Proposed Threshold Limit Value Research Articles

The occurrence of Mono/Di-Chloropropanol contaminants in food contact papers and their potential health risk

In this study, an accurate and sensitive technique (SPE-GC/MS) was developed for simultaneously measuring four chloropropanols in water extract of food contact papers (FCPs) with satisfactory recoveries (95.4–109%), while LOD and LOQ can be achieved at trace level (μg kg−1). The investigation of 126 FCPs in China indicated chloropropanols were widely presented in FCPs with 65.1% of detection frequency and 50.0% of non-compliance. Both the highest detection frequency and concentration were observed in kitchen papers. 3-MCPD and 1,3-DCP were found to be the predominant contaminants of FCPs with a mean concentration of 49.7 μg L−1 and 6.2 μg L−1 in water extract, respectively. 3-MCPD significantly accounted for the high concentration of chloropropanols at a value above 40 μg kg−1. The estimated daily intake for typical and high-exposure consumers to 3-MCPD is greater than the proposed threshold limit value, suggesting 3-MCPD released from FCPs may pose a potential health risk.

Review on Occupational Personal Solar UV Exposure Measurements

During leisure time, people can decide if they want to expose themselves to solar ultraviolet (UV) radiation and to what extent. While working, people do not have this choice. Outdoor workers are exposed to solar UV radiation (UVR) on a daily basis. This may pose a certain health risk, which can be estimated when the personal solar UVR exposure (PE) is known. During past decades, a variety of studies were conducted to measure PE of outdoor workers and our knowledge of the PE of outdoor workers has increased remarkably. As shown by this review, studies clearly indicate that PE of most outdoor workers exceeds the internationally proposed threshold limit value, which is comparable to 1.0 to 1.3 standard erythema dose (SED), respectively, to 1.1 to 1.5 UV Index received over one hour. Besides working in a high UVR environ, monotonic workflow (limited movement, nearly static posture) is a risk factor. In such cases, PE can be higher than ambient UVR. In this review, we provide also a list of milestones, depicting the progress and the most important findings in this field during the past 45 years. However, in many respects our knowledge is still rudimentary, for several reasons. Different measuring positions have been used so that measured PE is not comparable. Few studies were designed to enable the extension of measured PE to other locations or dates. Although the importance of a proper calibration of the measuring devices in respect to the changing solar spectrum was pointed out from the beginning, this is often not performed, which leads to high uncertainties in the presented PE levels. At the end of our review, we provide some key points, which can be used to evaluate the quality of a study respectively to support the design of future studies.

FRT Control Method Including Islanding Detection in PCS Model for Photovoltaic Generation

In this study, we made experiments by the simulated PV system for understanding the cause of disconnection when instantaneous voltage sag occurs. Moreover, it is understood that the PCS with the voltage phase jump detection method which is one of the main causes of the disconnection. We modeled it in the simulation. When fault occurs, even though the residual voltage is more than 20 % and the voltage sag time is within 1.0 sec, the PCS disconnected by the voltage phase jump detection was confirmed in the simulation results. If a large number of PV systems are interconnected in the power system, we verified through the simulation that the interaction caused by the disconnection which generated by the voltage phase jump detection. We proposed threshold limit value of islanding detection. The validity of proposed method was verified through the simulation in this study.

Validation of the ACGIH TLV for hand activity level in the OCTOPUS cohort: a two-year longitudinal study of carpal tunnel syndrome

