Industrial Hygiene Assessment Research Articles

Evaluation of waste anesthetic gas surveillance program and isoflurane exposures during animal and human surgery

Prolonged occupational exposure to waste anesthetic gases may have the potential to cause adverse health effects. Workplace exposure surveillance programs are intended to reduce health risk by evaluating exposures to waste anesthetic gases during surgical procedures. Both the personal breathing-zone and area measurements are used to assess occupational exposure in the operating theater. Direct-reading instruments provide real-time measurements and are useful for identifying leaks and evaluating on-the-spot corrective actions. Passive diffusion monitors quantify occupational exposures over time during surgery. The aim of this study was to evaluate a waste anesthetic gas surveillance program to understand occupational exposures and further improve data collection strategy. For this study, 76 survey reports from 2012 through 2014 were retrospectively reviewed to assess occupational exposures to isoflurane in 58 unique procedural rooms operated by the National Institutes of Health. The surveys included industrial hygiene assessments performed during animal and human surgical procedures. The survey reports were evaluated qualitatively and data from these reports was transcribed for quantitative analysis. Variations in sample strategy were observed between surveys and were attributed to ambiguity in the written surveillance program. The study also evaluated the relationship between isoflurane concentrations and sampling method, sampling location, patient type, or scavenging method. Isoflurane exposures were significantly higher among procedures performed on rodents compared to the patients with a large body mass (humans, non-human primates, and swine) (P < 0.05) and in procedures using the charcoal canister exhaust system compared with the central vacuum exhaust system. In addition, individuals performing the surgical procedure experienced elevated occupational exposures measured by both direct-reading instrument and passive diffusion monitors, that is, exposure was significantly higher as measured at the breathing-zone compared with any area within the room (P < 0.05). The study identified several inconsistencies and shortcomings in the surveillance program. Isoflurane concentrations measured during rodent procedures requires further review of work practices and engineering controls. Overall, the findings provide insights to further improve data collection, monitoring, and control of isoflurane exposures.

Measured removal rates of chrysotile asbestos fibers from air and comparison with theoretical estimates based on gravitational settling and dilution ventilation

Context: Industrial hygiene assessments often focus on activity-based airborne asbestos concentration measurements, but few empirical data exist regarding the fiber removal rate from air after activities cease.Objective: Grade 7T chrysotile indoor fiber settling (FS) rates were characterized using air sampling (NIOSH Method 7402).Materials and methods: Six replicate events were conducted in a 58 m3 study chamber (ventilation 3.5 ACH), in which chrysotile-contaminated work clothing was manipulated for 15 min followed by 30 min of no activity. The fiber concentration decay constant and removal rate were characterized using an exponential decay model based on the measurements.Results: Breathing zone airborne chrysotile concentrations decreased by 86% within 15–30 min after fiber disturbance, compared to concentrations during active disturbance (p < 0.05). Estimated mean time required for 99% of the phase contrast microscopy-equivalent (PCME) fibers to be removed from air was approximately 30 min (95% CI: 22–57 min). The observed effective FS velocity was 0.0034 m/s. This settling velocity was between 4.5-fold and 180-fold faster than predicted by two different particulate gravitational settling models. Additionally, PCME concentrations decreased approximately 2.5-fold faster than predicted due to air exchange alone (32 versus 79 min to 99% decrease in concentration).Discussion: Other measurement studies have reported similar airborne fiber removal rates, supporting the finding that factors other than gravitational settling and dilution ventilation contribute measurably to PCM fiber removal from air (e.g. impaction, agglomeration).Conclusion: Overall, the scientific weight of evidence indicates that the time necessary for removal of 99% of fibers greater than 5 μm in length (with aspect ratios greater than 3:1) is approximately 20–80 min.

