301
INTERVENTIONS TAKEN AT A HOMELESS SHELTER TO REDUCE TRANSMISSION OF
TUBERCULOSIS.
C. Coffey, C. Calvert, M. Duling, J. Hudnall, R. Lawrence, S. Martin, NIOSH, Morgantown, WV.
The National Institute for Occupational Safety and Health (NIOSH) provides technical assistance to internal and external partners regarding hazardous work site exposures. NIOSH engineers and scientists responded to a request from the National Center for HIV, STD, and TB Prevention and the Missouri Department of Health and Senior Services concerning a tuberculosis (TB) outbreak at the Salvation Army Harbor Light facility in St. Louis, Mo. Harbor Light is a shelter open to any adult male without a place to sleep. The shelter has three major components: (1) the drug treatment area, (2) the respite program, and (3) the transient, open-to-the-public program. The sleeping quarters in the main building house about 100 clients. The shelter has an “annex” in a neighboring building with sleeping quarters on two floors. Since 2000, there had been 19 confirmed cases of TB at the shelter, with two deaths. Of these 19 cases, 14 were epidemiologically linked to Harbor Light shelter use, particularly the Annex. Eight infected contacts were also linked. As a result of the findings, NIOSH made several recommendations to aid in the prevention of continuing TB transmission, including: improving shelter administrative practices (e.g., routine sign and symptoms review, chest X-rays, purified protein derivative tuberculin skin tests, and sputum screening) so that suspect clients are more readily identified, tested, and isolated; thoroughly cleaning and balancing all heating, ventilating, and air-conditioning systems and updating/retrofitting each to include minimum efficiency reporting value 14 filters, and installing in-duct and upper air ultraviolet germicidal irradiation fixtures. The implementation of these preventative measures gave the shelter an effective filtration rate of about 98% for airborne mycobacterium tuberculosis. Since these improvements were made, no new tuberculosis transmission has occurred at the shelter that assists about 1800 homeless clients per year.
302
VALIDATION OF A COMPUTATIONAL FLUID DYNAMICS MODEL DEVELOPED FOR A HOMELESS
SHELTER.
J. Hudnall, S. Martin, Jr., M. Duling, R. Lawrence, C. Calvert, C. Coffey, NIOSH, Morgantown, WV; V. Gandhi, Fluent Inc., Lebanon, NH.
Tracer gas measurements were compared to the results of a computational fluid dynamics (CFD) model developed for a homeless shelter. Sulfur hexafluoride tracer gas was released in the first floor air handling unit (AHU). Sampling occurred in two main areas, the Respite dormitory area and the Common room used for meetings and gatherings. The Respite area was divided into eight sampling sites, evenly located throughout the space. The Common room was divided into four sampling sites. Sampling started 30 minutes after dosing and continued at regular intervals for two hours. All sampling was done during the day while the shelter had the lowest occupancy, but many clients remained in the building during testing. Due to the shelter’s mission, client activity could not be controlled during testing, such as entering/exiting the building and opening doors between rooms. The AHU operated normally and continuously during tracer gas testing. A detailed set of physical measurements, including ventilation flow rates, were taken for use in developing the CFD model. Using these measurements, the model was identical to the actual space, except that furnishings were not included. A linear relationship between the CFD model and the actual tracer gas concentrations was found (r2 = 0.99 in the Respite area and r2 = 0.96 in the Common area); however, the decay rates from the model were different from tracer gas. This was expected as no information was put into the model regarding doors opening/closing, client movement inside the building, and leakage around windows, doors, and through cracks in the building envelope. Since no ductwork was included in the model, duct losses were not considered. This relationship provides validation that CFD modeling can confidently be used to analyze air flow patterns on the first floor of the shelter.
303
DUCT CLEANING ISSUES RELATED TO MOLD REMEDIATION.
L. Nguyen Thi, InAIR Environmental Ltd., Ottawa, ON, Canada.
Evaluation of duct cleanliness in a Canadian archival facility following mold remediation was performed.
