Reduction in welding fume and metal exposure of stainless steel welders: an example from the WELDOX study

Purpose

In a plant where flux-cored arc welding was applied to stainless steel, we investigated changes in airborne and internal metal exposure following improvements of exhaust ventilation and respiratory protection.

Methods

Twelve welders were examined at a time in 2008 and in 2011 after improving health protection. Seven welders were enrolled in both surveys. Exposure measurement was performed by personal sampling of respirable welding fume inside the welding helmets during one work shift. Urine and blood samples were taken after the shift. Chromium (Cr), nickel (Ni), and manganese (Mn) were determined in air and biological samples.

Results

The geometric mean of respirable particles could be reduced from 4.1 mg/m³ in 2008–0.5 mg/m³ in 2011. Exposure to airborne metal compounds was also strongly reduced (Mn: 399 vs. 6.8 μg/m³; Cr: 187 vs. 6.3 μg/m³; Ni: 76 vs. 2.8 μg/m³), with the most striking reduction inside helmets with purified air supply. Area sampling revealed several concentrations above established or proposed exposure limits. Urinary metal concentrations were also reduced, but to a lesser extent (Cr: 14.8 vs. 4.5 μg/L; Ni: 7.9 vs. 3.1 μg/L). Although biologically regulated, the mean Mn concentration in blood declined from 12.8 to 8.9 μg/L.

Conclusion

This intervention study demonstrated a distinct reduction in the exposure of welders using improved exhaust ventilation and welding helmets with purified air supply in the daily routine. Data from area sampling and biomonitoring indicated that the area background level may add considerably to the internal exposure.     

Comparison of urinary concentrations of 3-phenoxybenzoic acid among general residents in rural and suburban areas and employees of pest control firms

Objectives

The purpose of this study is to determine the levels of urinary 3-phenoxybenzoic acid (3-PBA) among general populations in rural and suburban areas and employees of pest control firms to evaluate the differences in the level of environmental or occupational pyrethroid (PYR) pesticides to which those populations are exposed.

Methods

Spot urine specimens were collected from male residents in a rural area (n = 143) and male residents in a suburban area (n = 66) in August of 2005 and 2007, respectively. Male employees of pest control firms, who also provided their urine specimens at the time of a health-checkup in August 2007, were classified either as sprayers (n = 14) or as non-sprayers (n = 16) according to the presence of spraying during the pre-checkup week. Urinary concentrations of 3-PBA were determined using gas chromatography–mass spectrometry and corrected for the urinary creatinine concentrations. An analysis of covariance was used to examine the statistical difference in 3-PBA concentrations between these four groups after adjustment for age, body mass index, and current smoking/drinking habits.

Results

Multiple comparisons indicated no differences in adjusted 3-PBA concentrations between the groups of general residents from the rural areas (0.33 μg/g cre in geometric mean) and suburban area (0.51 μg/g cre). The group of sprayers showed a much higher level of 3-PBA concentrations (25.0 μg/g cre) than the other three groups. A statistically significant difference, though to a lesser extent, was also exhibited in 3-PBA concentrations between the group of non-sprayers (5.6 μg/g cre) and that of general residents.

Conclusions

The results indicated that the levels of background low-dose exposure to PYRs are not likely to differ evidently among general populations according to the area of residence. Moreover, employees of pest control firms, who have been away from PYR spraying operations for a week or more, still retain much higher urinary 3-PBA concentrations than general populations.     

Occupational exposure to airborne mercury during gold mining operations near El Callao, Venezuela

