Last data update: Jun 17, 2024. (Total: 47034 publications since 2009)
Records 1-25 (of 25 Records) |
Query Trace: Deddens JA [original query] |
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Air, hand wipe, and surface wipe sampling for bisphenol A (BPA) among workers in industries that manufacture and use BPA in the United States
Hines CJ , Jackson MV , Christianson AL , Clark JC , Arnold JE , Pretty JR , Deddens JA . J Occup Environ Hyg 2017 14 (11) 882-897 For decades, bisphenol A (BPA) has been used in making polycarbonate, epoxy, and phenolic resins and certain investment casting waxes, yet published exposure data are lacking for U.S. manufacturing workers. In 2013-2014, BPA air and hand exposures were quantified for 78 workers at six U.S. companies making BPA or BPA-based products. Exposure measures included an inhalable-fraction personal air sample on each of two consecutive work days (n = 146), pre- and end-shift hand wipe samples on the second day (n = 74 each), and surface wipe samples (n = 88). Potential determinants of BPA air and end-shift hand exposures (after natural log transformation) were assessed in univariate and multiple regression mixed models. The geometric mean (GM) BPA air concentration was 4.0 microg/m3 (maximum 920 microg/m3). The end-shift GM BPA hand level (26 microg/sample) was 10-times higher than the pre-shift level (2.6 microg/sample). BPA air and hand exposures differed significantly by industry and job. BPA air concentrations and end-shift hand levels were highest in the BPA-filled wax manufacturing/reclaim industry (GMAir = 48 microg/m3, GMHand-End = 130 microg/sample) and in the job of working with molten BPA-filled wax (GMAir = 43 microg/m3, GMHand-End = 180 microg/sample), and lowest in the phenolic resins industry (GMAir = 0.85 microg/m3, GMHand-End = 0.43 microg/sample) and in the job of flaking phenolic resins (GMAIR = 0.62 microg/m3, GMHand-End = 0.38 microg/sample). Determinants of increased BPA air concentration were industry, handling BPA containers, spilling BPA, and spending ≥50% of the shift in production areas; increasing age was associated with lower air concentrations. BPA hand exposure determinants were influenced by high values for two workers; for all other workers, tasks involving contact with BPA-containing materials and spending ≥50% of the shift in production areas were associated with increased BPA hand levels. Surface wipe BPA levels were significantly lower in eating/office areas (GM = 9.3 microg/100 cm2) than in production areas (GM = 140 microg/100 cm2). In conclusion, worker BPA exposure was associated with tasks and conditions affecting both inhalation and dermal exposure. The potential for BPA-related health effects among these workers is unknown. |
Urinary bisphenol a (BPA) concentrations among workers in industries that manufacture and use BPA in the USA
Hines CJ , Jackson Matthew V , Deddens JA , Clark JC , Ye X , Christianson AL , Meadows JW , Calafat AM . Ann Work Expo Health 2017 61 (2) 164-182 Background: Bisphenol A (BPA) toxicity and exposure risk to humans has been the subject of considerable scientific debate; however, published occupational exposure data for BPA are limited. Methods: In 2013–2014, 77 workers at six US companies making BPA, BPA-based resins, or BPA-filled wax provided seven urine samples over two consecutive work days (151 worker-days, 525 samples). Participant information included industry, job, tasks, personal protective equipment used, hygiene behaviors, and canned food/beverage consumption. Total (free plus conjugated) BPA, quantified in urine by mass spectrometry, was detected in all samples. Results:The geometric mean (GM) creatinine-adjusted total BPA (total BPACR) concentration was 88.0 microg g−1 (range 0.78–18900 microg g - 1), approximately 70 times higher than in US adults in 2013–2014 (1.27 microg g-1). GM total BPACR increased during Day 1 (26.6-127 microg g- 1), decreased by pre-shift Day 2 (84.4 microg g - 1) then increased during Day 2 to 178 microg - 1. By industry, baseline and post-baseline total BPACR was highest in BPA-filled wax manufacturing/reclaim (GM = 111 microg g - 1) and lowest in phenolic resin manufacturing (GM = 6.56 microg g-1). By job, total BPACR was highest at baseline in maintenance workers (GM = 157 microg g−1) and post-baseline in those working with molten BPA-filled wax (GM = 441 microg g - 1). Workers in the job of flaking a BPA-based resin had the lowest concentrations at baseline (GM = 4.81 microg g−1) and post-baseline (GM = 23.2 µg g−1). In multiple regression models, at baseline, industry significantly predicted increased total BPACR (P = 0.0248); post-baseline, handling BPA containers (P = 0.0035), taking ≥3 process/bulk samples with BPA (P = 0.0002) and wearing a Tyvek coverall (P = 0.0042) significantly predicted increased total BPACR (after adjusting for total BPACR at baseline, time point, and body mass index). Conclusion: Several work-related factors, including industry, job, and certain tasks performed, were associated with increased urinary total BPACR concentrations in this group of manufacturing workers. The potential for BPA-related health effects among these workers is unknown. |
Is beryllium-induced lung cancer caused only by soluble forms and high exposure levels?
