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PubMed1985

Sensory irritation response to inhaled aldehydes after formaldehyde pretreatment.

Pretreatment of Fischer-344 (F-344) rats with formaldehyde (HCHO) induces significant cross tolerance to the sensory irritation properties of Cl2. The purpose of this study was to determine if HCHO pretreatment would cause sensory irritation cross tolerance to other inhaled aldehydes. Male F-344 rats, weighing 190 to 210 g, were pretreated with 15 ppm HCHO, 6 hr/day for 9 days, and challenged on the 10th day with a saturated (acetaldehyde, propionaldehyde, and butyraldehyde), unsaturated (acrolein and crotonaldehyde), or cyclic (cyclohexanecarboxaldehyde, 3-cyclohexene-1-carboxaldehyde, and benzaldehyde) aldehyde. The sensory irritation response in these animals was quantified by measuring respiratory rate depression in a head-only inhalation chamber using plethysmographic techniques. Control animals were challenged identically without prior pretreatment. In naive (nonpretreated) animals, the concentration eliciting a 50% decrease in respiratory rate (RD50) was 23 ppm or less for unsaturated aliphatic aldehydes. For cyclic and saturated aliphatic aldehydes, the RD50 ranged from 600 to 1000 ppm and 3000 to 6800 ppm, respectively. Formaldehyde pretreatment resulted in cross tolerance only with acetaldehyde (RD50 increased 3.5-fold) and acrolein (RD50 increased 5-fold). These results indicate that the development of cross tolerance following HCHO pretreatment is not a general phenomenon. Prediction of acceptable concentrations of occupational exposure for the prevention of sensory irritation in humans has been based primarily on RD50 data for mice. Comparison of the RD50 values obtained for rats in this investigation with previously published results for mice varied by over one-half an order of magnitude, thereby disputing the usefulness of data from F-344 rats in setting threshold limit values for the prevention of sensory irritation.

Aldehydes↗
PubMed1979

Evaluation of zinc protoporphyrin in an occupational environment.

Zinc protoporphyrin (ZnP) has been identified by several investigators as the predominant fluorescent porphyrin accumulating in erythrocytes as a result of chronic lead absorption or iron deficiency anemia. This report describes an evaluation of a new portable hematofluorometer for the determination of ZnP in finer puncture or venous blood samples. Samples were obtained from a number of employees in various job categories at steel operations throughout the United States to study the utility of ZnP as a biologic monitoring method in the occupational environment. Urinary lead, urinary aminolevulinic acid and blood lead were also determined on the same employees to examine any relationships among these measurers and to estimate a biologic threshold limit value for ZnP. The results of this investigation show that there is little elevation of the ZnP level with increasing blood level until the blood lead concentration reaches the area of 50--60 micrograms/dl. A biologic threshold level of 300 micrograms/dL, which correlates with a blood level of 60 micrograms/dL, is suggested as a guideline value for identifying workers requiring further investigation.

Aminolevulinic Acid↗
PubMed2004

Public health surveillance and incidence of adulthood Guillain-Barré syndrome in Spain, 1998-1999: the view from a sentinel network of neurologists.

Temporal variation in Guillain-Barré syndrome (GBS) warrants monitoring in certain situations. This study sought to describe a public-health-based GBS surveillance service in Spain and conduct pilot surveillance in the period 1998-1999. Neurologists from 11 hospitals countrywide, serving a population of 3.9 million, reported all patients, ages 20 years or over, admitted to hospital with suspected GBS. Cases that did not belong to the designated hospital catchment area or failed to fulfill diagnostic criteria after follow- up were excluded. Reported monthly incidence was compared against predicted incidence obtained from retrospective data (1985-1997) using a reported method based on 97.5% percentile values. Alarm thresholds for 2000 onwards were obtained by applying the same method to the updated 1985-1999 series. During the 2-year period, 98 GBS cases were reported, yielding an overall age-adjusted incidence of 1.26 per 100 000 population, with a breakdown by sex of 1.83 for males and 0.76 for females. Monthly incidence remained below or was similar to the corresponding threshold limit value. Seasonality with highest incidence in winter was more pronounced in the elderly. Preceding events, mainly respiratory infections, were identified in 71% of patients. Pilot two-year GBS surveillance in Spain resulted neither in alarm nor in preventive measures. Adult GBS incidence in Spain might be monitored by a surveillance system set up at short notice when a possible threat is perceived. A monthly incidence of over 3 per 100 000 person-years in the population aged 20 years or older would exceed threshold values.