Duct cleanliness criteria were based on a composite methodology which included visual inspection, a vacuum dust test method developed by the National Air Duct Cleaners Association, and surface mold sampling.
Duct cleaning was performed over several nights with the HVAC system shut off. Sampling and inspection was performed immediately following duct cleaning each night, prior to HVAC system morning startup.
This sampling and inspection protocol was intended to provide verification that ductwork did not become contaminated during remediation or subsequent duct cleaning activities, and that the ducts were cleaned to an acceptable level of cleanliness.
Five out of nine locations failed the dust cleanliness test, however levels of mold were found to be acceptable, with no known toxigenic species detected in any of the surface samples. The question of reasonable dust cleanliness criteria arose. As the visual inspection can be quite subjective, it is preferred to have a numerical measurement to support claims, but at what point do we draw the line between “clean” and “dirty?”
Additional problems encountered included the duct cleaning contractor commencing at wrong end of ducts. Recommendations for future projects include properly sequencing duct cleaning by ensuring HVAC system is off during cleaning, only one system is cleaned at a time, and cleaning is commenced at duct end closest to HVAC and continued along duct.
Specific duct cleaning procedures and evaluation criteria should be specified in the tender document and not left open for interpretation.
304
OCCUPATIONAL HYGIENE STUDY OF MOLD AND MYCOTOXINS AT AN RCMP DETACHMENT IN
ALBERTA, CANADA.
C. Wisdom, Wisdom Consultants, Edmonton, AB, Canada; G. Smith, Royal Canadian Mounted Police, Edmonton, AB, Canada.
The Royal Canadian Mounted Police (RCMP) is Canada’s national police force. The RCMP has 695 detachments across Canada. These detachments serve as office buildings for police officers and support staff. In 1999, RCMP Health Services started to receive health complaints from workers at a small detachment in Alberta. The RCMP initiated a study to determine the cause of the health complaints and remedial actions. This session describes the investigation into health complaints and the results of environmental sampling. The study centered on mold and mycotoxins. Workers began to feel ill after a basement flood in the mid-1990s. The majority of workers experienced burning/itchy eyes, nasal congestion, and/or skin rashes. Some reported swelling of the eyelids and throat effects. Fungi were detected in the air and on some surfaces. The numbers of airborne fungi, using an RCS sampler and culture methods, were higher outdoors than indoors. The median concentrations of airborne fungi were 919 CFUs/m3 outdoors, compared to 260 in the basement and 181 on the main floor. Cladosporium, Alternaria, Aspergillus, Penicillium, Fusarium, Scopulariopsis, Epicoccum, and Trichothecium species were found in the indoor air. Stachybotrys atra was not found in the air, but was present on furnace cooling coils. Stachybotrys atra along with Aspergillus, Penicillium, and Acremonium species were found on the drywall under a sink, behind outer walls, and in carpet swabs. Mycotoxins were present in two source samples. Phenylspirodrimanes, trichothecenes, and sterigmatocystin were detected. The study concluded that signs and symptoms were consistent with exposure to molds spores, fungal fragments, and/or mycotoxins. Most of the mold remained hidden until after the building was evacuated and drywall pieces were removed. The building was demolished in 2004 because of the mold infestation.
305
DISTRIBUTION OF VARIOUS FUNGI REPORTED ON DIFFERENT INDOOR SUBSTRATES.
