cancer. For these reasons, NIOSH researchers conducted a study of control systems for facilities using gallium arsenide. Seven walk-through surveys were performed to identify locations for detailed study which appeared to have effective controls; three facilities were chosen for in-depth evaluation. The controls were evaluated by industrial hygiene sampling. Including personal breathing zone and area air sampling for arsenic and arsine; wipe samples for arsenic also were collected. Work practices and the use of personal protective equipment were documented. This paper reports on the controls and the arsenic exposure results from the evaluation of the following gallium arsenide processes: Liquid Encapsulated Czochralski (LEC) and Horizontal Bridgeman (HB) crystal growing, LEC cleaning operations, ingot grinding/wafer sawing, and epitaxy. Results at one plant showed that in all processes except epitaxy, average arsenic exposures were at or above the OSHA action level of 5 micrograms/m3. While cleaning the LEC crystal pullers, the average potential arsenic exposure of the cleaning operators was 100 times the OSHA PEL. At the other two plants, personal exposures for arsenic were well controlled in LEC, LEC cleaning, grinding/sawing, and epitaxy operations.

A pilot study was carried out in the cell houses of three chlor alkali plants to assess level of exposure to mercury vapors among workers by air and biological monitoring. Overall airborne mercury concentrations (mg/m3) were found to range from 0.05 to 0.42 (mean, 0.21, n = 68). 0.03 to 0.16 (mean, .08. n = 49), and 0.02 to 0.17 (mean, 0.04, n = 26), whereas urinary mercury levels (mg/liter) of the exposed workers of the respective plants ranged from 0.076 to 0.592 (mean, 0.207, SD, 0.107, n = 19), 0.015 to 0.220 (mean, 0.070, SD, 0.054, n = 16), and 0.013 to 0.275 (mean, 0.06, SD, 0.054, n = 23). Unattended mercury spillage on the floor and improper sealing of the lids of the end boxes of electrolysis cells were found to be main factors attributing to prevalence of mercury vapors in excess of the permissible exposure limit of 0.05 mg/m3. Based on the deficiencies observed, appropriate control measures have been suggested to reduce airborne mercury vapor concentrations in the work environment.

The relation between lead in air (PbA) and lead in blood (PbB), concentrations was investigated among 44 workers in five major operations in a United States high volume, lead acid battery plant. The study covered a 30 month period in which workers received frequent PbA and PbB determinations, workers remained in a single job, and PbA concentrations averaged below the US Occupational Safety and Health Administration (OSHA) permissible exposure limit of 50 micrograms/m3. In both univariate and multivariable linear regressions, longitudinal analyses averaging PbA concentrations over the 30 month study period appeared superior to cross sectional analyses using only six month PbA averages to model PbB concentrations. The covariate adjusted coefficient (alpha value) for PbA (mu/m3) in models of PbB (micrograms/100 g) was 1.14. This figure is strikingly higher than that reported in previous studies in the lead acid battery industry in all of which PbA concentrations were substantially higher than in the current study. Plausible explanations for the difference in alpha values include non-linearity of the PbA-PbB curve, a higher fraction of large size particulate associated with higher PbA concentrations, survivor bias among workers exposed to higher PbA concentrations, and the cross sectional designs of most previous studies. Despite previously reported problems with the model used by OSHA to predict PbA-PbB relations, the findings of this study are in good agreement with the predictions of that model.

estimated 2-3 million workers are potentially exposed to benzene (ATSDR 1989). It is important to have cancer risk factors available for the evaluation of worker exposures in various settings. The risk factors for benzene published by the EPA are designed to evaluate general population exposure (not worker exposure) and do not include the results of recent studies. In this paper, risk factors are derived for the evaluation of worker cancer risk due to the inhalation and ingestion of benzene. These cancer risk factors are characterized by route, species, strain, sex, dose, dose rate/kg, and fraction of lifetime exposed. Such characterization facilitates the matching of a risk factor to any exposure situation. Example applications of the risk factors are presented. These examples concern OSHA's permissible exposure limit (PEL) for benzene, inhalation exposure at leaking underground gasoline storage tank sites (LUSTs), and ingestion of contaminated soil. MATERIALS AND METHODS Cancer risk factors are usually derived from experimental studies in units of excess risk/(mg/m 3) or excess risk/(mg/kg/day). Experimental studies can be animal or epidemiologic. In order to obtain a risk factor, it is first necessary to compute excess risk and equivalent human dose from an experimental study. Excess risk is the frequency of response in the exposed group corrected for the control group response. The equivalent human dose from an animal or epidemiology study is a function of the following variables: pharmacokinetics; body weight (or surface area); exposure concentration; daily Send reprint requests to W. Hallenbeck at the above address.