Objective: The National Institute for Occupational Safety and Health (NIOSH) recently conducted a cross–sectional study during gold mining operations near El Callao, Venezuela. The purpose of the study was to assess mercury exposures and mercury-related microdamage to the kidneys. The study consisted of concurrent occupational hygiene and biological monitoring, and an examination of the processing techniques employed at the different mining facilities. Mercury was used in these facilities to remove gold by forming a mercury-gold amalgam. The gold was purified either by heating the amalgam in the open with a propane torch or by using a small retort. Methods: Thirty-eight workers participated in this study. Some participants were employed by a large mining company, while others were considered “informal miners” (self-employed). Mercury exposure was monitored by sampling air from the workers' breathing zones. These full-shift air samples were used to calculate time-weighted average (TWA) mercury exposure concentrations. A questionnaire was administered and a spot urine sample was collected. Each urine sample was analyzed for mercury, creatinine, and N-acetyl-ß-d-glucosaminidase (NAG). Results: The range for the 8-h TWA airborne mercury exposure concentrations was 0.1 to 6,315?μg/m³, with a mean of 183?μg/m³. Twenty percent of the TWA airborne mercury exposure measurements were above the NIOSH recommended exposure limit (REL) of 50?μg/m³, and 26% exceeded the American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value (TLV) of 25?μg/m³. The mean urine mercury concentration was 101?μg/g creatinine (μg/g-Cr), and the data ranged from 2.5 to 912?μg/g-Cr. Forty–two percent of the study participants had urine mercury concentrations that exceeded the ACGIH biological exposure index (BEI) of 35?μg/g-Cr. Urinary NAG excretion is considered a biological marker of preclinical, nonspecific microdamage to the kidney's proximal tubule cells. The mean urine NAG concentration was 3.6 International Units/g-Cr (IU/g-Cr) with a range of 0.5 to 11.5?IU/g-Cr. Three workers had urine NAG levels in excess of the reference values. Correlation analyses found statistically significant correlations between airborne mercury exposure and urine mercury level (P=0.01), and between urine mercury level and urine NAG excretion (P=0.01). In addition, the airborne mercury exposure data and urine mercury data were segregated by job tasks. A Wilcoxon rank sum test revealed significant correlations between tasks and mercury exposure (P=0.03), and between tasks and urine mercury level (P=0.02). Conclusions: The tasks with the highest mean airborne mercury exposures were “burning the mercury-gold amalgam” and “gold refining/smelting”. Recommendations were provided for improving the retort design to better contain mercury, for ventilation in the gold shops, and for medical surveillance and educational programs.     

Accidental exposure to polychlorinated biphenyls (PCB) in waste cargo after heavy seas. Global waste transport as a source of PCB exposure

Objectives

After cargo with PCB-containing transformer oil waste was damaged in heavy seas, the vessel crew exposed to PCB developed itching and acne-form eruption of the skin. The objective of our study was to analyse this work-related incident and its effects on health.

Methods

Air and wipe test samples were taken in the ship for analysis of PCB (28/52/101/138/153/180); clinical investigations of all seafarers (n = 6) included lung function, chest X-ray, clinical chemistry and biomonitoring (plasma PCBs, chlorophenols in urine) measured after a latency of 7 weeks. The biomonitoring data were adjusted according to age-related reference values and validated against controls (n = 96).

Results

Biomonitoring showed elevated PCB-28-/52/-102/-138 congeners (mean 1.16/0.91/136, ∑PCB: 5.82 μg/l), which correlates with the dust samples from the cargo hold (∑PCB. 9,440 mg/m²) and with 6.1 and 5.0 μg/m³ in stern and bow cargo air samples. IgE elevation in two seafarers and substantial blood sedimentation rate increase with anaemia or pulmonary emphysema were unlikely to be caused by PCB exposure. Although two members showed slightly elevated airway resistance values, other lung function parameters were normal and reactive airways dysfunction syndrome due to PCBs could be excluded. Elevated chlorophenols in urine could contribute to the manifestation of chloracne.

Conclusions

PCB-52/-101/-138 found in plasma and in air samples confirm exposure to PCB. Acne-form skin eruptions were from occupational exposure to polychlorinated biphenyls in the spilt transformer oil. There were no other abnormal findings in medical and clinical examinations that could be attributed to PCBs. This does not exclude possible long-term effects.     

Systematic review and quantification of respiratory cancer risk for occupational exposure to hexavalent chromium

Aim

To investigate the exposure-risk relationship for occupational chromium (VI) exposure and lung cancer in order to establish exposure limits.

Methods

We systematically searched for studies reporting on occupational Cr(VI) exposure and cancers of the respiratory tract. To be included, studies needed to provide data for more than one level of occupational Cr(VI) exposure, adequately consider the confounder smoking and be of adequate methodological quality. Because direct genotoxicity was considered the predominant mechanism of carcinogenesis of Cr(VI), linear models were applied in order to fit risk data. Relative risks were calculated based on these linear regression models and then used to estimate excess absolute risks.