Adult↗
PubMed1986

Odor thresholds and irritation levels of several chemical substances: a review.

A collation of odor threshold data for approximately 450 chemical substances is presented. The range of odor thresholds reported in the literature is shown along with any reported threshold of irritation to humans. These data can assist the industrial hygienist in determining when an "odor" may be in excess of the Threshold Limit Value, when an organic vapor respirator is not acceptable due to the lack of an odor warning at the end of a cartridge life, and where odors may not indicate a hazard due to extremely low odor thresholds which may be well below the respective TLVs.

Air Pollutants, Occupational↗
PubMed2005

Monitoring human exposures to upper-room germicidal ultraviolet irradiation.

After decades of neglect, the resurgence of tuberculosis in the United States between 1985 and 1992 renewed interest in the use of upper room ultraviolet germicidal irradiation to interrupt the transmission of airborne infections. More recently the bioterrorism threat and the appearance of new pathogens with the potential for airborne spread, such as severe acute respiratory syndrome (SARS), have stimulated installations of upper-room irradiation systems. The objective is to flood the entire volume of a room above 6.5 ft with high intensity ultraviolet germicidal irradiation, while minimizing unintentional irradiance below 6.5 ft to avoid eye and skin irritation. Air exchanges between the upper and lower room result in air disinfection of the occupied space. Designers of these systems have adopted the practice of limiting the maximum lower room irradiance at every point to less than the continuous 8-hour time-weighted average threshold limit value, severely limiting the irradiation intensity in the upper room and thereby reducing one of the two major factors determining germicidal effectiveness, the other being room air mixing. The hypothesis of this study is that eye and skin exposure will be well below the recommended safe dose even when maximum eye-level irradiance levels in the room exceed the 8-hour continuous exposure threshold limit. The method employed was to have subjects wear a small photometer that recorded total ultraviolet dose over the period of exposure while subjects went about their normal routine, and comparing this value with a hypothetical dose calculated from the highest measured eye-level irradiance. The results of the study, based on a limited number of observations, confirmed the hypothesis. Observed doses were one-third to a factor of a hundred or more lower than the doses calculated from maximum eye-level irradiances measurements in the occupants' spaces.

Bioterrorism↗
PubMed1989

Respiratory health of brickworkers in Cape Town, South Africa. Appropriate dust exposure indicators and permissible exposure limits.

The predictive value for respiratory abnormalities of dust indicators was assessed for 268 brickworkers. The subjective/objective correlations were poor (r = 0.09). The subjective indicators were found to be predictive of early/mild abnormalities, while the objective indicators were better for more severe abnormalities. The respirable/total dust correlations were high (r = 0.99). Length of service was a good proxy predictor for most respiratory abnormalities, while respirable dust was a good proxy for respirable free silica. Simple screening measures with potential application in less-developed settings, like subjective questionnaire responses and total dust measurement, are suggested. The American Conference of Governmental Industrial Hygienists' threshold limit values for free silica and "nuisance" particulates appear to be too high to prevent the occurrence of abnormalities. The World Health Organization's health-based limit for respirable free silica (1 mg/m3) and hygienic standards of well below 5 mg/m3 would have prevented much of the respiratory abnormality found. Hygienic standards for dust and the concept of "nuisance" dust need to be reevaluated by further research.

Air Pollutants, Occupational↗
PubMed1994

Sensory irritation, pulmonary irritation and structure-activity relationships of alcohols.