S. Thiagarajan, P. Fallah, H. Burge, J. Gallup, Environmental Microbiology Lab Inc., San Bruno, CA.
Different indoor substrates tend to support the growth of a variety of fungal populations, depending on nutrient and water requirements. We have analyzed our data set of 76,000 direct microscopic examinations of materials from indoor environments to elucidate the population structures on different types of materials. We grouped substrates into 10 categories as follows: (i) dry wall/wallboard/other paper materials, (ii) asphalt paper, (iii) fiberglass material, (iv) other insulation materials, (v) carpeting material, (vi) wood and wood products, (vii) dust, (viii) soil material, (ix) fabric material, and (x) painted surfaces. For each of these categories, we evaluated the frequency of identification of more than 225 fungal taxa, many of which were reported for the first time from indoor environments. Stachybotrys species was the dominant fungus seen on dry wall (26.8%), wallboard (21.8%) and on other paper materials (22.7%). Cladosporium species were dominant on fiberglass (29.1%), wood (13.4%), painted surfaces (23.9%), and fabrics (15.4%). Acremonium species dominated asphalt paper samples (24.2%). Penicillium and Aspergillus species were most frequent in dust and on carpeting materials. Ascomycetes were most common in soil samples. In general, Cladosporium, Penicillium, Aspergillus, and Stachybotrys species were seen on all indoor substrate types. Few fungi that have not been or are rarely reported from indoor substrates included Microascus, Ascotricha, Monodictys, Engyodontium, Gliomastix, Graphium, Petriella species (all recovered on at least 1% of samples), and others that were less commonly recovered. These data document the different population structures that occupy materials in the indoor environment. Extensions of this study could permit predictions of the types of fungi likely to become abundant following specific water events.
306
RECOVERY OF SURFACE VIABLE MOLD FROM INDOOR ENVIRONMENT USING DIFFERENTIAL
CULTURE MEDIA.
S. Thiagarajan, P. Fallah, S. Dietrich, J. Gallup, Environmental Microbiology Lab Inc., San Bruno, CA.
Surface quantitative fungal culture has many advantages over nonviable direct examination sampling (tape lift and swab). It gives species level identification and enumerates. By using differential media as described below, it further enhances the results of xerophilic and cellulose-loving fungi. In this paper, surface quantitative fungal culture samples analyzed over a period of two years are reported according to their growth on different culture media and sample types. The three different media used were: (i) MEA, (ii) DG-18, and (iii) Cellulose media. Same data was examined according to different sample types that were received: (i) bulk, (ii) dust, and (iii) swab samples. Across the culture media, Stachybotrys species showed highest frequency (24%) in cellulose rich media. MEA showed high frequency of Penicillum species (20.8%), Cladosporium species (20.3%), and yeast (20.2%). By analyzing the data of xerophilic species on DG-18 media, Aspergillus versicolor (moderately xerophilic) showed higher frequency of 25.6%, followed by the extreme xerophilic species like Wallemia (20.1%) and Aspergillus glaucus (19.5%). Comparing the sample types, bulk samples showed high frequency of Penicillum species (24.7%), Stachybotrys species (12.3%) and Cladosporium species (11.0%). Dust sample had high frequency of Cladosporium species (21.3%), Penicillum species (20.8%), and yeast (10.8%), while swab samples showed high frequency of yeast (25.8%), Penicillum species (17.8%), and Cladosporium species (17.1%). Cellulose media was effective in identifying fungal species that grow on cellulosic materials such as drywall, wallboard, and paper material. DG-18 media was effective in projecting xerophilic species, which normally does not grow well in MEA media. MEA continues to be effective broad-spectrum media for fungal growth. The use of this three media can potentially provide a complete picture of surface viable mold in indoor environments.
307
FIELD PERFORMANCE OF THE BI-AIR CASSETTE FOR COLLECTING AIRBORNE MOLD SPORES.
