Perceived odor and irritation of isopropanol: a comparison between naïve controls and occupationally exposed workers

OBJECTIVES: To assess sensory irritation levels from isopropanol (IPA) unconfounded by subjective evaluations of odor for comparison against the recommended exposure limits (400 ppm threshold limit value (TLV); American Conference of Governmental Industrial Hygienists). METHOD: The lateralization method was used to assess intra-nasal irritation thresholds for IPA, while odor detection thresholds were also measured. Thresholds for 1-butanol and phenyl ethyl alcohol (PEA) were obtained as positive and negative irritant controls. To compare potency and hedonic characteristics, subjects provided subjective ratings of odor, irritation and annoyance intensity for three concentrations of each chemical. Workers occupationally exposed to IPA ( n=26) were compared with previously unexposed controls ( n=26). RESULTS: The (geometric) mean odor detection threshold for IPA was slightly higher among exposed workers than controls (39 ppm vs. 11 ppm). Lateralization thresholds measuring intra-nasal irritation were elevated when compared with controls (6,083 ppm in exposed workers vs. 3,361 ppm in na?ve controls), with a significantly higher proportion of phlebotomists being unable to lateralize the maximum concentration regarded as safe, than controls. Calculations of the 6th percentile for lateralization thresholds revealed that 95% of the sample did not experience sensory irritation below 512 ppm. Thus, while odor detection thresholds were well below the current recommended exposure limits, the irritation thresholds were well above these values. The odor, irritation and annoyance from IPA was perceived, on average, as between weak and almost strong, from lowest to highest concentration. CONCLUSIONS: The results indicate that current exposure guidelines would be adequately protective of the acute adverse effect of nasal sensory irritation, as operationally defined by the intra-nasal lateralization threshold. Exposures to higher concentrations should perhaps be evaluated on the basis of existing knowledge about systemic, rather than local (e.g., irritation), toxic effects. IPA appears to be a weak sensory irritant and occupational exposure to IPA appears to elicit small changes in sensitivity that do not generalize to other odorants (e.g., PEA and 1-butanol) and are likely to be reversible.     

A proposed approach for setting occupational exposure limits for sensory irritants based on chemosensory models

OBJECTIVES: Setting occupational exposure limits (OELs) for odorous or irritating chemicals is a global occupational health challenge. However, often there is inadequate knowledge about the toxicology of these chemicals to set an OEL and their irritation potencies are usually not recognized until they are manufactured or used in large quantities. METHODS: In this paper, the importance of accounting for risk perception and communication; conditioned responses; and interindividual variability in tolerance, detection and susceptibility with respect to setting an OEL are discussed in relation to three chemosensory models. These parameters and models were then used to construct a flowchart-style methodology that can be used to set an OEL for a specific chemical. RESULTS: The OEL identified for a chemical odorant or irritant will depend on the type of chemosensory effect that the chemical is likely to exhibit. For example, experience has shown that chemicals with a low odor threshold often require low OELs even though many are not toxic or do not cause irritation at those air concentrations. CONCLUSION: In order to establish the appropriate OEL, organizations need to agree upon the percentage of the workforce that they are attempting to protect and the types of toxicological end points that are sufficiently important to protect against (e.g. transient eye irritation, enzyme induction or other reversible effects). This is particularly true for sensory irritants. The method described in this paper could also be extended to setting limits for ambient air contaminants where risk perception plays a dominant role in whether the public views the exposure as being reasonable or safe.     

The influence of cognitive bias on the perceived odor, irritation and health symptoms from chemical exposure

