Organic acids and bases: review of toxicological studies

Organic acids and bases are among the most frequently used chemicals in the manufacturing industries. However, the toxicology of only a number of them has been fully characterized, and for fewer still have occupational exposure limits been established. This paper reviews the acute and chronic toxicity data of the organic acids and bases, and considers the mechanism by which these chemicals produce their effects. A methodology for establishing preliminary occupational exposure limits based on the physicochemical properties of these chemicals is presented. Workplace exposure limits for 20 organic acids and bases which currently have no exposure guidelines are suggested. Advice regarding appropriate medical treatment of exposure to these materials is discussed.     

某家具厂职业病危害现状调查

目的了解某家具厂职业病危害现状及防治对策。方法进行现场职业卫生调查,对作业场所的职业病危害因素进行检测,对接触职业病危害因素人员进行职业健康检查。结果该厂40.0%噪声检测点8 h等效A声级不符合GBZ 2-2007《工作场所有害因素职业接触限值》职业接触限值要求,噪声强度最高为89.3dB(A),木粉尘、滑石粉尘、苯、甲苯、二甲苯、乙酸丁酯的检测浓度均符合职业接触限值要求,接触有害作业的工人尚未发现与职业有关的异常情况。结论该厂职业病危害重点是噪声,应加强噪声的检测及防护。     

Extrapolating from toxicity data to occupational exposure limits: some considerations.

This paper evaluates procedures relevant to extrapolating from toxicity data in man and animals to Occupational Exposure Limits. It examines effects at or around the "No Observed Adverse Effect Level' (NOAEL) and the magnitude of safety factors which can be applied in developing occupational exposure limits for non-stochastic effects. The relationship between incidence of stochastic effect and occupational exposure limit is also discussed.     

The Uncertainty Factor in the setting of Occupational Exposure Standards

In recent years new programmes have appeared within the EC and OECD involving risk assessment of chemicals in relation to their potential health effects on various sections of the human population, including workers. As an element of such programmes judgements are required to be made about the acceptability of occupational exposure to chemicals at particular levels, taking into account the toxicological data available. Some of these programmes seek to establish ‘health-based’ occupational exposure limits. Uncertainty Factors have a significant influence in such considerations. There is a notable absence of published information in relation to the quantitative aspects of decision-making in this area.This paper discusses the current situation regarding Uncertainty Factors involved in deriving a ‘health-based’ occupational exposure limit, the Occupational Exposure Standard (OES) in the U.K. The Uncertainty Factors involved in the proposals of the WATCH (Working Group on the Assessment of Toxic Chemicals) panel of the Health and Safety Commission's Advisory Committee on Toxic Substances, for OES values for substances considered in the period 1990–1993 have been analysed.     

Dermal risk assessment in occupational medicine

The importance of dermal exposure has increased during the last few years mainly because of the reduction of respiratory exposure to toxicants. Pesticides, aromatic amines and polycyclic aromatic hydrocarbons are considered to be the chemicals with highest dermal risk. In the occupational exposure limit lists of the ACGIH and of many countries compounds that can be absorbed through the skin are identified by a skin notation. Usually the skin notation indicates that the percutaneous absorption of the chemical can contribute to the body burden. However, a generally accepted criterion for assigning skin notation does not exist. When it is possible to make standardized measurements of dermal exposure, it will be possible to develop Dermal Occupational Exposure Limits (DOEL) with which such measurements can be compared to enable a regulatory approach in the risk assessment field. However, the recent attempts to develop health-based DOELs have not been accepted, thus in practice their use has been limited.     

New EMF safety limits for occupational and public exposure in Poland

On July 23, 2001, new safety limits for occupational exposure to electromagnetic fields (EMF) were introduced in Poland. The limits have been based on the analysis of international recommendations, e.g., ICNIRP (1998), WHO (1998), IEEE standard (1999), drafts of European standards (ENV 1995), and a critical review of the world literature on the biological effects of EMF and health effects of exposure to EMF. Derived from safety limits for occupational exposure, new safety exposure limits for general population were introduced on November 28, 2003. In this paper mandatory procedures for setting limits of exposure to agents harmful to health in the workplace and natural environment are presented. The most essential provisions of two regulations, one issued by the Minister of Labour and Social Policy and the other by the Minister of the Environment, forming the basis of the modern system of EMF exposure control in Poland, are also discussed.     

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.     

