Current Occupational Exposure Research Articles

Airborne particulate matter and diesel engine exhaust on infrastructure construction sites in the Copenhagen metropolitan area.

Diesel engine exhaust (DEE) is carcinogenic and potentially hazardous for those working in close proximity to diesel-powered machines. This study characterizes workplace exposure to DEE and its associated particulate matter (PM) during outdoor construction activities. We sampled at 4 construction sites in the Copenhagen metropolitan area. We used portable constant-flow pumps and quartz-fiber filters to quantify personal exposure to elemental carbon (EC), and used real-time instruments to collect activity-based information about particle number and size distribution, as well as black carbon (BC) concentration. Full-shift measurements of EC concentration ranged from < 0.3 to 6.4 µg/m3. Geometric mean (GM) EC exposure was highest for ground workers (3.4 µg/m3 EC; geometric standard deviation, GSD = 1.3), followed by drilling rig operators (2.6 µg/m3 EC; GSD = 1.4). Exposure for non-drilling-rig machine operators (1.2 µg/m3 EC; GSD = 2.9) did not differ significantly from background (0.9 µg/m3 EC; GSD = 1.7). The maximum 15-min moving average concentration of BC was 17 µg/m3, and the highest recorded peak concentration was 44 µg/m3. In numbers, the particle size distributions were dominated by ultrafine particles ascribed to DEE and occasional welding activities at the sites. The average total particle number concentrations (PNCs) measured in near-field and far-field positions across all worksites were 10,600 (GSD = 3.0) and 6,000 (GSD = 2.8)/cm3, respectively. Sites with active drilling rigs saw significantly higher average total PNCs at their near-field stations (13,600, 32,000, and 9,700/cm3; GSD = 2.4, 3.4, and 2.4) than sites without (4,700/cm3; GSD = 1.6). Overall, the DEE exposures at these outdoor construction sites were below current occupational exposure limits for EC (10 µg/m3 in Denmark; 50 µg/m3 in the European Union), but extended durations of exposure to the observed DEE levels may still be a health risk.

Longitudinal changes in cardiovascular disease-related proteins in welders.

Occupational exposure to welding fumes is linked to a higher risk of cardiovascular disease; however, the threshold exposure level is unknown. Here, we aimed to identify changes in proteins associated with cardiovascular disease in relation to exposure to welding fumes. Data were obtained from two timepoints six years apart for 338 non-smoking men (171 welders, 167 controls); of these, 174 (78 welders, 96 controls) had measurements available at both timepoints. Exposure was measured as personal respirable dust (adjusted for personal protective equipment), welding years, and cumulative exposure. Proximity extension assays were used to measure a panel of 92 proteins involved in cardiovascular processes in serum samples. Linear mixed models were used for longitudinal analysis. The biological functions and diseases related to the identified proteins were explored using the Ingenuity Pathway Analysis software. At both timepoints, the median respirable dust exposure was 0.7mg/m3for the welders. Seven proteins were differentially abundant between the welders and controls and increased incrementally with respirable dust: FGF23, CEACAM8, CD40L, PGF, CXCL1, CD84, and HO1. CD84 was significant after adjusting for multiple comparisons. These proteins have been linked to disorders of blood pressure, damage related to clogged blood vessels, and chronic inflammatory disorders. Exposure to mild steel welding fumes below current occupational exposure limits for respirable particles and welding fumes in Europe and the US (1-5mg/m3) was associated with changes in the abundance of proteins related to cardiovascular disease. Further research should evaluate the utility of these proteins as prospective biomarkers of occupational cardiovascular disease.

P-010 Impact of paternal occupational exposures on fetal loss in the female partner: a systematic review