 Objective: Responses to volatile chemicals are often subjective and variable, both over time and across individuals. Although variability can derive from differences in individual olfactory sensitivity, the response to a chemical stimulus is also influenced by the complex environment surrounding the exposure, which can include the perceiver’s cognitive state. To explore the role of cognitive bias in chemical exposures, we evaluated whether information about the consequences of exposure to acetone could influence ratings of odor and irritation during exposure and/or the frequency or intensity of reported health symptoms following exposure. Methods: Ninety adults (mean age 33.7, range 25–64) with no history of occupational exposure to solvents, were exposed to 800 ppm acetone in a chamber for 20 min. To control for non-specific responses to the odor of acetone, the subjects were also exposed for 20 min to 200 ppm phenylethyl alcohol (PEA), a nonirritant volatile chemical that produces a distinct odor but does not elicit irritation in the vapor phase. Subjects were assigned to one of three groups (n=30/group); each group was given either a positive, negative or neutral bias towards the consequences of exposure to the chemicals in the study. During exposure, subjects rated the intensity of odor and irritation; following exposure, they completed symptom questionnaires. Results: During the 20-min exposure to acetone, the positive bias group exhibited the most adaptation to its odor and the lowest perceived irritation; following exposure they reported the fewest health symptoms. In contrast, the negative bias group rated higher levels of odor intensity and, on average, reported the most overall irritation; following exposure they reported significantly more health symptoms than the other groups. None of the demographic variables studied (e.g., age, gender, race, smoking status) were predictive of the response to odor or irritation. The perceived irritancy of acetone was well predicted by a linear combination of the perceived odor of acetone and the perceived irritation from PEA (the nonirritant), r ²=0.73. Conclusions: The results provide strong evidence that both the perceived odor and cognitive expectations about a chemical can significantly affect how individuals respond to it. Moreover, because naive control subjects appear to exhibit extreme variation in their cognitive evaluations of chemical effects, there may be limited value in using non-exposed controls to assess the irritancy of chemicals for worker populations. Received: 7 May 1996/Accepted: 20 September 1996     

Perceived odor,irritation, and health symptoms following short-term exposure to acetone

The subjectivity of irritancy judgments can bias attempts to establish exposure guidelines that protect individuals from the sensory irritation produced by volatile chemicals. At low to moderate chemical concentrations, naive and occupationally exposed individuals often show considerable variation in the reported levels of perceived irritation. Such variation could result from differences in exposure history, differences in the perceived odor of a chemical, or differences in generalized response tendencies to report irritation, or response bias. Thus, experimental evaluation of sensory irritancy must dissociate sensory irritation from response bias. To this end, judgments of perceived irritation from 800 ppm acetone were obtained from acetone-exposed workers and age- and gender-matched naive controls. To assess the role of response bias during exposure to odorants, subjects were also exposed to phenylethyl alcohol (PEA), an odorant that does not produce sensory irritation. Following exposure, subjects completed a subjective symptom survey that included symptoms that have been associated with long-term solvent exposures and symptoms that have not. Acetone-exposed workers and naive controls reported large differences in the perceived intensity of odor and irritation from acetone, yet no differences in the perception of PEA. However, for both groups, the most significant factors mediating reported irritancy and health symptoms from acetone were the perceived intensity of its odor and an individual's bias to report irritation from PEA. The perception of odor intensity and degree of response bias will differ between and within groups of exposed and naive individuals; hence, an assessment of the influence of these factors in experimental and workplace studies of chemical irritancy is warranted. Am. J. Ind. Med. 31:558–569, 1997. © 1997 Wiley-Liss, Inc.     

Local effects in the respiratory tract: relevance of subjectively measured irritation for setting occupational exposure limits

OBJECTIVES: Chemosensory effects of stimulation by a chemical can either be irritating (trigeminal stimulation) or odorous (olfactory stimulation) or both. For odorous irritants, a clear-cut distinction between odour and irritation is difficult to make. The differences in the lowest concentration found to be irritating to the respiratory tract in humans when compared to experimental animals has brought much debate in the process of setting occupational exposure limits (OELs) for such chemicals. In this paper it will be discussed as to how far subjectively measured sensory irritation threshold levels can be used to establish OELs. METHODS: Data on respiratory irritation of four odorous irritants were retrieved from public literature and discussed, viz. acetone, formaldehyde, furfural and sulphur dioxide. RESULTS: Objective measures of irritation yielded results that differed from subjective evaluations. Important factors modulating the reported levels of irritation and health symptoms include the perception of odour intensity, exposure history and the individual's bias to report irritation on the basis of his/her prejudice or knowledge of the compound. CONCLUSIONS: Subjective measures alone are less appropriate for establishing sensory irritation thresholds of odorous irritants and are, therefore, less suitable to establish OELs without supporting evidence. Objectively measured irritation in humans, the Alarie assay (an experimental animal test assessing the concentration that results in a 50% reduction of the breathing frequency) and repeated exposure studies in animals may be of help to study objective irritation. If subjective measurements are used to study sensory irritation, the study design should at least include: measurement of both incidence and severity determined at several concentrations, an appropriate (0 ppm) control condition, preferably a non-irritant odorant control exposure, validated questionnaires and correct concentration measurements.     

