Annals of Occupational Hygiene - current issue

Exposure Assessment of Workers to Airborne PCDD/Fs, PCBs and PAHs at an Electric Arc Furnace Steelmaking Plant in the UK

Aries, E., Anderson, D. R., Fisher, R. — 2008-06-05

Occupational exposure studies were undertaken at a UK electric arc furnace (EAF) steelmaking plant to investigate the exposure of workers via inhalation to dioxins, polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) including benzo[a]pyrene (B[a]P). Surveys were undertaken in areas including the melting shop, the casting department and a furnace control cabin. The highest concentrations of dioxins and PCBs were found inside the melting shop nearby EAFs, whereas dioxin and PCB concentrations in the casting department and inside the control cabin were significantly lower. Risk characterization was carried out by comparing the daily intake of dioxins and PCBs through inhalation with the recommended tolerable daily intake (TDI). Health risk assessments were also carried out by combining exposure data with inhalation cancer potency factors to quantify the cancer risk. For the most exposed category of workers (melting shop workers), the estimated daily intake via inhalation was 0.35 pg WHO-TEQ kg^–1 body weight (bw) in the worst case scenario. Considering that the average UK adult exposure to dioxins from the diet is 1.8 pg WHO-TEQ kg^–1 bw day^–1, the results indicated that the estimated daily intake of dioxins via inhalation at the EAF would not result in the recommended range of the TDI (1–4 pg WHO-TEQ kg^–1 bw day^–1) being exceeded. Cancer risks for a 40-year occupational exposure period were determined by multiplying the inhalation dose by the inhalation cancer potency factor for 2,3,7,8-tetrachlorodibenzo-p-dioxin. For melting shop workers, cancer risks from exposure to dioxins and PCBs ranged from 2.05 x 10^–5 to 7.54 x 10^–5. Under most regulatory programmes, excess cancer risks between 1.0 x 10^–4 and 1.0 x 10^–6 indicate an acceptable range of excess cancer risk, suggesting a limited risk from dioxin exposure for workers in the EAF plant. For the calculation of excess cancer risks, no account has been taken of the protection provided by protective respiratory equipment worn by EAF workers. If personal protective equipments were taken into consideration, it is likely that the excess cancer risks for EAF workers would have been lower and considered as negligible. The highest concentrations of PAHs were found in the melting shop and the casting areas of the plant. In the melting shop area, B[a]P concentrations ranged from 1.4 to 24.5 ng m^–3, with a mean value of 7 ng m^–3. No workplace exposure limits have been published by the Health and Safety Executive in the UK for PAHs; however, the B[a]P concentrations found were below the limit value of 150 ng m^–3 (8-h time-weighted average) specified for workplace exposure in France. Exposure assessment of workers to PAHs via inhalation was carried out by calculating a potential cancer risk considering a 40-year occupational exposure period and B[a]Peq concentrations. Estimated cancer risks for the most exposed category of workers (i.e. melting shop workers) ranged from 3.66 x 10^–6 to 1.64 x 10^–5. The cancer risks determined in this study were well within an acceptable range of excess cancer risk of 1.0 x 10^–4 to 1.0 x 10^–6, specified by the US Environmental Protection Agency.

Determinants of Wood Dust Exposure in the Danish Furniture Industry--Results from Two Cross-Sectional Studies 6 Years Apart

2008-06-05

Objectives: This paper investigates determinants of wood dust exposure and trends in dust level in the furniture industry of Viborg County, Denmark, using data from two cross-sectional studies 6 years apart.

Methods: During the winter 1997/1998, 54 factories were visited (hereafter study 1). In the winter 2003/2004, 27 factories were revisited, and personal dust measurements were repeated. In addition, 14 new factories were included (hereafter study 2). A total of 2303 woodworkers participated in study 1, and 2358 measurements from 1702 workers were available. From study 2, 1581 woodworkers participated and 1355 measurements from 1044 workers were available. Information on occupational variables describing potential determinants of exposures like work task, exhaust ventilation, enclosure and cleaning procedures were collected. A total of 2627 measurements and 1907 persons were included in the final mixed model in order to explore determinants of exposure and trends in dust level.

Results: The overall inhalable wood dust concentration (geometric means (geometric standard deviation)) has decreased from 0.95 mg/m³ (2.05) in study 1 to 0.60 mg/m³ (1.63) in study 2, representing a 7% annual decrease in dust concentration, which was confirmed in the mixed model. From study 1 to study 2 there has been a change towards less manual work and more efficient cleaning methods, but on the contrary also more inadequate exhaust ventilation systems. The following determinants were found to ‘increase’ dust concentration: sanding; use of compressed air; use of full-automatic machines; manual work; cleaning of work pieces with compressed air; kitchen producing factories and small factories (<20 employees). The following determinants of exposure were found to ‘decrease’ dust concentration: manual assembling/packing; sanding with adequate exhaust ventilation; adequate exhaust ventilation; vacuum cleaning of machines and special cleaning staff.

