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PubMed2000

Toxicological bases for the setting of health-related air pollution standards.

The development of air pollution standards ideally involves the integration of data from the disciplines of epidemiology, controlled clinical studies, and animal toxicology. Epidemiological studies show statistical associations between health outcomes and exposure; they cannot establish a definite cause-effect relationship. The utility of toxicological studies is to establish this relationship. Recently, there was simultaneous promulgation of a new National Ambient Air Quality Standard (NAAQS) for particulate matter < 2.5 microns in aerodynamic diameter (PM2.5) and a revised NAAQS for ozone (O3). The O3 NAAQS was based, in part, on a sound foundation of toxicological data from controlled exposure studies in humans and animals. It also relied on epidemiological studies of hospital admissions for respiratory diseases. Such studies also served as important bases for the new PM2.5 NAAQS. However, the most influential bases for the PM NAAQS were the numerous and generally consistent epidemiological studies that associated exposure with premature mortality in susceptible subpopulations and the inability of numerous hypothesized confounding factors to negate the associations. Using ozone and PM as examples, this paper discusses the scientific basis for NAAQS promulgations in situations in which the underlying database differed greatly in the extent of toxicological support.

Air Pollutants↗
PubMed2002

Toxicity of ultraviolet radiation exposure to the lens expressed by maximum tolerable dose.

The maximum tolerable dose (MTD2.3:16) for avoidance of cataract on exposure to ultraviolet radiation (UVR)-300 nm in the rat was here estimated at 3.65 kJ/m2. Sprague-Dawley rats were unilaterally exposed to UVR in the 300 nm wavelength region. One week after the exposure, the intensity of forward light scattering was measured. Toxicity for continuous response events can be estimated with MTD. Current safety standards for avoidance of cataract after exposure to UVR are based on a binary response event. It has, however, recently been shown that UVR-induced cataract is a continuous dose-dependent event. MTD provides a statistically well-defined criterion of toxicity for continuous response events.

Animals↗
PubMedDate not supplied

Asbestos exposures during reprocessing of automobile brakes and clutches.

Asbestos exposures of workers in three small factories reprocessing automobile brakes and clutches in Japan were investigated. Airborne asbestos was collected on a membrane filter using an air sampler. From 1982 to 1989, asbestos counting was performed on 295 samples (198 personal and 97 stationary), using phase contrast microscopy. Only chrysotile asbestos was detected. Workers who reprocessed automobile brakes and clutches were exposed to asbestos concentrations of 0.025-76.4 fibers/cm3. Geometric mean asbestos concentrations during attaching linings to brake shoes and attaching facings to clutch disks were 0.859 fibers/cm3 and 0.780 fibers/cm3, respectively. Concentrations during stripping worn brake linings and clutch facings were 0.484 fibers/cm3 and 0.382 fibers/cm3, respectively. Machine grinding and leveling of new brake-lining surfaces represent potential sources of heavy asbestos exposures, unless enclosures and local ventilation are efficient.

Asbestos, Serpentine↗
PubMed2006

Selected science: an industry campaign to undermine an OSHA hexavalent chromium standard.

While exposure to hexavalent chromium (Cr(VI)) has been associated with increased lung cancer risk for more than 50 years, the chemical is not currently regulated by the U.S. Occupational Safety and Health Administration (OSHA) on the basis of its carcinogenicity. The agency was petitioned in 1993 and sued in 1997 and 2002 to lower the workplace Cr(VI) exposure limit, resulting in a court order to issue a final standard by February 2006. Faced with the threat of stronger regulation, the chromium industry initiated an effort to challenge the scientific evidence supporting a more protective standard. This effort included the use of "product defense" consultants to conduct post hoc analyses of a publicly-funded study to challenge results viewed unfavorably by the industry. The industry also commissioned a study of the mortality experience of workers at four low-exposure chromium plants, but did not make the results available to OSHA in a timely manner, despite multiple agency requests for precisely these sorts of data. The commissioned study found a statistically significant elevation in lung cancer risk among Cr(VI)-exposed workers at levels far below the current standard. This finding changed when the multi-plant cohort was divided into two statistically underpowered components and then published separately. The findings of the first paper published have been used by the chromium industry to attempt to slow OSHA's standard setting process. The second paper was withheld from OSHA until it was accepted for publication in a scientific journal, after the rulemaking record had closed. Studies funded by private sponsors that seek to influence public regulatory proceedings should be subject to the same access and reporting provisions as those applied to publicly funded science. Parties in regulatory proceedings should be required to disclose whether the studies were performed by researchers who had the right to present their findings without the sponsor's consent or influence, and to certify that all relevant data have been submitted to the public record, whether published or not.