Results

Five studies of two cohorts of chromium production workers in Baltimore, Maryland, and Painesville, Ohio, were included. Based on different estimates for the exposure effect, the absolute excess risk was found to be “acceptable” (less than 4 per 10,000 according to the German Committee on Hazardous Substances, “AGS”) at a Cr(VI) concentration of 0.1 μg/m³, and became “intolerable” (more than 4 per 1,000) beyond a Cr(VI) concentration of 1 μg/m³.

Conclusion

Occupational exposure limits for Cr(VI) based on excess absolute risks can be derived from published data identified by a systematic literature review.     

Hexavalent chromium and isocyanate exposures during military aircraft painting under crossflow ventilation

Exposure control systems performance was investigated in an aircraft painting hangar. The ability of the ventilation system and respiratory protection program to limit worker exposures was examined through air sampling during painting of F/A-18C/D strike fighter aircraft, in four field surveys. Air velocities were measured across the supply filter, exhaust filter, and hangar midplane under crossflow ventilation. Air sampling conducted during painting process phases (wipe-down, primer spraying, and topcoat spraying) encompassed volatile organic compounds, total particulate matter, Cr[VI], metals, nitroethane, and hexamethylene diisocyanate, for two worker groups: sprayers and sprayer helpers (“hosemen”). One of six methyl ethyl ketone and two of six methyl isobutyl ketone samples exceeded the short term exposure limits of 300 and 75 ppm, with means 57 ppm and 63 ppm, respectively. All 12 Cr[VI] 8-hr time-weighted averages exceeded the recommended exposure limit of 1 µg/m³, 11 out of 12 exceeded the permissible exposure limit of 5 µg/m³, and 7 out of 12 exceeded the threshold limit value of 10 µg/m³, with means 38 µg/m³ for sprayers and 8.3 µg/m³ for hosemen. Hexamethylene diisocyanate means were 5.95 µg/m3 for sprayers and 0.645 µg/m³ for hosemen. Total reactive isocyanate group—the total of monomer and oligomer as NCO group mass—showed 6 of 15 personal samples exceeded the United Kingdom Health and Safety Executive workplace exposure limit of 20 µg/m³, with means 50.9 µg/m³ for sprayers and 7.29 µg/m³ for hosemen. Several exposure limits were exceeded, reinforcing continued use of personal protective equipment. The supply rate, 94.4 m³/s (200,000 cfm), produced a velocity of 8.58 m/s (157 fpm) at the supply filter, while the exhaust rate, 68.7 m³/s (146,000 cfm), drew 1.34 m/s (264 fpm) at the exhaust filter. Midway between supply and exhaust locations, the velocity was 0.528 m/s (104 fpm). Supply rate exceeding exhaust rate created re-circulations, turbulence, and fugitive emissions, while wasting energy. Smoke releases showing more effective ventilation here than in other aircraft painting facilities carries technical feasibility relevance.     

Exposure to respirable dust and manganese and prevalence of airways symptoms,among Swedish mild steel welders in the manufacturing industry

Purpose

Welding fume consists of metal fumes, e.g., manganese (Mn) and gases, e.g., ozone. Particles in the respirable dust (RD) size range dominate. Exposure to welding fume could cause short- and long-term respiratory effects. The prevalence of work-related symptoms among mild steel welders was studied, and the occupational exposure to welding fumes was quantified by repeated measurements of RD, respirable Mn, and ozone. Also the variance components were studied.

Method

A questionnaire concerning airway symptoms and occupational history was answered by 79 % of a cohort of 484 welders. A group of welders (N = 108) were selected and surveyed by personal exposure measurements of RD and ozone three times during 1 year.

Results

The welders had a high frequency of work-related symptoms, e.g., stuffy nose (33 %), ocular symptoms (28 %), and dry cough (24 %). The geometric mean exposure to RD and respirable Mn was 1.3 mg/m³ (min–max 0.1–38.3 mg/m³) and 0.08 mg/m³ (min–max <0.01–2.13 mg/m³), respectively. More than 50 % of the Mn concentrations exceeded the Swedish occupational exposure limit (OEL). Mainly, low concentrations of ozone were measured, but 2 % of the samples exceeded the OEL. Of the total variance for RD, 30 and 33 % can be attributed to within-worker variability and between-company variability, respectively.