Abstract Study question Are paternal occupational exposures associated with a higher risk of fetal loss in the unexposed female partner? Summary answer Significant positive associations between paternal occupational exposures and fetal loss were retrieved, for chemical and physical agents and for several occupations. What is known already Adverse pregnancy outcomes are frequent and, in its recently updated guidelines, the ESHRE reinforced the interest of exploring the father’s exposures. Nevertheless, causes of fetal loss are still most often investigated only in mothers. Paternal risk factors for fetal loss have been scarcely explored, particularly occupational exposures. Though, males appear to be more exposed to occupational reprotoxic agents than females and are not always aware or sufficiently informed of these exposures. Reprotoxic mechanisms of father’s occupational exposures may include sperm nucleus alteration, seminal fluid contamination and/or indirect exposure of the mother to paternal occupational environment (via linen, dust…). Study design, size, duration A systematic review of the literature using PRISMA 2020 methodology was performed for full text English and French language articles in the Pubmed MEDLINE, Google Scholar, Web of Science and Embase databases. Participants/materials, setting, methods We included only original studies published until December 2022, performed in humans, including a control group and performing a multivariate analysis. The fetal losses analysed were early and/or late and we did not exclude studies analysing stillbirths. We excluded studies in which the female partner was also occupationally exposed. The dose-response relationship and mechanisms of action were noted where described. Main results and the role of chance The 33 studies included analysed a total of 540,246 pregnancies from 8,183 couples or 114,093 exposed male workers, and were classified into 3 groups according to the occupational hazards studied. Regarding chemical agents, the risk of miscarriage was significantly increased in cases of paternal occupational exposure to Thiocarbamate(OR = 1.9, 95% CI 1.1-3.3), Carbaryl (OR = 1.9, 95% CI 1.9-3.1), Dichloro-Diphenyl-Trichloroethane (OR = 1.57, 95% CI 1.13-2.18), printing solvents (OR = 5.5, 95% CI 1.8-17.2), ethylene oxide (OR = 4.7, 95% CI 1.2-18.4), petroleum refinery solvents (OR = 2.2, 95% CI 1.3-3.8) and stainless steel welding fumes (RR = 3.5, 95% CI 1.3-9.1). Regarding physical agents, the risk of stillbirth or perinatal mortality was significantly increased with exposure to ionising (OR = 1.86, 95% CI 1.21-2.76) and nonionising radiation (RR = 2.23, 95% CI 1.08-4.62). Regarding the type of occupation, the risk of miscarriage or stillbirth was significantly increased among crushers, grinders and calenders (OR = 2.20, 95% CI 1.13-4.30), to seamstresses (OR = 2.54, 95% CI 1.29-5), sheet metal workers and commercial aircrew (OR = 2.85, 95% CI 1.30-6.23). The dose-response relationships showed divergent results. The mechanisms of action hypothesized were mainly germ cell mutations. Limitations, reasons for caution The publications selected were mostly published before 2010 and showed high variation in the population sizes, types of male occupational exposure, and in the nature and number of confounding factors used for the multivariate statistical analysis. Due to the various nature of exposures analysed, no meta-analysis could be performed. Wider implications of the findings Men should be made more aware of male-mediated occupational reproductive risks. Occupational health professionals should participate in the investigation of the causes of foetal loss and act on male occupational exposures that may impact pregnancy outcomes. Further high-powered prospective studies are needed, which should include paternal current occupational exposures. Trial registration number not applicable

Successful prevention of organic solvent induced disorders: history and lessons.

In this discussion paper, we describe the history of the science and societal action resulting in the mitigation of neurotoxic disorders from exposure to organic solvents at the workplaces in Sweden. When alkyd paints were introduced in large scale in construction painting in the 1960s and 1970s, Scandinavian unions voiced increasing concern as members reported symptoms like headache and vertigo, supported by participatory studies and case studies. Although acute and chronic neurotoxic effects were established for some specific solvents such as carbon disulphide, this was not the case for those used in the new paints. Union advocacy promoted formal epidemiological studies, providing increasing evidence for chronic neurotoxicity at levels far below current occupational exposure levels. The results were widely disseminated and accepted and led to concerted action with preventive measures, most importantly substitution of the organic solvents in paints for indoor use, but also drastic reductions in occupational exposure limits. The findings also resulted in funding of further research on solvent toxicity and the establishment of expert groups to advice authorities on occupational standards for exposure to chemicals. The substitution strategy was subsequently adopted in many other countries and occupational exposure limits were lowered, although several years or even decades later. While the societal context in Sweden was unique in many ways, we conclude that there are lessons to be learned from this preventive success when addressing current challenges.

Chronic occupational exposures to irritants and asthma in the CONSTANCES cohort

ObjectivesThe impact of chronic occupational exposures to irritants on asthma remains discussed. We studied the associations between occupational exposures and asthma, with specific interest for chronic exposure to irritants, including...