Case of accelerated silicosis in a sandblaster

Sandblasting is traditionally known as a high-risk profession for potential development of lung silicosis. Reported is a case of a sandblaster with confirmed accelerated silicosis, a condition rather rarely diagnosed in the Czech Republic. Initially, the patient presented with progressive dry cough and exertional dyspnoea. In the early diagnostic process, a possible occupational aetiology was considered given his occupational history and known high-risk exposure to respirable silica particles confirmed by industrial hygiene assessment at the patient’s workplace. The condition was confirmed by clinical, histological and autopsy findings. The patient died during lung transplantation, less than five years from diagnosis.

Occupational exposure assessment using antibody levels: exposure to avian leukosis/sarcoma viruses in the poultry industry

Avian leukosis/sarcoma viruses (ALSV) infect and cause cancers in chickens. Poultry workers are exposed to ALSV and other infectious agents in the workplace. This study examines if industrial hygiene assessment of antibody levels in poultry workers can identify risky job tasks at the higher exposure risk to an infectious agent, i.e., ALSV. We compared ALSV antibody levels in poultry workers and control subjects. Occupational and demographical factors were examined for an association with the exposure risk in poultry workers. We found that the antibody levels were significantly higher in poultry workers than in control subjects. Job category and age together were significantly associated with the antibody levels in workers. Certain job tasks were identified with significantly higher antibody levels as compared to others, implying that recommendations should be made to protect workers at these jobs. The findings of this study indicate that the measurement of antibody levels in workers can be useful for industrial hygiene assessment of exposure to infectious agents.

Exposure and genetics increase risk of beryllium sensitisation and chronic beryllium disease in the nuclear weapons industry

ObjectivesBeryllium sensitisation (BeS) and chronic beryllium disease (CBD) are caused by exposure to beryllium with susceptibility affected by at least one well-studied genetic host factor, a glutamic acid residue at...

Industrial hygiene assessment of reticuloendotheliosis viruses exposure in the poultry industry

Reticuloendotheliosis viruses (REV) are a group of retroviruses like avian leukosis/sarcoma viruses (ALSV) that naturally infect and cause cancers in chickens. We recently found that ALSV antibody levels were associated with job tasks in the poultry industry. The objectives of this study are to examine whether a similar association can be found with REV antibody levels and to examine the correlation between REV and ALSV antibody levels. Relative risk was estimated comparing REV antibody levels of 45 poultry workers with those of 44 controls. The expected mean antibody level was predicted for the association with employment by a generalized linear model. Correlation coefficient was measured between ALSV and REV antibody levels. REV antibody levels were significantly higher in poultry workers than in control subjects and were associated with gender and employment conditions, especially employment duration. The relative risk was significantly higher for some job categories. A significant correlation was observed between REV and ALSV antibody levels, which was strong among poultry workers, but weak among the control subjects. Antibody levels can be validly used to identify certain job tasks associated with high risk of exposure to REV in the workplace, and the practical implication is recommendations for protection at these job tasks. Importantly, in situations where there is exposure to multiple pathogens in the workplace, the analysis of antibody levels of one pathogen may sufficiently represent exposure to the other correlated pathogens. This suggested exposure assessment may hold true for pathogens with a similar route of transmission.

Development of occupational exposure limits for the Hanford tank farms

Production of plutonium for the United States’ nuclear weapons program from the 1940s to the 1980s generated 53 million gallons of radioactive chemical waste, which is stored in 177 underground tanks at the Hanford site in southeastern Washington State. Recent attempts to begin the retrieval and treatment of these wastes require moving the waste to more modern tanks and result in potential exposure of the workers to unfamiliar odors emanating from headspace in the tanks. Given the unknown risks involved, workers were placed on supplied air respiratory protection. CH2MHILL, the managers of the Hanford site tank farms, asked an Independent Toxicology Panel (ITP) to assist them in issues relating to an industrial hygiene and risk assessment problem. The ITP was called upon to help determine the risk of exposure to vapors from the tanks, and in general develop a strategy for solution of the problem. This paper presents the methods used to determine the chemicals of potential concern (COPCs) and the resultant development of screening values and Acceptable Occupational Exposure Limits (AOELs) for these COPCs. A total of 1826 chemicals were inventoried and evaluated. Over 1500 chemicals were identified in the waste tanks headspaces and more than 600 of these were assigned screening values; 72 of these compounds were recommended for AOEL development. Included in this list of 72 were 57 COPCs identified by the ITP and of these 47 were subsequently assigned AOELs. An exhaustive exposure assessment strategy was developed by the CH2MHILL industrial hygiene department to evaluate these COPCs.