Carcinogens, Environmental↗
PubMed2003

No evidence of dioxin cancer threshold.

The U.S. Environmental Protection Agency (EPA) has developed an estimate of the human cancer risk from dioxin, using the standard low-dose linear extrapolation approach. This estimate has been controversial because of concern that it may overestimate the cancer risk. An alternative approach has been published and was presented to the U.S. EPA Science Advisory Board's Dioxin Review Panel in November 2000. That approach suggests that dioxin is a threshold carcinogen and that the threshold is an order of magnitude above the exposure levels of the general population. We have reexamined the threshold analysis and found that the data have been incorrectly weighted by cohort size. In our reanalysis, without the incorrect weighting, the threshold effect disappears.

Carcinogens↗
PubMed2005

Occupational asthma and occupational rhinitis in hairdressers.

BACKGROUND: Hairdressers are at risk for occupational respiratory diseases, but the risk factors, causal agents, and underlying mechanisms are not completely defined. AIM: To describe the features of a large group of hairdressers consecutively referred to our center for suspected occupational asthma (OA) over an 8-year period, the type of occupational respiratory diseases, the etiologic agents, and the diagnostic tests. RESULTS: Forty-seven hairdressers (mean age, 25 years; range, 17 to 52 years) were studied. On the basis of the response to the specific inhalation challenge (SIC), 24 patients received a diagnosis of OA (51.1%), which was due to persulfate salts in 21 patients (87.5%), permanent hair dyes in 2 patients (8.3%), and latex in 1 patient (4.2%). Thirteen of these 24 patients (54.2%) also received a diagnosis of occupational rhinitis, which was due to persulfate salts in 11 patients (84.6%) and to paraphenylenediamine in two patients (15.4%). Patients with persulfate asthma had a long period of exposure to bleaching agents, a long latent period between the start of exposure and the onset of symptoms, and a prevalent eosinophilic airway inflammation in induced sputum. The skin-prick test with ammonium persulfate performed in a subset of patients gave negative results CONCLUSIONS: In the present study, we confirmed that persulfate salts are the major agents involved in OA and occupational rhinitis in hairdressers. The positive response to the SIC in only a part of the population of symptomatic exposed workers, the period between the starting of exposure and the onset of symptoms, the type of response to the SIC, and the high frequency of association of asthma with other diseases such as dermatitis and rhinitis suggest an immunologic mechanism that remains to be elucidated.

Adolescent↗
PubMedDate not supplied

[Norms and standards for radiofrequency electromagnetic fields in Latin America: guidelines for exposure limits and measurement protocols].

New technologies that use electromagnetic fields (EMF) have proved greatly beneficial to humankind. EMF are used in a variety of ways in the transmission of electrical energy and in telecommunications, industry, and medicine. However, some studies have shown that EMF could be detrimental to one's health, having found an association between exposure to EMF on the one hand, and the incidence of some types of cancer as well as behavioral changes on the other. Although so far there is no concrete proof that exposure to low-intensity EMF is hazardous, researchers continue to study the issue in an attempt to reach a consensus opinion and to establish safety standards. While developing and establishing such norms and standards have traditionally been the responsibility of international specialized agencies, national health authorities should take an active part in this process. Currently the Pan American Health Organization is promoting scientific research, often in the form of epidemiologic studies, in order to propose uniform norms and standards. Some Latin American countries, including Argentina, Brazil, Chile, Colombia, Costa Rica, Ecuador, Mexico, Peru, and Venezuela, have already enacted incomplete or partial legislation based on recommended international standards. This article describes the norms established in Latin America and the particular approach taken by each country.