Conclusions

Welders had a high prevalence of work-related symptom from the airways and eyes. The welders’ exposure to Mn was unacceptably high. To reduce the exposure further, control measures in the welding workshops are needed. Correct use of general mechanical ventilation and local exhaust ventilation can, for example, efficiently reduce the exposure.     

Exposure assessment using human biomonitoring for glyphosate and fluroxypyr users in amenity horticulture

Background

Pesticides and their potential adverse health effects are of great concern and there is a dearth of knowledge regarding occupational exposure to pesticides among amenity horticulturalists.

Lifetime exposure to arsenic in residential drinking water in Central Europe

Objective

Methods and results are presented for an arsenic exposure assessment integral to an epidemiological case–control study of arsenic and cancer—the European Commission funded ASHRAM (Arsenic Health Risk Assessment and Molecular Epidemiology) study carried out in some counties of Hungary, Romania and Slovakia.

Methods

The exposure history of each participant (N = 1,392) was constructed by taking into account how much water they consumed (as water, in drinks and in food), sources of drinking water in their various residences over their lifetime, and the concentrations of arsenic in their various water supplies measured by Hydride Generation-Atomic Absorption Spectrometry (HG-AAS). Concentrations of arsenic in previous water supplies were either derived from contemporary analyses of the same source, or from routine historical data from measurements performed by the authorities in each country. Using this approach, 80% of the recorded lifetime residential history was matched to an arsenic concentration. Seven indices of current, life time, and peak exposure were calculated.

Results

The exposure indices were all log-normally distributed and the mean and median lifetime average concentrations were in Hungary 14.7 and 13.3 μg l^?1, Romania 3.8 and 0.7 μg l^?1 and in Slovakia 1.9 and 0.8 μg l^?1, respectively. Overall 25% of the population had average concentrations over 10 μg l^?1 and 8% with exposure over 50 μg l^?1.

Conclusions

Careful assessment of arsenic in drinking water supplies (both current and previous) enabled the majority of study participants’ cumulative lifetime of potential exposure to arsenic in residential water to be characterised.     

Lead Exposure and Blood Pressure among Workers in Diverse Industrial Plants in Kenya

The study evaluated airborne exposures and blood lead (BPb) levels in 233 production workers at six diverse industrial plants in Kenya. Blood and personal breathing zone air samples were collected and analyzed for lead (Pb) using atomic absorption spectroscopy. Blood pressure (BP) levels were measured using a standard mercury sphygmomanometer. The results indicated mean airborne Pb levels ± standard deviation (SD) as follows: 183.2 ± 53.6 μg/m³ in battery recycling, 133.5 ± 39.6 μg/m³ in battery manufacturing, 126.2 ± 39.9 μg/m³ in scrap metal welding, 76.3 ± 33.2 μg/m³ in paint manufacturing, 27.3 ± 12.1 μg/m³ in a leather manufacturing, and 5.5 ± 3.6 μg/m³ in a pharmaceutical plant. The mean airborne Pb levels exceeded the U.S. Occupational Safety and Health Administration (OSHA) 8-hr time-weighted average (TWA) permissible exposure limit (PEL) for Pb of 50 μg/m³ in the battery manufacturing, battery recycling, welding, and paint manufacturing plants. Similarly, mean BPb concentrations exceeded the American Conference of Governmental Industrial Hygienists (ACGIH®) biological exposure index (BEI) for Pb of 30 μg/dl. A significant positive association was observed between BPb and breathing zone air Pb (R² = 0.73, P < 0.001). Approximately 30% of the production workers (N = 233) were in the hypertensive range with an average systolic and diastolic blood pressure (BP) of 134.7 ± 12.7 mmHg and 86.4 ± 8.9 mmHg, respectively. In the multivariate regression analysis, age, duration of work, airborne Pb and BPb levels were significantly associated (P < 0.05) with a change in BP. We recommend improved engineering controls, work practices, and personal hygiene to reduce Pb exposures. In addition, workers should undergo comprehensive medical surveillance to include BPb and BP testing, and airborne Pb assessments in all industries with significant lead exposures.     