Sensory irritation due to inhalation of n-pentanol, n-heptanol, sec-butanol and tert-pentanol was determined from the reflexively induced decrease in respiratory rate in CF-1 mice. The concentration-effect relations followed Michaelis-Menten equations, complying with receptor mediated processes. The relations were transformed into nearly rectilinear relationships in log concentration-effect plots, and the extrapolated threshold concentrations (RD-0) from the lines were 120, 28, 640 and 1210 ppm, respectively, obtained from the first 2 min of the exposure period. These values were comparable to those found in Swiss-Webster mice and to those obtained by electrophysiological experiments in Sprague-Dawley rats. The hydrophobic properties of the receptor biophase were found to approach that of the internal part of the bilayer membrane. Estimates on threshold limit values (TLV) were obtained and were found in reasonable agreement with the established values. The nose has a scrubbing effect, which reduces the concentration in the lungs in normal mice. n-Pentanol, sec-butanol and tert-pentanol decreased tidal volume in normal mice, explained either by an activation of receptors in the upper airways or by a sensitization of the stretch receptors. Two types of pulmonary responses were seen in tracheal-cannulated mice, which could be explained by an effect on stretch receptors and another type of lung receptors.

Administration, Inhalation↗
PubMed1987

Studies of transferrin in serum of workers exposed to organic solvents.

Earlier studies have shown that determination of the serum concentration of different forms of transferrin (isotransferrins) may be used to detect hepatic effects caused by alcohol abuse. The isotransferrin variant with an isoelectric point of 5.7 has been compared with the total amount of serum transferrin in order to study hepatic effects caused by occupational exposure to organic solvents. Eighteen workers from a paint industry were tested before and after their holiday and compared with two different groups, a total of 60 subjects. The solvent workers had significantly higher values both before and after their holiday. This suggests that the effects on the liver caused by organic solvents are similar to those caused by alcohol abuse and that this is a long term effect. The level of exposure to organic solvents was below the Swedish threshold limit values.

Adult↗
PubMed1992

Biological exposure limit for occupational exposure to coal tar pitch volatiles at cokeovens.

Biological monitoring is an efficient tool in the evaluation of exposure to chemical agents. However, the dose-response of adverse health effects using biological exposure indices and biological limit values are rarely available. This paper presents an estimation of the occupational exposure limit value of 1-hydroxypyrene in urine, a biological exposure indicator of polycyclic aromatic hydrocarbons (PAH). A large-scale study of the exposure of cokeoven workers to PAH, in which both air sampling (benzene soluble matter and individual PAH including benzo(a)pyrene) and biological monitoring (1-hydroxypyrene in urine) were applied, made it possible to establish an empirical mathematical relationship between the air sampling data and biological monitoring data. It was calculated that cokeoven workers with a urinary concentration of 1-hydroxypyrene of 2.3 mumol/mol creatinine after a 3-day working period equals the airborne threshold limit value (TLV) of coal tar pitch volatiles (CTPV). Epidemiological studies have quantified the relative risk of lung cancer for topside and non-topside cokeoven workers. The published environmental exposure data of topside and non-topside cokeoven workers were used to determine the time-average exposure. The data of 1-hydroxypyrene in the urine of cokeoven workers and data of epidemiological studies from different coke plants were combined according to the concentrations of PAH in the air. Thus, it was possible to establish an indirect relationship between lung cancer mortality risk and the biological exposure indicator for cokeoven workers. Exposure at the level of the suggested tentative biological exposure limit (BEL) of 2.3 mumol/mol creatinine is estimated to be equal to a relative risk of lung cancer of approximately 1.3.

Coal↗
PubMed1992

An environmental survey in chrysotile asbestos milling processes in India.

Environmental monitoring to determine airborne asbestos fiber levels has been carried out in four different mills processing chrysotile asbestos in the Cuddapah District (Andhra Pradesh) of India. The "membrane filter method" comprising standard asbestos sampling techniques, acetone-triacetin method for sample preparation, fiber counting, and sizing using the phase contrast optical microscope were adopted in the study. Fiber concentrations both with respect to personal exposures and processing areas were found in most of the cases to be much higher than the prescribed Threshold Limit Value (TLVs) of the developed and developing countries for chrysotile asbestos. By optical microscopy, fiber length distribution showed 70% of fibers in the milling processes were in size range > 5-10 microns, whereas in > 10-20 and > 20 microns, 20% and 8%, respectively. Fiber identification for major elemental content, also done by using scanning electron microscope equipped with an energy dispersive X-ray analyzer, indicated the presence of tremolite along with chrysotile. The study stresses the urgent need to adopt suitable engineering controls at the dust generating sources to reduce the fiber level in the mill environment below the threshold limit.

