8-hour Time-weighted Average Research Articles

Noise-Induced Hearing Loss: Should Surgeons Be Wearing Ear Protection During Primary Total Joint Arthroplasty?

The risk of noise-induced hearing loss (NIHL) to orthopedic surgeons due to occupational exposures is unknown. A level of 85 decibels (dB) over an 8-hour time-weighted average (TWA) is considered hazardous. We sought to identify whether manual and/or robotic arthroplasty procedures increase surgeons' risk of developing NIHL. At our institution, we prospectively collected intraoperative recordings with a microphone attached to the surgeon during manual total knee arthroplasty (TKA), manual total hip arthroplasty (THA), and robotic-assisted total knee arthroplasty (RTKA). Recordings taken in the operating room without operating room staff present served as baseline controls. The 172 recordings consisted of 46 baseline, 42 THA, 40 TKA, and 44 RTKA recordings. Decibel levels were reported as "maximum dB level" (the highest sound pressure level using an A-weighted dB scale), "LAeq" (the equivalent continuous sound level), "LCpeak" (the peak sound pressure level using a C-weighted dB scale), and "TWA" (the average dB level projected over an 8-hour period). The percentage of allowable daily noise dose was reported as "dose" and the measured dose projected over 8 hours as "projected dose." The recordings of surgeries had average maximum dB levels ranging from 106.0 to 108.0 dB, all significantly greater than controls. Robotic-assisted total knee arthroplasties had the highest average dose (18.7%) and average projected dose (252.0%). Our review of recordings at a single institution found that noise levels of RTKAs surpassed projected doses of 100%. Orthopedic surgeons performing more than 2 RTKAs per day may be at increased risk of NIHL. Further research is needed to assess the effectiveness of measures such as ear protection to minimize surgeons' exposure.

Noise exposure assessment of workers inspecting construction machinery vehicles in the Republic of Korea.

Previous studies have investigated the health hazards caused by exposure to the noise of heavy equipment used at construction sites. Korea's Ministry of Land, Infrastructure, and Transport operates a registration system for construction machinery, and regular safety inspections are mandatory. Although workers inspecting construction machinery vehicles are exposed to unwanted noise, no noise exposure assessment has been made regarding these workers in Korea. The time-weighted average (TWA) daily average noise exposure level among construction machinery inspectors at 18 inspection centers was 75.3 dB(A). Among the inspection steps, the exhaust gas inspection step was found to exhibit the highest noise exposure level, up to 100 dB(A). In Korea, if the noise level of a workplace exceeds 85 dB(A) as a TWA, workers are required to undergo special medical examinations. This study found that special medical examinations were required for two of the 18 target inspection centers (approximately 115 workers) as the 8-hour TWA noise level exceeded 85 dB(A). Therefore, regular noise exposure assessment and special medical examinations for noise are required to prevent inspectors from developing hearing disorders due to noise exposure.

Observational study on occupational exposure of dairy farmers to formaldehyde

ObjectivesTo provide insights into exposure of Dutch dairy farmers to formaldehyde derived from formalin footbaths used for cows. Dutch safety norms are set at a limit of 0.122 ppm during...

Noise exposure in pediatric otolaryngology clinic: A sound survey of a single-institution tertiary care facility