Schubauer-Berigan MK , Couch JR , Deddens JA . Occup Environ Med 2017 74 (8) 601-603 OBJECTIVES: The US Occupational Safety and Health Administration (OSHA) recently proposed a permissible exposure limit of 0.2 microg/m3 for beryllium, based partly on extrapolated estimates of lung cancer risk from a pooled occupational cohort. The purpose of the present analysis was to evaluate whether cohort members exposed at lower levels to mainly insoluble forms of beryllium exhibit increased risk of lung cancer. METHODS: We conducted Cox proportional hazards regression analyses among 75 lung cancer cases in age-based risk sets within two lower exposure plants in the pooled cohort followed from 1940 to 2005. We used categorical and power models to evaluate exposure-response patterns for mean and cumulative beryllium exposures in the two-plant cohort, comparing findings with the full pooled cohort. We also evaluated the distribution of exposure-years in each cohort by solubility class (soluble, insoluble and mixed). RESULTS: 98% of workers in the two-plant cohort were hired between 1955 and 1969. The mean beryllium exposure averaged 1.3 microg/m3 and the predominant form was insoluble. Adjusting for confounders, we observed a monotonic increase in lung cancer mortality across exposure categories in the two-plant cohort. The exposure-response coefficients (per unit ln exposure) were 0.270 (p=0.061) for mean exposure and 0.170 (p=0.033) for cumulative exposure, compared with 0.155 and 0.094 (respectively) in the full cohort. CONCLUSION: The low-exposure levels at these two plants and the predominance of insoluble beryllium suggest that the overall pooled cohort findings on which OSHA's lung cancer risk assessment is based are relevant for current workers exposed to any form of beryllium. |
Birth defects in infants born to employees of a microelectronics and business machine manufacturing facility
Silver SR , Pinkerton LE , Rocheleau CM , Deddens JA , Michalski AM , Van Zutphen AR . Birth Defects Res A Clin Mol Teratol 2016 106 (8) 696-707 BACKGROUND: Concerns about solvent releases from a microelectronics/business machine manufacturing facility in upstate New York led to interest in the health of former workers, including this investigation of birth defects in children of male and female employees. METHODS: Children born 1983 to 2001 to facility employees were enumerated and matched to New York State's Congenital Malformations Registry. Reported structural birth defects were compared with numbers expected from state rates (excluding New York City), generating standardized prevalence ratios (SPRs). Exposure assessors classified employees as ever/never potentially exposed at the facility to metals, chlorinated hydrocarbons, and other hydrocarbons during windows critical to organogenesis (female workers) or spermatogenesis (male workers). Among workers, adjusted prevalence ratios were generated to evaluate associations between potential exposures and specific birth defects. RESULTS: External comparisons for structural defects were at expectation for infants of male workers (SPR = 1.01; 95% confidence interval [CI], 0.77-1.29; n = 60) and lower for births to female workers (SPR = 0.84; 95% CI, 0.50-1.33; n = 18). Among full-term infants of male workers, ventricular septal defects (VSDs) were somewhat elevated compared with the general population (SPR = 1.58; 95% CI, 0.99-2.39; n = 22). Within the cohort, potential paternal metal exposure was associated with increased VSD risk (adjusted prevalence ratio = 2.70; 95% CI, = 1.09-6.67; n = 7). CONCLUSION: While overall SPRs were near expectation, paternal exposure to metals (primarily lead) appeared to be associated with increased VSD risk in infants. Take-home of occupational exposures, nonoccupational exposures, and chance could not be ruled out as causes. Case numbers for many defects were small, limiting assessment of the role of occupational exposures. |
Carbon nanotube and nanofiber exposure assessments: an analysis of 14 site visits
Dahm MM , Schubauer-Berigan MK , Evans DE , Birch ME , Fernback JE , Deddens JA . Ann Occup Hyg 2015 59 (6) 705-23 Recent evidence has suggested the potential for wide-ranging health effects that could result from exposure to carbon nanotubes (CNT) and carbon nanofibers (CNF). In response, the National Institute for Occupational Safety and Health (NIOSH) set a recommended exposure limit (REL) for CNT and CNF: 1 microg m-3 as an 8-h time weighted average (TWA) of elemental carbon (EC) for the respirable size fraction. The purpose of this study was to conduct an industrywide exposure assessment among US CNT and CNF manufacturers and users. Fourteen total sites were visited to assess exposures to CNT (13 sites) and CNF (1 site). Personal breathing zone (PBZ) and area samples were collected for both the inhalable and respirable mass concentration of EC, using NIOSH Method 5040. Inhalable PBZ samples were collected at nine sites while at the remaining five sites both respirable and inhalable PBZ samples were collected side-by-side. Transmission electron microscopy (TEM) PBZ and area samples were also collected at the inhalable size fraction and analyzed to quantify and size CNT and CNF agglomerate and fibrous exposures. Respirable EC PBZ concentrations ranged from 0.02 to 2.94 microg m-3 with a geometric mean (GM) of 0.34 microg m-3 and an 8-h TWA of 0.16 microg m-3. PBZ samples at the inhalable size fraction for EC ranged from 0.01 to 79.57 microg m-3 with a GM of 1.21 microg m-3. PBZ samples analyzed by TEM showed concentrations ranging from 0.0001 to 1.613 CNT or CNF-structures per cm3 with a GM of 0.008 and an 8-h TWA concentration of 0.003. The most common CNT structure sizes were found to be larger agglomerates in the 2-5 microm range as well as agglomerates >5 microm. A statistically significant correlation was observed between the inhalable samples for the mass of EC and structure counts by TEM (Spearman rho = 0.39, P < 0.0001). Overall, EC PBZ and area TWA samples were below the NIOSH REL (96% were <1 mug m-3 at the respirable size fraction), while 30% of the inhalable PBZ EC samples were found to be >1 mug m-3. Until more information is known about health effects associated with larger agglomerates, it seems prudent to assess worker exposure to airborne CNT and CNF materials by monitoring EC at both the respirable and inhalable size fractions. Concurrent TEM samples should be collected to confirm the presence of CNT and CNF. |
