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.     

Injury rate as an indicator of business success

Health and safety professionals and organizations have often suggested that promoting and improving health and safety in the workplace will improve business success. We conducted a study of all new small businesses that registered with the Workers' Compensation Board of British Columbia (WCB of BC) in the years 1993, 1995, 1996 and 1997, assessing their injury rate in the first 5 complete years of business. The data set represents 53,913 new businesses and 19,332 claims. Businesses were grouped by the number of years between registering for WCB coverage and termination of coverage. Injury rates were determined for each calendar year for each industry sector as injuries per 100 person-years, based on payroll information provided by the businesses. Across all industries, businesses that failed between 1 and 2 yr of start-up had an average injury rate of 9.71 while businesses that survived more than 5 yr had an average injury rate of only 3.89 in their first year of business (p<0.000001). The WCB of BC demonstrated a statistical correlation between health and safety in the workplace and the survival of a small business.     

Air sampling of nickel in a refinery

Air monitoring was conducted in a nickel base metal refinery to determine compliance with occupational exposure limits. The hypothesis stated that levels of airborne dust may pose a risk to worker health if compared to the relevant exposure limits. Exposure limits for nickel species are set for the inhalable nickel dust fraction. Personal air samples, representative of three selected areas were collected in the workers' breathing zones, using the Institute of Occupational Medicine (IOM) samplers. Real-time personal samples were collected randomly over a two-month period in three nickel production areas. Filter papers were treated gravimetrically and were analysed for soluble and insoluble nickel through inductive coupled plasma-mass spectrometry (ICP-MS). Measured concentrations were expressed as time weighted average exposure concentrations. Results were compared to South African occupational exposure limits (OELs) and to the threshold limit values (TLVs) set by the American Conference of Governmental Industrial Hygienists (ACGIH) to determine compliance. Statistical compliance was also determined using the National Institute for Occupational Safety and Health procedure as prescribed by South Africa's Hazardous Chemical Substances Regulations in 1995. In two of the areas it was found that exposure concentrations complied with the OELs. Some exposures exceeded the OEL values and most exposures exceeded the TLV values in the other area concerned. A comprehensive health risk assessment needs to be conducted to determine the cause of non-compliance.     

Evaluation of potential toxicity from co-exposure to three CNS depressants (toluene, ethylbenzene, and xylene) under resting and working conditions using PBPK modeling

Under OSHA and American Conference of Governmental Industrial Hygienists (ACGIH) guidelines, the mixture formula (unity calculation) provides a method for evaluating exposures to mixtures of chemicals that cause similar toxicities. According to the formula, if exposures are reduced in proportion to the number of chemicals and their respective exposure limits, the overall exposure is acceptable. This approach assumes that responses are additive, which is not the case when pharmacokinetic interactions occur. To determine the validity of the additivity assumption, we performed unity calculations for a variety of exposures to toluene, ethylbenzene, and/or xylene using the concentration of each chemical in blood in the calculation instead of the inhaled concentration. The blood concentrations were predicted using a validated physiologically based pharmacokinetic (PBPK) model to allow exploration of a variety of exposure scenarios. In addition, the Occupational Safety and Health Administration and ACGIH occupational exposure limits were largely based on studies of humans or animals that were resting during exposure. The PBPK model was also used to determine the increased concentration of chemicals in the blood when employees were exercising or performing manual work. At rest, a modest overexposure occurs due to pharmacokinetic interactions when exposure is equal to levels where a unity calculation is 1.0 based on threshold limit values (TLVs). Under work load, however, internal exposure was 87%higher than provided by the TLVs. When exposures were controlled by a unity calculation based on permissible exposure limits (PELs), internal exposure was 2.9 and 4.6 times the exposures at the TLVs at rest and workload, respectively. If exposure was equal to PELs outright, internal exposure was 12.5 and 16 times the exposure at the TLVs at rest and workload, respectively. These analyses indicate the importance of (1) selecting appropriate exposure limits, (2) performing unity calculations, and (3) considering the effect of work load on internal doses, and they illustrate the utility of PBPK modeling in occupational health risk assessment.     