BackgroundThe Occupational Safety and Health Administration (OSHA) considers acoustic exposure of 90 decibels (dB) an occupational risk for noise-induced hearing loss. Pediatric healthcare clinicians are exposed to considerable noise especially during invasive procedures, predisposing them to noise-induced hearing loss, increased work-related stress, and increased complications associated with intense noise exposure. While there has been extensive research in noise exposure in dentistry, to date there has been no research on noise exposure in the pediatric otolaryngology clinic setting. The objective of this study is to quantify the degree of noise exposure that pediatric otolaryngologists encounter in the clinical setting. MethodsA sound survey was performed of 420 pediatric otolaryngology clinic visits within a single-institution tertiary care facility from January 2022 to March 2022, with a total of 409 visits included. At each visit, noise was measured using a calibrated National Institute for Occupational Safety and Health (NIOSH) Sound Meter application, an iPad, and a microphone. The Equivalent Continuous Sound Pressure Level (LAeq), peak sound pressure level (SPL), C-weighted peak noise level (LCpeak), and the 8-hour time-weighted average (TWA) sound level were recorded. ResultsThe average LAeq was 61.1 dB, the median LAeq was 60.3 dB, and the average peak SPL was 80.5 dB. Only 0.5 % of visits reached an LAeq above 80 dB, however, 51 % were above 60 dB and 99 % were above 45 dB. No clinicians were exposed to noise exceeding established limits of safety. Patients younger than ten years old (p < 0.001) and those who underwent procedures such as cerumen removal (p < 0.001) elicited higher ranges of elevated noise. Multivariate analysis confirmed that increased age decreased acoustic exposure while procedures increased acoustic exposure. ConclusionsThe results of this study suggest that pediatric otolaryngology clinicians do not exceed hazardous noise limit exposure. However, they are exposed to levels above those which have been linked to stress, poor productivity, and stress-related disorders. This analysis also reports that patients who are younger and those that undergo procedures, specifically cerumen removal, tend to expose their providers to the highest levels of noise. This is the first study examining noise exposure in pediatric otolaryngology, and further research should evaluate the risks of noise exposure in this environment.

Assessment of semen quality of taxi drivers exposed to whole body vibration

Whole body vibration (WBV) is a recognized occupational hazard for many workers such as drivers and operators of heavy and light machinery and exposure to it is accompanied by physical and mental repercussions. Only the limited studies have been done on the effects of vibration exposure on reproductive indices, however vibration exposure has been indicated as being a hazardous agents with the potential of being able to directly affect the reproductive system. Considering the importance of infertility, the present study was conducted with the aim of investigating semen quality among taxi drivers in Tehran and determine the effect of exposure to WBV on sperm parameters. The study population consisted of 70 taxi drivers and 70 office employee who attended infertility clinics for diagnostic purposes in the past year. The participants had to meet the entry criteria of the study while also being willing to recruit. Data was collected in the form of demographic questionnaires and general health questionnaires as well as sperm analysis conducted in an infertility clinic according to standard laboratory guidelines. The 8-hour time-weighted average (TWA) exposure to of WBV in automobile was measured as per ISO 2631-1. The TWA exposure to WBV among the taxi drivers and office employees were 0.697 ± 0.13 m/s2 and 0.068 ± 0.09 m/s2 respectively (P < 0.05). A statistically significant difference in total sperm count, progressive motility, non-progressive motility and total motility was observed between the taxi drivers and the office employees (P < 0.05). According to the univariate analysis of variance, exposure to WBV had negative effect on sperm concentration, progressive motility and normal morphology (P > 0.05); moreover exposure to WBV resulted in the larger effect size (B) on sperm parameters than the demographic variables (P > 0.05). Being taxi drivers increase the chance of the decreased semen quality (P > 0.05). It is difficult to draw definitive conclusions regarding the effects of WBV while intervening factors exist, such as psychological stressors, quality of sleep, background issues as well as environmental factors such as chemical pollutants (heavy metals) or ergonomic factors (body posture and working while sitting down).