Conclusions: Despite a substantial drop in the dust concentration during the last 6 years in the furniture industry in Viborg County, further improvements are possible. There should be more focus on improved exhaust ventilation, professional cleaning methods and avoiding use of compressed air.

GABIE and Perkin Elmer Passive Sampler Performance under Fluctuating Concentration Conditions

Langlois, E. — 2008-06-05

Passive sampling is an approved and accurate method for the assessment of organic compound exposure over long sampling time. This method could be very convenient for the short-time exposure assessment, but passive samplers have to be validated for this use. In this article, the behaviour of two commercial passive samplers (GABIE and Perkin Elmer) under fluctuant concentration conditions is studied. Artificial atmospheres were produced in the laboratory and passive samplers were exposed to different concentration profiles. Both theoretical and experimental results detailed in the paper underline the capability of these two samplers to assess pollutant exposure either when the concentration is unsteady or when the sampling time is short. Then, a suitable sampling strategy is proposed for the assessment of short-term exposure, based on the association of a direct reading photoionization device and passive sampler.

Diffusive Sampling of C7-C16 Hydrocarbons in Workplace Air: Uptake Rates, Wall Effects and Use in Oil Mist Measurements

Simpson, A. T., Wright, M. D. — 2008-06-05

The measurement of semi-volatile hydrocarbons in workplace air is complicated by their readiness to condense to form aerosols or adsorb on to surfaces. The diffusive sampling and analysis by thermal desorption of alkanes up to hexadecane was investigated with the aim of quantifying vapour from petroleum distillate fractions and possibly differentiating particles from vapour in oil mist measurements of light mineral oil-based metalworking fluids. Diffusive uptake rates were measured on Perkin Elmer thermal desorption tube samplers packed with Tenax TA, and the potential for deposition within the tubes was examined. Hydrocarbon vapour was found to adsorb on the oxide layer that can develop on the sampler's internal walls. General measurements of mixed hydrocarbon vapours (i.e. petroleum distillate fractions) should not be unduly affected if concentrations are greater than ~5 mg m^–3 and the tubes are in good condition. For the purposes of differentiating light mineral oil mist and vapour from a total hydrocarbon measurement, it is unlikely that measuring the vapour separately could be used to calculate mist concentrations <3 mg m^–3 with sufficient accuracy.

Hazardous Off-Gassing of Carbon Monoxide and Oxygen Depletion during Ocean Transportation of Wood Pellets

Svedberg, U., Samuelsson, J., Melin, S. — 2008-06-05

Five ocean vessels were investigated for the characterization and quantification of gaseous compounds emitted during ocean transportation of wood pellets in closed cargo hatches from Canada to Sweden. The study was initiated after a fatal accident with several injured during discharge in Sweden. The objective with the investigation was to better understand the off-gassing and issues related to workers' exposure. Air sampling was done during transport and immediately before discharge in the undisturbed headspace air above the wood pellets and in the staircase adjacent to each hatch. The samples were analyzed with Fourier transform infrared spectroscopy and direct reading instruments. The following compounds and ranges were detected in samples from the five ships: carbon monoxide (CO) 1460–14650 ppm, carbon dioxide (CO₂) 2960–21570 ppm, methane 79.9–956 ppm, butane equivalents 63–842 ppm, ethylene 2–21.2 ppm, propylene 5.3–36 ppm, ethane 0–25 ppm and aldehydes 2.3–35 ppm. The oxygen levels were between 0.8 and 16.9%. The concentrations in the staircases were almost as high as in the cargo hatches, indicating a fairly free passage of air between the two spaces. A potentially dangerous atmosphere was reached within a week from loading. The conclusions are that ocean transportation of wood pellets in confined spaces may produce an oxygen deficient atmosphere and lethal levels of CO which may leak into adjacent access spaces. The dangerous combination of extremely high levels of CO and reduced oxygen produces a fast-acting toxic combination. Measurement of CO in combination with oxygen is essential prior to entry in spaces having air communication with cargo hatches of wood pellets. Forced ventilation of staircases prior to entry is necessary. Redesign, locking and labeling of access doors and the establishment of rigorous entry procedures and training of onboard crew as well as personnel boarding ocean vessels are also important.

