Peter B. Shaw

1-Pyrenol: A biomarker for occupational exposure to polycyclic aromatic hydrocarbons

Abstract A biological monitoring method using the major urinary metabolite of pyrene, 1-pyrenol, has been successfully used to assess the exposure of aluminum reduction plant workers to coal tar pitch-derived polycyclic aromatic hydrocarbons (PAHs). The method used high-performance liquid chromatography with a fluorescence detector. The net mean change between workers pre- and postshift urinary 1-pyrenol concentrations was seventeenfold greater than the net mean change found in controls. The data strongly indicated that the net change in urinary 1-pyrenol concentration in workers was greater than found in controls. Evidence for an effect due to smoking in this context was negligible. The data show a strong positive correlation between environmental pyrene and all 17 environmental PAHs that were analyzed and urinary 1-pyrenol, verifying that pyrene was an appropriate choice to use as a marker for coal tar pitch-derived PAHs.

Alternative Field Methods for Measuring Hearing Protector Performance

In comparison with the mandatory noise reduction rating (NRR) testing of every hearing protector sold in the United States, real-world tests of hearing protector attenuation are scarce. This study evaluated data from three potential field-test methods as compared with the subject-fit data from Method B of ANSI S12.6-1997 for the E.A.R(R) Express trade mark Pod Plug trade mark. The new field-test methods were the FitCheck headphone (FCH) method, FitCheck in sound field (FCSF) method, and bone-conduction loudness balance (BCLB) method, all of which can be administered in small single-person audiometric booths such as are commonly found in industry. Twenty normal-hearing and audiometrically competent subjects naive to hearing protector use were tested with the laboratory and the three field-test methods in a repeated-measures design. Repeated-measures models with structured covariance matrices were used to analyze the data. Significant effects were found for method, frequency, and first-order frequency-by-gender and frequency-by-method interactions. These effects and interactions were expected given the different psychophysical tasks. The FCSF and BCLB methods provided attenuations that were not significantly different from those found with Method B. Although the attenuations measured for the FCH method were statistically different (greater) than the attenuations from the other methods, the differences were within the magnitude of acceptable test-retest audiometric variability. The results suggest that the FCH and FCSF methods were both feasible and reliable methods for field testing. The FCH method is limited to testing earplugs, and the FCSF requires additional equipment to outfit the test booth, but could be used for testing all types of protectors.

Evaluation of smartphone sound measurement applications (apps) using external microphones—A follow-up study

This follow-up study examines the accuracy of selected smartphone sound measurement applications (apps) using external calibrated microphones. The initial study examined 192 apps on the iOS and Android platforms and found four iOS apps with mean differences of ±2 dB of a reference sound level measurement system. This study evaluated the same four apps using external microphones. The results showed measurements within ±1 dB of the reference. This study suggests that using external calibrated microphones greatly improves the overall accuracy and precision of smartphone sound measurements, and removes much of the variability and limitations associated with the built-in smartphone microphones.

Interactions of radiofrequency radiation on 2-methoxyethanol teratogenicity in rats.

Concurrent exposures to chemical and physical agents occur in the workplace; exposed workers include those involved with the microelectronics industry, plastic sealers and electrosurgical units. Previous animal research indicates that hyperthermia induced by an elevation in ambient temperature can potentiate the toxicity and teratogenicity of some chemical agents. We previously demonstrated that combined exposure to radiofrequency (r.f.; 10 MHz) radiation, which also induces hyperthermia and is teratogenic to exposed animals, and the industrial solvent 2‐methoxyethanol (2ME) produces enhanced teratogenicity in rats. A subsequent study replicated and extended that research by investigating the interactive dose‐related teratogenicity of r.f. radiation (sham exposure or maintaining colonic temperatures at 42.0°C for 0, 10, 20 or 30 min by r.f. radiation absorption) and 2ME (0, 75, 100, 125 or 150 mg/kg) on gestation days 9 or 13 of rats. The purpose of the present research is to determine the effects of r.f. radiation (sufficient to maintain colonic temperatures at 42.0°C for 10 min) on a range of doses of 2ME (0, 20, 40, 60, 80, 100, 120 and 140 mg kg−1) administered on gestation day 13 of rats. Focusing on characterizing the dose–response pattern of interactions, this research seeks to determine the lowest interactive effect level. Day 20 fetuses were examined for external and skeletal malformations. The results are consistent with previous observations. Dose‐related developmental toxicity was observed for 2ME both in the presence and absence of r.f. radiation. However, concurrent RF radiation exposure changed the shape of the dose–effect curve of 2ME. These data indicate that combined exposure effects should be considered when developing exposure guidelines and intervention strategies. © 1997 by John Wiley & Sons, Ltd.