Quantifying Farmers’ Exposure to Corn and Soybean Dust in On-Farm Grain Storage Bins

HighlightsOn-farm samples were used to analyze farmers’ exposure to dust while cleaning and unloading their grain bins.Over 18% of samples exceeded the 8-hour time-weighted average (TWA) concentration recommended by ACGIH for respirable dust, and over 27% of samples exceeded the ACGIH recommendation for total suspended particles.The results strengthen the need for relevant agricultural safety education programs to help farm workers understand the health hazards associated with grain dust.Abstract. Grain dust consists of grain particles, insect parts, silica, bacteria, fungi, and mycotoxins. The size of these airborne particulates is a concern because they can become deeply lodged in the respiratory tract. Exposure to grain dust can diminish overall lung function and lead to respiratory diseases such as asthma, chronic obstructive pulmonary disease (COPD), organic dust toxic syndrome (ODTS), chronic bronchitis, and hypersensitivity pneumonitis (farmer’s lung). Grain storage and handling facilities are primary work locations with high levels of grain dust concentrations. The objective of this study was to understand farmers’ exposure to grain dust while cleaning and unloading their grain bins. During on-farm dust sampling, researchers visited farms to collect dust samples for analysis. Two types of samples were taken. Integrated samples provided average concentrations of total dust and respirable dust while farmers performed their normal tasks in the grain bin. Real-time samples provided instantaneous concentrations of respirable dust (RESP) and total suspended particles (TSP) and how the variations changed during the farmers’ working periods. From the data collected in corn storage bins, RESP concentrations ranged from 4.1 to 6.6 mg m-3, and TSP concentrations ranged from 33 to 70.7 mg m-3. From the data collected in soybean storage bins, RESP concentrations ranged from 1.6 to 82.3 mg m-3, and TSP concentrations ranged from 8.9 to 146.8 mg m-3. Based on the calculated 8-hour time-weighted average (TWA) concentration of all samples, 18.2% of the 8-hour TWA RESP concentrations exceeded the ACGIH-recommended respirable dust concentration of 3 mg m-3, and 27.3% of the 8-hour TWA TSP concentrations exceeded the ACGIH-recommended total dust concentration of 610 mg m-3. The results strengthen the need for relevant agricultural safety education programs to help farm workers understand the health hazards associated with grain dust. Keywords: Grain dust concentrations, Occupational health, On-farm grain storage bins.

Evaluation of Airborne Asbestos Concentrations Associated with the Operation and Maintenance of Brakes and Clutches on Nonautomated Heavy Equipment.

This study evaluated the potential for chrysotile asbestos exposure during maintenance and operation of older, nonautomated heavy equipment with chrysotile-containing brake and clutch linings. Recent reports indicate that such equipment may be in current use in the U.S. and other locations, including developing countries, due to its lower cost and ease of maintenance compared to newer equipment. Personal and area airborne fiber concentrations were measured for cranes with draglines during brake and clutch repair, equipment operation, shop cleanup, and clothes handling of the mechanic's coveralls over a period of three days. The range of airborne chrysotile concentrations during the complete friction band replacement process, including band removal from the equipment, friction lining replacement, and reinstallation, ranged from 0.0053 to 0.0273 f/cc (phase contrast microscopy-equivalent or PCME) over 3.3 to 6.2 hours. Additional bench work tasks, including electric wire brushing, hand sanding, riveting, and compressed air use were also performed. Full shift airborne chrysotile concentrations (6.1–8.5 hours) for all combined maintenance activities were 0.0093, 0.0414, and 0.0445 f/cc (PCME), on days 1, 2, and 3, respectively. Personal short-term samples (14–36 minutes) for lining removal, installation, wire brushing, hand sanding, and compressed air use ranged from nondetect (ND) to 0.238 f/cc (PCME), below the U.S. Occupational Safety and Health Administration's (OSHA's) 30-minute excursion limit of 1 f/cc. Short-term samples during crane operation, shop cleanup, and simulated laundry activities with the mechanic's coveralls ranged from ND to 0.01 f/cc (PCME; 15–36 minutes). The results indicated that full-shift measured airborne chrysotile concentrations during the brake and clutch maintenance activities evaluated remained below the U.S. 8-hour time-weighted average (TWA) permissible exposure limit (PEL) for asbestos of 0.1 f/cc. The results are likely to be relevant to farmers, construction workers, and vehicle maintenance workers historically, as well as today for those who choose to continue using and maintaining such equipment.