消化内镜中心气溶胶产生及防控策略研究进展

 内镜诊疗操作的侵入性和清洗消毒操作的开放性等特点,使内镜中心已成为气溶胶产生的重点区域,医务人员长期气溶胶暴露后可对人体健康造成巨大危害。本文通过回顾国内外文献,对消化内镜中心的气溶胶来源、医务人员暴露风险以及防控策略等多方面进行综述,以期为内镜医务人员防范职业暴露,保障人体健康提供借鉴意见。     

Occupational Exposure to BTEX and Styrene in West Asian Countries: A Brief Review of Current State and Limits

The aim of introducing occupational exposure limits (OELs) is to use them as a risk management tool in order to protect workers’ health and well-being against harmful agents at the workplace. In this review we identify OELs for benzene, toluene, ethylbenzene, xylene (BTEX), and styrene concentrations in air and assess occupational exposure to these compounds through a systematic literature search of publications published in West Asian countries from 1980 to 2021. OELs for BTEX and styrene have been set in Iran and Turkey to levels similar to those in European countries and the US. The search yielded 49 full-text articles that cover studies of exposure assessment in six countries, but most (n=40) regard Iran. Average occupational exposure to benzene of workers in oil-related industries is higher than recommended OEL, while average occupational exposure to other compounds is lower than local OELs (where they exist). Currently, information about levels of occupational exposure to BTEX and styrene is insufficient in West Asian countries, which should be remedied through OEL regulation and application. Furthermore, coherent research is also needed to determine actual levels of occupational exposure, dose-responses, and the economic and technical capacity of local industries to address current issues.Key words: benzene, ethylbenzene, OEL, oil industry, risk management, toluene, xylene     

Measuring the impact of influenza vaccination on healthcare worker absenteeism in the context of a province-wide mandatory vaccinate-or-mask policy

ObjectivesIn 2012, British Columbia (BC) implemented a province-wide vaccinate-or-mask influenza prevention policy for healthcare workers (HCWs) with the aim of improving HCW coverage, and reducing illness in patients and staff. We assess post-policy impacts of HCW vaccination status on their absenteeism.MethodsWe matched individual HCW payroll data from December 1, 2012 to March 31, 2017 with annually self-reported vaccination status for BC health authority employees to assess sick rates (sick time as a proportion of sick time and productive time). We modelled adjusted odds ratios (OR) of taking any sick time, relative rates (RR) of sick time taken, and predicted mean sick rates by vaccination status in influenza (December 1–March 31) and non-influenza seasons (April 1 to November 30). We used two methods to assess changes in influenza season sick rates for HCWs who had a change in their vaccination status over the five years.ResultsHCWs who reported ‘early’ vaccination (before December 1 when the policy is in effect) were less likely to take sick time (OR 0.874, 95%CI: 0.866–0.881) and took less sick time (RR 0.907, 95%CI: 0.901–0.912) in influenza season compared to HCWs who did not report vaccination; whereas HCWs who reported ‘late’ (between December 1 and March 31, and subject to masking until vaccinated) had similar sick rates to HCWs who did not report vaccination. These trends were also observed in non-influenza season. Influenza season sick rates were similar for HCWs that had at least one year of ‘early’ vaccination and one year where vaccination was not reported over the five year period.ConclusionsOverall absenteeism is lower among HCWs who report vaccination versus those who do not report. However, absenteeism behaviours appear to be influenced by individual level factors other than vaccination status.     

Dermal absorption potential of industrial chemicals: criteria for skin notation

A dermal penetration rate (flux), predicted from physical properties of 132 chemicals, is suggested as an index of the dermal absorption potential of industrial chemicals. The prediction is designed for organic nonelectrolytes. Two reference values are recommended as criteria for skin notation: 1) dermal absorption potential, which relates to dermal absorption raising the dose of nonvolatile chemicals or biological levels of volatile chemicals 30% above those observed during inhalation exposure to TLV-TWA only--dermal absorption of chemicals belonging to this category should be considered when data obtained by biological monitoring are interpreted; and 2) dermal toxicity potential, which relates to dermal absorption that triples biological levels as compared with levels observed during inhalation exposure to TLV-TWA only. Chemicals belonging in this category should carry a skin notation. The toxicity criteria may not be valid for chemicals whose TLVs are based on preventing irritation and discomfort.     

The role of threshold limit values in U.S. air pollution policy.