Hearing loss prevention for carpenters: part 2 - demonstration projects using individualized and group training.

Two demonstration projects were conducted to evaluate the effectiveness of a comprehensive training program for carpenters. This training was paired with audiometry and counseling and a survey of attitudes and beliefs in hearing loss prevention. All participants received hearing tests, multimedia instruction on occupational noise exposure/hearing loss, and instruction and practice in using a diverse selection of hearing protection devices (HPDs). A total of 103 apprentice carpenters participated in the Year 1 training, were given a large supply of these HPDs, and instructions on how to get additional free supplies if they ran out during the 1-year interval between initial and follow-up training. Forty-two participants responded to the survey a second time a year later and completed the Year 2 training. Significant test-retest differences were found between the pre-training and the post-training survey scores. Both forms of instruction (individual versus group) produced equivalent outcomes. The results indicated that training was able to bring all apprentice participants up to the same desired level with regard to attitudes, beliefs, and behavioral intentions to use hearing protection properly. It was concluded that the health communication models used to develop the educational and training materials for this effort were extremely effective.

Relationship between comfort and attenuation measurements for two types of earplugs.

Noise-induced hearing loss is almost always preventable if properly fitted hearing protectors are worn to reduce exposure. Many individuals choose not to wear hearing protection because it may interfere with effective communication in the workplace or it may be uncomfortable. Hearing protector comfort has not received the same amount of attention as noise reduction capability. The present study was conducted to evaluate the comfort level of two different types of insert earplugs as well as the attenuation levels achieved by the earplugs. Attenuation levels were obtained with a commercially available earplug fit-test system, and the comfort ratings were obtained by questionnaire. The primary research objective was to determine whether hearing protector comfort was related to measured attenuation values. A linear mixed effects model provided evidence for an inverse relationship between comfort and attenuation.

Developmental toxicity interactions of salicylic acid and radiofrequency radiation or 2-methoxyethanol in rats.

Radiofrequency (RF) radiation is used in a variety of workplaces where workers are concurrently exposed to chemicals. Combined exposure to RF radiation (10 MHz) and the industrial solvent, 2-methoxyethanol (2ME), produces enhanced teratogenicity in rats. The purpose of the present research was to determine if the synergistic effects noted for RF radiation and 2ME are generalizable to other chemicals. Since salicylic acid (SA) is widely used as an analgesic and is teratogenic in animals, SA was selected to address generalizability. Based on the literature and our pilot studies, 0, 250, or 350 mg/kg SA were administered by gavage on gestation Day 9 or 13 to rats. Concurrently rats given SA on Day 9 were exposed to RF radiation sufficient to maintain colonic temperature at 41 degrees C for 60 min (or sham). Those given SA on Day 13 were also given 0 or 100 mg/kg 2ME (gavage). Dams were sacrificed on gestation Day 20, and the fetuses were examined for external malformations. The data provide no evidence of synergistic interactions between RF radiation and salicylic acid (resorptions and malformations). Limited evidence of antagonism was observed between 2ME and salicylic acid (fetal weights). This investigation highlights the importance of additional research on interactions in developmental toxicology, and emphasizes the need to consider combined exposure effects when developing both physical agent and chemical agent exposure guidelines and intervention strategies.