Exploration of associations between occupational exposures and current adult eczema

ObjectivesThere is a scarcity of evidence on occupational exposures that may increase eczema in adults. We aimed to investigate potential associations between occupational exposures and eczema in middle-aged adults.MethodsA lifetime...

The challenges of defining hormesis in epidemiological studies: The case of radiation hormesis

In the current radiation protection system, preventive measures and occupational exposure limits for controlling occupational exposure to ionizing radiation are based on the linear no-threshold extrapolation model. However, currently an increasing body of evidence indicates that this paradigm predicts very poorly biological responses in the low-dose exposure region. In addition, several in vitro and in vivo studies demonstrated the presence of hormetic dose response curves correlated to ionizing radiation low exposure. In this regard, it is noteworthy that also the findings of different epidemiological studies, conducted in different categories of occupationally exposed workers (e.g., healthcare, nuclear industrial and aircrew workers), observed lower rates of mortality and/or morbidity from cancer and/or other diseases in exposed workers than in unexposed ones or in the general population, then suggesting the possible occurrence of hormesis. Nevertheless, these results should be considered with caution since the identification of hormetic response in epidemiological studies is rather challenging because of a number of major limitations. In this regard, some of the most remarkable shortcomings found in epidemiological studies performed in workers exposed to ionizing radiation are represented by lack or inadequate definition of exposure doses, use of surrogates of exposure, narrow dose ranges, lack of proper control groups and poor evaluation of confounding factors. Therefore, considering the valuable role and contribution that epidemiological studies might provide to the complex risk assessment and management process, there is a clear and urgent need to overcome the aforementioned limits in order to achieve an adequate, useful and more real-life risk assessment that should also include the key concept of hormesis. Thus, in the present conceptual article we also discuss and provide possible approaches to improve the capacity of epidemiological studies to identify/define the hormetic response and consequently improve the complex process of risk assessment of ionizing radiation at low exposure doses.

Cumulative Radiation Dose from Medical Imaging in Children with Congenital Heart Disease: A Systematic Review

Children with congenital heart disease are exposed to repeated medical imaging throughout their lifetime. Although the imaging contributes to their care and treatment, exposure to ionising radiation is known to increase one's lifetime attributable risk of malignancy. A systematic search of multiple databases was performed. Inclusion and exclusion criteria were applied to all relevant papers and seven were deemed acceptable for quality assessment and risk of bias assessment. The cumulative effective dose (CED) varied widely across the patient cohorts, ranging from 0.96 mSv to 53.5 mSv. However, it was evident across many of the included studies that a significant number of patients were exposed to a CED >20 mSv, the current annual occupational exposure limit. Many factors affected the dose which patients received, including age and clinical demographics. The imaging modality which contributed the most radiation dose to patients was cardiology interventional procedures. Paediatric patients with congenital heart disease are at an increased risk of receiving an elevated cumulative radiation dose across their lifetime. Further research should focus on identifying risk factors for receiving higher radiation doses, keeping track of doses, and dose optimisation where possible.

Chemical characterization of combustion engine exhaust and assessment of helicopter deck operator occupational exposures on an offshore frigate class ship

Diesel engine exhaust (DE) consists of a complex mixture of gases and aerosols, originating from sources such as engines, turbines, and power generators. It is composed of a wide range of toxic compounds ranging from constituents that are irritating to those that are carcinogenic. The purposes of this work were to characterize DE originating from different engine types on a ship operating offshore and to quantify the potential exposure of workers on the ship’s helicopter deck to select DE compounds. Sampling was conducted on a Norwegian Nansen-class frigate that included helicopter operations. Frigate engines and generators were fueled by marine diesel oil, while the helicopter engine was fueled by high flash point kerosene-type aviation fuel. Exhaust samples were collected directly from the stack of the diesel engine and one of the diesel generator exhaust stacks, inside a gas turbine exhaust stack, and at the exhaust outlet of the helicopter. To characterize the different exhaust sources, non-targeted screening of volatile and semi-volatile organic compounds was performed for multiple chemical classes. Some of the compounds detected at the sources are known irritants, such as phthalic anhydride, 2,5-dyphenyl-p-benzoquinone, styrene, cinnoline, and phenyl maleic anhydride. The exhaust from the diesel engine and diesel generator was found to contain the highest amounts of particulate matter and gaseous compounds, while the gas turbine had the lowest emissions. Personal exposure samples were collected outdoors in the breathing zone of a helicopter deck operator over nine working shifts, simultaneously with stationary measurements on the helicopter deck. Elemental carbon, nitrogen dioxide, and several volatile organic compounds are known to be present in DE, such as formaldehyde, acrolein, and phenol were specifically targeted. Measured DE exposures of the crew on the helicopter deck were variable, but less than the current European occupational exposure limits for all compounds, except elemental carbon, in which concentration varied between 0.5 and 37 µg/m3 over nine work shifts. These findings are among the first published for this type of working environment.

