Biomonitoring of industrial styrene exposures.

Worker exposure to styrene in two fiberglass boat plants was evaluated using conventional sampling techniques. The use of expired air and urine metabolite concentrations as indicators of styrene exposure is evaluated. The concentration of mandelic acid, a styrene metabolite in urine, is quantitated for workers without and with intermittent personal respiratory protection. A urinary Biological Limit Value is determined for exposures to the Threshold Limit Value of styrene.     

Corporate occupational exposure limits: the current state of affairs

It has been claimed that the implementation of occupational exposure limits has been instrumental for the near elimination of serious occupational disease in the Western world. Although exposure limits or guides for most large volume chemicals have been established, the majority of the 10,000 chemicals which are routinely used in industry do not have them. As a result, many firms have chosen to establish internal limits to protect their employees as well as the persons who purchase those chemicals. This paper reviews the most important issues discussed in a 2-day symposium on corporate exposure limits which was sponsored by the AIHA Workplace Environment Exposure Limits Committee (WEEL). Thirteen representatives of industry and professional organizations presented papers which addressed various aspects of the process for setting internal exposure limits. The various policies and methodologies used by large American companies which have set limits for many years and their benefits were discussed. The history and function of Threshold Limit Values (TLVs) Maximum Allowable Concentrations (MACs), Permissible Exposure Limits (PELs) and Workplace Environment Exposure Limits (WEELs) also were reviewed. Some of the legal aspects of setting corporate limits and their role in the Product Safety arena were discussed.     

Corporate influence on threshold limit values

Investigations into the historical development of specific Threshold Limit Values (TLVs) for many substances have revealed serious shortcomings in the process followed by the American Conference of Governmental Industrial Hygienists. Unpublished corporate communications were important in developing TLVs for 104 substances; for 15 of these, the TLV documentation was based solely on such information. Efforts to obtain written copies of this unpublished material were mostly unsuccessful. Case studies on the TLV Committee's handling of lead and seven carcinogens illustrate various aspects of corporate influence and interaction with the committee. Corporate representatives listed officially as "consultants" since 1970 were given primary responsibility for developing TLVs on proprietary chemicals of the companies that employed them (Dow, DuPont). It is concluded that an ongoing international effort is needed to develop scientifically based guidelines to replace the TLVs in a climate of openness and without manipulation by vested interests.     

Neuropsychological function in solvent-exposed South African paint makers

Neuropsychological and neurological function were investigated in 228 organic solvent exposed paint manufacturing workers in two factories. Solvent exposure was expressed as both American Conference of Governmental Industrial Hygienists 1990 Threshold Limit Value equivalents and total hydrocarbon parts per million. The World Health Organization (WHO) neurobehavioral core test battery, the Neurobehavioural Evaluation System--2 (NES-2), and the UNISA Neuropsychological Assessment Procedure (UNAP) were used to measure outcomes, and a Vibratron II was used to measure peripheral vibration sensation. Exposures were generally below the Threshold Limit Value, and no exposure effect was found. Possible explanations for this finding are discussed, including low exposure, exposure, and outcome misclassification, together with inappropriateness, nonvalidity, and relative insensitivity of neuropsychological tests. Only age predicted Vibratron score. Some tests were clearly inappropriate for use in developing countries. Neuropsychological tests were sensitive to educational level, age, alcohol consumption, and cultural indicators. The WHO tests in particular showed good construct validity for neuropsychological functions and should be more formally validated for use in developing countries. Nevertheless, a major problem of cultural dependence is evident for all neuropsychological tests used in this study, and methods for bypassing this problem in less developed settings are discussed.     

Monitoring latex risk: detection of airborne and glove allergens

BACKGROUND: Latex is a relevant occupational and environmental allergen, strongly related to the extensive use of natural rubber products. OBJECTIVES: Threshold Limit Values have to be identified, as well as biocompatible materials in order to avoid sensitization or appearance of allergic symptoms. METHODS: In this paper we consider the main methods, which have been used to detecting latex allergens for environmental monitoring of airborne and latex products. RESULTS: We report our experience in such afield, and our approach to the latex problem, suggesting that quantification of allergens, which is currently applicable according to well standardized methods, should be adopted by manufacturers, agency and consumer organization.     