Setting occupational exposure limits in humans: contributions from the field of experimental psychology

Psychophysical methods from the field of experimental psychology are evaluated for their utility in the derivation of occupational exposure limits (OELs) for volatile chemicals based on acute sensory irritation in humans. The lateralization threshold method, which involves the localization of trigeminal vapor to the stimulated nostril, is evaluated for its underlying assumptions, reliability and validity. Whole body exposures, on the other hand, which involve the controlled, ambient exposure of human subjects to the irritant at one or a series of concentrations for an extended period are also discussed. It is concluded that the single-organ psychophysical method is largely resistant to response bias is practical and economical. However, its reliability and validity need further assessment. Whole body exposures, while having enhanced ecological validity, are more prone to demand characteristics, response bias, and subject beliefs than the traditional psychophysical procedures. An approach that involves the exposure of only the most sensitive organs such as the eyes and nose, via a mask or facebox, could facilitate the administration and alternation of odorant/irritant stimuli over a wide range of concentrations while enhancing ecological validity.     

Chronic Ammonia Inhalation and Interstitial Pulmonary Fibrosis: A Case Report and Review of the Literature

Ammonia is an irritant gas with a characteristic pungent odor, which is widely used in industry. Inasmuch as ammonia is highly soluble in water and, upon inhalation, is deposited in the upper airways, occupational exposures to ammonia have commonly been associated with sinusitis, upper airway irritation, and eye irritation. Acute exposures to high levels of ammonia have also been associated with diseases of the lower airways and interstitial lung. In this study, the authors report on a patient with long-term, repetitive occupational exposure to ammonia at levels at or above odor recognition who developed interstitial lung disease. The scientific literature on inhaled ammonia exposure is reviewed and discussed. The authors conclude that the taking of a careful occupational exposure history for patients presenting with shortness of breath associated with ammonia exposure may assist with an early diagnosis, thus allowing for treatment early in the disease process and prevention of further exposure.     

Chronic ammonia inhalation and interstitial pulmonary fibrosis: a case report and review of the literature

Ammonia is an irritant gas with a characteristic pungent odor, which is widely used in industry. Inasmuch as ammonia is highly soluble in water and, upon inhalation, is deposited in the upper airways, occupational exposures to ammonia have commonly been associated with sinusitis, upper airway irritation, and eye irritation. Acute exposures to high levels of ammonia have also been associated with diseases of the lower airways and interstitial lung. In this study, the authors report on a patient with long-term, repetitive occupational exposure to ammonia at levels at or above odor recognition who developed interstitial lung disease. The scientific literature on inhaled ammonia exposure is reviewed and discussed. The authors conclude that the taking of a careful occupational exposure history for patients presenting with shortness of breath associated with ammonia exposure may assist with an early diagnosis, thus allowing for treatment early in the disease process and prevention of further exposure.     

Olfactory function in workers exposed to styrene in the reinforced-plastics industry

BACKGROUND: Impairment of olfactory function in humans has been associated with occupational exposure to volatile chemicals. To investigate whether exposure to styrene was associated with olfactory impairment, olfactory function was examined in workers with a minimum of 4 years exposure to styrene in the reinforced-plastics industry (current mean exposure: 26 ppm, range: 10-60 ppm; historic mean dose: 156 ppm-years, range: 13.8-328 ppm-years) and in a group of age- and gender-matched, unexposed controls. METHODS: Olfactory function was assessed using a standardized battery that included tests of threshold sensitivity for phenylethyl alcohol (PEA), odor identification ability, and retronasal odor perception. Odor detection thresholds for styrene were also obtained as a measure of specific adaptation to the work environment. RESULTS: No differences were observed between exposed workers and controls on tests of olfactory function. Elevation of styrene odor detection thresholds among exposed workers indicated exposure-induced adaptation. CONCLUSIONS: The present study found no evidence among a cross-section of reinforced-plastics industry workers that current or historical exposure to styrene was associated with impairment of olfactory function. Taken together with anatomical differences between rodent and human airways and the lack of evidence for styrene metabolism in human nasal tissue, the results strongly suggest that at these concentrations, styrene is not an olfactory toxicant in humans.     