J. Spurgeon, Bayshore Environmental Inc., Placentia, CA.
The field performance of the Bi-Air® cassette has been compared to the Air-O-Cell® cassette for the collection of airborne fungal spores. The Air-O-Cell is useful for collecting grab samples, with sampling times of 5–10 minutes. The Bi-Air cassette, a filter cassette that has been adapted for spore counting, is most useful for sampling times of 10 minutes to six hours, and is shown to be capable of collecting time-weighted average samples. The cassettes were compared based on indoor samples collected over several years. The GM concentrations for Asp/pen spores were 2697 s/m³ for long-term Bi-Air samples and 585 s/m³ for short-term Air-O-Cell samples; a ratio of 4.6. The GM concentrations for Cladosporium spores were 2133 s/m³ for long-term Bi-Air samples and 607 s/m³ for short-term Air-O-Cell samples; a ratio of 3.5. The GM concentration for long-term indoor samples was about four times the GM for short-term samples. In addition, the difference in the GM concentrations was statistically significant based on a comparison of the 95% confidence intervals on the GMs. There was very little difference in the distributions for the Bi-Air and the Air-O-Cell at short sample times, and the difference was not statistically significant. The differences in the performance of the two samplers appeared to be due to the sample time. This result simply confirmed the generally accepted preference for collecting TWA samples whenever possible. The long-term Bi-Air samples also exhibited less variability compared to the short-term Air-O-Cell samples. Sets of three samples each collected with the Air-O-Cell had RSD values of 80 to 150%, while the comparable RSD values for long-term Bi-Air samples collected in the same rooms varied from 20 to 50%. The reduced variability associated with the long-term samples made it easier to discriminate between typical and contaminated environments using smaller sample sizes.
308
POTABLE WATER QUALITY IN AN AGING OFFICE BUILDING.
L. Nguyen Thi, InAIR Environmental Ltd., Ottawa, ON, Canada.
Lead levels in the water distribution system of a large Canadian office building were found to exceed the federally prescribed maximum acceptable level. The main line into the building was tested and found to be acceptable, suggesting a building problem rather than a municipal water supply issue.
The lead problem was initially dealt with by installing reverse osmosis (RO) treatment systems on 23 fountains in the building. Follow-up testing confirmed the lead levels had been reduced to an acceptable level, but found elevated general bacterial levels (HPC count) in all fountains. Despite following the filter manufacturer’s maintenance protocol and replacing all the filters, 21 of 23 fountains remained out of compliance for HPC. This could not be easily resolved and the fountains housing the RO filters were taken out of service.
Facilities management proceeded to install 23 5-gallon water coolers throughout the building. Routine testing on these coolers found elevated HPC levels in most. Establishment of a regular maintenance and documentation program according to Health Canada guidelines for bottled water coolers was recommended. Instead, facilities management removed the coolers and is now distributing water in 500-ml bottles to building occupants.
In this case, a circuitous path eventually led to an acceptable solution resulting in water of acceptable quality delivered to building occupants.
This case study illustrates that care is needed in remediation to avoid replacing one problem with another. Maintenance and monitoring of 5-gallon water coolers and RO filters is important to ensure compliance for bacterial levels. Further investigation may be required to explore the appropriateness of HPC guidelines (< 500 counts per 1 ml in Canada) as they apply to water filters and coolers.
309
SAMPLING DESIGN AS A CHALLENGE IN ENVIRONMENTAL EXPOSURE ASSESSMENT LITIGATIONS.
A. Ibrahim, Environmental and Clinical Research Consulting Group–UCLA Fellowship Graduate 2003, Santa Monica, CA.
Background. Quantification of exposure requires designing an efficient sampling strategy. Sampling strategy is influenced by the objective(s) of the sampling process and the problem being investigated to reach a valid conclusion, especially in studies that involve litigation. Estimate unreliability as a result of convenience sampling usage can have profound effect on decisions. Probability-based sampling of a given population meets the requirements and provides confidence limits needed for accuracy. Non-probability sampling (judgment or convenience) often is potentially misleading, biased, and provides no confidence limits thus less reliable. Purpose. To review, examine, and evaluate sampling design trends in environmental exposure published articles and suggest a sampling design model. Methods. We carried out a systematic retrospective review of articles reporting quantification of environmental exposure between 1993 and 2003. Inclusion criteria. Studies from American Journal of Industrial Medicine, American Industrial Hygiene Association Journal, Archives Environmental Health, and Environmental Research reporting quantifications of environmental exposure using electronic search word environmental exposure. Results. 10/10 (100%) studies reported results based on convenience sampling, and 3/10 (33%) were used for litigation purposes. The proportion of studies omitting justification and discussion of sampling design was 7/10 (70%). Recruitment strategy and sampling strategy were not sufficient to address randomness and homogeneity of population characteristics. Conclusion. Reporting trends reveal inconsistent and insufficient information about elements of sampling design important for scientifically-based decision making. Extrapolation of non-probability-based sampling results should be avoided as it may lead to wrong conclusions. Other efficient sampling designs as cluster sampling, adaptive cluster, or composite sampling should be sought. Environmental researchers should count on sampling professionals or statisticians to perform accurate sampling design.