This paper analyzes the role of threshold limit values (TLVs) in national air pollution policy during the 1980s, a period in which the Environmental Protection Agency (EPA) sought to delegate to individual states the authority to evaluate and regulate airborne toxic substances. We focus on 20 carcinogens and 11 substances with non-genotoxic health effects that were regulated by local air toxics programs using TLVs. Data from EPA's National Air Toxics Information Clearinghouse indicate that maximum TLV-based Ambient Air Level guidelines (AALs) frequently exceed minimum TLV-based AALs by a factor of greater than 1,000. Cancer potency data from EPA's Integrated Risk Information System suggest significant risks remain at TLV-based AALs. Cancer risks at the median TLV-based AAL exceed 1,000 cases per million exposed persons for cadmium (1,040), nickel and its compounds (1,420), propylene oxide (1,550), coke oven emissions (1,860), benzene (2,500), arsenic and its compounds (7,300), N-nitrosodimethylamine (21,000), asbestos (21,500), and ethylene dibromide (55,000). We also summarize published studies that report non-genotoxic health effects in workers exposed at levels near the TLV for 11 substances whose AALs were based on TLVs. Contrary to the assumption frequently made by state air toxics program, TLVs cannot be taken to represent no observed effect levels (NOELs) for regulatory purposes.     

Healthcare use before and after a workplace injury in British Columbia, Canada

Objectives

There is growing evidence that occupational injuries influence workers'' emotional and physical wellbeing, extending healthcare use beyond what is covered by the Workers'' Compensation Board (WCB).

Methods

The authors used an administrative database that links individual publicly funded healthcare and WCB data for the population of British Columbia (BC), Canada. They examined change in service use, relative to one year before the injury, for workers who required time off for their injuries (lost time = LT) and compared them to other injured workers (no lost time = NLT) and individuals in the population who were not injured (non‐injured = NI).

Results

LT workers increased physician visits (22%), hospital days (50%), and mental healthcare use (43% physician visits; and 70% hospital days) five years after the injury, relative to the year before the injury, at a higher rate than the NI group. For the NLT workers, the level of increased use following the injury was between that of these two groups. These patterns persisted when adjusting for registration in the BC Medical Service Plan (MSP) and several workplace characteristics.

Conclusions

Although the WCB system is the primary mechanism for processing claims and providing information about workplace injury, it is clear that the consequences of workplace injury extend beyond what is covered by the WCB into the publicly funded healthcare system.     

Data solutions for the 21st century: CEFIC's vision and intentions. The European Chemical Industry Council

Information on workplace exposures to chemicals has a role and importance that goes beyond compliance with occupational exposure limits (OELs). In particular, the increasing use of exposure data in regulatory risk assessment processes places added demands on the need to collect such information. Industry's challenge is to respond to these developments in a manner that ensures data are obtained, archived, and analyzed to standards consistent with evolving stakeholder expectations.     

Corporate influence on threshold limit values

Investigations into the historical development of specific Threshold Limit Values (TLVs) for many substances have revealed serious shortcomings in the process followed by the American Conference of Governmental Industrial Hygienists. Unpublished corporate communications were important in developing TLVs for 104 substances; for 15 of these, the TLV documentation was based solely on such information. Efforts to obtain written copies of this unpublished material were mostly unsuccessful. Case studies on the TLV Committee's handling of lead and seven carcinogens illustrate various aspects of corporate influence and interaction with the committee. Corporate representatives listed officially as "consultants" since 1970 were given primary responsibility for developing TLVs on proprietary chemicals of the companies that employed them (Dow, DuPont). It is concluded that an ongoing international effort is needed to develop scientifically based guidelines to replace the TLVs in a climate of openness and without manipulation by vested interests.     

Development and implementation of a Heat Alert and Response System in rural British Columbia

SettingIn 2018, a regional health authority in British Columbia (BC) initiated a multi-year project to support planning and response to extreme heat. Climate projections indicate that temperatures in the southern interior of BC will continue to increase, with concomitant negative impacts on human health. Successful climate change adaptation must include cross-sectoral action, inclusive of the health sector, to plan for and respond to climate-related events, including extreme heat.InterventionThe objective of this project was to support the development and implementation of a Heat Alert and Response System (HARS) in a small, rural community. The health authority facilitated collaboration among provincial and local governments, community organizations, and First Nations partners to assess community assets, draft a plan for extreme heat, and prepare for a community-supported response during heat events.OutcomesStakeholders expressed the importance of utilizing existing partnerships and community resources, such as physical and procedural infrastructure, in which to embed the HARS. It was imperative that the plan be simple, concise, and considerate of the community’s unique context. Educational materials and a tailored method of dissemination were important for collective and individual risk mitigation.ImplicationsA community-driven approach that utilized existing assets allowed for integration of HARS within municipal response plans and established infrastructure. The result is a sustainable public health intervention that has the potential to mitigate the negative health effects of extreme heat. Knowledge acquired through this initiative is informing similar HARS planning processes in other rural BC communities.     