Objective Measurement of Listening Device Use and Its Relation to Hearing Acuity.

ObjectivesTo examine whether adolescents exceed recommended noise exposure limits when using personal listening devices (PLDs) and to investigate the relationship between objectively measured PLD use and hearing thresholdsStudy DesignCross-sectional study.SettingThis study was embedded within an ongoing prospective birth cohort study in Rotterdam, the Netherlands. Data were collected from May 2017 to September 2019.MethodsA smartphone application was developed to measure daily noise exposure from PLDs. Listening habits were monitored among 314 adolescents with a mean age of 13 years 7 months (SD, 5 months), of whom 51.6% were male. Hearing acuity was measured by pure tone audiometry, and tympanometry was performed in both ears.ResultsWithin the study group, 2.2% adolescents exceeded the recommended daily noise dose (85 dBA as an 8-hour time-weighted average) among all days when the application was active and 9.9% when among only the listening days. No significant correlation was found between the daily noise dose from PLDs and pure tone thresholds.ConclusionsThe majority of adolescents exhibited listening habits that could be considered safe. As noise-induced hearing loss develops slowly over time, it could be that the effects of PLD use on hearing are not evident yet in this young population with a relatively short duration of PLD use.

Real-time air monitoring of occupational exposures to particulate matter among hairdressers in Maryland: A pilot study.

Hairdressers are exposed to particulate matter (PM), a known air pollutant linked to adverse health effects. Still, studies on occupational PM exposures in hair salons are sparse. We characterized indoor air PM concentrations in three salons primarily serving an African/African American (AA) clientele, and three Dominican salons primarily serving a Latino clientele. We also assessed the performance of low-cost sensors (uRAD, Flow, AirVisual) by comparing them to high-end sensors (DustTrak) to conduct air monitoring in each salon over 3days to quantify work shift concentrations of PM2.5 , respirable PM (RPM), and PM10 . We observed high spatial and temporal variability in 30-min time-weighted average (TWA) RPM concentrations (0.18-5518μg/m3 ). Readings for the uRAD and AirVisual sensors were highly correlated with the DustTrak (R2 =0.90-0.99). RPM 8-hour TWAs ranged from 18 to 383µg/m3 for AA salons, and 9-2115µg/m3 for Dominican salons. Upper 95th percentiles of daily RPM exposures ranged from 439 to 2669µg/m3 . The overall range of 30-min TWA PM2.5 and PM10 concentrations was 0.13-5497 and 0.36-,541μg/m3 , respectively. Findings suggest that hairdressers could be overexposed to RPM during an 8-hour shift. Additional comprehensive monitoring studies are warranted to further characterize temporal and spatial variability of PM exposures in this understudied occupational population.

Noise Exposure Monitoring on the Segmental Box Girder Casting Process from a Concrete Casting Yard

Noise exposure monitoring is essential to assess noise exposure circumstances and provide a noise control plan to minimize noise exposure problems in the workplace. In Malaysia, occupational noise exposure problems have been increasing, especially in the construction industry. Hence, this study aims to investigate the noise exposure problem in a construction casting yard in Malaysia. The objectives of the study were to measure the current occupational noise exposure problem and to propose a noise control action. Field measurement was carried out at a segmented box girder casting yard under the Mass Rapid Transit (MRT) construction project in Selangor, Malaysia. A total of six case studies from four different construction trades had been conducted. This study plotted noise maps and measured personal noise exposure levels for the three construction trades. The results showed that the equivalent sound level exceeded the action level of 85 dBA for these trades. Besides, the bar cutting trade with an 8-hour time-weighted average of 92.3 dBA exceeded the permissible exposure limit of 90 dBA. The noise reduction rating of the hearing protection device was evaluated, and appropriate noise control action was proposed. The proposed noise reduction rating was 32 dBA, so it is expected to reduce the time-weighted average sound level below 80 dBA for this workplace. In conclusion, the results could disseminate to construction workers to raise their risk awareness regarding the noise exposure issue in the workplace. The noise mapping information could also be used for the design of the engineering control to reduce the noise exposure level in the construction workplace.