Dupuytren’s disease is a work-related disorder: results of a population-based cohort study

ObjectivesDupuytren’s disease (DD) is a fibroproliferative disorder of the hands, characterised by the development of fibrous nodules and cords that may cause disabling contractures of the fingers. The role of...

Changes in Infection Prevention Practices and Occurrence of Skin Symptoms among Healthcare Workers, Cleaners and Day-care Workers in Norway during the COVID-19 Pandemic

The COVID-19 pandemic has resulted in increased attention on infection prevention measures. This study aims to assess whether changes in hand hygiene procedures, use of personal protective equipment and moisturizers during the first year of the COVID-19 pandemic were associated with changes in the occurrence of skin symptoms among healthcare workers, cleaners, and day-care workers. A total of 602 participants (40%) responded to an electronic questionnaire, including questions on previous and current occupational exposure and skin problems. Increased frequency of hand washing, use of hand disinfectants, use of disposable gloves and moisturizers were all associated with an increased symptom score on the hands, wrists, forearms. Participants who increased their use of masks or respirators had a higher risk of facial skin symptoms, compared with those with non-increased occupational exposure. In conclusion, a change of behaviour among healthcare workers, cleaners and day-care workers during the first year of the COVID-19 pandemic, with an increase in occupational exposures and use of moisturizers, was associated with higher occurrence of facial skin symptoms and symptoms on the hands, wrists and forearms.

Occupational Exposure of Hairdressers to Airborne Hazardous Chemicals: A Scoping Review.

Introduction: Exposure to hazardous chemicals released during hairdressing activities from hair care products puts hairdressers at risk of adverse health effects. Safety assessments of hair products are mainly focused on consumers, but exposure for professional hairdressers might be substantially higher. Objective: To identify and assess available research data on inhalation exposures of professional hairdressers. Methods: A systematic search of studies between 1 January 2000 and 30 April 2021 was performed in Medline, Embase, Web of Science and in Cochrane registry, toxicological dossiers of the Scientific Committee on Consumer Safety (SCCS) of the European Commission as well as the German MAK Commission. Studies reporting quantitative data on airborne concentrations of chemicals in the hairdresser’s workplace were considered. The outcome was an airborne concentration of chemicals in the working environment, which was compared, when possible, with current occupational exposure limits (OEL) or guidance levels. Results: In total, 23 studies performed in 14 countries were included. The average number of hairdressing salons per study was 22 (range 1–62). Chemicals most frequently measured were formaldehyde (n = 8), ammonia (n = 5), total volatile organic compounds (TVOC) (n = 5), and toluene (n = 4). More than fifty other chemicals were measured in one to three studies, including various aromatic and aliphatic organic solvents, hydrogen peroxide, persulfate, and particulate matter. Most studies reported environmental air concentrations, while personal exposure was measured only in seven studies. The measured air concentrations of formaldehyde, ammonia, and TVOC exceeded OEL or guidance values in some studies. There was large variability in measuring conditions and reported air concentrations differed strongly within and between studies. Conclusion: Hairdressers are exposed to a wide spectrum of hazardous chemicals, often simultaneously. Airborne concentrations of pollutants depend on salon characteristics such as ventilation and the number of customers but also on used products that are often country- or client-specific. For exposure to formaldehyde, ammonia, and TVOC exceeding OELs or guidance values for indoor air was observed. Therefore, occupational exposure should be taken into account by safety regulations for hair care products.