In March 2007, the National Institute for Occupational Safety and Health (NIOSH) was asked to evaluate the noise exposure of employees in the Nutrition and Food Services Department of a large hospital, because of noise concerns raised after the installation of the PowerSoak® dishwashing system. Eleven employees (two cooks, eight food service workers, and a materials handler) contributed 13 full-shift and two task-based personal noise dosimetry measures over two days. The noise levels for two food service workers assigned to the pots and pans room (85.1 and 85.2dBA), a cook working in the food preparation area (85.9 dBA), and a food service worker assigned to the dishwashing room (89.5 dBA) exceeded the NIOSH Recommended Exposure Limit (REL); however, none of the measures exceeded the Occupational Safety and Health Administration (OSHA) Permissible Exposure Limit (PEL). The noise level from the PowerSoak® dishwashing system alone was not excessive, but additional noise from the food preparation area (primarily from blenders and utensils), and from metal-to-metal contact between stainless steel pots and pans and metal racks, may explain exposures above the NIOSH REL for employees in the pots and pans room. The cooks were exposed to many intermittent impact noise sources, such as, metal-to-metal contact between utensils and the use of industrial-size blenders. We recommended that metal-to-metal contact be reduced as much as possible throughout the Nutrition and Food Services Department, and hearing protectors be provided to employees in the dishwashing room until engineering controls were in place.

The U.S. Occupational Safety and Health Administration (OSHA) has proposed a revised 8-hour permissible exposure limit (PEL) for cadmium in air of either 1 or 5 micrograms/m3, based upon the prevention of lung cancer and kidney dysfunction. To evaluate the scientific basis for these alternative standards, we compare the OSHA estimates of risk, derived from mathematical modelling of selected studies, to empirical data on lung cancer and kidney dysfunction in the published literature. At least seven epidemiologic studies examine renal tubular proteinuria by cumulative cadmium exposure. Three suggest increased proteinuria at cumulative exposures below 500 micrograms/m3-year (equivalent to a PEL of 11.1 micrograms/m3 over 45 working years). One shows prevalence increasing at cumulative exposures between 100 and 299 micrograms/m3 (equivalent to a PEL between 2.2 and 6.6 micrograms/m3). Insufficient data exist to estimate a no-effect level for kidney toxicity. For lung cancer, qualitative evidence of carcinogenicity in humans is seen in four of five occupational cohorts. Quantitative estimates of risk based on epidemiologic data provide lower and more plausible estimates of lifetime risk than do estimates from a rodent bioassay. The data overall suggest that the PEL for cadmium should not exceed 5 micrograms/m3 to protect workers from kidney dysfunction and lung cancer over a working lifetime.

This article briefly reviews the history of the current threshold limit value and the permissible exposure limit for occupational dusts derived originally from the Nuisance Dust standard. Chronic inhalation studies of appropriate design are described in terms of their key findings and potential impact on the dust standards, especially modern, experimental studies which have been affected by the problem of dust overloading. Many studies show that dust overloading produces a significant and progressive retardation of macrophage-mediated dust removal leading to various dysfunctional and pathologic changes which confound the interpretation of chronic toxicity study findings. Assuming that there may be a human counterpart to this condition at the same milligram dust per gram lung concentration, extrapolation modeling can be used to show that the current occupational dust limits do not protect worker lungs from this eventuality. Several bases for substantially reducing the current occupational standards are discussed.

A review of the data cited by OSHA in its final standard for exposure to benzene provides no clear scientific basis for a short-term-exposure limit (STEL). While leukemia and bone marrow toxicity were related to cumulative exposures of benzene received by workers, no evidence was presented that the rate of exposure at a given cumulative exposure contributed to the effects. Likewise, animal experiments suggested that exposures of several hours duration at a given level of benzene induced more bone-marrow toxicity when administered 3 rather than 5 days/week but did not indicate that the rate of exposure over shorter time scales played any role. The toxicokinetics of benzene in humans were also studied to determine whether nonlinear dose-rate effects would be likely to result from peak exposures associated with an exposure dose of 8 ppm-hr, which is allowed under the permissible exposure limit. This led to three conclusions. First, the concentration of benzene in the bone marrow should be sufficiently damped that the impact of a peak exposure should be minimal. Second, the peak concentration of benzene in the liver should be within the capacity of the cytochrome P450 system to maintain first-order metabolism. And finally, the maximum blood concentration of metabolites should be well below levels which have been shown to induce toxic effects in vitro. Taken together, the toxicokinetic relationships and the absence of clear experimental dose-rate effects suggest that the current STEL for benzene is unwarranted, assuming that 8-hr average exposures are kept below 1 ppm. While the argument can be made, on the basis of health considerations, that the existing 8-hr limit for benzene is too high, the rate of exposure during short periods appears to be irrelevant. Thus, we recommend that health professionals focus upon long-term exposures to benzene received by large numbers of workers rather than devote scarce resources to evaluate transient air levels.