Japanese administrative control level of respirable dust and determination of crystalline silica in dust

In Japan, there are two commonly used regulations on respirable dust concentration: the Occupational Exposure Limit (OEL), recommended by the Japan Society for Occupational Health, and the Administrative Control Level (ACL). Both depend on the crystalline silica content in dust. Until 2004, the ACL for respirable dust conformed to the OEL. However, the ACL was revised in 2005 in light of the OEL and the American Conference of Governmental Industrial Hygienists (ACGIH)'s Threshold Limit Value (TLV), same value as National Institute for Occupational Safety and Health (NIOSH)'s Recommended Exposure Limit (REL). In this paper, the author intends to clarify the stringency of the current ACL by comparing it with the OEL and the ACGIH's TLV. In addition, the effect of the analytical error due to the phosphoric acid method in the current and former ACLs is shown.     

Passive colorimetric dosimeter tubes for ammonia, carbon monoxide, carbon dioxide, hydrogen sulfide, nitrogen dioxide and sulfur dioxide

Colorimetric, stain length, personal dosimeters operating by gas diffusion have been developed to determine worker exposure for up to an eight-hour period for several inorganic airborne contaminants in the range of their Threshold Limit Values. Length of stain, colorimetric dosimeters have been made for the detection of ammonia (NH3), carbon monoxide (CO), carbon dioxide (CO2), hydrogen sulfide (H2S), nitrogen dioxide (NO2), and sulfur dioxide (SO2) in air. For each gas detection system, the sampler depends on the transfer of the gas by diffusion into a glass tube containing a colorimetric length of stain indicator. The stain length developed in a given period of time is compared to a calibration chart to determine, on the spot, the average gas concentration to which the dosimeter has been exposed. These dosimeters are known by the trade name Vapor Gard.     

Noise at sea: Characterization of extended shift noise exposures among U.S. Navy aircraft carrier support personnel

The purpose of this investigation was to characterize 12-hr on-duty, 12-hr off-duty, and 24-hr noise exposures among U.S. Navy aircraft carrier support personnel. Noise dosimetry samples were collected for 47 aircraft carrier support personnel while at sea during airwing carrier qualifications. L_eq measurements during 12-hr on-duty, 12-hr off-duty, and over 24-hr periods were compared to Threshold Limit Values. Four similar exposure groups (SEGs) were created based upon departmental assignment and similarity of work tasks: (1) Administration/Religious Ministries/Legal/Training, (2) Combat Systems/Operations, (3) Medical/Dental, and (4) Supply. Equivalent sound level (Leq) measurements in decibels “A” weighted (dBA) were compared to determine significant differences between each group according to 12-hr on-duty, 12-hr off-duty, and 24-hr periods. Mean 24-hr noise levels ranged from 69–88 dBA with 22% exceeding the 80 dBA Threshold Limit Value. Twelve-hr on-duty noise levels ranged from 71–90 dBA with 17% exceeding the 83 dBA 12-hr on-duty Threshold Limit Value. Twelve-hr off-duty noise exposure ranged from 68–84 dBA with 95% exceeding the 70 dBA American Conference of Governmental Industrial Hygienists threshold classified as effective quiet to allow for temporary threshold shift recovery. Welch Analysis of Variance and Dunnett T3 post hoc tests revealed SEG 2 had significantly higher 24-hr noise exposures than SEG 3 (p?=?0.019) and SEG 4 (p?=?0.045). SEG 2 had significantly higher 12-hr on-duty noise exposure than SEG 3 (p?=?0.030). One Way Analysis of Variance revealed no significant differences between 12-hr off-duty noise exposures according to SEG (p = .096). Some aircraft carrier support personnel had 12-hr on-duty and 24-hr noise exposures exceeding Threshold Limit Values with a large proportion exceeding the 70 dBA effective quiet limit during 12-hr off-duty periods. Results suggest personnel that are typically considered low risk for hazardous noise exposure (<85 dBA) during 8-hr shifts may have a greater risk of noise exposure when considering full 12-hr and 24-hr shifts when working and living in close proximity.     