Meta-analysis of the effect of low-level occupational benzene exposure on human peripheral blood leukocyte counts in China

To investigate the effect of low-level occupational benzene exposure on human peripheral blood leukocyte counts of the workers, domestic and foreign published research data on the change of human peripheral blood leukocyte counts under low-level occupational benzene exposure from January 1990 to December 2020 were collected and analyzed. According to the literature inclusion and exclusion criteria, 18 independent studies from 12 publications were selected for meta-analysis to explore the effect of low-level occupational benzene exposure on human peripheral blood leukocyte counts. The results showed that the peripheral blood leukocyte counts abnormal rates of low-level occupational benzene exposure group were higher than those of the control group, and the difference was statistically significant. Low-level occupational benzene exposure could result in a relatively higher abnormal rate of peripheral blood leukocyte counts in the exposed population, indicating that low-level occupational benzene exposure at workplaces specified by the current benzene occupational exposure limit in China would affect the peripheral blood leukocyte counts of the workers, thus benzene with concentrations under the limit in the ambient air of workplace could be still harmful to the health of the exposed workers. The results of this study could provide a scientific basis for future revision of the benzene occupational exposure limit in China, and could also be a reference for the formulation of environmental standard concerning benzene in China in the future.

Characterization of occupational exposure to pesticides and its impact on the health of rural women

Objective: To characterize the profile of occupational exposure to pesticides and its impact on women’s health. Method: This is a prospective and descriptive study with a quantitative approach. The study population included all patients attended at Francisco Beltrao Cancer Hospital (Ceonc) from May 2015 to December 2018 (n=315). The characterization of their exposure profile was obtained through an interview using a form applied by trained researchers contained 60 questions related to women’s pesticide exposure and their health status. The questions referred to past and current occupational pesticide exposure profile, intoxication, and health history from women and their families. All collected data were analyzed in the Statistical Package for the Social Sciences package (SPSS 25.0). Results: A total of 265 individuals (84.2%) have lived some part of their life in the countryside, and 70% were categorized as occupationally exposed to pesticides. Most of them (57%) were directly exposed, mainly by washing pesticide-contaminated clothes and personal protective equipment used in pesticide pulverization without glove protection. Cancer cases in the family were the main disease reported (68.3%). Further, 57% of interviewed women had a breast cancer diagnosis but no significance between breast cancer occurrence and pesticide exposure was observed. Conclusion: The form allowed us to characterize the profile of occupational pesticide exposition in rural women, alerting them to their severe contamination. This approach can be useful to characterize the occupational exposure profiles of rural workers living in other rural regions of Brazil that use pesticides.

Organophosphate pesticide exposure as a risk factor for attempted suicide in Cape Town, South Africa: A case-control study

Pesticides are a commonly used agent for suicide in many Low- and Middle-Income countries (LMICs). However, accumulating evidence suggests that exposure to organophosphate (OP) pesticide may also increase the risk of suicide. We conducted a hospital-based case-control study to investigate whether prior household, garden or occupational OP exposure were associated with attempted suicide using conditional logistic regression modeling. Participants who attempted suicide with any means and were admitted to two Western Cape Province hospitals in South Africa were compared to a sample of controls matched by age, sex and time of admission with unrelated conditions, between August 2015 and August 2017. The means of attempted suicide was not recorded. OP exposure was determined by dialkyl phosphate (DAP) metabolites detected in hair and by environmental and occupational history. Approximately 85% of participants reported using pesticides in the home or garden and 15% of participants reported current or past occupational exposure while working on a farm. Attempted suicide was not associated with reported home or garden OP use (Odds ratio [OR] = 0.59, 95%CI 0.33–1.04), hair DAP metabolites (OR = 1.00, 95%CI 0.98–1.02) or current or past agricultural work (OR = 1.08, 95%CI 0.62–1.87), but was associated with hazardous drinking and unemployment with no household income. We found no evidence that attempted suicide was associated with environmental or occupational pesticide use in an urban South African population attending an emergency center.

Estimation of Airborne Vapor Concentrations of Oil Dispersants COREXIT™ EC9527A and EC9500A, Volatile Components Associated with the Deepwater Horizon Oil Spill Response and Clean-up Operations.