A study was conducted to evaluate the feasibility of reducing or eliminating airborne lead concentrations at a covered, outdoor firing range by using totally copper-jacketed ammunition. Used in the study were 38-caliber-special police revolvers, and firings were conducted with 38-caliber, totally copper-jacketed bullets. The mean lead levels in general area air samples and personal breathing zone samples were 9.53 micrograms/m3 and 5.88 micrograms/m3, respectively, calculated as an 8-hr, time-weighted average (TWA). The mean copper levels in general area samples and personal breathing zone samples were 0.8 micrograms/m3 and 1.43 micrograms/m3, respectively. These concentrations in general area air samples and personal breathing zone samples were well below the current Occupational Safety and Health Administration (OSHA) permissible exposure limit (PEL) for occupational exposure to inorganic lead (50 micrograms/m3) and for copper (100 micrograms/m3). No significant difference was found between blood lead levels before and after firing totally copper-jacketed bullets. Based on comparison with results from a comparable study using nonjacketed lead ammunition, it was concluded that the use of totally copper-jacketed bullets significantly reduced airborne lead levels by a factor of 21 in the personal breathing zone samples and by a factor of 7.5 in the general area air samples.

Six polyurethane foam workers were shown to have TDI-induced asthma by specific inhalation challenge testing. All remained in the workplace in jobs with minimal TDI exposures. Mean and time-weighted average exposure concentration for the asthmatic group was 0.64 +/- 0.46 ppb, less than 5 percent of the permissible exposure limit and significantly less (p less than 0.01) than the mean TWA exposures occurring in the foam line and the finishing workers. Serial evaluation of the respiratory health of these six showed all persisted with respiratory symptoms, none had improvement in bronchial hyperresponsiveness to methacholine, and three had a greater than 15 percent decline in FEV1 on one of the days of spirometric testing over the five-year period from 1982 to 1986. Although we could not have predicted the outcome of asthma had these workers left the workplace and ceased isocyanate exposure entirely, occupational asthma persisted despite negligible ongoing TDI exposures.

The process of alumina production involves refining of bauxite ore into tri-hydrated alumina (Al2O3, 3H2O) by chemical method followed by process of calcinations. This method possesses various kinds of dust hazards in its work environment amongst the people involved. Poor health of industrial employees in India is due to its occupational environment (Park & Park, 1970), which is a major concern now-a-days. Attempts have been made to recognize the potential sources of airborne dust and to assess the dust load upon exposed workers at different work sites of alumina plants by comparing the observations with the standard values called 'Threshold Limit Values' (T.L.V.) assigned by the international body ACGIH (American Conference of Governmental and Industrial Hygienists), USA, and also permissible exposure limit values prescribed in the second schedule Section F of Factories Act (Amendment), 1987. Alumina plant operation includes various physical operations like crushing, grinding, conveying, loading, transporting, etc., which generate finer particles. It can cause serious health hazards on inhalation, depending upon its size, shape, constituents and duration of exposure. Out of all these parameters, concentration of respirable fraction of airborne dust (0.5 to 5.0 micron size) and its free silica content have been reported to cause lung fibrosis as well as occupational disorders. In the present study, attempts have been made to make a survey of respirable fraction of the airborne dust (that remains suspended in air for quite an appreciable time) associated with various operations according to job profiles. It also outlines the probable control measures in order to provide a healthy working environment. Present work aims at identifying and evaluating the degree of workplace dust with special reference to respirable fraction and for recommending suitable suggestive control measures for an effective management of occupational environment.

Noise‐induced hearing loss continues to afflict workers in many occupational settings despite longstanding recognition of the problems and well‐known methods of prevention and regulations. Sound levels associated with heavy construction equipment range from 80 to 120 dB(A) and power tools commonly used in construction produce sound levels up to 115 dB(A). The focus of the research was to determine the noise exposures of heavy construction equipment operators while documenting the workers’ tasks, (i.e., hauling, moving, and/or pushing construction material). Time‐motion studies were performed at the construction sites and were used to correlate the noise dosage with the work performed by equipment operators. The cumulative dose for the operator was then plotted with references to work tasks, to identify the tasks that caused the greatest noise exposure. Three construction sites were examined and located in the western Pennsylvania and eastern Ohio areas. The types of construction equipment studied included asphalt pavers, backhoes, bulldozers, compaction equipment, excavators, haul trucks, telehandlers, and wheeled loaders. The results showed that bulldozer operators consistently had the highest noise exposures, ranging from a NIOSH REL (Recommended Exposure Limit) dose of 844% to 25 836% and an OSHA PEL (Permissible Exposure Limit) dose of 139% to 1397%.