This study aimed to evaluate the risk of musculoskeletal disorders to the hand-wrist system. The American Conference of Governmental Industrial Hygienists (ACGIH) proposed threshold limit values (TLV©) based on hand activity level (HAL) and normalized peak force (PF). We validated ACGIH TLV© in OCTOPUS, a large cohort study on carpal tunnel syndrome (CTS). Industrial and service workers were followed from 2000-2003. We classified subjects with respect to action limit (AL) and TLV. Case definitions were: (i) self-reported symptoms; and (ii) combination of symptoms and positive nerve conduction studies. Poisson regression models including age, gender, body mass index, and presence of predisposing pathologies were conducted to estimate incidence rate ratios (IRR) of CTS. There were 4097 eligible workers. Of these, 236 (5.8%) were non-responders, 2194 (53.6%) had a complete follow-up, 728 (17.8%) were lost after intermediate assessment, and 939 (22.9%) were lost after baseline. Among the 3860 subjects with complete information at baseline, 2599 (67.3%) were women [mean age 38.1 [standard deviation (SD) 9.5] years; mean body mass index (BMI) 23.8 (SD 3.9) kg/m2]. ACGIH TLV© classification predicted both CTS symptoms [IRR between AL and TLV 2.43 [95% confidence interval (95% CI) 1.77-3.33]; above TLV 3.32 (95% CI 2.34-4.72)] and CTS confirmed by nerve conduction studies [IRR between AL and TLV 1.95 (95% CI 1.21-3.16); above TLV 2.70 (95% CI 1.48-4.91)]. We found a dose-response relationship between ACGIH TLV© classification and risk of CTS. The increased risk observed for workers exposed between AL and TLV suggests that the current AL and TLV might not be sufficiently protective.

Monitoring and assessment of airborne fungi in Kolkata, India, by viable and non-viable air sampling methods

The composition and variability of airborne fungal spores were studied using two complementary sampling methods in an outdoor environment in Kolkata suburb for 2 years, from November 2002 to October 2004. For monitoring the total fungal spore burden in the air, Burkard 7-day volumetric sampler was used, whereas Andersen two-sage viable sampler was used for isolating the cultivable airborne fungi. Among the 37 fungal spore types identified in the air samples, the predominant ones were Cladosporium, unidentified ascospores, unidentified basidiospores, Aspergilli/Penicilli, Nigrospora, Periconia, Chaetomium, Drechslera, Alternaria, Coprinus, Ganoderma, Pithomyces, and rust spores. Only six fungal spore types (Alternaria, Aspergilli/Penicilli, Cladosporium, Curvularia, Drechslera, and Nigrospora) were recovered in common by the two samplers. For Aspergilli/Penicilli, Drechslera, and Nigrospora, the spore concentration was underestimated in the non-viable sampling method (Burkard sampler). In general, higher spore count was recorded in winter. The highest fungal species variability was observed in early monsoon (June). Relative humidity could significantly predict the seasonal periodicity of the maximum number of airborne spores. The total airborne fungi concentration recorded in the study (15-16 × 10(3) spores m(-3) of air) was lower than the proposed threshold limit value for clinical significance, suggesting apparently no or less airborne-fungi-exposure-related health risk in the sampling area. Cladosporium cladosporioides was recorded beyond the proposed threshold limit value in January 2003 and March 2004; Aspergillus fumigatus and Aspergillus nidulans in winter that might have posed considerable health risk to sensitized individuals.

Evaluation of environmental levels of aromatic hydrocarbons in gasoline service stations by gas chromatography

The volume of gasoline sold in refuelling operations and the ambient temperature, can increase significantly the environmental levels of aromatic hydrocarbon vapours and subsequently, the occupational risk of gasoline service station attendants, specially in the case of benzene. We have evaluated the occupational exposure to aromatic hydrocarbons by means of personal-breathing-zone samples of gasoline vapours in a service station attendant population. This evaluation was carried out using diffusive samplers, in two periods at quite different temperatures (March and July). A significant relationship between the volume of gasoline sold during the shift and the ambient concentration of benzene, toluene, and xylenes was found for each worker sampled. Furthermore a significant difference was found between the time-weighted average concentration of aromatic compounds measured in March, with ambient temperatures of 14–15°C and July, with temperatures of 28–30°C. In addition, 20% of the population sampled in the last period were exposed to a time-weighted average concentration of benzene above the proposed Threshold Limit Value of 960 μg/m 3 of the American Conference of Governmental Industrial Hygienists (ACGIH).