Trends in worker hearing loss by industry sector, 1981-2010
Masterson EA , Deddens JA , Themann CL , Bertke S , Calvert GM . Am J Ind Med 2015 58 (4) 392-401 BACKGROUND: The purpose of this study was to estimate the incidence and prevalence of hearing loss for noise-exposed U.S. workers by industry sector and 5-year time period, covering 30 years. METHODS: Audiograms for 1.8 million workers from 1981-2010 were examined. Incidence and prevalence were estimated by industry sector and time period. The adjusted risk of incident hearing loss within each time period and industry sector as compared with a reference time period was also estimated. RESULTS: The adjusted risk for incident hearing loss decreased over time when all industry sectors were combined. However, the risk remained high for workers in Healthcare and Social Assistance, and the prevalence was consistently high for Mining and Construction workers. CONCLUSIONS: While progress has been made in reducing the risk of incident hearing loss within most industry sectors, additional efforts are needed within Mining, Construction and Healthcare and Social Assistance. |
Flavoring exposure in food manufacturing
Curwin BD , Deddens JA , McKernan LT . J Expo Sci Environ Epidemiol 2014 25 (3) 324-33 Flavorings are substances that alter or enhance the taste of food. Workers in the food-manufacturing industry, where flavorings are added to many products, may be exposed to any number of flavoring compounds. Although thousands of flavoring substances are in use, little is known about most of these in terms of worker health effects, and few have occupational exposure guidelines. Exposure assessment surveys were conducted at nine food production facilities and one flavor manufacturer where a total of 105 area and 74 personal samples were collected for 13 flavoring compounds including five ketones, five aldehydes, and three acids. The majority of the samples were below the limit of detection (LOD) for most compounds. Diacetyl had eight area and four personal samples above the LOD, whereas 2,3-pentanedione had three area samples above the LOD. The detectable values ranged from 25-3124 ppb and 15-172 ppb for diacetyl and 2,3-pentanedione respectively. These values exceed the proposed National Institute for Occupational Safety and Health (NIOSH) recommended exposure limit for these compounds. The aldehydes had the most detectable samples, with each of them having >50% of the samples above the LOD. Acetaldehyde had all but two samples above the LOD, however, these samples were below the OSHA PEL. It appears that in the food-manufacturing facilities surveyed here, exposure to the ketones occurs infrequently, however levels above the proposed NIOSH REL were found. Conversely, aldehyde exposure appears to be ubiquitous. |
Mortality among a cohort of U.S. commercial airline cockpit crew
Yong LC , Pinkerton LE , Yiin JH , Anderson JL , Deddens JA . Am J Ind Med 2014 57 (8) 906-14 BACKGROUND: We evaluated mortality among 5,964 former U.S. commercial cockpit crew (pilots and flight engineers). The outcomes of a priori interest were non-chronic lymphocytic leukemia, central nervous system (CNS) cancer (including brain), and malignant melanoma. METHODS: Vital status was ascertained through 2008. Life table and Cox regression analyses were conducted. Cumulative exposure to cosmic radiation was estimated from work history data. RESULTS: Compared to the U.S. general population, mortality from all causes, all cancer, and cardiovascular diseases was decreased, but mortality from aircraft accidents was highly elevated. Mortality was elevated for malignant melanoma but not for non-chronic lymphocytic leukemia. CNS cancer mortality increased with an increase in cumulative radiation dose. CONCLUSIONS: Cockpit crew had a low all-cause, all-cancer, and cardiovascular disease mortality but elevated aircraft accident mortality. Further studies are needed to clarify the risk of CNS and other radiation-associated cancers in relation to cosmic radiation and other workplace exposures. |
Prevalence of workers with shifts in hearing by industry: a comparison of OSHA and NIOSH hearing shift criteria
Masterson EA , Sweeney MH , Deddens JA , Themann CL , Wall DK . J Occup Environ Med 2014 56 (4) 446-55 OBJECTIVE: The purpose of this study was to compare the prevalence of workers with National Institute for Occupational Safety and Health significant threshold shifts (NSTS), Occupational Safety and Health Administration standard threshold shifts (OSTS), and with OSTS with age correction (OSTS-A), by industry using North American Industry Classification System codes. METHODS: From 2001 to 2010, worker audiograms were examined. Prevalence and adjusted prevalence ratios for NSTS were estimated by industry. NSTS, OSTS, and OSTS-A prevalences were compared by industry. RESULTS: Twenty percent of workers had an NSTS, 14% had an OSTS, and 6% had an OSTS-A. For most industries, the OSTS and OSTS-A criteria identified 28% to 36% and 66% to 74% fewer workers than the NSTS criteria, respectively. CONCLUSIONS: Use of NSTS criteria allowing for earlier detection of shifts in hearing is recommended for improved prevention of occupational hearing loss. |
Carbon nanotube dosimetry: from workplace exposure assessment to inhalation toxicology