Neurobehavioral Effects of Organic Solvents Exposure Among Wood Furniture Makers in Ile-Ife, Osun State, Southwestern Nigeria.

Furniture making industries are small scale businesses that commonly use organic solvents. There has been minimal focus on the health effects of this chemical hazard on the nervous system among furniture makers in Nigeria. The present study aimed to assess the association between organic solvents exposure and neurobehavioral status of furniture makers, using electronic technicians as a comparison group. A comparative cross-sectional study design was employed. A sample size of 108 was calculated for each group. A semi-structured interviewer-administered questionnaire was used to obtain data on the socio-demographic variables and use of personal protective equipment (PPE). A proforma was developed to collect neurobehavioral assessment data. A checklist was used to assess the furniture makers' workshops. Air was sampled from all of the workshops in both the study and comparison groups to determine the concentration of total volatile organic compounds (TVOCs). The use of PPE was poor in both the study and comparison groups, with no significant difference between them (34.4% and 37.7% respectively). Total volatile organic compound and formaldehyde (HCHO) concentrations were significantly higher at the furniture makers' workshops compared with electronic technicians (p<0.001) for both chemicals. The 8-hour time-weighted average of TVOC was also higher in the furniture makers' workshops (4.4±0.6 mg/m3) compared with the control group (0.3±0.3 mg/m3). The neurobehavioral symptoms score was significantly higher among the study group relative to the comparison group (p<0.001). There was a significant difference in the outcome of the auditory verbal learning test, total recall (p=0.005), and delayed recall (p=0.003). There was no significant association between solvent exposure index and findings from the simple reaction time test. Poor compliance with the use of PPE among furniture makers may increase their exposure to organic solvents. There were more neurobehavioral changes in the furniture makers with a higher exposure index. Measures are needed to educate artisans about workrelated chemical hazards and ensure compliance with basic occupational safety and hygiene standards. Obtained. Ethics approval was obtained from the Health Research and Ethics Committee of the Institute of Public Health, Obafemi Awolowo University (IPH/OAU/12/1049). The authors declare no competing financial interests.

Alterations in immune and renal biomarkers among workers occupationally exposed to low levels of trichloroethylene below current regulatory standards

ObjectivesThe occupational exposure limit for trichloroethylene (TCE) in different countries varies from 1 to 100 ppm as an 8-hour time-weighted average (TWA). Many countries currently use 10 ppm as the...

Derivation of an occupational exposure limit for diacetyl using dose-response data from a chronic animal inhalation exposure study.

Occupational exposure limits (OELs) have been previously proposed for diacetyl; however, most of these values are based on worker cohort studies that are known to have several limitations and confounders. In this analysis, an 8hour time-weighted average (TWA) OEL for diacetyl was derived based on data from a chronic, 2year animal inhalation study recently released by the US National Toxicology Program. In that study, complete histopathology was conducted on male and female mice and rats exposed to 0, 12.5, 25 or 50ppm diacetyl. Several responses in the lower respiratory tract of rats (the more sensitive species) were chosen as the critical endpoints of interest. Benchmark concentration (BMC) modeling of these endpoints was used to estimate BMC values associated with a 10% extra risk (BMC10 ) and the associated 95% lower confidence bound (BMCL10 ), which were subsequently converted to human equivalent concentrations (HECs) using a computational fluid dynamics-physiologically based pharmacokinetic (CFD-PBPK) model to account for interspecies dosimetry differences. A composite uncertainty factor of 8.0 was applied to the human equivalent concentration values to yield 8hour TWA OEL values with a range of 0.16-0.70ppm. The recommended 8hour TWA OEL for diacetyl vapor of 0.2ppm, based on minimal severity of bronchiolar epithelial hyperplasia in the rat, is practical and health-protective.