1998 equivalence of sensory responses to single and mixed volatile organic compounds at equimolar concentrations.

Exposure to low levels of chemicals indoors is often to a mixture of volatile organic compounds (VOCs). It is of interest to determine if the symptomatic and sensory responses can be attributed to a single chemical or to a mixture of chemicals. To determine if sensory or symptomatic responses differ with exposure to single or mixed VOCs, 100 female subjects participated in a 6-hr exposure study. Subjects were exposed to one of six equimolar concentrations equivalent to 24 mg/m3 toluene, control, m-xylene, n-butyl acetate, m-xylene plus n-butyl acetate, a mixture of 21 chemicals including n-butyl acetate and m-xylene, and to the same mixture of chemicals without n-butyl acetate and m-xylene (19 chemicals). The results indicated that there was no difference in reporting of symptoms or sensory responses between the exposures. When the control group was added, some variables, primarily odor intensity and nasal irritation, attained significance.     

Acute sensory irritation from exposure to isopropanol (2-propanol) at TLV in workers and controls: objective versus subjective effects

OBJECTIVES: Phlebotomists occupationally exposed to isopropanol (IPA) (2-propanol) and na?ve controls (n = 12 per group) were exposed to the time-weighted average threshold limit value of 400 p.p.m. IPA for 4 h in an environmental chamber to investigate: (i) acute effects of sensory irritation using subjective health symptom reports and objective, physiological end-points; and (ii) differences in measured effects in relation to exposure history. METHODS: Before, during and after exposure subjects gave self-reports of health complaints. During exposure subjects rated the intensity of the odor, sensory irritation and annoyance. Objective end-points of ocular hyperemia, nasal congestion, nasal secretion and respiration were obtained at various times before, during and after exposure. Results were compared with exposure to phenylethyl alcohol (PEA), a negative control for irritation, and to clean air (CA), a negative control for odor and irritation, using a within-subjects design. RESULTS: Significantly higher intensity ratings of odor, irritation and annoyance were reported during the exposure to IPA, when compared with exposure to CA or PEA. Nevertheless, the overall level of reported sensory irritation to IPA was low and perceived as 'weak' on average. Health symptom ratings were not significantly elevated for IPA as compared with PEA or CA exposure. The only physiological end-point that showed a change exclusively in the IPA condition was respiration frequency: relative to baseline, respiration frequency increased in response to IPA in both groups. No differences were encountered between the occupationally exposed and the control groups. CONCLUSIONS: The increase in respiration frequency in response to IPA may reflect either a reflexive change due to sensory irritation (an autonomic event) or a voluntary change in breathing in response to perception of an unpleasant, solvent-like odor (a physiological event caused by cognitive mediation). Our findings on objective end-points, including nasal and ocular sensory irritation, did not confirm subjective irritation reports. Irritation reports and odor intensity decreased, rather than increased, over time, lending credence to the cognitive argument and suggesting that the elevated subjective responses to IPA may be mediated by responses to its odor.     

The role of odor and irritation, as well as risk perception, in the setting of occupational exposure limits

Objective: This paper reviews current research regarding the relationship between odor perception or irritation and setting an occupational exposure limit (OEL). Special focus was directed at those settings where a small fraction of persons report unacceptable responses to concentrations well below the OEL. Methods: We evaluated the published literature on the topic of irritation and olfactory response to exposure to industrial chemicals. More than a dozen researchers have been active in this area over the past 10 years. Results: It was found that for some chemicals, even when one maintains airborne concentrations below a particular OEL, this level of exposure may not be adequate to prevent all persons from reporting an appreciable adverse response. In some cases, worker’s pre-existing belief systems about the source of an odor may be sufficient to require that they have not be exposed to any detectable concentration. In addition, detection of odors by workers may tap into the person’s aversion to odors, in general. In both situations, it is often necessary to address these specific issues through risk communication and dealing directly with risk perception. Conclusions: For practical reasons, the current objective of organizations charged with setting OELs for chemicals is to identify concentrations that do not cause irritation or widespread reports of unpleasant sensory stimulation in the vast majority of workers (e.g., about 80–95%).     