The Deepwater Horizon (DWH) drilling unit explosion above the Macondo oil well on 20 April 2010 caused the release of approximately 4.9 million barrels (779 million L) of oil into the Gulf of Mexico. As part of a larger spill response and clean-up effort, approximately 1.84 million gallons (6.81 million L) of chemical dispersants COREXIT™ EC9500A and COREXIT™ EC9527A were applied to the resultant oil slicks through spraying on the water surface by plane and by vessel and through injection at the release source near the seabed. The GuLF STUDY is investigating the health effects of workers involved in the oil spill response and clean-up after the DWH explosion, and estimates of possible exposure to chemical dispersants were needed. Exposures were estimated to the volatile components of COREXIT™ EC9500A [petroleum distillates, hydrotreated light, and propylene glycol (PG)] and of COREXIT™ EC9527A [2-butoxyethanol (2-BE) and PG] using two of AIHA IHMOD2.0© mathematical modeling tools along with the dispersants' chemical and physical properties. Monte Carlo simulations were used to reflect uncertainty in input parameters with both the two-box, constant emission model and the near and mid field plume model for indoor and outdoor activities, respectively. Possible exposure scenarios considered various evaporation rates, sizes of the dispersant pool, wind speeds, and ventilation rates. For the two-box model, mean near field exposure estimates to 2-BE ranged from 0.9 to 5.7 ppm, while mean far field estimated exposures ranged from 0.3 to 3.5 ppm. Estimates of mean near field plume model exposures ranged from 0.01 to 3.7 ppm at 2.5 ft from the source, and <0.01 to 0.3 ppm at 10 ft from the source. Estimated exposures to PG were approximately 10% of the calculated 2-BE exposures and exposures to petroleum distillates about 40% higher than the 2-BE estimates. Results indicate that compared with current occupational exposure guidelines, overexposure to petroleum distillates and PG probably did not occur in our study, but under some conditions, for short periods, exposure to 2-BE may have exceeded the limits for peak exposures. These estimates were developed for use in job-exposure matrices to estimate exposures of workers having contact with dispersant vapors for the GuLF STUDY.

Severity of parkinsonism associated with environmental manganese exposure

BackgroundExposure to occupational manganese (Mn) is associated with neurotoxic brain injury, manifesting primarily as parkinsonism. The association between environmental Mn exposure and parkinsonism is unclear. To characterize the association between environmental Mn exposure and parkinsonism, we performed population-based sampling of residents older than 40 in Meyerton, South Africa (N = 621) in residential settlements adjacent to a large Mn smelter and in a comparable non-exposed settlement in Ethembalethu, South Africa (N = 95) in 2016–2020.MethodsA movement disorders specialist examined all participants using the Unified Parkinson Disease Rating Scale motor subsection part 3 (UPDRS3). Participants also completed an accelerometry-based kinematic test and a grooved pegboard test. We compared performance on the UPDRS3, grooved pegboard, and the accelerometry-based kinematic test between the settlements using linear regression, adjusting for covariates. We also measured airborne PM2.5-Mn in the study settlements.ResultsMean PM2.5-Mn concentration at a long-term fixed site in Meyerton was 203 ng/m3 in 2016–2017 – approximately double that measured at two other neighborhoods in Meyerton. The mean Mn concentration in Ethembalethu was ~ 20 times lower than that of the long-term Meyerton site. UPDRS3 scores were 6.6 (CI 5.2, 7.9) points higher in Meyerton than Ethembalethu residents. Mean angular velocity for finger-tapping on the accelerometry-based kinematic test was slower in Meyerton than Ethembalethu residents [dominant hand 74.9 (CI 48.7, 101.2) and non-dominant hand 82.6 (CI 55.2, 110.1) degrees/second slower]. Similarly, Meyerton residents took longer to complete the grooved pegboard, especially for the non-dominant hand (6.9, CI -2.6, 16.3 s longer).ConclusionsEnvironmental airborne Mn exposures at levels substantially lower than current occupational exposure thresholds in the United States may be associated with clinical parkinsonism.

HBM4EU chromates study - Reflection and lessons learnt from designing and undertaking a collaborative European biomonitoring study on occupational exposure to hexavalent chromium.