Dust and chemical exposures, and miscarriage risk among women textile workers in Shanghai, China

Introduction:To investigate possible associations between miscarriage and occupational exposures in the Shanghai textile industry.Methods:A retrospective cohort study of miscarriages among 1752 women in the Shanghai textile industry was conducted. Reproductive...

Improving Occupational Safety and Health in Bangladesh

The majority of the population in Bangladesh is employed in manual handling tasks, but adequate protections for these workers do not exist. Conditions at a boulder handling site, saw mill, rice packaging plant and construction site show the need for comprehensive reforms in occupational safety and health legislation and practice in Bangladesh. New policies on training, industrial hygiene, safety equipment, and risk assessment are necessary to protect workers in a rapidly developing economy.

Use of a Pharmacokinetic Model and Single Urine Voids to Estimate the Dosing Profiles of Pesticide Applicators

P-155 Introduction: Pesticide biomonitoring studies typically collect spot urine samples due to low subject burden and cost compared to total urine collection. However, single voids will bias daily dose estimates due to the changing time course of the analytes in the body and urine after exposure events. A single void may still be able to accurately estimate dose over longer time periods when used in conjunction with a pharmacokinetic (PK) model to establish the relationship between absorbed dose and urinary metabolites as a function of time. Methods: Composite and single-void urine samples from fourteen farmers were measured for concentrations of 2,4-D or the chlorpyrifos metabolite TCP. Composite samples were collected over 24-hour intervals starting 24 hours prior to application through 96 hours post-application. The single voids analyzed were collected on the morning after the application day. Biomarker excretion rates from single-void samples, adjusted for baseline concentration, were entered into an inverse PK model to predict FD, the dermally absorbed dose during the exposure event. A one-compartment model with first-order absorption and elimination rate constants was used and PK parameters were taken from the literature. FD was then entered into a model in a forward manner using STELLA software to estimate elimination of the analytes over time. The urinary output of the analytes (μg) predicted by the models during the first 24-hours post-application were compared to measured values. Results: The TCP and 2,4-D models reduced the bias associated with using a single-void surrogate for daily dose. The average percent error between the measured and modeled TCP 24-hour output estimates was 20%, compared to 80% between measured TCP 24-hour output and single-void output (adjusted upwards using subject-specific daily urine volume). Average percent error between the measured and modeled 2,4-D 24-hour output estimates was 25%, compared to 147% between 2,4-D measured 24-hour output and single-void output (using subject-specific daily urine volume). Discussion and Conclusions: Despite the small sample size, our findings demonstrate that PK models improved the capability of single-void samples to estimate a farmer's daily dose after a known exposure to two non-persistent pesticides. Model parameter uncertainty, inter-individual variability, product formulation differences and urine undercollection likely contributed to the disagreement between modeled and measured output. The described methodology has wide applications in epidemiology, industrial hygiene, and risk assessment where there is currently a lack of practical techniques to measure absorbed dose at reasonable cost.