Assessment of chlorpyrifos exposure and absorbed daily doses among infants living in an agricultural area of the Province of Jiangsu,China

Purpose

Chlorpyrifos (CPF) is one of the most widely used organophosphorous pesticides in China. However, few reports on CPF pesticide exposure and body burden of infants at 2 years of age in China are available. The aim of this study was to assess the exposure level and the absorbed daily dose (ADD) of CPF among infants from an agricultural area of Jiangsu, China, and determine whether the infants’ estimated dose exceeds the recommended reference dose (RfD) and the population adjusted dose (PAD) set by U.S. Environmental Protection Agency (EPA).

Methods

In our study, 364 infants at 2 years of age who lived in the agricultural area of Jiangsu Province (China) were enrolled into the biomonitoring study from June 2011 to January 2012. CPF exposure was estimated based on both questionnaire survey and measured results of urinary metabolite 3,5,6-trichloro-2-pyridinol (TCPy) of CPF by high-performance liquid chromatography. Furthermore, the ADD of CPF among infants was also evaluated and compared with the RfD and the PAD values issued by EPA.

Results

Urinary TCPy was detected in more than 70 % of the urine samples among 364 infants. The unadjusted and creatinine-adjusted geometric means in these subjects for TCPy were 1.33 μg/L and 6.73 μg/g Cre., respectively. Infants lived nearby (100 m distance) plantations or green parks present significantly higher levels of urinary TCPy than those lived far away (p = 0.045). Urinary TCPy levels were also significantly higher in infants who had frequent hand-to-mouth activities than those with less frequency (p = 0.037). Urinary TCPy concentrations in the infants at 2 years of age in Jiangsu were lower than those in the children at 2–6 years of age in the USA. The median estimated ADD of CPF in this study (0.07 μg/kg/day) was much lower than the acute and chronic RfDs (5 and 0.3 μg/kg/day, respectively) announced by EPA, but higher than the chronic PAD (cPAD) (0.03 μg/kg/day) for children. Additionally, the 75th percentile of the estimated ADD in our study was 2.5 times as much as the cPAD from EPA, even assuming only half of the TCPy amount from CPF exposure.

Conclusions

Our findings revealed that infants at 2 years of age in Jiangsu of China were widely exposed to CPF pesticide. The estimated ADD probably suggested that about 25 % of the enrolled infants were at potential risk of pesticide exposure, which warned of urgency to eliminate the potential exposure risk to infants living in agricultural areas of China.     

Major congenital malformations and residential proximity to a regional industrial park including a national toxic waste site: An ecological study

Background

Air pollution in São Paulo is constantly being measured by the State of Sao Paulo Environmental Agency, however there is no information on the variation between places with different traffic densities. This study was intended to identify a gradient of exposure to traffic-related air pollution within different areas in São Paulo to provide information for future epidemiological studies.

Methods

We measured NO₂ using Palmes' diffusion tubes in 36 sites on streets chosen to be representative of different road types and traffic densities in São Paulo in two one-week periods (July and August 2000). In each study period, two tubes were installed in each site, and two additional tubes were installed in 10 control sites.

Results

Average NO₂ concentrations were related to traffic density, observed on the spot, to number of vehicles counted, and to traffic density strata defined by the city Traffic Engineering Company (CET). Average NO₂concentrations were 63μg/m³ and 49μg/m³ in the first and second periods, respectively. Dividing the sites by the observed traffic density, we found: heavy traffic (n = 17): 64μg/m³ (95% CI: 59μg/m³ – 68μg/m³); local traffic (n = 16): 48μg/m³ (95% CI: 44μg/m³ – 52μg/m³) (p < 0.001).

Conclusion

The differences in NO₂ levels between heavy and local traffic sites are large enough to suggest the use of a more refined classification of exposure in epidemiological studies in the city. Number of vehicles counted, traffic density observed on the spot and traffic density strata defined by the CET might be used as a proxy for traffic exposure in São Paulo when more accurate measurements are not available.     