Occupational Exposure to Acrylamide in Closed System Production Plants: Air Levels and Biomonitoring

The aim of this study was to evaluate biomarkers of acrylamide exposure, including hemoglobin adducts and urinary metabolites in acrylamide production workers. Biomarkers are integrated measures of the internal dose, and it is total acrylamide dose from all routes and sources that may present health risks. Workers from three companies were studied. Workers potentially exposed to acrylamide monomer wore personal breathing-zone air samplers. Air samples and surface-wipe samples were collected and analyzed for acrylamide. General-area air samples were collected in chemical processing units and control rooms. Hemoglobin adducts were isolated from ethylenediamine teraacetic acid (EDTA)–whole blood, and adducts of acrylamide and glycidamide, at the N-terminal valines of hemoglobin, were cleaved from the protein chain by use of a modified Edman reaction. Full work-shift, personal breathing zone, and general-area air samples were collected and analyzed for particulate and acrylamide monomer vapor. The highest general-area concentration of acrylamide vapor was 350 μg/cm3 in monomer production. Personal breathing zone and general-area concentrations of acrylamide vapor were found to be highest in monomer production operations, and lower levels were in the polymer production operations. Adduct levels varied widely among workers, with the highest in workers in the monomer and polymer production areas. The acrylamide adduct range was 15–1884 pmol/g; glycidamide adducts ranged from 17.8 to 1376 p/mol/g. The highest acrylamide and glycidamide adduct levels were found among monomer production process operators. The primary urinary metabolite N-acetyl-S-(2-carbamoylethyl) cysteine (NACEC) ranged from the limit of detection to 15.4 μg/ml. Correlation of workplace exposure and sentinel health effects is needed to determine and control safe levels of exposure for regulatory standards.

Heat and humidity buildup under earmuff-type hearing protectors.

A major barrier to effective wear of hearing protection is comfort. This study examined several comfort indicators in the earmuff-type hearing protectors. Twenty subjects wore hearing protectors instrumented with two different temperature/humidity measurement systems (Omega and iButton) while walking a corridor for about 25 min. The instruments recorded the temperature and humidity every 10 s and their results were compared. In addition, skin surface pH was measured at the ear canal entrance before and after the task. Finally, the subject indicated earmuff comfort at the beginning and end of the session. Earmuff comfort decreased significantly over the course of the walking task. Ear canal pH became slightly less acidic, but the change was not statistically significant. The two temperature/humidity systems provided comparable results. Heat increased at about 0.3°F while humidity built up at about 0.5%/min. However, the study found some limitations on the instrumentation. The complexity of the electrical connections and equipment in the Omega probe system led to loss of three subjects data. The iButton device was more robust, but provided only 256 gradations of temperature and relative humidity. Even with its limitations, the iButton device would be a valuable tool for field studies. The present study showed that the buildup of heat and humidity can be modeled using linear equations. The present study demonstrates that relatively inexpensive tools and a low-exertion task can provide important information about the under-earmuff environment, which can inform assumptions about comfort during use.

Synthesis, characterization, and use of 2-[(2H9)butoxy]acetic acid and 2-(3-methylbutoxy)acetic acid as an internal standard and an instrument performance surrogate, respectively, for the gas chromatographic-mass spectrometric determination of 2-butoxyacetic acid, a human metabolite of 2-butoxyethanol

Abstract 2-[(2H9)Butoxy]acetic acid and 2-(3-methylbutoxy)acetic acid were synthesized, mixed with 2-butoxyacetic acid, and separated by capillary gas chromatography on a fused-silica column with a length of 50 m, inside diameter of 0.200 mm, and a “free fatty acid phase” wall coating of 0.3 μm film. 2-[(2H9)Butoxy]acetic acid, 2-butoxyacetic acid, and 2-(3-methylbutoxy)acetic acid were baseline resolved at retention times of 13.55, 13.78, and 15.20 min; 2-(3-methylbutoxy)acetic acid having a peak efficiency of 360 000. Mass spectrometric detection using selected ion monitoring at m/z 66, 57, and 71 showed linear analytical responses from 0.04 ng to at least 200 ng with a limit of detection of 0.04 ng for 2-butoxyacetic acid.