Electromagnetic Fields↗
PubMed2002

Spatial variability in toxicity indicators used to rank chemical risks.

OBJECTIVES: This study used 6 different measures of toxicity to explore spatial and statistical variations in relative risk indicators of Toxic Release Inventory emissions. METHODS: Statistical and spatial correlations between the 6 indices were computed for individual South Carolina facilities. RESULTS: Although the 6 toxicity indices are not highly correlated in theory, they have more commonality in practice. There was significant spatial variation in the indices by individual facility level. CONCLUSIONS: Environmental justice researchers must be cognizant of differences in toxicity indices because the choice of the toxicity measure can alter (statistically and spatially) the results of equity analyses and lead to erroneous conclusions.

Data Collection↗
PubMed2004

Perspectives on new chemical regulatory framework and research direction in Korea.

In response to new information about the health risk of chemical and concern expressed by academia, labor, and industry, chemical regulatory framework under Industrial Safety and Health Act was completely restructured in Year 2003 to be more systematic and to meet the particular needs in Korea. The history and the current status of chemical regulatory framework in the Republic of Korea are reviewed.

Chemical Industry↗
PubMed2005

Assessment of respirable dust and its free silica contents in different Indian coalmines.

Assessment of respirable dust, personal exposures of miners and free silica contents in dust were undertaken to find out the associated risk of coal workers' pneumoconiosis in 9 coal mines of Eastern India during 1988-91. Mine Research Establishment (MRE), 113A Gravimetric Dust Sampler (GDS) and personal samplers (AFC 123), Cassella, London, approved by Director General of Mines Safety (DGMS) were used respectively for monitoring of mine air dust and personal exposures of miners. Fourier Transform Infra-red (FTIR) Spectroscopy determined free silica in respirable dusts. Thermal Conditions like Wet Bulb Globe Temperature (WBGT) index, humidity and wind velocity were also recorded during monitoring. The dust levels in the face return air of both, Board & Pillar (B&P) and Long Wall (LW) mining were found above the permissible level recommended by DGMS, Govt. of India. The drilling, blasting and loading are the major dusty operations in B&P method. Exposures of driller and loader were varied between, 0.81-9.48 mg/m3 and 0.05-9.84 mg/m3 respectively in B&P mining, whereas exposures of DOSCO loader, Shearer operator and Power Support Face Worker were varied between 2.65-9.11 mg/m3, 0.22-10.00 mg/m3 and 0.12-9.32 mg/m3 respectively in LW mining. In open cast mining, compressor and driller operators are the major exposed groups. The percentage silica in respirable dusts found below 5% in all most all the workers except among query loaders and drillers of open cast mines.

Coal Mining↗
PubMed2006

A study on compliance to hearing conservation programme among industries in Negeri Sembilan, Malaysia.

Noise is one of the hazards faced by workers. A cross-sectional study was conducted among industries in Negeri Sembilan with the objective to assess their compliance to Hearing Conservation Programme (HCP). The other objectives of this study were to determine the factors influencing it and to show the industries' compliance to each element of the programme. It was also to identify the association between compliance to HCP and the prevalence of hearing impairment and standard threshold shift. Data for this study were collected using questionnaires sent by mail and also the results of the latest audiometric tests. A total of 167 industries were analysed for this study. It was found that 41.3% of these industries fully complied to the programme. It was also found that the industries preferred to provide hearing protection device (92.8%) and least complied to noise control (61.1%). There were significant associations (p<0.05) between compliance and number of employees, status of ownership and the presence of officer in charge of hearing conservation programme. Having at least 150 employees actually raised the compliance to HCP in two folds (beta = 0.717, OR = 2.048, C.I 95% = 1.063 to 3.944). The prevalences of hearing impairment and standard threshold shift were 23.9% and 5.2% respectively. There was no significant association between the prevalence for hearing impairment and compliance to HCP. The prevalence for standard threshold shift was inversely related to compliance. This study showed that compliance percentage need to be improved as an effort to prevent the hearing problems among workers exposed to noise.

Adult↗
PubMed2001

Ketone bodies in milk and blood of dairy cows: relationship between concentrations and utilization for detection of subclinical ketosis.