Air Pollutants, Occupational↗
PubMed1991

Complex mixtures in industrial workspaces: lessons for indoor air quality evaluations.

Acceptable occupational exposure levels for hundreds of airborne concentrations of dusts, vapors, fumes, and gases have been set by consensus organizations and regulatory bodies for decades. These levels have established tremendous precedent and are tempting reference values in the relatively new field of indoor air quality evaluations where validated criteria are greatly needed. The American Conference of Government Industrial Hygienists (ACGIH) has been the most visible and productive group setting these guidelines for industrial exposure. The ACGIH Chemical Substances Committee has published an annual list of threshold limit values (TLVs) for more than 40 years. Currently the list covers more than 400 substances. In 1989, the Occupational Safety and Health Administration (OSHA) published updated permissible exposure limits (PELs) for approximately 600 substances. Most PELs before this update were adopted from the 1968 ACGIH list of TLVs and consensus standards of the American Standards Association. This OSHA update has resulted in reductions of 212 PELs and the addition of 164 new levels. The magnitude of the problem of protecting workers can be seen by the small fraction that the OSHA PELs represent of the more than 60,000 entries in the National Institute for Occupational Safety and Health's Registry of Toxic Effects of Chemical Substances. None of these levels, whether guidelines or regulatory requirements, are established based on any possible synergistic effect with other chemicals. The only guidance given by the ACGIH for synergistic effects is that such cases must be determined individually. Clearly, there are major drawbacks in using occupational standards and guidelines for evaluating the health effects of chemical agents that can be found in office settings, often in concentrations orders of magnitude less than what is routinely measured in the workplace. These guidelines are even less valuable when the concern is the complex mixing of chemicals in nonoccupational environments.

Air Pollutants, Occupational↗
PubMedDate not supplied

Exposure limits for ultra-short wave radiation in work environments.

Exposure limit values for ultra-short wave radiation of humans were derived on the basis of epidemiological survey and experimental exposure of rabbits. Eighteen male rabbits were divided into 4 groups randomly. Three groups were irradiated with ultra-short waves (100 MHz) at 35, 1.5-3.5, and 0.07 mW/cm2 power density in an E-polarized TEM Cell at 24 +/- 4 degrees C ambient temperature. The last group in a sham chamber served as controls. Irradiation was performed 3 hours per day, 5 days per week for 24 weeks. Thermal effects occurred in the group irradiated at 35 mW/cm2. The thermal threshold limit value was set at 1.5 mW/cm2. An epidemiological survey was carried out on 136 factory workers and TV operators exposed over one year to ultra-short wave radiation at 0.2 mW/cm2. They were compared with 108 controls. The only complaint of the exposed group was neurosis. The exposure limit value (ELV) to short wave radiation was set at 0.2 mW/cm2 by using a 15- and 20-fold safety factor.

Animals↗
PubMed1987

Changes in lung ATP concentration in the rat after low-level phosgene exposure.

Inhibition of mitochondrial respiratory activity and decreased lung adenosine triphosphate (ATP) concentration occur following exposure to 240 ppm.min phosgene. To determine the relationship between energy stores and the onset of phosgene-induced pulmonary edema, we measured the ATP concentration in rapidly frozen rat lung tissue before and during pulmonary edema. Male Sprague-Dawley rats were exposed to phosgene for four hours at concentrations of 0.05 to 1.0 ppm (12, 30, 60, 120, and 240 ppm.min). Lung wet and dry weight and ATP concentration were measured immediately after exposure and for three days postexposure. The accumulation of lavage fluid protein (LFP) was also measured as an index of damage or edema due to phosgene. Lung dry weight was significantly elevated one day postexposure to 0.5 ppm phosgene, while the LFP was elevated by 0.2 ppm phosgene. Time course studies at these doses of phosgene showed that decreased ATP levels preceded the onset of edema or increase in lung weight. The ATP values expressed on a per-lung basis showed that ATP levels were significantly lowered immediately following phosgene exposure, suggesting that the ATP changes were not the result of edema. This study is the first demonstration of a biochemical change that occurs following exposure to phosgene at a level significantly below the threshold limit value for this gas.