310
A RETROSPECTIVE CHEMICAL EXPOSURE ASSESSMENT OF BENZENE AND CARBON TETRACHLORIDE
FOR A UNITED STATES NAVAL SHIPYARD.
J. Couch, Westat, Cincinnati, OH; D. Fleming, NIOSH, Cincinnati, OH; A. Herman, Constella Group, Cincinnati, OH.
A retrospective chemical exposure assessment of workers at the Portsmouth Naval Shipyard (PNS) has been completed as part of a multisite case-control study of leukemia mortality and external radiation. A method was developed to assign exposure scores based on year, job title, and shop utilizing an exposure weighting factor: 1, 0.5, 0.1, 0.01, and 0. The weighting factor was assigned for each year, job title, and shop based upon knowledge of work activities, chemical monitoring and inventory data, engineering controls, and personal protective equipment. A work history database was created from shipyard employment records. The 363 original job titles were collapsed into 88 job titles. The 177 PNS subjects were employed at various times between 1917 and 1998, and 80 (45.2%) were classified as solvent exposed for at least one year at PNS. An exposure score was calculated for each year, job title, and shop combination for both benzene and carbon tetrachloride by multiplying the exposure level weighting factor (WF) by the duration (D) in hours per day, and the frequency (F) in days per year, Σ(WF*D*F)job/shop. The average annual exposure score (AAES) for years with a minimum of 10 subjects peaked in 1945 with a combined solvent score of 233. The highest AAES for benzene and carbon tetrachloride occurred in 1945 and 1940, respectively. Cumulative benzene scores were greatest for painters, and cumulative carbon tetrachloride scores were greatest for electricians. The most frequent job titles were pipefitter, electrician, and laborer. The exposure scores, normalized to current occupational limits, will be used to compare the study subjects across the multisite study. Exposure scores are not intended to directly represent actual exposures; they are used to categorically rank the study subjects across the multiple sites.
311
A HISTORICAL CHEMICAL EXPOSURE STRATEGY DEVELOPED TO ANALYZE EXPOSURES OF
LABORATORY WORKERS AT SAVANNAH RIVER SITE.
A. Markey, Westat, Cincinnati, OH.
Chemical exposure scores were developed as part of a cohort mortality epidemiologic study exploring associations among causes of deaths and exposures to external ionizing radiation, internal radiation, and chemicals. Historical chemical exposure strategies were developed for chemical laboratory workers (CLWs) employed between 1951 and 1974 at the Savannah River Site to determine relative levels of chemical exposure, and to classify the exposure into two chemical categories. Work histories were compiled using available information from medical and personnel records. The 1143 study subjects had 85 unique CLW job titles which were collapsed into 12 chemical laboratory job titles with the most frequent being chemist, chemical engineer, and lab supervisor. The exposure assessment strategy involved calculation of chemical exposure scores for CLWs using number of days employed along with weighting factors for collapsed job title and decade. Job title weighting factors of 0.01, 0.006, 0.003, and 0.0005 were based on evaluation of the frequency of hands-on activities with chemicals. Decade weighting factors of 3, 2.5, 2, and 1 were developed through a comprehensive review of process descriptions, chemical inventories, and limited industrial hygiene monitoring data and the decreases reflect improvements in laboratory technique, instrumentation, engineering controls, and increased safety awareness through time. Exposures were classified into two categories based on department function and chemical utilization: (1) primarily inorganic, or (2) probable organic. Individual chemical exposure scores along with categories of exposure will be used in risk models for the epidemiologic study. The chemical exposure score provides a tool for ranking subjects’ potential for exposure; it is not intended to provide actual exposure estimates for study subjects.