The fourth edition of the National Institute for Occupational Safety and Health (NIOSH) Manual of Analytical Methods contains a new, simplified procedure for elemental analysis in workplace atmospheres by Inductively Coupled Argon Plasma Atomic Emission Spectroscopy (ICP-AES) titled NIOSH 7303. This method uses hot block digestion with hydrochloric acid (HCl) and nitric acid (HNO3). The method was presented as fully valid for elemental beryllium. It was further investigated and also found to be valid for beryllium sulfate tetrahydrate and has a recovery efficiency of about 80 % for beryllium oxide. Additionally, no matrix effect on beryllium analysis is apparent by NIOSH 7303 for five common sampling media: polyvinylchloride filters, mixed cellulose ester filters, Whatman® 42 filters, Ghost™ wipes, and Palintest® wipes. Finally, the method has been reevaluated and found to produce a beryllium detection level of 0.0002 μg/mL (0.005 μg/sample for air samples) and a quantifiable level of 0.0005 (0.0125 μg/sample). At this detection limit, the Occupational Safety and Health Administration Permissible Exposure Limit (PEL) of 0.002 mg/m3 can be achieved at the method's detection level with an air sample of 2.5 L or one tenth of the PEL with a sample of 25 L under the prescribed preparation and analytical conditions.

Portable X-ray fluorescence (XRF) technology may provide faster turn-around without compromising accuracy when assessing personal exposures to metals such as lead, but it has only been tested in limited field environments. This study is part of a series, where different sampler types are used to collect airborne lead in different environments for presentation to a portable XRF analyzer. In this case personal samples were taken at a bronze foundry where lead is added to an alloy of copper, zinc and iron to improve casting, using the closed-face 37 mm cassette, the 37 mm GSP or "cone" sampler, the 25 mm Institute of Occupational Medicine (IOM) inhalable sampler, the 25 mm Button sampler, and the open-face 25 mm cassette. Mixed cellulose-ester filters were used in all samplers. Following XRF analysis the samples were extracted with acid and analyzed by inductively coupled plasma optical emission spectroscopy (ICP). For lead, all five samplers gave correlations (r(2)) greater than 0.9 between the two analytical methods over the entire range of found lead mass, which encompassed both the action level and the permissible exposure limit enforced in the USA by the Occupational Safety and Health Administration (OSHA). However, a correction was required to adjust linear regression trendlines to give a 1 : 1 correlation for the average of three readings across the GSP sampler, and a similar correction was required for the single readings from the IOM sampler and the 25 mm filter cassette. The bias possibly is due to interference from other metals, possibly copper which can absorb the fluorescent radiation of lead. In the case of the Button sampler, the bias is larger, indicating a further source of error, perhaps due to the thickness of the deposit. However, in all cases, correction of the lead results did not greatly affect the overall percentage of samples where the XRF result was within 25% of the ICP result, although it did improve the overall accuracy of the results. The GSP, IOM and Button samplers are suitable candidates for further evaluation as compatible with on-site XRF analysis for lead and other metals. It is important to check carefully factory pre-set instrument calibrations, as a bias in the calibration for copper was observed.