Adenosine Triphosphate↗
PubMedDate not supplied

Heat stress and strain in an aluminum smelter.

Studies of worker heat stress and strain in aluminum smelters have found that heat exposure likely to exceed the American Conference of Governmental Industrial Hygienists' threshold limit value (TLV) and that the dose-response relationship between heat stress and strain was weak. A heat stress model based on climatic data and a task analysis indicated exposures to heat stress in excess of the TLV during the July/August study period. To study the impact of working above the TLV, heat strain data (i.e., oral temperature, recovery heart rate, average heart rate) were collected. Recovery heart rates indicated high strain most of the time, and oral temperatures after peak demands were above the no-strain threshold of 37.5 degrees C about a quarter of the time, indicating that heat stress had an effect. About 95% of the readings were below 38.0 degrees C, the acute oral temperature threshold for a safe exposure. Average heart rates over 6- and 12-hour intervals were generally below acceptable limits of 120 and 110 bpm, respectively. Oral temperature and average heart rates indicated good control of heat stress exposures. Because recovery heart rates were high, some employees were working near their individual limits. The dose-response relationship for recovery heart rate and oral temperature were examined against the level of heat stress above the TLV. There was no relationship between oral temperature and heat stress level. There was an apparent trend toward higher recovery heart rates with heat stress. The lack of a dose-response relationship may be explained by brief periods of very high wet bulb globe temperatures that drove the time-weighted average up out of proportion to the physiological response.

Aluminum↗
PubMed1992

Lack of renal changes in stainless steel welders exposed to chromium and nickel.

Biochemical markers of kidney damage were examined in 52 male stainless steel welders (manual metal arc welding) exposed to chromium and nickel. No difference was found in the mean urinary excretion of total proteins, albumin, protein 1, transferrin, retinol-binding protein, lactate dehydrogenase, lysozyme, or beta-N-acetylglucosaminidase in a comparison with matched referents. Beta 2-microglobulin was slightly increased in those welders with a urinary chromium concentration of greater than 64.5 nmol.mmol-1 creatinine. The prevalences of abnormal values did not differ from those observed in the reference group. No correlation was found between the concentrations of chromium or nickel in urine and that of proteins or enzymes. No consistent or clinically significant renal impairment was revealed among the stainless steel welders exposed to a chromium air concentration slightly above the current threshold limit value of the American Conference of Governmental Industrial Hygienists for water-soluble hexavalent chromium compounds (50 micrograms.m-3).

Acute Kidney Injury↗
PubMed1985

Projected uptake and toxicity of selenium compounds from the environment.

Industrial workers and members of the general public may be exposed to selenium by inhalation of selenium in the workplace or atmosphere or by ingestion of selenium in food. A model has been developed to evaluate the potential uptake of selenium in body tissues by these two exposure routes. Rates were estimated for transport of selenium between five compartments including lung, gastrointestinal tract, blood, liver and other tissues. Results of model simulations were compared to published tissue distribution information obtained from single inhalation exposures of rats and dogs to radiolabeled selenium compounds at concentrations from 20 mg/m3 to 20 micrograms/m3 with initial body burdens of selenium ranging from 28 to 0.09 micrograms Se/kg body wt. The model was then modified to predict equilibrium organ concentrations of selenium in people after continual exposure to selenium in the air or in the diet. Daily intake levels of 100 micrograms/day and a fractional absorption value of 0.8 were used. With an air concentration of 1 ng Se/m3, model predictions indicated that most of the total body selenium in people is likely to come from their diet because selenium in the urban atmosphere contributes a very small part of the total body selenium. However, continual inhalation of selenium at the threshold limit value (TLV; 200 micrograms/m3) could contribute significantly to the total body burden of selenium. Levels of selenium predicted in lung, liver, and blood after inhalation of selenium at the TLV were 22,000, 1200, and 440 ng Se/g tissue. Predicted lung concentrations were near those that produced toxic effects in animals after ingestion of Se.