A review of world literature finds iron oxides noncarcinogenic

Iron oxide appeared in the first list of 154 Threshold Limit Values adopted by the American Conference of Governmental Industrial Hygienists at its April 1949 annual meeting. It was set to control dust and fume at the recommended value of 15 mg/M3, at the time, the limit for an inert or "nuisance" dust, and was based on studies of welders made earlier by the U.S. Dept. of Labor and by Drinker and Nelson. By 1964, the TLV was tentatively reduced to 10 mg/M3 after a considerable body of literature had accumulated not only on the health experience of welders, but of other occupations involving iron oxides as well. As a group, these studies indicated that 15 mg/M3 permitted too great accumulations of iron pigmentation in the lung whose chronic retention effects were not known with certainty. Also, an occasional report of cancer of the lungs appeared particularly among British hematite miners, although these findings were immediately questioned on statistical grounds. In seeming confirmation of these early reports of cancer, an alarming number of reports of cancer of the lung and respiratory tract among welders and foundrymen began to appear by 1970, reaching a crescendo by the end of that decade. As past chairman of the TLV Committee, I decided to examine the bases of these findings. This review is the result of this examination.     

The contribution of acute toxicity in animals to occupational exposure limits of chemical substances

The correlations of lethal doses of various industrial chemicals for rats and mice with occupational exposure limit values were investigated. 50% lethal dose (LD50) values obtained by oral (p.o.) and intraperitoneal (i.p.) injection and 50% lethal concentration (LC50) values obtained by inhalation exposure were collected from Registry of Toxic Effects of Chemical Substances (RTECS). Threshold Limit Value (Time-Weighted Average) (TLVs-TWA) and Threshold Limit Value (Short Term Exposure Limit) (TLVs-STEL) recommended by American Conference of Governmental Industrial Hygienists (ACGIH) were used as exposure limits. TLVs-TWA or TLVs-STEL and LD50 or LC50 values obtained for the rats were plotted on logarithmic scales on the ordinate and abscissa, respectively. High correlations were obtained between these parameters. The order of correlations was: TLVs-STEL vs. LC50s > TLVs-TWA vs. LC50s > TLVs-TWA vs. LD50s i.p. > TLVs vs. LD50s p.o. The same calculations for the relationship between TLVs and lethal doses in mice were also performed. The order of the three types of correlations was same as that of the rats; however, correlation coefficients for TLVs-STEL vs. LC50s and for TLVs-TWA vs. LC50s obtained in mice were smaller than those in rats. TLVs-TWA are, therefore, well correlated with LC50 values rather than LD50 values, particularly with those in rats. High correlations between TLVs-STEL vs. LC50s were also obtained, as had been expected before calculation. The equation: TLV-TWA = 10b x (LC50)a can be obtained from these plottings, where the values a and b are taken from each linear regression line. TLV-TWA for each chemical can be calculated by using LC50 and the equation. The upper and lower 95% confidence limits for calculated TLV-TWA were TLV-TWA (calculated from LC50) x 22.9 and TLV-TWA (calculated)/22.9, respectively, where LC50 for rats expressed in ppm x hr was used.     

But they are not thresholds: A critical analysis of the documentation of threshold limit values