The objective of this study was to investigate the relationship between the concentrations of the different ketone bodies in milk and blood and to evaluate these concentrations for the detection of subclinical ketosis. A total of 60 multiparous cows were used. Concentrations of acetone, acetoacetate, and beta-hydroxybutyrate were analyzed quantitatively in blood and milk, and the Ketolac strip test was used for semiquantitative determination of beta-hydroxybutyrate in milk. Cows were defined subclinically ketotic when their concentration of blood beta-hydroxybutyrate was over 1200 micromol/L. High correlation coefficients were observed between blood acetone and blood acetoacetate, and between blood and milk acetone. On the contrary, concentrations of milk and blood beta-hydroxybutyrate were poorly correlated with the other concentrations of ketone bodies. The Ketolac strip test overestimated the concentrations of beta-hydroxybutyrate in milk. For the detection of subclinical ketosis, the best sensitivity-specificity combination was obtained with the determination of acetoacetate in blood or milk, with threshold concentrations of 125 and 50 micromol/L, respectively. Determination of beta-hydroxybutyrate in the milk via an enzymatic analysis or via the Ketolac strip test provided valuable results, with threshold concentrations of 70 and 100 micromol/L, respectively. The simplicity of use of the Ketolac strip test makes it a valuable way to investigate subclinical ketosis.

3-Hydroxybutyric Acid↗
PubMedDate not supplied

Exposure of school employees to extremely low frequency magnetic fields.

This study was initiated to determine and compare daily occupational exposure (OE) and non-occupational exposure (NOE) of three employee groups of teachers, maintenance workers and secretarial staff in a Canadian school district. The time-weighted average (TWA) individual OE for subjects ranged from 0.4-3.8 milligauss (mG), and the TWA NOE ranged from 0.2-7.1 mG. TWA OE and NOE were 1.2 mG and 1.5 mG for teachers, 1.8 mG and 1.2 mG for maintenance workers, and 2.9 mG and 2.1 mG for secretarial staff. The differences between TWA OE and NOE of each group and also among the three groups were not statistically significant. OE and NOE of secretarial staff exceeded 10 mG 9.0% and 6.4% of the time--significantly (p < 0.001) higher rates than those of OE and NOE of teachers (1.0% and 1.4%) and maintenance workers (2.8% and 0.1%). Exposures were well below recommended criteria.

Adult↗
PubMedDate not supplied

Urinary fluoride as an exposure index in aluminum smelting.

Urinary fluoride was evaluated as an exposure index for a prospective study of asthma in an aluminum smelter. Two studies were conducted to evaluate the relationship between airborne exposure and urinary excretion over a workweek, and to describe exposures among jobs and over time. Thirty-two subjects were evaluated on Days 1 and 3 of a 3-day workweek. On each day, spot urine samples were collected prior to the start of work and again at the end of the shift. Samples were analyzed for fluoride and expressed as milligrams fluoride per gram of creatinine. Airborne exposures to total particulate, fluoride particulate, and hydrogen fluoride (HF; using a 37-mm filter cassette containing a filter and treated back-up pad) were also evaluated on each subject. In the second study, postshift urine samples were collected from asthma study volunteers in three surveys extending over 1.5 years and analyzed for fluoride. Average airborne exposures were 15.7, 4.1, and 0.7 mg/m3 for particulates, particulate fluorides and HF, respectively, and were substantially higher among carbon setters than other workers. However, average urine fluorides among the same workers were reasonably low, 1.3 and 3.0 mg/g creatinine in pre- and postshift urine samples, respectively. Carbon setters, who routinely wore respiratory protection during high exposure periods, had urinary fluoride levels similar to those of other potroom personnel. A significant variation in dose, as expressed by postshift urinary fluoride levels, was observed between potroom and nonpotroom jobs and over three survey periods. These results suggest that postshift urinary fluorides provide a reasonable exposure index for surveillance of exposure levels for an epidemiologic study, and that a substantial variation of exposure occurs between jobs and over time. Although urinary fluorides may be used for exposure surveillance, additional details on individual exposure agents and patterns of exposure over time are required for complete assessment.

Air Pollutants, Occupational↗