Erdely A , Dahm M , Chen BT , Zeidler-Erdely PC , Fernback JE , Birch ME , Evans DE , Kashon ML , Deddens JA , Hulderman T , Bilgesu SA , Battelli L , Schwegler-Berry D , Leonard HD , McKinney W , Frazer DG , Antonini JM , Porter DW , Castranova V , Schubauer-Berigan MK . Part Fibre Toxicol 2013 10 (1) 53 BACKGROUND: Dosimetry for toxicology studies involving carbon nanotubes (CNT) is challenging because of a lack of detailed occupational exposure assessments. Therefore, exposure assessment findings, measuring the mass concentration of elemental carbon from personal breathing zone (PBZ) samples, from 8 U.S.-based multi-walled CNT (MWCNT) manufacturers and users were extrapolated to results of an inhalation study in mice. RESULTS: Upon analysis, an inhalable elemental carbon mass concentration arithmetic mean of 10.6 mug/m3 (geometric mean 4.21 mug/m3) was found among workers exposed to MWCNT. The concentration equates to a deposited dose of approximately 4.07 mug/d in a human, equivalent to 2 ng/d in the mouse. For MWCNT inhalation, mice were exposed for 19 d with daily depositions of 1970 ng (equivalent to 1000 d of a human exposure; cumulative 76 yr), 197 ng (100 d; 7.6 yr), and 19.7 ng (10 d; 0.76 yr) and harvested at 0, 3, 28, and 84 d post-exposure to assess pulmonary toxicity. The high dose showed cytotoxicity and inflammation that persisted through 84 d after exposure. The middle dose had no polymorphonuclear cell influx with transient cytotoxicity. The low dose was associated with a low grade inflammatory response measured by changes in mRNA expression. Increased inflammatory proteins were present in the lavage fluid at the high and middle dose through 28 d post-exposure. Pathology, including epithelial hyperplasia and peribronchiolar inflammation, was only noted at the high dose. CONCLUSION: These findings showed a limited pulmonary inflammatory potential of MWCNT at levels corresponding to the average inhalable elemental carbon concentrations observed in U.S.-based CNT facilities and estimates suggest considerable years of exposure are necessary for significant pathology to occur at that level. |
Use of and occupational exposure to indium in the United States
Hines CJ , Roberts JL , Andrews RN , Jackson MV , Deddens JA . J Occup Environ Hyg 2013 10 (12) 723-33 Indium use has increased greatly in the past decade in parallel with the growth of flat-panel displays, touchscreens, optoelectronic devices, and photovoltaic cells. Much of this growth has been in the use of indium tin oxide (ITO). This increased use has resulted in more frequent and intense exposure of workers to indium. Starting with case reports and followed by epidemiological studies, exposure to ITO has been linked to serious and sometimes fatal lung disease in workers. Much of this research was conducted in facilities that process sintered ITO, including manufacture, grinding, and indium reclamation from waste material. Little has been known about indium exposure to workers in downstream applications. In 2009-2011, the National Institute for Occupational Safety and Health (NIOSH) contacted 89 potential indium-using companies; 65 (73%) responded, and 43 of the 65 responders used an indium material. Our objective was to identify current workplace applications of indium materials, tasks with potential indium exposure, and exposure controls being used. Air sampling for indium was either conducted by NIOSH or companies provided their data for a total of 63 air samples (41 personal, 22 area) across 10 companies. Indium exposure exceeded the NIOSH recommended exposure limit (REL) of 0.1 mg/m(3) for certain methods of resurfacing ITO sputter targets, cleaning sputter chamber interiors, and in manufacturing some inorganic indium compounds. Indium air concentrations were low in sputter target bonding with indium solder, backside thinning and polishing of fabricated indium phosphide-based semiconductor devices, metal alloy production, and in making indium-based solder pastes. Exposure controls such as containment, local exhaust ventilation (LEV), and tool-mounted LEV can be effective at reducing exposure. In conclusion, occupational hygienists should be aware that the manufacture and use of indium materials can result in indium air concentrations that exceed the NIOSH REL. Given recent findings of adverse health effects in workers, research is needed to determine if the current REL sufficiently protects workers against indium-related diseases. |
A prospective study of carpal tunnel syndrome: workplace and individual risk factors
Burt S , Deddens JA , Crombie K , Jin Y , Wurzelbacher S , Ramsey J . Occup Environ Med 2013 70 (8) 568-74 OBJECTIVES: To quantify the risk for carpal tunnel syndrome (CTS) from workplace physical factors, particularly hand activity level and forceful exertion, while taking into account individual factors including age, gender, body mass index (BMI), and pre-existing medical conditions. METHODS: Three healthcare and manufacturing workplaces were selected for inclusion on the basis of range of exposure to hand activity level and forceful exertion represented by their jobs. Each study participant's job tasks were observed and evaluated onsite and videotaped for further analysis, including frequency and duration of exertion and postural deviation. Individual health assessment entailed electrodiagnostic testing of median and ulnar nerves, physical examination and questionnaires at baseline with annual follow-up for 2 years. RESULTS: The incidence of dominant hand CTS during the study was 5.11 per 100 person-years (29 cases). Adjusted HRs for dominant hand CTS were as follows: working with forceful exertion ≥20% but <60% of the time: 2.83 (1.18, 6.79) and ≥60% of the time vs <20%: 19.57 (5.96, 64.24), BMI ≥30 kg/m2 (obesity): 3.19 (1.28, 7.98). The American Conference for Governmental Industrial Hygienists (ACGIH) Threshold Limit Value (TLV) for hand activity level also predicted CTS, HR=1.40 (1.11, 1.78) for each unit increase in the TLV ratio, controlling for obesity and job strain. CONCLUSIONS: Workplace and individual risk factors both contribute to the risk for CTS. Time spent in forceful exertion can be a greater risk for CTS than obesity if the job exposure is high. Preventive workplace efforts should target forceful exertions. |