Heat exposure in the Canadian workplace

Exposure to excessive heat is a physical hazard that threatens Canadian workers. As patterns of global climate change suggest an increased frequency of heat waves, the potential impact of these extreme climate events on the health and well‐being of the Canadian workforce is a new and growing challenge. Increasingly, industries rely on available technology and information to ensure the safety of their workers. Current Canadian labor codes in all provinces employ the guidelines recommended by the American Conference of Governmental Industrial Hygienists (ACGIH) that are Threshold Limit Values (TLVs) based upon Wet Bulb Globe Temperature (WBGT). The TLVs are set so that core body temperature of the workers supposedly does not exceed 38.0°C. Legislation in most Canadian provinces also requires employers to install engineering and administrative controls to reduce the heat stress risk of their working environment should it exceed the levels permissible under the WBGT system. There are however severe limitations using the WGBT system because it only directly evaluates the environmental parameters and merely incorporates personal factors such as clothing insulation and metabolic heat production through simple correction factors for broadly generalized groups. An improved awareness of the strengths and limitations of TLVs and the WGBT index can minimize preventable measurement errors and improve their utilization in workplaces. Work is on‐going, particularly in the European Union to develop an improved individualized heat stress risk assessment tool. More work is required to improve the predictive capacity of these indices. Am. J. Ind. Med. 53:842–853, 2010. © 2010 Wiley‐Liss, Inc.     

Health care workers’ ability and willingness to report to duty during catastrophic disasters

Catastrophic disasters create surge capacity needs for health care systems. This is especially true in the urban setting because the high population density and reliance on complex urban infrastructures (e.g., mass transit systems and high rise buildings) could adversely affect the ability to meet surge capacity needs. To better understand responsiveness in this setting, we conducted a survey of health care workers (HCWs) (N=6,428) from 47 health care facilities in New York City and the surrounding metropolitan region to determine their ability and willingness to report to work during various catastrophic events. A range of facility types and sizes were represented in the sample. Results indicate that HCWs were most able to report to work for a mass casualty incident (MCI) (83%), environmental disaster (81%), and chemical event (71%) and least able to report during a smallpox epidemic (69%), radiological event (64%), sudden acute respiratory distress syndrome (SARS) outbreak (64%), or severe snow storm (49%). In terms of willingness, HCWs were most willing to report during a snow storm (80%), MCI (86%), and environmental disaster (84%) and least willing during a SARS outbreak (48%), radiological event (57%), smallpox epidemic (61%), and chemical event (68%). Barriers to ability included transportation problems, child care, eldercare, and pet care obligations. Barriers to willingness included fear and concern for family and self and personal health problems. The findings were consistent for all types of facilities. Importantly, many of the barriers identified are amenable to interventions.     

The impact of systematic occupational health and safety management for occupational disorders and long-term work attendance

Despite several years of conducting formalized systematic occupational health and safety management (SOHSM), as required by law in Sweden and most other industrialized countries, there is still little evidence on how SOHSM should be approached to have an impact on employees' health. The aim of this study was to investigate the importance of SOHSM, considering structured routines and participation processes, for the incidence of occupational disorders and the prevalence of long-term work attendance among home care workers (HCWs). Municipal human service organizations were compared concerning (a) their structured routines and participation processes for SOHSM and (b) employee health, i.e. the municipal five-year incidence of occupational disorders and prevalence of work attendance among HCWs. National register-based data from the whole population of HCWs (n=154 773) were linked to register-data of occupational disorders and prevalence of long-term work attendance. The top managers and safety representatives in selected high- and low-incidence organizations (n=60) answered a questionnaire about structure and participation process of SOHSM. The results showed that prevalence of long-term work attendance was higher where structure and routines for SOHSM (policy, goals and plans for action) were well organized. Highly structured SOHSM and human resource management were also related to high organizational incidence of reported occupational disorders. Allocated budget and routines related to HCWs' influence in decisions concerning performance of care were also related to long-term work attendance. The participation processes had a weak effect on occupational disorders and work attendance among HCWs. Reporting occupational disorders may be a functional tool to stimulate the development of effective SOHSM, to improve the work environment and sustainable work ability.     