北京市某高新企业2006—2008年度职业病危害因素检测结果及其防控措施

目的了解某高新企业的职业病危害因素现状,以利于加强高新企业的职业卫生管理工作。方法2006—2008年连续3年对某高新企业进行作业环境中职业病危害因素进行检测,依据《工作场所有害因素职业接触限值第1部分:化学有害因素》、《工作场所空气中有害物质监测的采样规范》进行检测及评价,并对其防控措施进行分析。结果该高新企业主要生产区的砷化氢等13种职业病危害因素的浓度,连续3年的检测结果均符合国家标准接触限值。结论认真贯彻执行《中华人民共和国职业病防治法》,从源头上控制职业病危害因素,采取有效措施在高新企业职业病防控工作中是行之有效的措施。     

Isocyanates in Australia: Current exposure to an old hazard

Exposure to isocyanates has consistently been reported as the most common cause of occupational asthma. The objectives of this study were to assess how many Australian workers are currently exposed to isocyanates, identify the occupations with highest proportion of exposed workers and identify the main circumstances of exposures. Data comes from the Australian Workplace Exposure Study-Asthma, a national telephone survey which explored the prevalence of current occupational exposure to 227 asthmagens, grouped into 27 groups, among current Australian workers aged 18–65 years. A web-based tool, OccIDEAS, was used to collect job task information and to assign exposure to asthmagens, including isocyanates. Of the 4,878 eligible participants, 2.5% of them were deemed to be probably exposed to isocyanates at work in their current job (extrapolated to 3.0% of the Australian working population). The majority of those exposed were males (90.8%). The most common tasks undertaken that led to these exposures were using expanding foam fillers/sprays and isocyanate and/or polyurethane paints. Exposure occurred mainly among construction workers, wood workers, and painters or printers. This study investigating occupational exposure to isocyanates in a national working population provides information that can be used to inform the direction of occupational interventions and policies to decrease occupational asthma.     

Results of clinical-toxicological assessments performed in the Poison Control Centre in Zagreb over a 10-year period

The aim of this study was to see which harmful substances and which occupational settings most often required toxicological assessment, to evaluate exposure data provided by employers and to see to what extent could this assessment rely on actual measurements of harmful substances in a working environment. We reviewed the documentation that was submitted for toxicological assessment in all patients referred from occupational health physicians between 1992 and 2001. From 1992 to 2001, the Poison Control Centre performed a total of 260 toxicological evaluations of occupational exposure to harmful chemicals. In 162 cases (62%), measurements of harmful substance concentrations in the working environment would have been of primary significance for the best comparison of potential adverse effects and the level of exposure. The most frequent was exposure to organic solvents in the production line and the use of various paints and varnishes, adhesives and thinners in shoe, chemical and metal-processing industry. Follows exposure to respiratory irritants, mostly in plastic and metal processing. However, measurement data of harmful substances in the working environment were available only in 24 cases, that is, in 9% of all documents submitted for toxicological assessment. Exposure to organic solvents is characteristic for a large number of work places in industry and small enterprises in Croatia, and it is necessary to carry out a more comprehensive study about the real levels of exposure and modes of effective control. It is important because the EU regulations on the indicative occupational exposure limits (OELs) of harmful substances in the working environment, that will soon be implemented into Croatian legislation, recommend a reduction of maximum allowable concentrations (MAC) for commonly used solvents.     

Scrutinizing ACGIH risk assessments: the trichloroethylene case

BACKGROUND: The American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit values (TLVs) for occupational exposure to chemicals and physical agents have been very influential in the setting of occupational exposure limits in many countries. METHODS: Three ACGIH risk assessments of the chlorinated solvent trichloroethylene (TCE) [ACGIH (1989): 5th edition; ACGIH (1992): 5th edition. Revised Vol II; ACGIH (1996): Suppl. 6th edition] are compared to 26 other risk assessments made of the same chemical substance. The documents are compared in terms of their overall conclusions and the data selected for assessment. RESULTS: It is shown that these ACGIH risk assessment documents were based on incomplete and biased data sets. CONCLUSIONS: The data on which the ACGIH [ACGIH (1996): Suppl. 6th edition] base their TCE risk assessment do not adequately reflect the available scientific knowledge about TCE toxicity and carcinogenicity. This may have influenced their conclusion that TCE is not carcinogenic in either animals or humans which stand out compared to contemporary risk assessments.     

Adjusting occupational exposure limits for moonlighting, overtime, and environmental exposures.

A mathematical model is used to predict relative body burdens of inhaled contaminants in workers who work two jobs or overtime, or who experience off-the-job exposure to air contaminants. Expected "peak" or maximum body burdens from multiple exposures are compared to those expected from the "normal" occupational exposure on which TLVs and Permissible Exposure Limits (PELs) arebased (five 8-hour days per week with zero off-the-job exposure). The model is designed to predict what adjustments to the TLVs and PELs are necessary to avoid accumulation of excess peak body burdens of contaminants from the additional exposures incurred. The general application of models to determine occupational exposure limits is reviewed, and several models are compared.     

Use of physiologically based pharmacokinetic models to establish biological exposure indexes.