Occupational exposure assessment in carbon nanotube and nanofiber primary and secondary manufacturers: mobile direct-reading sampling
Dahm MM , Evans DE , Schubauer-Berigan MK , Birch ME , Deddens JA . Ann Occup Hyg 2012 57 (3) 328-44 RESEARCH SIGNIFICANCE: Toxicological evidence suggests the potential for a wide range of health effects from exposure to carbon nanotubes (CNTs) and carbon nanofibers (CNFs). To date, there has been much focus on the use of direct-reading instruments (DRIs) to assess multiple airborne exposure metrics for potential exposures to CNTs and CNFs due to their ease of use and ability to provide instantaneous results. Still, uncertainty exists in the usefulness and interpretation of the data. To address this gap, air-monitoring was conducted at six sites identified as CNT and CNF manufacturers or users and results were compared with filter-based metrics. METHODS: Particle number, respirable mass, and active surface area concentrations were monitored with a condensation particle counter, a photometer, and a diffusion charger, respectively. The instruments were placed on a mobile cart and used as area monitors in parallel with filter-based elemental carbon (EC) and electron microscopy samples. Repeat samples were collected on consecutive days, when possible, during the same processes. All instruments in this study are portable and routinely used for industrial hygiene sampling. RESULTS: Differences were not observed among the various sampled processes compared with concurrent indoor or outdoor background samples while examining the different DRI exposure metrics. Such data were also inconsistent with results for filter-based samples collected concurrently at the same sites [Dahm MM, Evans DE, Schubauer-Berigan MK et al. (2012) Occupational exposure assessment in CNT and nanofiber primary and secondary manufacturers. Ann Occup Hyg; 56: 542-56]. Significant variability was seen between these processes as well as the indoor and outdoor backgrounds. However, no clear pattern emerged linking the DRI results to the EC or the microscopy data (CNT and CNF structure counts). CONCLUSIONS: Overall, no consistent trends were seen among similar processes at the various sites. The DRI instruments employed were limited in their usefulness in assessing and quantifying potential exposures at the sampled sites but were helpful for hypothesis generation, control technology evaluations, and other air quality issues. The DRIs employed are nonspecific, aerosol monitors, and, therefore, subject to interferences. As such, it is necessary to collect samples for analysis by more selective, time-integrated, laboratory-based methods to confirm and quantify exposures. |
Prevalence of hearing loss in the United States by industry
Masterson EA , Tak S , Themann CL , Wall DK , Groenewold MR , Deddens JA , Calvert GM . Am J Ind Med 2012 56 (6) 670-81 BACKGROUND: Twenty-two million workers are exposed to hazardous noise in the United States. The purpose of this study is to estimate the prevalence of hearing loss among U.S. industries. METHODS: We examined 2000-2008 audiograms for male and female workers ages 18-65, who had higher occupational noise exposures than the general population. Prevalence and adjusted prevalence ratios (PRs) for hearing loss were estimated and compared across industries. RESULTS: In our sample, 18% of workers had hearing loss. When compared with the Couriers and Messengers industry sub-sector, workers employed in Mining (PR = 1.65, CI = 1.57-1.73), Wood Product Manufacturing (PR = 1.65, CL = 1.61-1.70), Construction of Buildings (PR = 1.52, CI = 1.45-1.59), and Real Estate and Rental and Leasing (PR = 1.59, CL = 1.51-1.68) had higher risks for hearing loss. CONCLUSIONS: Workers in the Mining, Manufacturing, and Construction industries need better engineering controls for noise and stronger hearing conservation strategies. More hearing loss research is also needed within traditional "low-risk" industries like Real Estate. (Am. J. Ind. Med. (c) 2012 Wiley Periodicals, Inc.) |
Efficacy of the revised NIOSH lifting equation to predict risk of low back pain due to manual lifting: expanded cross-sectional analysis
Waters TR , Lu ML , Piacitelli LA , Werren D , Deddens JA . J Occup Environ Med 2011 53 (9) 1061-7 OBJECTIVE: To evaluate whether the Revised NIOSH Lifting Equation (RNLE) is a valid tool for assessing risk of low back pain (LBP) due to manual lifting by using combined data from two cross-sectional studies of 1-year prevalence. METHODS: Results from a symptom and occupational history questionnaire and RNLE analysis for 677 subjects employed in 125 manual lifting jobs at nine industrial sites were combined from two studies. RESULTS: The odds of LBP increased as the lifting index (LI) increased from 1.0 to 3.0. A statistically significant odds ratio (OR) was found for both the 1 < LI ≤ 2 (OR = 1.81) and the 2 < LI ≤ 3 categories (OR = 2.26). For jobs with an LI value greater than 3.0, however, the OR remained nonsignificant. The 2 < LI ≤ 3 group remained statistically significant after adjusting for age, gender, body mass index, and psychosocial factors. CONCLUSIONS: It is clear that as the LI increases, the risk of LBP increases. Longitudinal studies are needed. |
Determinants of captan air and dermal exposures among orchard pesticide applicators in the Agricultural Health Study