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.     

But they are not thresholds: A critical analysis of the documentation of threshold limit values

Threshold Limit Values (TLVs) represent conditions under which the TLV Committee of the American Conference of Governmental Industrial Hygienists (ACGIH) believes that nearly all workers may be repeatedly exposed without adverse effect. A detailed research was made of the references in the 1976 Documentation to data on “industrial experience” and “experimental human studies.” The references, sorted for those including both the incidence of adverse effects and the corresponding exposure, yielded 158 paired sets of data. Upon analysis it was found that, where the exposure was at or below the TLV, only a minority of studies showed no adverse effects (11 instances) and the remainder indicated that up to 100% of those exposed had been affected (8 instances of 100%). Although, the TLVs were poorly correlated with the incidence of adverse effects, a surprisingly strong correlation was found between the TLVs and the exposures reported in the corresponding studies cited in the Documentation. Upon repeating the search of references to human experience, at or below the TLVs, listed in the more recent, 1986 edition of the Documentation, a very similar picture has emerged from the 72 sets of clear data which were found. Again, only a minority of studies showed no adverse effects and TLVs were poorly correlated with the incidence of adverse effect and well correlated with the measured exposure. Finally, a careful analysis revealed that authors' conclusions in the references (cited in the 1976 Documentation) regarding exposure-response relationships at or below the TLVs were generally found to be at odds with the conclusions of the TLV Committee. These findings suggest that those TLVs which are justified on the basis of “industrial experience” are not based purely upon health considerations. Rather, those TLVs appear to reflect the levels of exposure which were perceived at the time to be achievable in industry. Thus, ACGIH TLVs may represent guides of levels which have been achieved, but they are certainly not thresholds.     

如何预防医务人员COVID-19感染：来自中国武汉的经验

 在新型冠状病毒肺炎（COVID-19）大流行的背景下,全球已有数以千计的医务人员感染新型冠状病毒（SARS-CoV-2）,并有人因此失去生命。在疫情早期,中国发生了医务人员感染。由于对SARS-CoV-2的特点认识有限,湖北有3,000多名医务人员在疫情暴发初期感染了SARS-CoV-2。由于当地医院医务人员工作超负荷,超过4.2万名医务人员（包括军队医务人员）,从全国各地被派往湖北。在疫情最严重的时期,中国有十分之一的重症监护医生在武汉工作。在中国抗击COVID-19的过程中,虽然在疫情早期发生了一定数量的医务人员感染SARS-CoV-2,但通过及时采取预防措施,包括快速诊断,及时对患者进行隔离,强调医务人员的安全,加强医务人员基本防护知识培训和统一管理等有效防护措施,国家援鄂医疗队42,632名队员最终未报告感染,并且当地医院医务人员感染病例显著减少,说明医务人员院内感染COVID-19是完全可以预防的。本文旨在阐述中国武汉疫情期间,如何通过采取有效措施预防医务人员感染SARS-CoV-2。     

Development, Evaluation, and Application of Sediment Quality Targets for Assessing and Managing Contaminated Sediments in Tampa Bay, Florida

Tampa Bay is a large, urban estuary that is located in west central Florida. Although water quality conditions represent an important concern in this estuary, information from numerous sources indicates that sediment contamination also has the potential to adversely affect aquatic organisms, aquatic-dependent wildlife, and human health. As such, protecting relatively uncontaminated areas of the bay from contamination and reducing the amount of toxic chemicals in contaminated sediments have been identified as high-priority sediment management objectives for Tampa Bay. To address concerns related to sediment contamination in the bay, an ecosystem-based framework for assessing and managing sediment quality conditions was developed that included identification of sediment quality issues and concerns, development of ecosystem goals and objectives, selection of ecosystem health indicators, establishment of metrics and targets for key indicators, and incorporation of key indicators, metrics, and targets into watershed management plans and decision-making processes. This paper describes the process that was used to select and evaluate numerical sediment quality targets (SQTs) for assessing and managing contaminated sediments. These SQTs included measures of sediment chemistry, whole-sediment and pore-water toxicity, and benthic invertebrate community structure. In addition, the paper describes how the SQTs were used to develop site-specific concentration-response models that describe how the frequency of adverse biological effects changes with increasing concentrations of chemicals of potential concern. Finally, a key application of the SQTs for defining sediment management areas is discussed.