3-Nitro-1,2,4-triazol-5-one (2014).

3-Nitro-1,2,4-triazol-5-one (NTO) is a potential replacement for energetics in military munitions. It is a component of IMX-101, a munition designed to prevent unintentional detonation. This report summarizes the dermal, oral, and inhalation animal toxicity data, including the results of genotoxicity and limited reproductive and developmental studies. NTO has an acute LD50 in rats and mice of >5000 mg/kg, is a potential eye and skin irritant, but does not induce skin sensitization. Acute inhalation toxicity studies in rats were negative, but testicular hypoplasia was observed in a 14-day oral study in rats administered NTO at >500 mg/kg/day. Similar findings were noted in an oral 90-day study at dosages >315 mg/kg/day and in reproductive toxicity studies at >125 mg/kg/day. NTO did not cause any developmental defects. All genotoxicity studies were negative. ADME and pharmacokinetics data showed rapid uptake and elimination of NTO from both inhalation and oral intakes. Biotransformation by liver microsomes demonstrated two separate pathways, one aerobic and the other anaerobic. NTO is not considered an endocrine disruptor. There is very little human data regarding NTO or the IMX-101 mixtures. Using testicular changes in rats as the point of departure for deriving a Workplace Environmental Exposure Level (WEEL) for NTO, the resulting BMDL10 was 40 mg/kg/day, and the 8-hour time-weighted average was 2 mg/m2.

OCCUPATIONAL EXPOSURE AND WORK PRACTICES AMONG ETHYLENE OXIDE STERILIZATION WORKERS

Introduction: Ethylene Oxide (EtO) is a colorless flammable, gas or liquid. In the health care setting, EtO is commonly used for sterilizing heat- and moisture-sensitive medical equipment to prevent health-care associated infections. Aim of work: To assess the Ethylene Oxide (EtO) occupational exposure and work practices among the EtO sterilization workers. Materials and methods: This study included 28 hospital EtO sterilization workers and 32 controls, all of them filled self-administered questionnaire including questions on their demographic characteristics, work experience, and associated symptoms with special attention to pulmonary, digestive, neurologic, hematologic, reproductive, dermatologic and ophthalmologic symptoms. Liver, kidney and ventilatory function tests were carried out for all participants. Work practices of the EtO sterilization workers were assessed. Moreover, EtO 8-hour time weighted average (TWA) and short term 15 minutes personal monitoring were measured. Results: Both 8- hour TWA and short term 15 minutes personal monitoring of the EtO sterilization workers were below the OSHA recommended EtO levels and proper work practices were followed by the workers but 30% of them were not fit tested for respirators use. The study revealed insignificant difference between the EtO sterilization workers and the controls concerning clinical symptoms, liver, kidney and ventilatory function tests. However, the mean of the white blood cells and the lymphocytes absolute numbers were higher among EtO sterilization workers compared to that of the controls, but within the normal range. Conclusion: Routine monitoring of EtO sterilizers; training, proper work practices and periodic medical evaluation of the EtO sterilization workers are important preventive measures to protect them from the harmful effects of EtO. Further research is recommended to study the health effects of EtO exposure at levels below the OSHA 8-hour TWA for EtO

The Relations between Polycyclic Aromatic Hydrocarbons Exposure and 1-OHP Levels as a Biomarker of the Exposure.