Hines CJ , Deddens JA , Coble J , Kamel F , Alavanja MC . Ann Occup Hyg 2011 55 (6) 620-33 OBJECTIVES: To identify and quantify determinants of captan exposure among 74 private orchard pesticide applicators in the Agricultural Health Study (AHS). To adjust an algorithm used for estimating pesticide exposure intensity in the AHS based on these determinants and to compare the correlation of the adjusted and unadjusted algorithms with urinary captan metabolite levels. METHODS: External exposure metrics included personal air, hand rinse, and dermal patch samples collected from each applicator on 2 days in 2002-2003. A 24-h urine sample was also collected. Exposure determinants were identified for each external metric using multiple linear regression models via the NLMIXED procedure in SAS. The AHS algorithm was adjusted, consistent with the identified determinants. Mixed-effect models were used to evaluate the correlation between the adjusted and unadjusted algorithm and urinary captan metabolite levels. RESULTS: Consistent determinants of captan exposure were a measure of application size (kilogram of captan sprayed or application method), wearing chemical-resistant (CR) gloves and/or a coverall/suit, repairing spray equipment, and product formulation. Application by airblast was associated with a 4- to 5-fold increase in exposure as compared to hand spray. Exposure reduction to the hands, right thigh, and left forearm from wearing CR gloves averaged approximately 80%, to the right and left thighs and right forearm from wearing a coverall/suit by approximately 70%. Applicators using wettable powder formulations had significantly higher air, thigh, and forearm exposures than those using liquid formulations. Application method weights in the AHS algorithm were adjusted to nine for airblast and two for hand spray; protective equipment reduction factors were adjusted to 0.2 (CR gloves), 0.3 (coverall/suit), and 0.1 (both). CONCLUSIONS: Adjustment of application method, CR glove, and coverall weights in the AHS algorithm based on our exposure determinant findings substantially improved the correlation between the AHS algorithm and urinary metabolite levels. |
Thyroxine and free thyroxine levels in workers occupationally exposed to inorganic lead
Bledsoe ML , Pinkerton LE , Silver S , Deddens JA , Biagini RE . Environ Health Insights 2011 5 55-61 BACKGROUND: The effects of lead exposure on thyroid function are unclear. METHODS: Serum thyroxine (T4) was evaluated among 137 lead-exposed workers and 83 non-exposed workers. Free thyroxine (FT4) was evaluated among a subset of these workers. Exposure metrics included blood lead level (BLL), which reflects recent exposure, zinc protoporphyrin (ZPP), a marker of intermediate-duration lead exposure, exposure duration, and estimated cumulative exposure. Multiple linear regression results were adjusted for age, race, and current smoking status. RESULTS: Mean BLLs were 38.9 mcg/dL in lead exposed workers and 2.1 mcg/dL in non-exposed workers. The adjusted mean T4 and FT4 concentrations among exposed and non-exposed workers were similar. While T4 was not significantly related to any of the exposure metrics, FT4 was inversely related to the logged values of both exposure duration and cumulative exposure, but not to ZPP or BLL. CONCLUSIONS: The findings suggest that FT4 levels may be related to long-term lead exposure. |
Occupational exposure to diisononyl phthalate (DiNP) in polyvinyl chloride processing operations
Hines CJ , Hopf NB , Deddens JA , Silva MJ , Calafat AM . Int Arch Occup Environ Health 2011 85 (3) 317-25 PURPOSE: Diisononyl phthalate (DiNP) is primarily used as a plasticizer in polyvinyl chloride (PVC) materials. While information is available on general population exposure to DiNP, occupational exposure data are lacking. We present DiNP metabolite urinary concentrations in PVC processing workers, estimate DiNP daily intake for these workers, and compare worker estimates to other populations. METHODS: We assessed DiNP exposure in participants from two companies that manufactured PVC materials, a PVC film manufacturer (n = 25) and a PVC custom compounder (n = 12). A mid-shift and end-shift urine sample was collected from each participant and analyzed for the DiNP metabolite mono(carboxy-isooctyl) phthalate (MCiOP). Mixed models were used to assess the effect on MCiOP concentrations of a worker being assigned to (1) a task using DiNP and (2) a shift where DiNP was used. A simple pharmacokinetic model was used to estimate DiNP daily intake from the MCiOP concentrations. RESULTS: Creatinine-adjusted MCiOP urinary concentrations ranged from 0.42-80 mcg/g in PVC film and from 1.11-13.4 mcg/g in PVC compounding. PVC film participants who worked on a task using DiNP (n = 7) had the highest MCiOP geometric mean (GM) end-shift concentration (25.2 mcg/g), followed by participants who worked on a shift where DiNP was used (n = 11) (17.7 mcg/g) as compared to participants with no task (2.92 mcg/g) or shift (2.08 mcg/g) exposure to DiNP. The GM end-shift MCiOP concentration in PVC compounding participants (4.80 mcg/g) was comparable to PVC film participants with no task or shift exposure to DiNP. Because no PVC compounding participants were assigned to tasks using DINP on the day sampled, DiNP exposure in this company may be underestimated. The highest DiNP intake estimate was 26 mcg/kg/day. CONCLUSION: Occupational exposure to DiNP associated with PVC film manufacturing tasks were substantially higher (sixfold to tenfold) than adult general population exposures; however, all daily intake estimates were less than 25% of current United States or European acceptable or tolerable daily intake estimates. Further characterization of DiNP occupational exposures in other industries is recommended. |
Maternal exposure to polychlorinated biphenyls and the secondary sex ratio: an occupational cohort study