312
DEVELOPMENT AND VALIDATION OF AIR SAMPLING METHODS FOR THE PHARMACEUTICAL
INDUSTRY: THE NEED FOR A STANDARDIZED PROCEDURE.
M. Hsieh, S. Martens, M. Puskar, Abbott Laboratories, North Chicago, IL.
Effective employee protection in the pharmaceutical workplace is reliant on sound industrial hygiene and engineering decisions and the basis for sound decisions is accurate sampling data. However, accurate sampling data can only be generated using a well-validated sampling and analytical method. To date there is no universally accepted protocol for the development and validation of air sampling methods for the pharmaceutical industry. Due to the substantial differences in current method validation practices, sampling data can vary considerably depending on which lab’s “validated method” is used for analysis. In a current study, a survey concerning method development procedures was conducted among six labs that participate in the Pharmaceutical Round Robin Proficiency Testing Program. The survey focused on method validation topics, including: validation range, sample extraction, sample extract stability and evaluation of air sensitivity, storage stability, and field sampling. Survey results showed that the typical method validation range spanned from 0.0005 times the occupational exposure limit (OEL) to 16 times the OEL. Although five of the six labs surveyed employed in-cassette extraction, only four of the labs evaluated extract stability, for study times varying from one to five days. Although all six labs performed air sensitivity and storage stability studies, the procedures varied significantly in the concentration level, storage conditions, and storage times studied. Only two of the six labs performed field evaluations to assess the validity of the sampling method under field conditions. Based on actual method development data, there is solid evidence to support the importance of in-cassette extraction and the need to thoroughly evaluate sample and extract stability. Data suggests that failure to thoroughly validate a sampling method can lead to significant negative bias in sampling data. The noted method validation inconsistencies warrant efforts to develop a pharmaceutical air sampling protocol that is universally accepted.
313
QUANTITATIVE AND QUALITATIVE ASSESSMENT OF ROOM CLEANLINESS POST SPILL CLEAN UP
USING CLEANING TECHNIQUES USED FOR HIGHLY POTENT PHARMACEUTICALS.
M. Coggins, T. Dennis, M. Byrne, National University of Ireland–Galway, Galway, Ireland; B. Ward, S. Shope, Eli Lilly, Tippecanoe Laboratories, Lafayette,, IN.
The risk assessment of potential exposures from particulates with low OELs often requires analytical air monitoring which is both time consuming and costly.
The study aim was to determine the effectiveness of internally developed spill cleaning procedures to adequately reduce surface and airborne residues to acceptable low concentrations such that analytical confirmation testing would not necessarily be required. A number of controlled “non-visible” and “visible” spill scenarios were created using a placebo material, milled lactose monohydrate. Particulate dispersion methodologies were developed to reproducibly contaminate room surfaces to a non-visible surface loading of 1–4 µg/cm2, as measured by Petri settling plate analytical analysis. Visible spill scenarios included the particulate dispersion with additional prescribed liquid slurry spills. Trained personnel cleaned the rooms using fog/misting and repeated deluge rinsing internally developed procedures. Cleaning effectiveness was quantified by analysis of both surface swab and aggressive air monitoring samples. A qualitative evaluation of the efficiency of both cleaning methods was also completed using a fluorescent tracer dye.
Similar conclusions were observed from both the qualitative and the quantitative study, demonstrating comparable surface cleaning efficiencies for both procedural techniques, with 104 to 105 reductions from pre-contamination levels.
Horizontal surfaces proved more difficult to clean than vertical surfaces and had significantly more variability in results and lower efficiencies. Variability in cleaning efficiencies appeared lower when operators were presented with a visible spill versus a non-visible trace release. The study highlighted the importance of developing improved methods for horizontal surface cleaning and the need to consider analytical data for the cleaning confirmation for highly potent particulates with low OELs. The study also demonstrated the effectiveness of low-cost fluorescent dyes in evaluating cleaning effectiveness for water-soluble chemicals.