Threshold Limit Values (TLVs) represent conditions under which the TLV Committee of the American Conference of Governmental Industrial Hygienists (ACGIH) believes that nearly all workers may be repeatedly exposed without adverse effect. A detailed research was made of the references in the 1976 Documentation to data on “industrial experience” and “experimental human studies.” The references, sorted for those including both the incidence of adverse effects and the corresponding exposure, yielded 158 paired sets of data. Upon analysis it was found that, where the exposure was at or below the TLV, only a minority of studies showed no adverse effects (11 instances) and the remainder indicated that up to 100% of those exposed had been affected (8 instances of 100%). Although, the TLVs were poorly correlated with the incidence of adverse effects, a surprisingly strong correlation was found between the TLVs and the exposures reported in the corresponding studies cited in the Documentation. Upon repeating the search of references to human experience, at or below the TLVs, listed in the more recent, 1986 edition of the Documentation, a very similar picture has emerged from the 72 sets of clear data which were found. Again, only a minority of studies showed no adverse effects and TLVs were poorly correlated with the incidence of adverse effect and well correlated with the measured exposure. Finally, a careful analysis revealed that authors' conclusions in the references (cited in the 1976 Documentation) regarding exposure-response relationships at or below the TLVs were generally found to be at odds with the conclusions of the TLV Committee. These findings suggest that those TLVs which are justified on the basis of “industrial experience” are not based purely upon health considerations. Rather, those TLVs appear to reflect the levels of exposure which were perceived at the time to be achievable in industry. Thus, ACGIH TLVs may represent guides of levels which have been achieved, but they are certainly not thresholds.     

Occupational Exposure to 1,3-Dichloropropene (Telone® II) in Hawaiian Pineapple Culture

1,3-dichloropropene (DCP), the primary constituent of Telone® II, is a subsoil fumigant that has supplanted 1,2-dibromo-3-chloropropane (DBCP) and ethylene dibromide (EDB) as primary fumigant in Hawaiian pineapple culture. To determine the potential for adverse health effects, an environmental survey was done to assess worker exposures. Exposures were predominantly below 1 ppm, which is the no-effect level determined with experimental animals, and the Threshold Limit Value (TLV) recommended by the American Conference of Governmental Industrial Hygienists (ACGIH).     

Occupational exposure to 1,3-dichloropropene (Telone II) in Hawaiian pineapple culture

1,3-dichloropropene (DCP), the primary constituent of Telone II, is a subsoil fumigant that has supplanted 1,2-dibromo-3-chloropropane (DBCP) and ethylene dibromide (EDB) as primary fumigant in Hawaiian pineapple culture. To determine the potential for adverse health effects, an environmental survey was done to assess worker exposures. Exposures were predominantly below 1 ppm, which is the no-effect level determined with experimental animals, and the Threshold Limit Value (TLV) recommended by the American Conference of Governmental Industrial Hygienists (ACGIH).     

Analysis of formic acid in air samples

The method reported here is for formic acid in air. Air containing formic acid is drawn through a midget impinger containing 15 ml of 0.1 N NaOH at a rate of one liter per minute for 42 minutes. An aliquot from the impinger is treated with an equal volume of ethanol-sulfuric acid mixture in a gastight reaction vial to produce ethyl formate. Because ethyl formate is volatile, an analysis of its vapor contained in the vial (headspace analysis) can be performed. The ethyl formate is analyzed by gas chromatography and its quantity is proportional to the quantity of formic acid contained in the reaction vial. With a relative standard deviation of 11 percent the method is precise enough for evaluating airborne formic acid at 0.1 of Threshold Limit Value of 9 mg/m3.     

Occupational exposure limits for novel work schedules.

Work schedules other than 7 to 8 hr/day and 40 hr/week are being introduced in many industrial operations. Novel work schedules, such as four 10-hour workdays per week or three 12-hour workdays per week for three weeks followed by four 12-hour workdays for three weeks and several other plans are presently being used. The Threshold Limit Values (TLV) do not apply to such novel schedules. Modified occupational limits, which are calculable from the methods suggested in this report, estimate the needed reduction in the TLV to provide protection for exposed workers. A simple system is suggested, but should be cautiously applied with good medical surveillance. Industrial hygiene experience with novel work schedules will ultimately provide the real requirements for acceptable exposures under such work conditions.     

Quest for a gasoline TLV

The major components in gasoline vapor generated during tank truck loading operations are identified. By analyzing 95 separate gasoline vapor samples, a mean Threshold Limit Value (TLV) for mixtures of about 300 ppm is calculated using 1976 TLV's for the individual hydrocarbons, if available. For compounds without an assigned TLV, a safe exposure value is estimated. Maximum levels of leaded gasoline additives tetraethyl/tetramethyllead, ethylene dibromide and ethylene dichloride are also estimated.     

The UK Committee on Radioactive Waste Management.