Personal and area air samples were taken at a scrap lead smelter operation in a bullet manufacturing facility. Samples were taken using the 37-mm styrene-acrylonitrile closed-face filter cassette (CFC, the current US standard device for lead sampling), the 37-mm GSP or "cone" sampler, the 25-mm Institute of Occupational Medicine (IOM) inhalable sampler, and the 25-mm Button sampler (developed at the University of Cincinnati). Polyvinylchloride filters were used for sampling. The filters were pre- and post-weighed, and analyzed for lead content using a field-portable X-ray fluorescence (XRF) analyzer. The filters were then extracted with dilute nitric acid in an ultrasonic extraction bath and the solutions were analyzed by inductively coupled plasma optical emission spectroscopy. The 25-mm filters were analyzed using a single XRF reading, while three readings on different parts of the filter were taken from the 37-mm filters. The single reading from the 25-mm filters was adjusted for the nominal area of the filter to obtain the mass loading, while the three readings from the 37-mm filters were inserted into two different algorithms for calculating the mass loadings, and the algorithms were compared. The IOM sampler was designed for material collected in the body of the sampler to be part of the collected sample as well as that on the filter. Therefore, the IOM sampler cassettes were rinsed separately to determine if wall-loss corrections were necessary. All four samplers gave very good correlations between the two analytical methods above the limit of detection of the XRF procedure. The limit of detection for the 25-mm filters (5 microg) was lower than for the 37-mm filters (10 microg). The percentage of XRF results that were within 25% of the corresponding ICP results was evaluated. In addition, the bias from linear regression was estimated. Linear regression for the Button sampler and the IOM sampler using single readings and the GSP using all tested techniques for total filter loading gave acceptable XRF readings at loadings equivalent to sampling at the OSHA 8-hour Action Level and Permissible Exposure Limit. However, the CFC only had acceptable results when the center reading corrected for filter area was used, which was surprising, and may be a result of a limited data set. In addition to linear regression, simple estimation of bias indicated reasonable agreements between XRF and ICP results for single XRF readings on the Button sampler filters, (82% of the individual results within criterion), and on the IOM sampler filters (77% or 61%--see text), and on the GSP sampler filters using the OSHA algorithm (78%). As a result of this pilot project, all three samplers were considered suitable for inclusion in further field research studies.

Attempts to limit occupational exposure to lead culminated in the adoption of a comprehensive lead standard by OSHA in 1978. In the past decade what was considered to be safe levels were shown to result in subclinical toxicity. Another problem is that certain classes of workers are not covered by the OSHA standard. Inadequate enforcement of the standards due to insufficient inspectors has led to excessive exposure to lead. Fetal protection policies exclude women of child-bearing ages from industries that utilize lead. It is recommended that OSHA lower the permissible exposure limit (PEL) from 50 {mu}g/cubic meter to 20 {mu}g/cubic meter. Further, the biological limit value for lead in blood should be lowered from 2.42 {mu}mol/l to 0.97 {mu}mol/l. A worker should not be allowed to return to the workplace until his or her blood level has fallen to 0.48 {mu}mol/l. In some instances, respirators will be necessary to achieve the lower exposure levels. Additional recommendations would eliminate exclusionary practices from the workplace, implement vigorous enforcement of standards, and discourage non-essential use of lead.

Available industry guidelines and federal standards have failed to fully protect workers from chemical toxicity: none exist for most chemicals, many are biased toward what can easily be achieved, and many were developed long after health consequences became evident. Limitations of occupational air contaminant standards in the United States are well illustrated by standard-setting for the neurotoxin n-hexane. In the 1940s, the American Conference of Governmental Industrial Hygienists (ACGIH) first promulgated industrial guidelines known as "threshold limit values" (TLVs), including an 8-hour time-weighted average of 500 ppm for inspired n-hexane. Despite subsequent recognition of the neurotoxicity of n-hexane with industrial outbreaks of polyneuropathy beginning in the 1960s, the TLV for n-hexane remained unchanged until 1976 when a value of 100 ppm was adopted. Because a growing number of clinical reports have identified clinical and subclinical neurotoxicity from n-hexane near, at, and below the current time-weighted average TLV of 50 ppm, even this level is too high to protect all workers. In part due to procedural and political constraints, the Occupational Safety and Health Administration (OSHA) has independently developed only a small number of exposure standards in the past 25 years, and has been incapable of providing needed revisions for existing standards. Most OSHA standards--including those for n-hexane--were adopted in 1971 from the 1968 ACGIH TLVs and have never been revised. From 1971 to 1989 the OSHA permissible exposure level (PEL) for n-hexane remained at 500 ppm, 5-10 times as great as other contemporary standards. To help correct its regulatory backlong, OSHA promulgated 375 new or revised PELs in 1989--including a new standard of 50 ppm for n-hexane--but all of these were vacated by the 11th U.S. Court of Appeals in 1992. As a result, the current OSHA PEL for n-hexane remains at the 500 ppm level adopted in 1971, which even then was too high based upon available scientific evidence. New information over this long period, including that obtained from industrial outbreaks of disease due to chemical exposures, has not been incorporated into revised federal standards.

The Occupational Safety & Health Administration has issued a final standard limiting worker exposure to methylene chloride. The new eight-hour time-weighted permissible exposure limit (PEL) is 25 ppm. The previous PEL was 500 ppm. According to OSHA, about 238,000 workers in more than 92,000 establishments are exposed to methylene chloride every year. The compound is used for paint stripping and in aerosols, plastics manufacture, metal-degreasing operations, urethane foam production, and pharmaceuticals. It is not flammable and does not contribute significantly either to air pollution or depletion of stratospheric ozone. OSHA has set the new standard low because of indications that methylene chloride is carcinogenic. Laboratory animal studies show that it can cause cancers in rats and mice, and some epidemiologic data indicate it may cause cancer in exposed workers. Based on OSHA's risk assessment from these data, the agency estimates that exposure at 25 ppm will result in 3.6 excess cancer deaths per 1,00...