Using respirators and goggles to control exposure to air pollutants in an anatomy laboratory

BACKGROUND: Engineering or administrative methods are often insufficient or impractical to control exposure to chemicals in anatomy laboratories. This study explored the feasibility of wearing one or a combination of respirators and goggles used as personal protective equipment (PPE) to control exposure in one such laboratory. METHODS: A group of 28 subjects were briefly trained in wearing PPE, fit-tested, and asked to complete a questionnaire regarding their subjective reaction after wearing the assigned PPE ensemble while working in the laboratory. The subjects' exposure to formaldehyde was also measured and generally exceeded the recommended limits. RESULTS: When a full-face respirator or the combination of a half-mask respirator and goggles was worn, a majority of subjects reported no odor problem and no irritation to eyes or upper respiratory system. Subjects accepted the PPE to certain degrees, but those using respirators encountered difficulties communicating with others. CONCLUSIONS: The combination of a half-mask respirator and goggles was the most feasible ensemble to control exposure to air pollutants in an anatomy laboratory.     

Sensory irritation and multiple chemical sensitivity.

Many of the symptoms described in Sick Building Syndrome (SBS) and multiple chemical sensitivity (MCS) resemble the symptoms known to be elicited by airborne irritant chemicals. Irritation of the eye, nose, and throat is common to SBS, MCS, and sensory irritation (SI). Difficulty of breathing is often seen with SBS, MCS, and pulmonary irritation (PI). We therefore asked the question: can indoor air pollutants cause SI and/or PI? In laboratory testing in which mice breathed the dilute volatile emissions of air fresheners, fabric softeners, colognes, and mattresses for 1 h, we measured various combinations of SI and PI as well as airflow decreases (analogous to asthma attacks). Air samples taken from sites associated with repeated human complaints of poor air quality also caused SI, PI, and airflow limitation (AFL) in the mice. In previous publications, we have documented numerous behavior changes in mice (which we formally studied with a functional observational battery) after exposure to product emissions or complaint site air; neurological complaints are a prominent part of SBS and MCS. All together, these data suggest that many symptoms of SBS and MCS can be described as SI, PI, AFL, and neurotoxicity. All these problems can be caused by airborne irritant chemicals such as those emitted by common commercial products and found in polluted indoor air. With some chemical mixtures (e.g., emissions of some fabric softeners, disposable diapers, and vinyl mattress covers) but not others (e.g., emissions of a solid air freshener), the SI response became larger (2- to 4-fold) when we administered a series of two or three 1-h exposures over a 24-h period. Since with each exposure the intensity of the stimulus was constant yet the magnitude of the response increased, we concluded that there was a change in the sensitivity of the mice to these chemicals. The response was not a generalized stress response because it occurred with only some mixtures of irritants and not others; it is a specific response to certain mixtures of airborne chemicals. This is one of the few times in MCS research that one can actually measure both the intensity of the stimulus and the magnitude of the response and thus be allowed to discuss sensitivity changes. The changing SI response of the mice might serve as a model of how people develop increasing sensitivity to environmental pollutants. Intensive study of this system should teach us much about how people respond to and change sensitivity to airborne irritant chemicals.     

Does seasonal allergic rhinitis increase sensitivity to ammonia exposure?

Allergic inflammation in the upper airways represents a wide-spread health issue: Little is known about whether it increases sensitivity to airborne chemicals thereby challenging established exposure limits that neglect such differences in susceptibility. To investigate the role of pre-existing allergic inflammation, 19 subjects with seasonal allergic rhinitis (SAR) and 18 control subjects with low risk of sensitization were exposed for 4 h to ammonia in two concentrations (cross-over design): 2.5 ppm (odor threshold) and 0–40 ppm (occupational exposure limit: 20 ppm TWA). Prior to the whole-body exposure, it was confirmed that subjects with SAR showed persistent inflammation outside the pollen season as indicated by increased exhaled nitric oxide and total immunoglobulin E in serum compared to controls. Despite concentration-dependent increases in chemosensory perceptions and acute symptoms, SAR status did not modulate subjective effects of exposure. Moreover, SAR status did not affect the investigated physiological endpoints of sensory irritation: While eye-blink recordings confirmed weak ocular irritation properties of ammonia at 0–40 ppm, this effect was not enhanced in SAR subjects compared to controls. Irrespective of SAR status, exposure to 0–40 ppm ammonia did not result in a cortisol stress response, objective nasal obstruction as measured with anterior active rhinomanometry, or an inflammatory response as indexed by substance P, tumor-necrosis-factor α, and high-mobility-group protein 1 in nasal lavage fluid. At least for the malodorous compound ammonia, these results do not support the hypothesis that SAR enhances chemosensory effects in response to local irritants. Before generalizing this finding, more compounds as well as sensitization to perennial allergens need to be investigated.     