Polycyclic aromatic hydrocarbons (PAHs) are the products of incomplete combustion or pyrolysis of various organic materials. Their ubiquity in the environment leads to measurable levels of exposure. However, the exposure varies strongly between different regions in Europe. Some PAHs with four or more rings are suspected to be human carcinogens. Therefore, the occupational and/or environmental exposure to PAHs may cause a significant health risk. The aim of the study was to evaluate current levels of PAH exposure in defined groups of workers. The industrial sites selected in this survey involved PAHs originating from coal tar pitch, carbon black, bitumen, and rubber fumes. Based on the historical data, the sites were expected to exhibit quantifiable levels of exposure to PAHs. The total study population consisted of 139 persons: 108 workers (85 males and 23 females) workers were occupationally exposed in aluminium production, the production of graphite electrodes, road construction, or the rubber forming industry and 31 control individuals in two groups. The highest concentrations – 8-hour time-weighted average (TWA) levels (sum of 16 components according to the EPA list), as expected, were found in the aluminium production plant (55.15 µg.m−3) and production of graphite electrodes (54.25 µg.m−3). The lowest concentrations were found in personal air samples of road construction workers (1.93 µg.m−3). The concentrations of 1-hydroxypyrene as a pyrene metabolite (1-OHP) in the urine of the exposed group of workers were found in levels 0.74 µmol.mol−1 creatinine before the exposure and 2.27 µmol.mol−1 creatinine after the exposure (arithmetic mean values). 1-OHP concentrations in post-shift urine samples were highly correlated with the total airborne PAHs concentrations and pyrene concentrations in air. The correlation coefficients (rS) between 1-OHP concentration and pyrene or total PAHs in air were 0.710 and 0.752 (p < 0.05). This statistical analysis confirmed the effect of the occupational exposure to PAHs and pyrene on body burden in workers. However, a modifying effect of gender, smoking habits, dietary intake, genetically modified metabolism, and the use of medication on the toxicokinetics of pyrene was not determined as significant. Based on the results a strong correlation between the concentration of 1-OHP in urine as an exposure biomarker and the concentration of pyrene or PAH was affirmed.

High pressure air jet in the endoscopic preparation room: risk of noise exposure on occupational health.

After high-level disinfection of gastrointestinal endoscopes, they are hung to dry in order to prevent residual water droplets impact on patient health. To allow for quick drying and clinical reuse, some endoscopic units use a high pressure air jet (HPAJ) to remove the water droplets on the endoscopes. The purpose of this study was to evaluate the excessive noise exposure with the use of HPAJ in endoscopic preparation room and to investigate the risk to occupational health. Noise assessment was taken during 7 automatic endoscopic reprocessors (AERs) and combined with/without HPAJ use over an 8-hour time-weighted average (TWA). Analytical procedures of the NIOSH and the ISO for noise-induced hearing loss were estimated to develop analytic models. The peak of the noise spectrum of combined HPAJ and 7 AERs was significantly higher than that of the 7 AERs alone (108.3 ± 1.36 versus 69.3 ± 3.93 dBA, P < 0.0001). The risk of hearing loss (HL > 2.5 dB) was 2.15% at 90 dBA, 11.6% at 95 dBA, and 51.3% at 100 dBA. The odds ratio was 49.1 (95% CI: 11.9 to 203.6). The noise generated by the HPAJ to work over TWA seriously affected the occupational health and safety of those working in an endoscopic preparation room.

Noise Exposure Assessment in a Dental School

ObjectivesThis cross-sectional study was performed in the Dental School of Prince of Songkla University to ascertain noise exposure of dentists, dental assistants, and laboratory technicians. A noise spectral analysis was taken to illustrate the spectra of dental devices.MethodsA noise evaluation was performed to measure the noise level at dental clinics and one dental laboratory from May to December 2010. Noise spectral data of dental devices were taken during dental practices at the dental services clinic and at the dental laboratory. A noise dosimeter was set following the Occupational Safety and Health Administration criteria and then attached to the subjects' collar to record personal noise dose exposure during working periods.ResultsThe peaks of the noise spectrum of dental instruments were at 1,000, 4,000, and 8,000 Hz which depended on the type of instrument. The differences in working areas and job positions had an influence on the level of noise exposure (p < 0.01). Noise measurement in the personal hearing zone found that the laboratory technicians were exposed to the highest impulsive noise levels (137.1 dBC). The dentists and dental assistants who worked at a pedodontic clinic had the highest percent noise dose (4.60 ± 3.59%). In the working areas, the 8-hour time-weighted average of noise levels ranged between 49.7-58.1 dBA while the noisiest working area was the dental laboratory.ConclusionDental personnel are exposed to noise intensities lower than occupational exposure limits. Therefore, these dental personnel may not experience a noise-induced hearing loss.