Rocheleau CM , Bertke SJ , Deddens JA , Ruder AM , Lawson CC , Waters MA , Hopf NB , Riggs MA , Whelan EA . Environ Health 2011 10 (1) 20 BACKGROUND: Though commercial production of polychlorinated biphenyls was banned in the United States in 1977, exposure continues due to their environmental persistence. Several studies have examined the association between environmental polychlorinated biphenyl exposure and modulations of the secondary sex ratio, with conflicting results. OBJECTIVE: Our objective was to evaluate the association between maternal preconceptional occupational polychlorinated biphenyl exposure and the secondary sex ratio. METHODS: We examined primipara singleton births of 2595 women, who worked in three capacitor plants at least one year during the period polychlorinated biphenyls were used. Cumulative estimated maternal occupational polychlorinated biphenyl exposure at the time of the infant's conception was calculated from plant-specific job-exposure matrices. A logistic regression analysis was used to evaluate the association between maternal polychlorinated biphenyl exposure and male sex at birth (yes/no). RESULTS: Maternal body mass index at age 20, smoking status, and race did not vary between those occupationally exposed and those unexposed before the child's conception. Polychlorinated biphenyl-exposed mothers were, however, more likely to have used oral contraceptives and to have been older at the birth of their first child than non-occupationally exposed women. Among 1506 infants liveborn to polychlorinated biphenyl-exposed primiparous women, 49.8% were male; compared to 49.9% among those not exposed (n = 1089). Multivariate analyses controlling for mother's age and year of birth found no significant association between the odds of a male birth and mother's cumulative estimated polychlorinated biphenyl exposure to time of conception. CONCLUSIONS: Based on these data, we find no evidence of altered sex ratio among children born to primiparous polychlorinated biphenyl-exposed female workers. |
Evaluating bias from birth-cohort effects in the age-based Cox proportional hazards model
Hein MJ , Schubauer-Berigan MK , Deddens JA . Epidemiology 2011 22 (2) 249-56 The nested case-control design is frequently used to evaluate exposures and health outcomes within the confines of a cohort study. When incidence-density sampling is used to identify controls, the resulting data can be analyzed using conditional logistic regression (equivalent to stratified Cox proportional hazards regression). In these studies, exposure lagging is often used to account for disease latency. In light of recent criticism of incidence-density sampling, we used simulated occupational cohorts to evaluate age-based incidence-density sampling for lagged exposures in the presence of birth-cohort effects and associations among time-related variables. Effect estimates were unbiased when adjusted for birth cohort; however, unadjusted effect estimates were biased, particularly when age at hire and year of hire were correlated. When the analysis included an adjustment for birth cohort, the inclusion of lagged-out cases and controls (assigned a lagged exposure of zero) did not introduce bias. |
Analysis of lognormally distributed exposure data with repeated measures and values below the limit of detection using SAS
Jin Y , Hein MJ , Deddens JA , Hines CJ . Ann Occup Hyg 2010 55 (1) 97-112 Studies of determinants of occupational exposure frequently involve left-censored lognormally distributed data, often with repeated measures. Left censoring occurs when observations are below the analytical limit of detection (LOD); repeated measures data results from taking multiple measurements on the same worker. A common method of dealing with this type of data has been to substitute a value (such as LOD/2) for the censored data followed by statistical analysis using the 'usual' methods. Recently, maximum likelihood estimation (MLE) methods have been employed to reduce bias associated with the substitution method. We compared substitution and MLE methods using simulated lognormally distributed exposure data subjected to varying amounts of censoring using two procedures available in SAS: LIFEREG and NLMIXED. In these simulations, the MLE method resulted in less bias and performed well even for censoring up to 80%, whereas the substitution method resulted in considerable bias. We illustrate the NLMIXED procedure using a dataset of chlorpyrifos air measurements collected from termiticide applicators on consecutive days over a 5-day workweek. We provide sample SAS code for several situations including one and two groups, with and without repeated measures, random slopes, and nested random effects. |
Risk of lung cancer associated with quantitative beryllium exposure metrics within an occupational cohort
Schubauer-Berigan MK , Deddens JA , Couch JR , Petersen MR . Occup Environ Med 2010 68 (5) 354-60 OBJECTIVES: Beryllium has been identified as a human carcinogen on the basis of animal and epidemiological studies. The authors recently reported updated associations between lung cancer and beryllium exposure in a large, pooled occupational cohort. The authors conducted the present study to evaluate the shape of exposure-response associations between different exposure metrics and lung cancer in this cohort, considering potential confounders (race, plant, professional and short-term work status, and exposure to other lung carcinogens). METHODS: The authors conducted Cox proportional hazards regression analyses of lung cancer risk with cumulative, mean and maximum 'daily weighted average' (DWA) exposure among 5436 workers, using age-based risk sets. Different exposure-response curves were fitted to the exposure metrics, including categorical, power, restricted cubic spline and piecewise log-linear fits. RESULTS: The authors found significant positive associations between lung cancer and mean (p<0.0001) and maximum (p<0.0001) exposure, adjusting for age, birth cohort and plant, and for cumulative (p=0.0017) beryllium exposure, adjusting for these factors plus short-term work status and exposure to asbestos. The best-fitting models were generally categorical or piecewise log-linear, with the steepest increase in lung cancer risk between 0 and 10 mug/m(3) for both mean and maximum DWA exposure and between 0 and 200 mug/m(3)-days for cumulative DWA exposure. The estimated mean DWA beryllium exposure associated with 10(-3) excess lifetime risk based on the piecewise log-linear model is 0.033 mug/m(3). CONCLUSION: This study provides evidence that lung cancer risk is elevated at levels near the current US Occupational Safety and Health Administration beryllium exposure limit of 2.0 mug/m(3) DWA for workers. |
Cohort mortality study of workers at seven beryllium processing plants: update and associations with cumulative and maximum exposure