Evaluation of Bioaerosols in a Municipal Solid Waste Recycling and Composting Plant

Abstract Both the processing of solid waste and the composting of organic matter generate airborne biological contaminants. For this type of environment, some authors have proposed Threshold Limit Values (TLV) of 10,000 Colony Forming Units per cubic meter (CFU/m3) of air for total bacteria, and 1,000 CFU/m3 of air for Gram-negative bacteria. Endotoxins produced by Gram-negative bacteria can cause fever and respiratory problems. Diarrhea and gastrointestinal problems can also be caused by Gram-negative bacteria. Other researchers have found Aspergillus fumigatus, which is considered an opportunistic pathogenic fungus, in the nose and throat of people exposed to compost. The objectives of this study were to evaluate the microbiological content of indoor and outdoor air, to detect concentrations of total and Gram-negative bacteria exceeding their proposed TLV, and to suggest corrective measures based on the technical and scientific literature. Air sampling was carried out twice in one day using Andersen sam...

AN EVALUATION OF AIRBORNE NICKEL, ZINC, AND LEAD EXPOSURE AT HOT DIP GALVANIZING PLANTS

Industrial hygiene surveys were conducted at three hot dip galvanizing plants to determine occupational exposure to nickel, zinc, and lead. All three plants employed the "dry process" and used 2% nickel, by weight, in their zinc baths. A total of 32 personal and area air samples were taken. The air samples were analyzed for nickel, zinc, and lead. Some samples were also analyzed for various species of nickel (i.e., metallic, soluble, and oxidic). The airborne concentrations observed for nickel and its three species, zinc, and lead at the three plants were all well below the current and proposed threshold limit values recommended by the American Conference of Governmental Industrial Hygienists (ACGIH).

Monitoring of Nitrous Oxide in Operating Rooms: Identification of Sources and Estimation of Occupational Exposure

In an academic hospital, nitrous oxide (N2O) levels were measured continuously and detailed workplace observations made in three different operating rooms for 18 days. The study was designed to determine the exposure of different categories of staff to nitrous oxide, to localize and quantify the emissions, and to predict and validate the effect of corrective measures. Nitrous oxide levels appeared to be highly time and place dependent; all staff, except for surgeons, were exposed to N2O levels (8-hour time-weighted average) above 25 parts per million. The most important contributor to total release of N2O was the ventilator (about 70%), especially during artificial respiration of the patient. A simulation model was developed and used to predict the effect of technical improvement of the ventilators and use of scavenging during anesthesia (total 58% reduction of release). The model shows that under these conditions, without altering room ventilation rates, room air circulation can be increased up to 50% without exceeding the proposed threshold limit value (25 parts per million). Measurement of N2O levels after intervention showed a reduction in the area surrounding the ventilator of about 80%, thereby reducing occupational exposure of all staff to below 18 parts per million.

Enhancement of Low-Level Magnetic Fields by Ferromagnetic Objects

Abstract Low-intensity magnetic fields, generally considered to be safe from a bioeffects standpoint, may cause problems to workers who wear cardiac pacemakers. Low-intensity magnetic fields can interfere with pacemaker circuitry and can cause cardiac arrythmias in some pacemaker wearers. This interference can occur at field levels above approximately 14 Gauss (1.4 milliTesla). In research presented in this article, magnetic field “enhancement” by ferromagnetic objects (nonmagnetic metallic objects containing iron) was investigated. It was demonstrated that ferromagnetic objects, if placed in a magnetic field, can increase local magnetic field intensities by an order of magnitude. Ferromagnetic enhancement of magnetic fields can increase apparently safe magnetic fields (below the proposed Threshold Limit Value of 10 Gauss or 1.0 mTesla) to levels which are unsafe for some cardiac pacemaker wearers. Because of these risks, the authors recommend posting warning signs in workplaces where magnetic fields are ...