The UK Committee on Radioactive Waste Management is charged with recommending to Government, by July 2006, options for the long term management of the UK's radioactive waste legacy. These options should inspire public confidence. Now, more than halfway into the time allotted, we, as two former members of the Committee, express our concerns at the wayward approach that has been adopted. The Committee has placed emphasis on gaining public confidence but this has been done at the expense of recruiting the best scientific expertise in the management of radioactive waste, an act which we believe will actually undermine public confidence. Furthermore, given also the immense importance of this decision to public safety, national security and the national interest, we believe urgent steps should be taken to review the Committee's process, its management and its sponsorship.     

Effect of bit wear on hammer drill handle vibration and productivity

The use of large electric hammer drills exposes construction workers to high levels of hand vibration that may lead to hand-arm vibration syndrome and other musculoskeletal disorders. The aim of this laboratory study was to investigate the effect of bit wear on drill handle vibration and drilling productivity (e.g., drilling time per hole).

A laboratory test bench system was used with an 8.3 kg electric hammer drill and 1.9 cm concrete bit (a typical drill and bit used in commercial construction). The system automatically advanced the active drill into aged concrete block under feed force control to a depth of 7.6 cm while handle vibration was measured according to ISO standards (ISO 5349 and 28927). Bits were worn to 4 levels by consecutive hole drilling to 4 cumulative drilling depths: 0, 1,900, 5,700, and 7,600 cm.

Z-axis handle vibration increased significantly (p<0.05) from 4.8 to 5.1 m/s² (ISO weighted) and from 42.7–47.6 m/s² (unweighted) when comparing a new bit to a bit worn to 1,900 cm of cumulative drilling depth. Handle vibration did not increase further with bits worn more than 1900 cm of cumulative drilling depth. Neither x- nor y-axis handle vibration was effected by bit wear. The time to drill a hole increased by 58% for the bit with 5,700 cm of cumulative drilling depth compared to a new bit.

Bit wear led to a small but significant increase in both ISO weighted and unweighted z-axis handle vibration. Perhaps more important, bit wear had a large effect on productivity. The effect on productivity will influence a worker's allowable daily drilling time if exposure to drill handle vibration is near the ACGIH Threshold Limit Value.^[1] ACGIH: 2017 TLVs and BEIs: Threshold Limit Values, ACGIH, Cincinnati, OH (2017). [Google Scholar] Construction contractors should implement a bit replacement program based on these findings.     

Formaldehyde and paraformaldehyde study in funeral homes.

Formaldehyde is a toxic gas and classed as an upper respiratory irritant. The gas possesses distinctive physiological properties causing symptoms familiar to many formaldehyde workers, such as: burning of the eyes, lacrimation, and general irritation of the upper respiratory passages. To demonstrate this toxic action of formaldehyde a study was conducted in embalming rooms of funeral homes to determine the concentration and its effect on the embalmers at this level. The control measures in these establishments were also evaluated and found to be inadequate in some respects. Paraformaldehyde powders were sized and found to contain a respirable fraction. The results of the study show that these workers verified the fact that formaldehyde is an irritant at levels that are below the present Threshold Limit Value.     

Combined effect of ozone and sulfuric acid on pulmonary function in man

A potential effect of the combination of ozone and sulfuric acid mist (H2SO4) on respiratory function has been postulated for humans simultaneously exposed to these two pollutants. Nine young men were exposed to 0.25 ppm ozone (O3), 1200-1600 micrograms/m3 sulfuric acid aerosol (H2SO4), and a combination of O3 and H2SO4. During the 2-hr exposures, the subjects exercised (ventilation = 30 L/min) three times for 20 min each. Air temperature was 35 degrees C and relative humidity 83%. Pulmonary function changes after exposure to ozone alone were not expected and were not demonstrated. If a reaction between the combination of O3 and H2SO4 and pulmonary function occurred, pulmonary function responses may have been anticipated following the combination exposure, but no significant changes were seen. It was concluded that the combination of ozone and sulfuric acid aerosol at levels in excess of Threshold Limit Values (TLV) levels do not cause pulmonary dysfunction.