Airborne Concentrations of Asbestos Onboard Maritime Shipping Vessels (1978-1992)

2008-06-05

The exposure of shipyard workers to asbestos has been frequently investigated during the installation, repair or removal of asbestos insulation. The same level of attention, however, has not been directed to asbestos exposure of maritime seamen or sailors. In this paper, we assemble and analyze historical industrial hygiene (IH) data quantifying airborne asbestos concentrations onboard maritime shipping vessels between 1978 and 1992. Air monitoring and bulk sampling data were compiled from 52 IH surveys conducted on 84 different vessels, including oil tankers and cargo vessels, that were docked and/or at sea, but these were not collected during times when there was interaction with asbestos-containing materials (ACMs). One thousand and eighteen area air samples, 20 personal air samples and 24 air samples of unknown origin were analyzed by phase contrast microscopy (PCM); 19 area samples and six samples of unknown origin were analyzed by transmission electron microscopy (TEM) and 13 area air samples were analyzed by scanning electron microscopy (SEM). In addition, 482 bulk samples were collected from suspected ACMs, including insulation, ceiling panels, floor tiles, valve packing and gaskets. Fifty-three percent of all PCM and 4% of all TEM samples were above their respective detection limits. The average airborne concentration for the PCM area samples (n = 1018) was 0.008 fibers per cubic centimeter (f cc^–1) (95th percentile of 0.040 f cc^–1). Air concentrations in the living and recreational areas of the vessels (e.g. crew quarters, common rooms) averaged 0.004 f cc^–1 (95th percentile of 0.014 f cc^–1), while air concentrations in the engine rooms and machine shops averaged 0.010 f cc^–1 (95th percentile of 0.068 f cc^–1). Airborne asbestos concentrations were also classified by vessel type (cargo, tanker or Great Lakes), transport status (docked or underway on active voyage) and confirmed presence of ACM. Approximately 1.3 and 0% of the 1018 area samples analyzed by PCM exceeded 0.1 and 1 f cc^–1, respectively. This data set indicates that historic airborne asbestos concentrations on these maritime shipping vessels, when insulation–handling activities were not actively being performed, were consistently below contemporaneous US occupational standards from 1978 until 1992, and nearly always below the current permissible exposure limit of 0.1 f cc^–1.

Sharps Injuries in Healthcare Waste Handlers

Blenkharn, J. I., Odd, C. — 2008-06-05

Clinical waste disposal carries with it a risk of serious and possibly life-threatening infection. Combining confidential questionnaires and structured interviews with discrete observation, the attitudes and approach to safe handling of bulk clinical wastes by staff in a specialist waste treatment facility were assessed. With particular attention to glove use and hand hygiene, observations were supplemented by review of group-wide accident and incident records, with emphasis on sharps injuries and related blood and bloodstained body fluid exposures. Deficiencies in glove selection and use, and in hand hygiene, were noted despite extensive and on-going training and supervision of waste handlers. Though ballistic puncture-resistant gloves protect against sharps injury, these were uncomfortable in use and were sometimes rejected by waste handlers who preferred thin-walled nitrile gloves that were more comfortable in use though provide no resistance to penetrating injury. Among the waste handlers working for a single specialist waste disposal company, sharps injuries (n = 40) occurred at a rate of approximately 1 per 29 000 man hours. Injuries were caused by hypodermic needles from improperly closed or overfilled sharps boxes (n = 6) or from sharps incorrectly discarded into thin-walled plastic sacks intended only for soft wastes (n = 34). Most injuries occurred to the fingers or hands. No seroconversions occurred, though two individuals suffered anxiety/stress disorder necessitating prolonged leave of absence with professional counselling and support. Glove use and hand hygiene must feature prominently in the on-going training of waste handlers. Though ballistic gloves afford protection against sharps injury, the initial segregation and safe disposal of clinical wastes by healthcare professionals must provide the primary control measure. Despite robust and unambiguous legislation and good practice guidelines, serious errors by healthcare staff that result in the disposal of hypodermic needles and other sharps to thin-walled plastic waste sacks places waste handlers at risk of bloodborne virus infection. Further improvement in the standards of waste segregation and disposal by healthcare professionals are still required to protect ancillary and support staff and waste handlers working in the disposal sector.

Performance of Laboratories Analysing Welding Fume on Filter Samples: Results from the WASP Proficiency Testing Scheme

Stacey, P., Butler, O. — 2008-06-05

This paper emphasizes the need for occupational hygiene professionals to require evidence of the quality of welding fume data from analytical laboratories. The measurement of metals in welding fume using atomic spectrometric techniques is a complex analysis often requiring specialist digestion procedures. The results from a trial programme testing the proficiency of laboratories in the Workplace Analysis Scheme for Proficiency (WASP) to measure potentially harmful metals in several different types of welding fume showed that most laboratories underestimated the mass of analyte on the filters. The average recovery was 70–80% of the target value and >20% of reported recoveries for some of the more difficult welding fume matrices were <50%. This level of under-reporting has significant implications for any health or hygiene studies of the exposure of welders to toxic metals for the types of fumes included in this study. Good laboratories' performance measuring spiked WASP filter samples containing soluble metal salts did not guarantee good performance when measuring the more complex welding fume trial filter samples. Consistent rather than erratic error predominated, suggesting that the main analytical factor contributing to the differences between the target values and results was the effectiveness of the sample preparation procedures used by participating laboratories. It is concluded that, with practice and regular participation in WASP, performance can improve over time.