From chemosensory thresholds to whole body exposures—experimental approaches evaluating chemosensory effects of chemicals

Objectives: To ensure safety and health the avoidance of adverse chemosensory effects is essential at workplaces where volatile chemicals are used. The present study describes psychophysical approaches that provide information for the evaluation of such effects. Methods: By means of a modified staircase procedure the odor (OT) and irritation thresholds (IT) of 15 irritants were determined. These basic chemosensory properties, confining the chemosensory effect range, were investigated in a random sample of 144 persons stratified for gender and age. Those irritants exhibiting high chemosensory potency were selected for the second psychophysical part of the study. Forty-eight persons, again stratified for gender and age, rated the intensity of 13 trigeminal and olfactory perceptions elicited by nine ascending concentrations of the irritants, ranging from the odor to the irritation threshold of the respective substances. Results: Across the investigated chemicals the transition from concentrations eliciting pure olfactory stimulation (OT) to trigeminal stimulation (IT) differed markedly. The carboxylic acids yielded narrow ranges from odor to irritation thresholds, while for the amines (cyclohexylamine, dimethylamine, and trimethylamine) and the esters (ethyl formate and ethyl acetate) these ranges were somewhat wider. The two chemosensory thresholds of ethyl acrylate and ammonia were farthest from each other. Gender and age had only weak impact on the chemosensory thresholds. At present, the results of the intensity ratings could be given for six substances. Among them, the rated pungency for cyclohexylamine, formic acid, and ethyl acetate increased strongest across the nine applied concentrations. Conclusions: By means of these psychophysical approaches a diverse class of chemicals can be described and compared with respect to their chemosensory potency. This information can be used twofold (a) for the evaluation of existing studies reporting sensory irritations and (b) for the design of experimental exposure studies.     

Cytological changes and conjunctival hyperemia in relation to sensory eye irritation

In general, irritation is a physiological response to a chemical or physical stimulus involving objective changes (e.g., local redness and edema) and subjective sensations (e.g., pruritus and pain). The perception of an irritating stimulus in the eyes and the upper airways is called sensory irritation. Sensory irritation is a prevalent symptom in relation to complaints about indoor air quality. The intensity of perceived sensory irritation in humans has mainly been evaluated using psychophysical methods. However, perceived sensory irritation is dependent on the subject expressing the symptoms; that is, it is a subjective measure. This is a problem in assessment of irritation effects from air pollution or other factors, since the expression of the irritation symptoms may be biased by, for example, interaction with other people and odors. The subjectivity of the measures is an important complication in several studies dealing with problems regarding indoor air quality. The bias problems make it important to complement the psychophysical measurements of sensory irritation with objective assessments of irritation. In addition, only little is known about the association between sensory irritation and possible physiological/pathological changes in the mucosal membranes in relation to studies of indoor air. Two studies (study 1 and study 2) were conducted to investigate changes in conjunctival hyperemia and conjunctival fluid cytology for subjects exposed to volatile organic compounds (VOCs) in their eyes only. Eight subjects participated in study 1. Each subject was exposed to three different mixtures of VOCs. A total of 16 subjects participated in study 2. Half of the subjects were exposed to 1-octene and the other half, to n-butanol. In both studies, photographs of bulbar conjunctiva were taken and conjunctival fluid was sampled before and after exposure. Moreover, the perceived irritation intensities were registered continuously during exposure. Overall, perceived irritation intensity and conjunctival hyperemia increased with increasing exposure concentrations, whereas cytological changes in the conjunctival fluid samples did not seem to be related to exposure concentration, perceived irritation, or changes in conjunctival hyperemia. Received: 4 April 1997 / Accepted: 25 September 1997     

Evaluation and application of the RD50 for determining acceptable exposure levels of airborne sensory irritants for the general public