Schubauer-Berigan MK , Couch JR , Petersen MR , Carreon T , Jin Y , Deddens JA . Occup Environ Med 2010 68 (5) 345-53 OBJECTIVES: To extend follow-up of cause-specific mortality in workers at seven beryllium processing plants and to estimate associations between mortality risk and beryllium exposure. METHODS: 9,199 workers were followed for mortality from 1940 through 2005. Standardised mortality ratios (SMRs) were estimated based on US population comparisons for lung, nervous system and urinary tract cancers, chronic obstructive pulmonary disease (COPD), chronic kidney disease, and categories containing chronic beryllium disease (CBD) and cor pulmonale. Associations with maximum and cumulative exposure were calculated for a subset of the workers. RESULTS: Overall mortality in the cohort compared with the US population was elevated for lung cancer (SMR 1.17; 95% CI 1.08 to 1.28), COPD (SMR 1.23; 95% CI 1.13 to 1.32), and the categories containing CBD (SMR 7.80; 95% CI 6.26 to 9.60) and cor pulmonale (SMR 1.17; 95% CI 1.08 to 1.26). Mortality rates for most diseases of interest increased with time-since-hire. For the category including CBD, rates were substantially elevated compared to the US population across all exposure groups. Workers whose maximum beryllium exposure was ≥10 mug/m(3) had higher rates of lung cancer, urinary tract cancer, COPD and the category containing cor pulmonale than workers with lower exposure. Significant positive trends with cumulative exposure were observed for nervous system cancers (p=0.0006) and, when short-term workers were excluded, lung cancer (p=0.01), urinary tract cancer (p=0.003) and COPD (p<0.0001). CONCLUSION: These findings reaffirm that lung cancer and CBD, and suggest that COPD and nervous system and urinary tract cancers, are related to beryllium exposure. Cigarette smoking and exposure to other lung carcinogens are unlikely to explain these elevations. |
Estimated daily intake of phthalates in occupationally exposed groups
Hines CJ , Hopf NB , Deddens JA , Silva MJ , Calafat AM . J Expo Sci Environ Epidemiol 2009 21 (2) 133-41 Improved analytical methods for measuring urinary phthalate metabolites have resulted in biomarker-based estimates of phthalate daily intake for the general population, but not for occupationally exposed groups. In 2003-2005, we recruited 156 workers from eight industries where materials containing diethyl phthalate (DEP), dibutyl phthalate (DBP), and/or di(2-ethylhexyl) phthalate (DEHP) were used as part of the worker's regular job duties. Phthalate metabolite concentrations measured in the workers' end-shift urine samples were used in a simple pharmacokinetic model to estimate phthalate daily intake. DEHP intake estimates based on three DEHP metabolites combined were 0.6-850 mug/kg/day, with the two highest geometric mean (GM) intakes in polyvinyl chloride (PVC) film manufacturing (17 mug/kg/day) and PVC compounding (12 mug/kg/day). All industries, except phthalate manufacturing, had some workers whose DEHP exposure exceeded the U.S. reference dose (RfD) of 20 mug/kg/day. A few workers also exceeded the DEHP European tolerable daily intake (TDI) of 50 mug/kg/day. DEP intake estimates were 0.5-170 mug/kg/day, with the highest GM in phthalate manufacturing (27 mug/kg/day). DBP intake estimates were 0.1-76 mug/kg/day, with the highest GMs in rubber gasket and in phthalate manufacturing (17 mug/kg/day, each). No DEP or DBP intake estimates exceeded their respective RfDs. The DBP TDI (10 mug/kg/day) was exceeded in three rubber industries and in phthalate manufacturing. These intake estimates are subject to several uncertainties; however, an occupational contribution to phthalate daily intake is clearly indicated in some industries.Journal of Exposure Science and Environmental Epidemiology advance online publication, 16 December 2009; doi:10.1038/jes.2009.62. |
The hypothalamus-pituitary-testis axis in boys during the first six months of life: a comparison of cryptorchidism and hypospadias cases with controls
Pierik FH , Deddens JA , Burdorf A , de Muinck Keizer-Schrama SM , Jong FH , Weber RF . Int J Androl 2009 32 (5) 453-61 It is inconclusive whether the feedback mechanisms of the hypothalamus-pituitary-testis (HTP) axis are already established in the first 6 months of life, partly due to the dramatic changes in HPT-axis hormone levels over this period. Moreover, it is unclear whether these hormone levels are aberrant in boys with cryptorchidism or hypospadias, and therefore predictive for future fertility. We studied the regulation mechanisms of the HTP axis, and the effect of age, in boys 1-6 months of age. Secondly, we studied testicular function - as reflected by HPT hormones - in newborns with cryptorchidism or hypospadias. Sera from a population sample of infants with cryptorchidism (n = 43), hypospadias (n = 41) and controls (n = 113) were analyzed for inhibin B, anti-Mullerian hormone (AMH), testosterone, luteinizing hormone (LH), follicle stimulating hormone (FSH) and sex hormone binding globulin (SHBG). LH, testosterone, non-shbg-bound testosterone (NSBT), and AHM levels showed significant age-related trends. After age-correction, a negative correlation between FSH and inhibin B was observed (r = -0.43). The only significant group-differences were lower testosterone and NSBT levels in cryptorchidism cases, with a mean testosterone of 1.8 and 2.6 nmol/L and a mean NSBT of 0.48 and 0.70 nmol/L for cryptorchidism cases and controls, respectively. The higher levels of LH, testosterone, and NSBT in boys born pre-term or with a low birthweight indicate that abnormal prenatal development may determine postnatal testis function. Our results support the hypothesis that the inhibin B - FSH feedback loop is already functional before puberty. The lower testosterone and NSBT levels indicate that disturbed Leydig cell function can already be detected early after birth in cryptorchid boys. |
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