Asbestos Ban in India

Rapidly industrializing India is described by the International Monetary Fund as a young, disciplined, and vibrant economy with a projected growth of 6.7% for 2005. The total workforce of 397 million has only 7% of workers employed in the organized sector with construction, where asbestos exposure is prevalent, employing 4.4%. The domestic production of asbestos declined from 20,111 tons in 1998-1999 to 14,340 tons in 2002-2003. The imports from Russia and Canada increased from 61,474 tons in 1997-1998 to 97,884 tons in 2001-2002. The production of asbestos cement products went up from 0.68 million tons in 1993-1994 to 1.38 million tons in 2002-2003. The asbestos industry has been delicensed since March 2003. The number of asbestos-based units stood at 32, with the western state of Maharashtra having the largest number. According to official figures, the industry employs 8000 workers. The occupational exposure standard is still 2 fibers/mL, worse still, mesothelioma is not recognized as an occupational disease. The latest cancer registry data have no information on mesothelioma. The health and safety legislation does not cover 93% of workers in the unorganized sector where asbestos exposures are extremely high. Workers remain uninformed and untrained in dealing with asbestos exposure. Enforcement agencies are not fully conscious of the risks of asbestos exposure. Industrial hygiene assessment is seldom carried out and pathologists do not receive training in identifying mesothelioma histopathologically. The lack of political will and powerful influence of the asbestos industry are pushing India toward a disaster of unimaginable proportion.

Mortality update of workers exposed to acrylonitrile in The Netherlands.

To study the possible carcinogenic effects of acrylonitrile, we updated the follow up of a cohort of 2842 acrylonitrile workers. The comparison group consisted of 3961 workers from a nitrogen fixation plant. Industrial hygiene assessments quantified past exposure to acrylonitrile, 8-hour averages as well as peak exposure, the use of personal protective equipment, and exposure to other potential carcinogenic agents. Standardized mortality ratios were calculated to adjust for the effect of age distribution, length of follow up, and temporal changes in background mortality rates. Cumulative dose-effect relations were determined for 3 exposure categories and 3 latency periods. The results show that no cancer excess seems related to exposure to acrylonitrile. This additional follow up of a cohort of 2842 workers exposed to acrylonitrile further supports the notion that occupational exposures to acrylonitrile that have occurred in the past have not noticeably increased workers' cancer mortality rates.

Modeling of methyl isothiocyanate air concentrations associated with community illnesses following a metam-sodium sprinkler application.

A series of illnesses occurred in Earlimart, CA on November 13, 1999 following a metam-sodium sprinkler application to a potato field on the southern edge of the town. Case information was obtained from direct interviews, from illness complaints filed with state or county agencies, or from illness reports filed by community physicians for 173 subjects. Air concentrations of the by-product methyl isothiocyanate (MITC) during the episode were estimated based upon the Industrial Source Complex Short-Term (ISC3) air dispersion model, estimates from prior metam-sodium monitoring studies, and data from weather stations in two adjoining communities. Weather station data indicated that the November 13th incident corresponded with a temperature inversion at approximately 5:00 p.m. and a shift in the direction of prevailing wind from northwest to southeast. On the edge of Earlimart, 1-hr time weighted average (TWA) MITC concentration estimates ranged from 0.5 to 1 ppm. Of the 173 subjects, 170 had MITC-compatible symptoms, including eye or upper respiratory irritation (77.6%), non-specific systemic symptoms (64.7%), and lower respiratory symptoms (20.0%). 78.2% were exposed within 0.5 miles of the northern edge of the treated field where average 1 hr MITC concentrations exceeded the 800 ppb ocular irritation threshold. ISC3 modeling is a useful means of evaluating MITC concentrations for illness episodes when industrial hygiene assessment is not possible.

Parental lead exposure and total anomalous pulmonary venous return.