Terms such as ‘‘doubling rate’’ and ‘‘time‐intensity trading relation’’ have given way to the ‘‘exchange rate’’ in recent years, which is the number of decibels permitted in a standard or criterion for each doubling or halving of exposure duration. Whereas most European nations, several Canadian provinces, and some U.S. agencies use the 3‐dB exchange rate, the Department of Labor’s 5‐dB exchange rate is widely used in the U.S. Many of the premises on which the 5‐dB rule were based have proven to be faulty, and although it supposedly takes intermittencies into account, it actually allows uninterrupted exposures at relatively high sound levels. Evidence from studies of laboratory animals indicates that there is some reduction of threshold shift from intermittent exposures, yet epidemiological data do not support this concept in actual working conditions. The likely reason for this discrepancy is that industrial working conditions do not provide sufficient opportunity to recover from TTS. An analysis of the origins of the 5‐dB rule, as well as evidence from field and laboratory studies supports the adoption of the 3‐dB rule, with the possible addition of a small adjustment in the permissible exposure limit for certain outdoor occupations.

Proposed Draft International Standard DIS 11041, described and developed by the International Organisation for Standardisation (ISO), involves sampling air by drawing it though a membrane filter with a paper back-up pad, both of which have been treated with sodium carbonate solution. Particulate arsenic compounds and arsenic(III) oxide vapour are collected, but not arsine. The filter and pad are digested using nitric acid, sulfuric acid and hydrogen peroxide. The resultant solution is boiled down to sulfuric acid fumes and then made up to volume with water. Aliquots of the sample solution are prepared for hydride generation by the addition of hydrochloric acid and potassium iodide. Analysis by both continuous flow and flow injection hydride generation atomic absorption spectrometry (HG-AAS) is described. The method exhibits a recovery of > 95%. It can be adapted to determine nanogram to milligram levels of collected arsenic, making it suitable for testing compliance with the widely differing limit values stipulated in government health legislation of different countries, e.g., 0.1 mg m–3 UK Maximum Exposure Limit (MEL), 0.01 mg m–3 US Occupational Safety and Health Administration (OSHA) Permissible Exposure Limit (PEL) and 0.002 mg m–3 US National Institute of Occupational Safety and Health (NIOSH) Short Term Limit Value. The International Standard will supplement existing internationally adopted analytical standards, such as NIOSH 7901 which employs electrothermal atomic absorption spectrometry, and NIOSH 7900, which employs HG-AAS but which for safety reasons requires the use of a fume cupboard suitable for handling perchloric acid. It should be useful to a wide range of laboratories, including those with limited AAS facilities. This paper describes the testing protocol used to validate the method and gives results obtained to date, including some obtained by laboratories using the analytical method in an inter-laboratory exercise.

The solvent, 2-ethoxyethanol, induced complete embryomortality in pregnant rats exposed to three times the current Federal permissible exposure limit (PEL). Following exposure to ethoxyethanol at a concentration only one-half the current PEL, the offspring evidenced behavioral and neurochemical deviations from controls. Subsequent studies found that ingestion of ethanol with concomitant inhalation of ethoxyethanol vapors early in pregnancy appeared to reduce the number of both behavioral and neurochemical deviations found for ethoxyethanol. In contrast, the concomitant exposure to ethanol and ethoxyethanol later in gestation potentiated the behavioral and neurochemical effects of ethoxyethanol. This research indicates that the industrial solvent 2-ethoxyethanol presents an occupational reproductive hazard and raises the issue of the importance of an interaction of social habits with occupational exposure to such hazards. The results would suggest that occupational physicians should advise pregnant workers in the chemical industry of the adverse effects of ethanol during pregnancy and of the possible interactions with other chemicals and should encourage them to be especially cautious with ethanol consumption since they may be at greater risk.