BACKGROUND: The RD(50) (exposure concentration producing a 50% respiratory rate decrease) test evaluates airborne chemicals for sensory irritation and has become an American Society for Testing and Materials (ASTM) standard method. Past studies reported good correlations (R(2)) between RD(50)s and the occupational exposure limits, particularly threshold limit values (TLVs). OBJECTIVE: The main purpose of this study was to examine the relationship between RD(50)s and human sensory irritation responses in a quantitative manner, particularly for chemicals that produce burning sensation of the eyes, nose, or throat, based on lowest observed adverse effect levels (LOAELs) reported for human subjects. METHODS: We compared RD(50)s with LOAELs and acute reference exposure levels (RELs). RELs, developed by the California Environmental Protection Agency's Office of Environmental Health Hazard Assessment, represent a level at which no adverse effects are anticipated after exposure. We collected RD(50)s from the published literature and evaluated them for consistency with ASTM procedures. We identified LOAELs for human irritation and found 25 chemicals with a corresponding RD(50) in mice. DISCUSSION: We found the relationship between RD(50)s and LOAELs as log RD(50) = 1.16 (log LOAEL) + 0.77 with an R(2) value of 0.80. This strong correlation supports the use of the RD(50) in establishing exposure limits for the public. We further identified 16 chemical irritants with both RD(50)s and corresponding acute RELs, and calculated the relationship as log RD(50) = 0.71 (log REL) + 2.55 with an R(2) value of 0.71. This relationship could be used to identify health protective values for the public to prevent respiratory or sensory irritation. CONCLUSION: Consequently, we believe that the RD(50) has benefits for use in setting protective levels for the health of both workers and the general population.     

Health risk assessment and the practice of industrial hygiene

It has been claimed that there may be as many as 2000 airborne chemicals to which persons could be exposed in the workplace and in the community. Of these, occupational exposure limits have been set for approximately 700 chemicals, and only about 30 chemicals have limits for the ambient air. It is likely that some type of health risk assessment methodology will be used to establish limits for the remainder. Although these methods have been used for over 10 yr to set environmental limits, each step of the process (hazard identification, dose-response assessment, exposure assessment, and risk characterization) contains a number of traps into which scientists and risk managers can fall. For example, regulatory approaches to the hazard identification step have allowed little discrimination between the various animal carcinogens, even though these chemicals can vary greatly in their potency and mechanisms of action. In general, epidemiology data have been given little weight compared to the results of rodent bioassays. The dose-response extrapolation process, as generally practiced, often does not present the range of equally plausible values. Procedures which acknowledge and quantitatively account for some or all of the different classes of chemical carcinogens have not been widely adopted. For example, physiologically based pharmacokinetic (PB-PK) and biologically based models need to become a part of future risk assessments. The exposure evaluation portion of risk assessments can now be significantly more valid because of better dispersion models, validated exposure parameters, and the use of computers to account for complex environmental factors. Using these procedures, industrial hygienists are now able to quantitatively estimate the risks caused not only by the inhalation of chemicals but also those caused by dermal contact and incidental ingestion. The appropriate use of risk assessment methods should allow scientists and risk managers to set scientifically valid environmental and occupational standards for air contaminants.     

某聚氯乙烯生产企业化学毒物危害分析

目的分析某生产企业聚氯乙烯生产过程中产生的化学毒物及其危害关键控制点,为企业化学毒物防护提供依据。方法采用现场职业卫生学调查、工作场所化学毒物检测、个体TWA检测相结合的方法对企业存在的化学毒物进行分析。结果在聚氯乙烯的生产过程中,作业场所存在化学毒物较多,主要包括氯乙烯、聚氯乙烯、聚乙烯醇、过氧化物、异链烷烃类、聚乙烯乙酸酯、氢氧化钠、氨、盐酸、甲醇、柴油、一氧化碳、二氧化碳、二氧化硫、氮氧化物、臭氧、二氧化锰等。其中废水槽下风向的巡检位氯乙烯15min检测浓度最大值为35．4mg／m^3,超过最大超限倍数的0．4倍;气柜排放口、反应釜底部排放阀氯乙烯15min检测浓度分别为20．2mg／m^3和24．8mg／m^3,接近职业接触限值;其余检测点的各化学毒物浓度小于职业接触限值。结论化学毒物关键控制点为气柜排放口、反应釜排放阀以及废水槽,应加强其防毒措施。