Investigators from the Baltimore-Washington Infant Study (BWIS) reported an association between self-reported maternal lead exposure and total anomalous pulmonary venous return (TAPVR) in their offspring. This association was further evaluated in the BWIS population using a more sensitive exposure estimate. Cases included 54 live-born infants with TAPVR; controls were a stratified random sample of 522 live-born infants from the BWIS control group. Parental lead exposure was based on three assessment methods, including: an industrial hygiene assessment, an a priori job exposure matrix, and self-reported exposures. A parent was classified as exposed to lead if he/she was classified as exposed by any one of the assessment methods. Approximately 17% of case mothers and 11% of control mothers were classified as exposed to lead during the three months prior to conception through the first trimester (odds ratio [OR], 1.57; 95% confidence interval [CI], 0.64-3.47). Among fathers, 61% of case fathers and 46% of control fathers were classified as exposed to lead during the six months prior to conception (paternal critical period) (OR, 1.83; 95% CI, 1.00-3.42). During the paternal critical period, when only the father was exposed compared to neither parent exposed, the OR for any lead exposure and TAPVR was 1.65 (95% CI, 0.84-3.25). This study supports a possible association between paternal lead exposure and TAPVR. Further studies are warranted using validated assessment methods for occupational and nonoccupational lead exposures to corroborate this association and to elucidate the possible biological mechanism. Birth Defects Research (Part A), 2004.

Historical cohort investigation of spontaneous abortion in the Semiconductor Health Study: epidemiologic methods and analyses of risk in fabrication overall and in fabrication work groups.

The risk of spontaneous abortion (SAB) in the semiconductor industry was examined in a historical cohort study of pregnancies at 14 companies. We identified female employees who had worked for at least 6 months and whose ages ranged from 18 to 44 years during the 1986-1989 study period. Using company records, we included all fabrication-room (fab) employees and an approximately equal number of nonfabrication (nonfab) employees, for a total sample of 7,269. Telephone interviews with 6,088 women (84%) identified 904 eligible pregnancies and 113 SABs. Exposure classification was based on questionnaire and industrial hygiene assessments of tasks the women performed during the first trimester of pregnancy. Using logistic regression to control for age, smoking, ethnicity, education, income, year of pregnancy, and stress, we found a higher risk of SAB in fab employees than in nonfab employees (15.0% of fab pregnancies ended in SAB vs. 10.4% of nonfab pregnancies, adjusted relative risk [RR] = 1.43, 95% CI = 0.95-2.09). Analysis of fab work groups showed that the highest relative risk was in masking employees (17.5% SAB rate, adjusted RR = 1.78, 95% CI = 1.17-2.62 in comparison with nonfab employees). Within masking, the highest risk was found in etching-related process employees (22.2% SAB rate, adjusted RR = 2.08, 95% CI = 1.27-3.19 in comparison to nonfab employees.

Increased risk of lung cancer in the melting department of a second ontario steel manufacturer

A study of lung cancer among workers at an electric arc steel making operation was performed to follow up on the observation of a lung cancer cluster in the melt shop of another plant. The study group comprised 335 deceased men identified from plant records. Eight of thirty men who had ever worked in the pouring pit area died of lung cancer (PMR 276; p less than 0.01), but increased risk was not found elsewhere in the melting department. There was a significant trend in lung cancer risk with the length of employment in the pit area during a time window 18-30 years before death. Smoking data suggested that smoking alone could not account for the increased risk. An industrial hygiene assessment found present exposures to carcinogenic metals and silica to be within current guidelines. No polycyclic aromatic hydrocarbons were detected. This is the second steel plant for which we have found increased lung cancer risk in the pouring areas. The causative factors have not yet been identified.

Evidence for Dermal Absorption as the Major Route of Body Entry During Exposure of Transformer Maintenance and Repairmen to PCBs

Traditional industrial hygiene assessment of exposure to polychlorinated biphenyls (PCBs) has long focused on air concentrations as a surrogate measure of worker dose. Evidence is presented to support the hypothesis that the dermal and dermal/oral routes of worker PCB exposure are major contributors to total PCB body burden in the group of transformer maintenance and repair personnel studied. Additional evidence is presented to demonstrate the critical role of work practices in determining PCB exposure. These hypotheses challenge the long-held notion of the pre-eminent importance of respiratory exposure to PCBs.

Evidence for dermal absorption as the major route of body entry during exposure of transformer maintenance and repairmen to PCBs.