Parental Exposure to Bisphenol A During Pregnancy and the Anogenital Distance of Male Offspring

PP-29-087 Background/Aims: Bisphenol A (BPA), an endocrine disruptor with both estrogenic and antiandrogenic effects, has been found to have widespread human exposure. The effect of prenatal exposure to BPA on offspring in human beings remains largely unknown. We examined the association between parental occupational exposure to BPA during pregnancy and anogenital distance (AGD), an androgen sensitive endpoint, in male offspring. Methods: Boys from families in which parent(s) did or did not have occupational exposure to BPA were examined. Their AGDs were measured during a physical examination. Parental BPA exposure level during the index pregnancy was measured by TWA8 (8-hour time-weighted average) derived from personal air measurement and employment history. Results: A total of 153 boys were included in the final analysis. After controlling for boys' ages and weights using linear regression, parental occupational exposure to BPA during pregnancy was associated with decreased AGD in male offspring with a dose-response relationship: compared to boys from unexposed families, coefficient (β) for AGD associated with occupational exposure to BPA were −2.74, −3.27, −5.77, −10.89, and −11.91 for the boys from families with paternal low TWA8, paternal high TWA8, maternal low TWA8, maternal high TWA8, and parental both exposed, respectively (trend test: P < 0.01). Conclusion: Our findings provide the first epidemiologic evidence that prenatal BPA exposure may be associated with shortened AGD in male offspring, indicating a potential disturbing interference of BPA with the development of fetal reproductive systems. This finding has important public health implications because of ubiquitous BPA exposure.

Preliminary study: Formaldehyde exposure in laboratories of Sharjah university in UAE

ObjectivesLaboratory technicians, students, and instructors are at high risk, because they deal with chemicals including formaldehyde. Thus, this preliminary study was conducted to measure the concentration of formaldehyde in the laboratories of the University of Sharjah in UAE.Materials and Methods:Thirty-two air samples were collected and analyzed for formaldehyde using National Institute for Occupational Safety and Health (NIOSH) method 3500. In this method, formaldehyde reacts with chromotropic acid in the presence of sulfuric acid to form a colored solution. The absorbance of the colored solution is read in spectrophotometer at wavelength 580 nm and is proportional to the quantity of the formaldehyde in the solution.Results:For the anatomy laboratory and in the presence of the covered cadaver, the mean concentration of formaldehyde was found to be 0.100 ppm with a range of 0.095–0.105 ppm. Whereas for the other laboratories, the highest mean concentration of formaldehyde was 0.024 ppm in the general microbiology laboratory and the lowest mean concentration of formaldehyde was 0.001 ppm in the environmental health laboratory. The 8-hour (time-weighted average) concentration of formaldehyde was found to be ranging between 0.0003 ppm in environmental health laboratory and 0.026 ppm in the anatomy laboratory.Conclusions:The highest level of concentration of formaldehyde in the presence of the covered cadaver in anatomy laboratory exceeded the recommended ceiling standard established by USA-NIOSH which is 0.1 ppm, but below the ceiling standard established by American Conference of Governmental Industrial Hygienists which is 0.3 ppm. Thus, it is recommended that formaldehyde levels should be measured periodically specially during the dissection in the anatomy laboratory, and local exhaust ventilation system should be installed and personal protective equipment such as safety glass and gloves should be available and be used to prevent direct skin or eye contact.