Measurement of area and personal breathing zone concentrations of diesel particulate matter (DPM) during oil and gas extraction operations,including hydraulic fracturing

Diesel engines serve many purposes in modern oil and gas extraction activities. Diesel particulate matter (DPM) emitted from diesel engines is a complex aerosol that may cause adverse health effects depending on exposure dose and duration. This study reports on personal breathing zone (PBZ) and area measurements for DPM (expressed as elemental carbon) during oil and gas extraction operations including drilling, completions (which includes hydraulic fracturing), and servicing work.

Researchers at the National Institute for Occupational Safety and Health (NIOSH) collected 104 full-shift air samples (49 PBZ and 55 area) in Colorado, North Dakota, Texas, and New Mexico during a four-year period from 2008–2012. The arithmetic mean (AM) of the full shift TWA PBZ samples was 10 µg/m³; measurements ranged from 0.1–52 µg/m³. The geometric mean (GM) for the PBZ samples was 7 µg/m³. The AM of the TWA area measurements was 17 µg/m³ and ranged from 0.1–68 µg/m³. The GM for the area measurements was 9.5 µg/m³. Differences between the GMs of the PBZ samples and area samples were not statistically different (P > 0.05).

Neither the Occupational Safety and Health Administration (OSHA), NIOSH, nor the American Conference of Governmental Industrial Hygienists (ACGIH) have established occupational exposure limits (OEL) for DPM. However, the State of California, Department of Health Services lists a time-weighted average (TWA) OEL for DPM as elemental carbon (EC) exposure of 20 µg/m³. Five of 49 (10.2%) PBZ TWA measurements exceeded the 20 µg/m³ EC criterion. These measurements were collected on Sandmover and Transfer Belt (T-belt) Operators, Blender and Chemical Truck Operators, and Water Transfer Operators during hydraulic fracturing operations.

Recommendations to minimize DPM exposures include elimination (locating diesel-driven pumps away from well sites), substitution, (use of alternative fuels), engineering controls using advanced emission control technologies, administrative controls (configuration of well sites), hazard communication, and worker training.     

Serum leptin and total dietary energy intake: the INTERLIPID Study

Purpose

It has been hypothesized that leptin-induced appetite suppression is impaired in obese individuals, but little human evidence is available documenting this. We investigated relations between serum leptin and total energy intake using INTERLIPID/INTERMAP data on Japanese–Americans in Hawaii and Japanese in Japan.

Methods

Serum leptin and nutrient intakes were examined by standardized methods in men and women aged 40–59 years from two population samples, one Japanese–American in Hawaii (88 men, 94 women), the other Japanese in central Japan (123 men, 111 women). Multiple linear regression analyses stratified by BMI category (<25 kg/m², 25–29.9 kg/m², and ≥30 kg/m²) with adjustment for possible confounders were used to examine the relation between log-leptin and total dietary energy intake.

Results

In multivariate regression analyses, in those with BMI < 25 kg/m² and in those with BMI between 25 and 29.9 kg/m², log-leptin was not significantly related to total dietary energy intake; in those with BMI ≥ 30 kg/m², it was significantly inversely related to total dietary energy intake (P = 0.029), independent of body weight and physical activity. Physical activity score was significantly positively related to total dietary energy intake only in participants with BMI < 25 kg/m² (P < 0.001).

Conclusion

Leptin was significantly inversely associated with dietary energy intake in obese persons, but not in overweight and normal-weight persons.     

Urban mercury pollution in the City of Paramaribo, Suriname

Atmospheric mercury pollution related to gold mining activities is a matter of concern in the Republic of Suriname. The first measurements of total gaseous mercury (TGM) in ambient air in Suriname at different sites are presented in this study. Our study shows that Suriname has a TGM mercury background level of 1.45–1.52 ng/m³, with a mean of 1.4 ng/m³ which is in agreement with global background concentrations (1.5–2.0 ng/m³) (Feng et al. Sci Total Environ 304:61–72, 2003; Li et al. Sci Total Environ 395:72–79, 2008). Emissions of mercury from gold buy up shops in the City of Paramaribo result in TGM maximum concentrations of 109.4 ng/m³ (15 min average) and a mean concentration level of 5.6 ng/m³ at this urban measurement location. These levels are comparable with that of world cities in Asia and North America. However, per capita Paramaribo loads 3.5–6.5 times more TGM into the atmosphere than Changchun City (Fang et al. Sci Total Environ 330:159–170, 2004) and the occurring spikes are 5.3 times higher and much longer in duration then those in New York City (Carpi and Chen Water Air Soil Pollut 140:371–379, 2002). According to health standard institutions these concentrations represent no risk for the general public. However, a survey inside and in the close vicinity (<100 m) of the gold buy up shops shows mercury concentration levels that surpass the National Institute for Occupational Safety and Health recommended exposure level of 50 μg/m³ inside and the minimal risk level of 0.2 μg/m³ of the Agency for Toxic Substances and Disease Registry outside.     