The EU human biomonitoring initiative, HBM4EU, aims to co-ordinate and advance human biomonitoring (HBM) across Europe. As part of HBM4EU, we presented a protocol for a multicentre study to characterize occupational exposure to hexavalent chromium (Cr(VI)) in nine European countries (HBM4EU chromates study). This study intended to collect data on current occupational exposure and to test new indicators for chromium (Cr) biomonitoring (Cr(VI) in exhaled breath condensate and Cr in red blood cells), in addition to traditional urinary total Cr analyses. Also, data from occupational hygiene samples and biomarkers of early biological effects, including genetic and epigenetic effects, was obtained, complementing the biomonitoring information. Data collection and analysis was completed, with the project findings being made separately available. As HBM4EU prepares to embark on further European wide biomonitoring studies, we considered it important to reflect on the experiences gained through our harmonised approach. Several practical aspects are highlighted for improvement in future studies, e.g., more thorough/earlier training on the implementation of standard operating procedures for field researchers, training on the use of the data entry template, as well as improved company communications. The HBM4EU chromates study team considered that the study had successfully demonstrated the feasibility of conducting a harmonised multicentre investigation able to achieve the research aims and objectives. This was largely attributable to the engaged multidisciplinary network, committed to deliver clearly understood goals. Such networks take time and investment to develop, but are priceless in terms of their ability to deliver and facilitate knowledge sharing and collaboration.

Early occupational exposure to lead on neutrophil-to-lymphocyte ratio and genotoxicity

BackgroundLead (Pb) is known to induce detrimental health effects in exposed populations, including hematotoxicity and genotoxicity. Complete blood count (CBC) is a cost-effective and easy way to determine toxicity, and variations in proportion of different types of leukocytes: neutrophil-to-lymphocyte ratio (NLR) and lymphocyte-to-monocyte ratio (LMR) are further evidence of hematotoxicity. However, few studies have been conducted to systematically evaluate effects of occupational Pb exposure on NLR and LMR, and their associations with genotoxicity. ObjectivesOur study was aimed to systematically assess the effects of current occupational Pb exposure on NLR and LMR, and their associations with genotoxicity. MethodsOur investigation was performed on 1176 workers from a newly built battery factory in North China. The workers had just entered their current job position in recent years and most of them had no previous history of occupational exposure to Pb. Blood lead levels (BLLs) and leukocytes indices were detected for all participants. Cytokinesis-blocked micronucleus assay (MN; n = 675) and alkaline comet assay (% tail DNA; n = 869) were used to assess genotoxicity. Multivariate linear and Poisson regression analyses were conducted to examine associations between leukocytes indices, genotoxic biomarkers and BLLs with adjustment for covariates. Spearman correlation and mediation analyses were used to investigate relationships between NLR and genotoxicity. ResultsAmong all the exposed workers, NLR increased with increasing BLLs. However, WBC and LMR did not change significantly. Significant and dose-dependent increases in both MN frequencies and % tail DNA were observed among groups with different exposure doses. Compared with the normal NLR group (1.48 ≤ NLR < 4.58), the high NLR group (NLR ≥ 4.58) had higher % tail DNA. In addition, there was a significant and positive association between NLR and % tail DNA among all the workers, and % tail DNA mediated 15% of the effect of Pb on increasing NLR. ConclusionOur large-scale population study shows that Pb exposure increased NLR and induced genotoxicity. There was an association between elevated NLR and DNA damage. In addition, the mediation effect of % tail DNA on the relationship between BLLs and NLR provided mechanistic evidence that certain mechanisms, e.g. inflammation, may be involved in elevation of NLR from Pb exposure. Therefore, NLR may be a convenient and sensitive biomarker for indication of Pb toxicity. Further studies are needed to validate the proposed mechanism and NLR as a biomarker.

Probabilistic pharmacokinetic modeling of airborne lead corresponding to toxicologically relevant blood lead levels in workers

The Department of Defense (DOD) commissioned the National Research Council (NRC) to assess the potential health effects associated with exposure of DOD personnel to lead (Pb) at firing ranges. In that report, NRC concluded that the current Occupational Safety and Health Administration permissible exposure limit and the blood lead levels (BLLs) on which it was based were not sufficiently protective of worker populations covered under the general industry standard. In support of future selection of an occupational exposure limit, the relationship of airborne Pb levels to BLLs is of interest to the DOD. A subset of the BLLs identified as relevant to the management of health risks of exposed workers was selected as targets for extrapolation to equivalent airborne Pb values. The existing O'Flaherty physiologically based pharmacokinetic model for Pb in humans was modified to facilitate probabilistic predictions of DOD worker population BLLs, including 95th percentile values, based on current worker characteristics. Workplace airborne Pb 8-h time-weighted average concentrations of 1.1, 4.0, 6.8, or 9.8 μg/m3 are anticipated to maintain BLLs below 5, 10, 15, or 20 μg/dl, respectively, in the vast majority of DOD workers exposed to Pb under full-time working lifetime occupational exposure.