Traditional industrial hygiene assessment of exposure to polychlorinated biphenyls (PCBs) has long focused on air concentrations as a surrogate measure of worker dose. Evidence is presented to support the hypothesis that the dermal and dermal/oral routes of worker PCB exposure are major contributors to total PCB body burden in the group of transformer maintenance and repair personnel studied. Additional evidence is presented to demonstrate the critical role of work practices in determining PCB exposure. These hypotheses challenge the long-held notion of the pre-eminent importance of respiratory exposure to PCBs.

Occupational asthma from inhaled egg protein.

We evaluated workers and performed an industrial hygiene assessment at a plant where raw eggs are processed into powdered egg yolk and whole egg. Egg dust levels in the packaging room straddled the American Conference of Governmental Industrial Hygienists' (ACGIH) exposure guideline of 10 mg/m3 for nuisance dust. We obtained medical histories from 25 workers, and performed physical examinations, spirometry, and serial determinations of peak expiratory flow rate (PEFR) by portable meter every 3 hrs (while awake) for 7 days. We defined symptomatic bronchial lability to be a decrement in PEFR on any one day of 20% or more of the day's maximum, with concurrent symptoms. Skin-prick tests and serum assays for specific IgE by the radioallergosorbent (RAST) method were performed to assess sensitivity to commercial egg proteins, egg protein fractions, and freshly prepared extracts of whole egg powder and yolk. We classified participants as definite cases of asthma if both the examining physician diagnosed asthma and symptomatic bronchial lability was demonstrated by serial PEFR determinations. Definite noncases of asthma were those participants in whom the physician did not diagnose asthma and in whom symptomatic bronchial lability was not demonstrated by PEFR. All five definite cases, compared to three of 16 definite noncases of asthma, had one or more positive skin-prick tests to egg proteins. Four of five cases, compared to 0 of 14 noncases, who had serum determinations, had an elevated RAST to one or more of the egg proteins. This study demonstrates that occupational asthma associated with IgE-mediated allergy to egg proteins occurs among workers exposed to inhaled egg proteins.

Industrial hygiene, chemical and biological assessments of exposures to a chlorinated phenolic sapstain control agent.

A two-year study of the occupational exposure of workers in a lumber mill to a wood preservative containing chlorophenol has been conducted. The methods were biological (urine) monitoring, industrial hygiene assessment and a questionnaire related to worker-perceived health effects. Approximately 40 workers exposed to the wood preservative and 40 unexposed controls working in other locations of the plant participated in the study. Evaluation of work conditions, assessment of urinary levels of tetra- and pentachlorophenol, and administration of a medical questionnaire were performed at a six-month intervals over a two-year period. Industrial hygiene ratings of exposures and adequacy of protection were evaluated in relation to the results of biological monitoring. Workers who came into contact with freshly treated and still wet wood had consistently higher urinary levels of tetrachlorophenol. Workers stationed adjacent to the spray applicator also had higher tetrachlorophenol levels. There was no statistically significant relationship between the subjective ratings by the industrial hygienist of exposure and adequacy of worker protection with the urinary levels of tetrachlorophenol. Nor was there a consistent pattern linking exposure ratings with adequacy of protection. The short half-life of tetrachlorophenol in the urine makes this a good indicator of only the most recent exposure. The differences in urinary levels between controls and exposed workers were large, with averages of 240.4 ppb for exposed workers and 14.6 for controls. Traditional industrial hygiene evaluation techniques, in conjunction with biological monitoring, proved to be the most effective method of assessing both exposure and work practices. Exposed workers reported a statistically significant increase of positive answers to known signs and symptoms of chlorophenol exposure compared with the controls. There was no statistically significant relationship between the number of these health problems reported and the mean urinary levels of tetra- or pentachlorophenol for the exposed group; however, for certain variables (heavy vs. light exposure, inadequate vs. adequate protection, greater than 100 ppb urinary tetrachlorophenol vs. less than 100 ppb), those with heavier exposure, inadequate protection or higher urinary tetrachlorophenol reported on the average more health problems over the two-year period. Firm statistical conclusions could not be drawn because of the small size of the study population.