This paper presents a simulation modeling approach to establish biological exposure indexes (BEIs) from ambient occupational exposure limits (OELs). A physiologically based pharmacokinetic (PB-PK) model was used to describe the disposition of volatile organic chemicals in the human. The model was used to simulate an exposure regimen similar to a typical work schedule. Exposure concentrations were set to equal the ambient OELs of the corresponding chemicals. Chemical concentrations in the expired air and blood and concentrations of metabolites in the urine were estimated with the PB-PK model for this exposure condition. Because the OELs establish the criteria for ambient exposure to chemicals, the concentrations of chemicals or their metabolites in biological media resulting from exposure to the OELs would likewise define acceptable exposure standards. On the basis of this rationale and method, BEIs were developed for 13 common industrial organic chemicals.     

Radiofrequency/microwave protection guides

Limits for exposure to electromagnetic fields at RF and microwave frequencies have, at times, been subject to criticism and controversy. In many cases the controversy results from a lack of absolute proof that some nominal levels of exposure are safe, from a misunderstanding of how to apply the limits, and from a lack of understanding (by critics) of the rationale upon which the limits were developed and of the consensus process required for approval. Exposure limits, based on rather simple models, were developed during the early 1950s and have been used extensively without revision for almost three decades (and still are by various organizations including the U.S. Department of Labor). During the past decade, however, these limits have been modified extensively to reflect both the increase in knowledge of bioeffects associated with exposure to electromagnetic energy and the advances in dosimetry and, also, to overcome obvious shortcomings in the earlier exposure guides. This paper will review the exposure criteria developed during the past decade by the American National Standards Institute and the National Council on Radiation Protection and Measurements, with particular emphasis on the underlying rationale.     

Work exposures to animal neurocarcinogens

The initiation of brain tumors has been demonstrated in animals exposed to industrial chemicals, results which have not been demonstrated in humans. This report describes the National Occupation Exposure Survey conducted by the National Institute of Occupational Safety and Health during the years 1981-1983, which included information about 16 known and suspected animal neurocarcinogens. Acrylonitrile, ethylene oxide, and 1-H-benzotriazole had national exposure estimates of more than 50,000 workers. The health services industry had the largest number of workers potentially exposed to a single agent and the most diverse exposures in the workplace. These data provide some evidence for the pattern and presence of animal neurocarcinogens in the occupational environment and provide a basis on which to begin to develop occupational exposure tools and to prioritize further research.     

Applications of a job classification system in occupational epidemiology.

An occupational preventive medicine program attempts to control exposure so workers experience no detrimental effect on health. In a chemically complex industry, the definition of exposure is difficult because of the many different chemicals used and produced, the many different jobs and processes with qualitatively different exposures, and the movement of workers from job to job. Jobs have therefore been grouped on the basis of process or product into functionally homogeneous categories called occupational titles (OT''s). Work experience can now be quantified independent of exposure (or by the dominant toxicants in each OT) and compared to health outcomes. Examples are discussed of the application of OT''s to studies of the mortality and morbidity experience in the rubber industry, and the development of dose-response relations.     

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.     

我国化学物质职业接触限值研究规范与建议

本文在研究国内外职业接触限值的内涵基础上,详述了化学物质职业接触限值的制定规范,指出我国化学物质职业接触限值尚未解决的问题,并建议下一步制修订工作中要明确提出接触限值依据的关键效应和保护水平,应正确理解超限倍数概念,尽快制定职业接触限值的非常规工作制下的调整指南,阐明联合作用及其应用等,以其为今后化学物质职业接触限值的制修订的提供借鉴。     

Odor, irritation and perception of health risk

OBJECTIVES: Understanding the potential for volatile chemicals to elicit chemosensory irritation in the upper respiratory tract is critical to setting occupational exposure limits that are protective of comfort and well-being for the majority of workers. However, the determination of irritant potency for any volatile chemical has been limited by the lack of reliable and non-invasive assays for studying sensory irritation in humans and a failure to appreciate the many non-sensory factors that can influence the reactions to an odor or an irritant in the workplace. METHODS: This paper reviews the issues involved in distinguishing and measuring sensations of odor and irritation from volatile chemicals, and describes recent developments in psychophysical methods for evaluating chemical irritancy in humans, and discusses some of the many non-sensory factors such as exposure history, attitudes and expectations and personality variables that can significantly alter the perception of odor, irritation and health risk following exposure to a volatile chemical. RESULTS: The availability of safe, non-invasive assays to measure directly odor and irritant responses in the species of interest, humans, can both simplify and improve accuracy in the process of developing appropriate occupational exposure guidelines. CONCLUSIONS: Objective measures of irritation onset obtained in conjunction with subjective responses can lend valuable input to the decision process for determining occupational exposure limits but should always account for other factors (e.g., cognitive or emotional) that may be modulating the subjective response.     

Comparison of regulations on occupational carcinogens in several industrialized countries

Regulations controlling the manufacture and use of carcinogens in the industrial setting of various countries are examined. In addition, the occupational exposure limits (OEL) of chemicals known or suspected to be carcinogenic in humans are listed, and criteria for the establishment of OELs are discussed. It is also stressed that control measures should not be confined to a few developed countries, and it is hoped that attracting attention to their unevenness will contribute to the implementation of a more efficient primary prevention of cancer.