314
INDUSTRIAL HYGIENE FIELD SITE PERSONAL MONITORING TO DOCUMENT OCCUPATIONAL
EXPOSURES TO CRYSTALLINE SILICA DURING CONCRETE CUTTING WORK.
J. Koehn, S. Coleman, Ian Koehn, M.S., CIH Inc., Houston, TX.
During 2004, a workplace exposure assessment project was specifically undertaken addressing various concrete cutting and sawing operations. Based on a recent OSHA Special Emphasis Program for crystalline silica, the goal of a developed task force was to submit representative personal air monitoring data. An in-depth workplace exposure assessment was conducted for separate company job positions. Full work shift breathing zone monitoring in accordance with NIOSH Methods 0600 and 7500 was completed during July through September for each type of concrete work operations: wall saw, wire saw, slab saw, core drilling, hand saw, and backhoe for load and haul. Extensive site documentation regarding project type, purpose, trade/job, tasks, tools, control measures, ventilation, dust levels, description of work environment, sampling criteria, weather conditions, and PPE were specifically noted.
Personal occupational exposures were recorded below the current PELs for respirable dust and three forms of crystalline silica for this monitoring project. A certified industrial hygienist performed all monitoring work, direct observations, and documentation of job work tasks. The project sampling strategy was implemented at each field site and all personal samples were analyzed by a local AIHA-accredited laboratory. Digital photographs were documented of the job field-site work activities. Available control measures were appropriately utilized by concrete-cutting personnel including water on tool or saw blade, shroud on tool, isolation, and remote control saw operation.
A final project report was prepared summarizing all the laboratory analytical data and the pertinent workplace exposure assessment information. Separate personal exposure data was reported along with a chronology of the full day shift-work activities for each job site location.
315
A METHODOLOGICAL ASPECT WHEN SAMPLING AND ANALYSING FOR HYDROCHLORIC ACID AT
PICKLING BATHS.
J. Karlsson, C. Gustavsson, Department of Occupational and Environmental Medicine, Lund, Sweden; A. Blomqvist, A. Karlsson, Department of Occupational and Environmental Medicine, Halmstad, Sweden.
Aim. To investigate exposure in a study of airway symptoms and dental erosions. Subjects. Three metal finishing plants (one hot dip galvanizing, two nickel/chromium-plating) with 26 workers. These workers were compared with 38 age-matched nonexposed persons manufacturing tools in a mechanical workshop. Methods. Technical examination through air sampling of acid vapour/mist on absorbent tubes containing washed silica gel and a glass fiber filter plug (for mist). In addition, particulate chloride, ammonium, and zinc were captured on mixed cellulose ester filters. Most of the samples were taken in the breathing zone using personal equipment. They were analysed using ion chromatography, inductive coupled plasma mass spectrometry, and FIA. Medical and odontological examination including a questionnaire about working conditions, symptoms, smoking habits and diet, spirometry, and occurrence of dental erosion. This presentation concentrates on the result of the air measurements and methodological questions. Results. The concentration of hydrochloric acid in the air around the pickling bath at the hot dip galvanization plant did not exceed 1 mg/m³ as an average value for a whole working day. The Swedish TLV, which is a ceiling value, is 8 mg/m³. More than 50% of the acid was collected as mist, which was an unexpected finding as one normally talks about hydrochloric acid vapour. The other two plants, which were more automatized, used sulphuric acid and the concentration in air was very low, 1/20 of the TLV. At the galvanization plant the exposure to zinc chloride at the zinc kettle was rather high and equivalent to half of the Swedish TLV. Conclusion. It is crucial to analyse the glass fiber filter plug in the silica gel tube also for hydrochloric acid despite its low boiling point. The impact of stirring of the pickling bath and condensation because of high air humidity needs to be further investigated.
Posted May 30, 2005