Pneumoproteins in sewage workers exposed to sewage dust

Purpose

The association between exposure to bacteria and endotoxins in sewage dust and the serum concentrations of pneumoproteins in sewage treatment plant workers were studied.

Methods

Forty-four workers from eight sewage treatment plants and 38 reference workers participated in the study. Microbial aerosol was collected by personal inhalable samplers. The concentrations of bacteria and endotoxins were determined by fluorescence microscopy and the Limulus assay, respectively. Pneumoproteins (Clara cell protein: CC16, and Surfactant proteins A and D: SP-A, SP-D) were determined by ELISA in blood samples collected post-shift.

Results

The exposure to dust ranged from 0.02 to 9.3 (geometric mean (GM) 0.3 mg/m³, of bacteria from 0.3 to 4,900 × 10³ (GM 27 × 10³) cells/m³ and endotoxins from 1 to 3,160 (GM 28) EU/m³. The exposed workers had lower CC16 [arithmetic mean (AM) 4.9 ng/ml] compared to the referents (AM 6.4 ng/ml, p < 0.01). No significant difference was observed for SP-D and SP-A. Exposure to bacteria was positively associated with CC16 (p < 0.05) and SP-D (p < 0.05), adjusting for possible confounders.

Conclusions

This study showed that exposed workers had lower serum concentration of CC16 as compared to the referents, which may reflect a long-term effect on secretion of these pneumoproteins. The positive association between exposure to bacteria and the serum concentrations of CC16 and SP-D may be explained by a transient increased permeability of the lung–blood barrier.     

Experimental exposure of healthy subjects with emissions from a gas metal arc welding process—part II: biomonitoring of chromium and nickel

Objectives

The objective of this study was to investigate whether there is a relationship between the external exposure dose of chromium and nickel caused by a metal active gas welding process with a solid high-alloyed steel welding wire and inner exposure of subjects. In order to perform welding fume exposure under controlled and standardized conditions, the investigations were conducted in the “Aachen Workplace Simulation Laboratory”.

Methods

To perform biological monitoring of chromium and nickel, blood and urine samples of 12 healthy male non-smokers who never worked as welders were collected before and after a 6-h exposure to ambient air (0 mg/m³) and to welding fumes of a metal active gas welding process once with a concentration of the welding fume of 1 mg/m³ and once with a concentration of 2.5 mg/m³.

Results

Although the internal exposure to chromium and nickel in this study was comparatively low, the subjects showed significantly increased concentrations of these metals in urine after exposure to welding fume compared to the values at baseline. Moreover, the observed increase was significantly dose dependent for both of the substances.

Conclusion

For the biological monitoring of chromium and nickel in urine of subjects exposed to welding fumes, a dependency on exposure dose was seen under standardized conditions after a single exposure over a period of 6 h. Thus, this study contributes to a better understanding of the relationship between ambient and biological exposures from welding fumes and provides a good basis for evaluating future biological threshold values for these metals in welding occupation.     