Absorption↗
PubMed2001

Evaluation of health and safety risks in municipal solid waste recycling plants.

Designers and managers of recycling processing plants need to be informed about the inherent occupational health and safety risks; however, there are few studies in the literature describing these risks. Therefore, the objectives of this project were to document the biological, chemical, physical, and ergonomic risks in three household-waste recycling plants. Bioaerosols (molds and bacteria) were measured using the methodology recommended by the American Society for Testing and Materials (ASTM). Chemical contaminants and physical agents suspected of being present in this type of environment were measured using the standard methods of the Quebec Occupational Health and Safety Research Institute (IRSST). The ergonomic part of the study identified the work requirements and risk factors causing the workers' physical symptoms. In summer, the average concentrations of total bacteria were greater than the Scandinavian guideline of 10,000 colony forming units per cubic meter of air (CFU/m3) in the receiving areas in plants 1 and 3, in the sorting areas of the three plants, and in shipping in plants 1 and 3. When the average concentrations of gram-negative bacteria were compared to the Scandinavian guideline of 1000 CFU/m3 of air, only the sorting department in plant 2 in summer exceeded this value. Average indoor concentrations of molds that were statistically significantly greater than those measured in the upwind outdoor air were measured in all departments in plants 1 and 3, regardless of the season, and only in sorting in plant 2 during the summer. The only chemical contaminant measured at average concentrations greater than 50% of the Threshold Limit Values (TLVs) proposed by the American Conference of Governmental Industrial Hygienists (ACGIH) was CO in the sorting departments in plants 1 and 2 during the winter. Noise exceeded the ACGIH TLV in plant 2. The workers' physical symptoms seem to be caused by the posture and effort required while remaining in a stationary position. Action must be focused on improving aspects such as work organization and personal protection and on informing citizens of the need for cleanliness of the material to be recycled.

Accidents, Occupational↗
PubMed1997

Electrophysiological investigation of central, peripheral and autonomic nerve function in workers with long-term low-level exposure to carbon disulphide in the viscose industry.

OBJECTIVE: Neurotoxicity of carbon disulphide (CS2) is well known. The air concentration at the workplace at which such adverse effects can first be observed is the subject of controversial discussion. METHODS: In a cross-sectional study on CS2-exposed workers peripheral motor and sensory nerve conduction studies, somatosensory evoked potentials, thermotesting and investigation of forced respiration sinus arrythmia have been carried out. The data from 222 workers exposed to CS2 in the viscose industry were evaluated and compared with data from 191 employees from the same factory with similar physical and psychological stress factors but without detectable occupational contact to neurotoxic substances. Median exposure to CS2 was below the currently valid occupational-medical threshold limit value (MAK-value) of 10 ppm. Multiple linear or multiple logistic regression analysis was used to check for statistical differences. RESULTS: Binary evaluation (comparison of exposed persons versus controls after multiple linear regression) revealed a slightly lower value in the exposed group for the motor nerve conduction velocity (MNCV, -0.76 m/s, median 48 m/s), but a long way from pathological thresholds. No dose-response relationship could be found within the exposed group for any evaluation criteria of CS2-exposure. Somatosensory evoked potentials, thermotesting and analysis of heart rate variability yielded no indication of a neurotoxic effect of CS2. CONCLUSION: Isolated decrease of MNCV in binary evaluation is, with regard to the known mechanism of CS2-neurotoxicity and the lack of a dose-response relationship, obviously not due to toxic effects. We interpret our results as showing that an adverse effect of carbon disulphide at the exposure ranges found was not detectable in the exposed group.

Adult↗