Effects of airborne upper sonic and ultrasonic acoustic radiation and proposed threshold limit values for human exposure

In 1974, a literature search and a field study by these authors and co‐workers at the Environmental Acoustics Laboratory were completed and sought to evaluate industrial exposure to airborne acoustic radiation above 10 kHz. The reported effects of exposure to such radiation and the three existing sets of human exposure limits for airborne upper sonic and ultrasonic acoustic radiation proposed by investigators from three different countries (the USA, England, and Russia) were documented and discussed as part of a final report prepared for the sponsor [P. L. Michael, R. L. Kerlin, G. R. Bienvenue, and J. H. Prout, An Evaluation of Industrial Acoustic Radiation Above 10 KHz, Environmental Acoustics Laboratory, The Pennsylvania State University, University Park, PA, Final Report, Contract No. HSM‐99‐72‐125, Physical Agents Branch, NIOSH, Cincinnati, OH, p. 210 (February 1974)]. These results will be presented and discussed, and, in particular, their role as part of the documentation for the threshold limit va...

American conference of governmental industrial hygienists proposed threshold limit value for noise : AnonAmerican Industrial Hygiene Association Journal Nov–Dec, 1968 29.6, 537–540 Abstr in Occupational Safety and Health Abstracts (CIS 2020 - 1969)

American conference of governmental industrial hygienists proposed threshold limit value for noise : AnonAmerican Industrial Hygiene Association Journal Nov–Dec, 1968 29.6, 537–540 Abstr in Occupational Safety and Health Abstracts (CIS 2020 - 1969)

Determination of Volatile Toxic Substances in the Air by Means of a Coupled Gas Chromatograph-Mass Spectrometer System

Abstract A method is described for quantitative determination of specific organic substances in the air in the presence of other, highly-concentrated air impurities. The required selectivity is achieved by the application of a coupled gas chro-matograph-mass spectrometer system. By concentration of the organic material from a one liter sample volume of air, reproducible detection limits of 1 ppb (10−9) have been obtained. Application of the method for the specific detection of bis(chloro-methyl) ether and dimethylsulfate is discussed. The proposed threshold limit values of these substances are 1 and 10 ppb, respectively. Bis(chloromethyl) ether is formed as a byproduct in chloromethylation reactions; dimethylsulfate has been manufactured for many years in large quantities and is used in methylation reactions. A reliable air monitoring system in both these important industrial processes is of great importance.

American Conference of Governmental Industrial Hygienists' proposed threshold limit value for noise.

Abstract The American Conference of Governmental Industrial Hygienists has proposed a Threshold Limit Value for Noise. The limit for broad band noise would be 92 decibels, as measured on the A-scale of a sound level meter (dBA), for exposure of 4 to 8 hours per day; 97 dBA for 2 to 4 hours; 102 dBA for 1 to 2 hours; and 107 dBA for less than 1 hour. The limit for narrow bands of noise or pure tones would be 5 decibels lower than that for broad band noise. A limit of 140 decibels peak sound-pressure level for impulsive or impact noise is recommended.

A survey of the petroleum solvent inhalation exposure in Detroit dry cleaning plants.

Abstract A survey was conducted on a random sample of 30 out of a total of 140 dry cleaning plants operating in the City of Detroit and using petroleum solvents. Solvent in air concentrations were measured during various portions of the dry cleaning cycle and found to be below the proposed Threshold Limit Value of 200 ppm. The weighted exposure for a complete dry cleaning cycle was found to be 65 ppm for the solvent with a flash point of 105°F., 47 ppm for the solvent with a flash point of 120°F., and 25 ppm for a solvent with a flash point of 140°F. In Detroit, actual dry cleaning operations approximated four hours per 8-hour day. Accordingly, the weighted 8-hour exposure was 35 ppm, 25 ppm and 15 ppm respectively.