Effect of ventilation velocity on hexavalent chromium and isocyanate exposures in aircraft paint spraying

Exposure control system performance was evaluated during aircraft paint spraying at a military facility. Computational fluid dynamics (CFD) modeling, tracer gas testing, and exposure monitoring examined contaminant exposure vs. crossflow ventilation velocity. CFD modeling using the RNG k-? turbulence model showed exposures to simulated methyl isobutyl ketone of 294 and 83.6 ppm, as a spatial average of five worker locations, for velocities of 0.508 and 0.381 m/s (100 and 75 fpm), respectively. In tracer gas experiments, observed supply/exhaust velocities of 0.706/0.503 m/s (136/99 fpm) were termed full-flow, and reduced velocities were termed 3/4-flow and half-flow. Half-flow showed higher tracer gas concentrations than 3/4-flow, which had the lowest time-averaged concentration, with difference in log means significant at the 95% confidence level. Half-flow compared to full-flow and 3/4-flow compared to full-flow showed no statistically significant difference. CFD modeling using these ventilation conditions agreed closely with the tracer results for the full-flow and 3/4-flow comparison, yet not for the 3/4-flow and half-flow comparison. Full-flow conditions at the painting facility produced a velocity of 0.528 m/s (104 fpm) midway between supply and exhaust locations, with the supply rate of 94.4 m³/s (200,000 cfm) exceeding the exhaust rate of 68.7 m³/s (146,000 cfm). Ventilation modifications to correct this imbalance created a midhangar velocity of 0.406 m/s (80.0 fpm). Personal exposure monitoring for two worker groups—sprayers and sprayer helpers (“hosemen”)—compared process duration means for the two velocities. Hexavalent chromium (Cr[VI]) exposures were 500 vs. 360 µg/m³ for sprayers and 120 vs. 170 µg/m³ for hosemen, for 0.528 m/s (104 fpm) and 0.406 m/s (80.0 fpm), respectively. Hexamethylene diisocyanate (HDI) monomer means were 32.2 vs. 13.3 µg/m³ for sprayers and 3.99 vs. 8.42 µg/m³ for hosemen. Crossflow velocities affected exposures inconsistently, and local work zone velocities were much lower. Aircraft painting contaminant control is accomplished better with the unidirectional crossflow ventilation presented here than with other observed configurations. Exposure limit exceedances for this ideal condition reinforce continued use of personal protective equipment.     

Respirable dust and silica exposure among World Trade Center cleanup workers

The cleanup effort following the destruction of the World Trade Center (WTC) was unprecedented and involved removal of 1.8 million tons of rubble over a nine-month period. Work at the site occurred 24 hr a day, 7 days a week and involved thousands of workers during the process. The Occupational Safety and Health Administration (OSHA) conducted personal and area exposure sampling during the cleanup of the site. Secondary data analysis was performed on OSHA air sampling data for respirable dust and silica from September 2001 to June 2002 at the WTC recovery site to characterize workers' exposure. Results for silica and respirable particulate were stratified by area and personal samples as well as job task for analysis. Of 1108 samples included in the analysis, 693 were personal and 415 were area. The mean result for personal silica samples was 42 μg/m³ (Range: 4.2–1800 μg/m³). Workers identified as drillers had the highest mean silica exposure (72 μg/m³; range: 5.8–800 μg/m³) followed by workers identified as dock builders (67 μg/m³; range: 5.8–670 μg/m³). The mean result for personal samples for respirable particulate was 0.44 mg/m³ (range: 0.00010–13 mg/m³). There were no discernable trends in personal respirable dust and silica concentrations with date.     

Chronic low-level arsenic exposure reduces lung function in male population without skin lesions

Objectives

The respiratory effects of chronic low-level arsenic exposure from groundwater have been investigated in West Bengal, India.

Methods

The participants (834 non-smoking adult males) were subdivided in two groups: an arsenic-exposed group (n = 446, mean age 35.3 years) drinking arsenic-contaminated groundwater (11–50 μg/L) and a control group of 388 age-matched men drinking water containing <10 μg/L of arsenic. Arsenic in water samples was measured by atomic absorption spectroscopy. The prevalence of respiratory symptoms was documented by structured, validated questionnaire. Pulmonary function test (PFT) was assessed by portable spirometer.

Results

Compared with control, the arsenic-exposed subjects had higher prevalence of upper and lower respiratory symptoms, dyspnea, asthma, eye irritation and headache. Besides, 20.6 % of arsenic-exposed subjects had lung function deficits (predominantly restrictive and combined types) compared with 13.6 % of control (p < 0.05). A positive association was observed between arsenic concentration in drinking water and the prevalence of respiratory symptoms, while a negative association existed between arsenic level and spirometric parameters.

Conclusions

The findings suggest that even low-level arsenic exposure has deleterious respiratory effects.