Lung cancer risk in relation to airborne levels of hexavalent chromium was analyzed for chromium chemical production workers studied by Hayes, Lilienfeld, and Snell. Hayes et al [18] had observed statistically significant increases in lung cancer mortality among chromium chemical production workers hired during 1945-1959 and followed to mid-1977. A dose-response was observed by Hayes et al. in that long-term workers had a higher lung cancer risk than short-term workers. Concurrent exposure data for the study plant were abstracted from the records of a local health department. The usual air concentration of hexavalent chromium was estimated as 413 micrograms per cubic meter (micrograms/m3) during 1945-1949. Cumulative exposure estimates for individual workers could not be developed with available information. Instead, cumulative exposures in terms of micrograms/m3-years were estimated for groups of short-term workers and long-term workers (cumulative exposure = usual exposure level in micrograms/m3 X average length of exposure). For workers hired during 1945-1949, cumulative exposures were estimated as 670 and 3,647 micrograms/m3-years for short-term and long-term workers, respectively. Like most estimates based on historical data, these exposure estimates are subject to uncertainty. Nevertheless, these results suggest a potential excess risk of death from lung cancer among U.S. workers exposed to the current permissible exposure limit (PEL) for hexavalent chromium of 52 micrograms/m3 because such workers could accumulate exposures (micrograms/m3-years) similar to those associated with excess risk in Hayes et al's cohort. Moreover, many current workers are estimated to be exposed to levels above the PEL. Further exploration of the dose-response relationship for chromium carcinogenesis is indicated.

The production of large (greater than 25-ft) fiber-reinforced plastic (FRP) yachts has presented problems of styrene exposure in excess of the Occupational Safety and Health Administration permissible exposure level (OSHA PEL) of 100 ppm. Also, the National Institute for Occupational Safety and Health (NIOSH) is currently recommending a 10-hour workshift, 40-hour workweek time weighted average (TWA) of 50 ppm for styrene. Meeting this challenge will require a system of engineering, work practice, personal protective equipment, and monitoring control measures. NIOSH has performed a study of the engineering controls in three FRP yacht plants. Work practices and the use of personal protective equipment (PPE) were also considered in the evaluation. The three systems evaluated included a dilution system, a local ventilation system, and a push-pull ventilation system. The cost of constructing and operating these systems was not evaluated in this study. Study results indicated that each type of ventilation system can meet the present PEL of 100 ppm styrene; however, it is not certain that these systems can meet a lower PEL of 50 ppm styrene.

Workplace exposures to airborne chemicals are regulated in the U.S. by the Occupational Safety and Health Administration (OSHA) via the promulgation of permissible exposure limits (PELs). These limits, usually defined as eight-hour time-weighted average values, are enforced as concentrations never to be exceeded. In the case of chronic or delayed toxicants, the PEL is determined from epidemiological evidence and/or quantitative risk assessments based on long-term mean exposures or, equivalently, cumulative lifetime exposures. A statistical model was used to investigate the relation between the compliance strategy, the PEL as a limit never to be exceeded, and the health risk as measured by the probability that an individual's long-term mean exposure concentration is above the PEL. The model incorporates within-worker and between-worker variability in exposure, and assumes the relevant distributions to be log-normal. When data are inadequate to estimate the parameters of the full model, as it is in compliance inspections, it is argued that the probability of a random measurement being above the PEL must be regarded as a lower bound on the probability that a randomly selected worker's long-term mean exposure concentration will exceed the PEL. It is concluded that OSHA's compliance strategy is a reasonable, as well as a practical, means of limiting health risk for chronic or delayed toxicants.

The inhalation of beryllium causes a serious lung disease characterised by pronounced radiographic and functional impairments and occurs in workers engaged in the extraction and manufacture of the metal. This paper describes the beryllium exposure levels and refining processes in a large beryllium factory operating since the 1930s. Lifetime beryllium exposure histories were estimated for the 309 workers present at a health survey conducted in 1977. Beryllium exposure levels in the plant were high for many years, with some estimated exposure levels in excess of 100 micrograms/m3. As late as 1975, there were exposures to beryllium above 10 micrograms/m3 in some jobs. After about 1977, the plant was in compliance with the permissible exposure limit of 2.0 micrograms/m3. The median cumulative exposure in this cohort was 65 micrograms/m3-years and the median duration of exposure was 17 years. From these data a series of exposure parameters, functions of the exposure histories that characterise biologically important dimensions of exposure were calculated for each worker.

This report introduces a new method for comparing the performance of industrial hygiene decision criteria and provides equations which generalize the NIOSH action-level concepts to permit direct comparison between four different sets of decision thresholds. Because of the requirement for 95% confidence, neither the Permissible Exposure Limit Action Level (Acute Hazards) nor the Average Exposure Limit Action Level (Chronic Hazards) are likely to make a decision about the acceptability of real workplaces. Both the Legal Action Level and the OSHA Compliance Criteria do make such decisions. On the basis of one sample, OSHA is much more lenient than the Legal Action Level. However, the probability of a citation increases dramatically with the number of statistically independent samples an OSHA Compliance Officer is able to collect.

OSHA activities are reviewed with respect to the development of a coke oven emissions standard. The final emissons standard promulgated in 1976 set a permissible exposure limit of 150 mg/cu m of the benzene soluble fraction of total particulate matter. Unlike most OSHA standards, this standard also set very detailed and specific engineering and work practice controls. Problems of implementing the requirements within the industry as it exists today are discussed.

The adoption of the OSHA noise amendment has made it necessary to make two different noise exposure measurements. These are the employee's exposure with reference to the action level criteria, which requires a threshold of 80 dBA, and the employee's exposure with reference to the permissible exposure limit, which employs a 90 dBA threshold. In addition to the time constraints involved in measuring employee exposure in relation to two different thresholds, many organizations will not have access to equipment capable of performing these separate tasks simultaneously. Based on 242 simultaneous exposure measurements of both the action level and the permissible exposure level criteria, this paper describes a method which uses one noise exposure criteria measurement to predict an employee's exposure at the other.

Although OSHA promulgates standards for chemical exposures on the basis of workers' relative risk of acquiring chronic disease, it interprets the limits as absolute levels never to be exceeded. This poses a dilemma to the gathering of useful information which can be used to assess and reduce exposures, because employers can maximize compliance outcomes by minimizing exposure monitoring. The result is that, in the absence of adequate information, the working population's true risk of acquiring disease is essentially unknown and average exposures of several times the permissible exposure limit (PEL) can be declared in compliance. The dilemma could be resolved if OSHA would define compliance in terms of one or more parameters of the cumulative exposure distribution. Since OSHA's current method of assessing risks is based upon average exposures, enforcement of the PEL as the limit of each worker's true mean exposure would be internally consistent. This change could have the effect of encouraging employers to monitor exposures since the confidence interval surrounding the mean can be narrowed with increased sample size.

Lead exposures from paint sanding and chipping during ship overhaul were evaluated. Several hundred workers were included in the study. Lead concentrations in 275 bulk paint samples ranged from 0.03% to 17.0% with a 0.25% geometric mean. The geometric mean air lead concentration was 61.0 micrograms/m3 when these paints were sanded and 2.4 micrograms/m3 when they were chipped. Air lead concentrations exceeded the Occupational Safety and Health Administration (OSHA) permissible exposure limit (PEL) when paints containing as little as 0.2% lead were sanded but did not exceed the PEL or the action level when paints containing up to 6.0% lead were chipped. Poor correlation was found between paint lead contents and air lead concentrations for sanding (r = -0.27) and for chipping (r = 0.44). Similarly, poor correlation was found between air lead concentrations and blood lead levels for sanding (r = -0.14) and chipping (r = 0.24). Despite higher air lead concentrations, sanders' blood lead levels were not elevated compared with chippers and were only slightly elevated compared with non-lead workers. An extensive blood monitoring program was found to be particularly effective in assessing lead exposures and uptake while air lead monitoring was of limited value because of the high variability in air lead concentrations and in the nature of the sanding and chipping work during the overhaul. Lead-worker training was felt to be a particularly effective control measure. Blood samples collected toward the end of the overhaul revealed that blood lead and zinc protoporphyrin levels were not rising as the overhaul progressed and neared completion.

To evaluate patterns of occupational exposure to styrene monomer in the boat-building industry, we conducted industrial hygiene surveys in seven fiberglass-reinforced plastic boat-fabrication plants. A total of 397 personal breathing zone air samples were collected on workers in four key job categories: gel coating and hull, deck, and small-parts lamination. We found that exposure to styrene in 234 (59%) of the personal samples exceeded the NIOSH-recommended time-weighted average (TWA) standard of 50 parts per million (ppm), and 96 (24%) of these samples exceeded the OSHA eight-hour TWA permissible exposure limit of 100 ppm. From highest to lowest average exposure potential, the job categories ranked in the following order: hull lamination (range 2-183 ppm, mean 78 ppm), deck lamination (range 12-160 ppm, mean 73 ppm), gel coating (range 5-94 ppm, mean 48 ppm), and small-parts lamination (range 9-130 ppm, mean 45 ppm). The former two categories composed a higher-exposure group, and the latter two tended to form a lower-exposure group. Exposures in these jobs appear to be proportional to resin consumption. Statistical analyses indicated that the parameter that most affects exposure potential is job category. Within a job category, part size, configuration, and surface area are important determinants of exposure. The principal reason for high exposures was the absence of control technologies and, in particular, the absence of adequate ventilation.