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PubMed1979

[Fluorine content in the urine and in the serum of hydrofluoric acid workers as an index of health administration (author's transl)].

The behavior of fluoride ion level in the urine and in the serum was measured as an index for health care of workers exposed to hydrofluoric acid, the effect of fluorine-containing foodstuff intake by the workers being considered at the same time. For this study, 250 hydrofluoric acid workers and as a control group 1,600 non-hydrofluoric-acid workers were examined. All workers, ranging in age from 15 to 59 years old, came from the same electronics factory. Fluorides in the biological fluids were measured by using the fluoride ion-specific electrode method and the electrode potential recording method concurrently. The fluoride ion levels (geometric mean) in the urine and in the serum of the non-hydrofluoric-acid workers were determined to be 0.59 ppm and 12 ppb, respectively. Among the influences of fluorine-containing foodstuff on fluoride content in the biological fluids, the effect of black tea and/or green tea intake was particularly remarkable. In the case of the non-hydrofluoric-acid workers, the concentration increased to about double of the control value. Similarly in a diet test on volunteers, the concentration increased about six times. As for the response to tea intake with the lapse of time, the concentration in the urine specimen (spot urine, S.G. corrected: 1.024) reached the maximum value three hours after the intake. In the case of the serum specimen, the maximum value was recorded one hour after the intake, and the influence of the intake continued for several hours. These results suggest that, in the medical examination of hydrofluroic acid workers, restriction of intake of tea and in some cases even a fasting program would have to be introduced as necessary pre-conditions. Upon observation of fluorine concentration in the urine with the lapse of time of hydrofluoric acid workers restricting tea intake, it was confirmed that the trend of the day-to-day variation was small. But that of the in-a-day variation, namely, an increase in the concentration toward the end of daily working hours was obvious. By introduction of these well-regulated methods, it has become possible to properly evaluate even the influence of hydrofluoric acid on the workers irregularly exposed to a hydrofluoric acid environment having a lower concentration than that of the threshold limit value (3 ppm). However, in view of ease of collection and measurement of specimens, speed, and degree of response to the exposure, it can be concluded that the measurement of fluorine content in the urine is more advantageous as an index for the health care than that in the serum. For this reason it is desirable that the former method should be given priority from the view point of prevailing industrial hygiene laws and regulations.

Adolescent↗
PubMedDate not supplied

Threshold of toxicological concern for chemical substances present in the diet: a practical tool for assessing the need for toxicity testing.

The de minimis concept acknowledges a human exposure threshold value for chemicals below which there is no significant risk to human health. It is the underlying principle for the US Food and Drug Administration (FDA) regulation on substances used in food-contact articles. Further to this, the principle of Threshold of Toxicological Concern (TTC) has been developed and is now used by the Joint FAO/WHO Expert Committee on Food Additives (JECFA) in their evaluations. Establishing an accepted TTC would benefit consumers, industry and regulators, since it would preclude extensive toxicity evaluations when human intakes are below such threshold, and direct considerable time and cost resources towards testing substances with the highest potential risk to human health. It was questioned, however, whether specific endpoints that may potentially give rise to low-dose effects would be covered by such threshold. In this review, the possibility of defining a TTC for chemical substances present in the diet was examined for general toxicity endpoints (including carcinogenicity), as well as for specific endpoints, namely neurotoxicity and developmental neurotoxicity, immunotoxicity and developmental toxicity. For each of these endpoints, a database of specific no-observed-effect levels (NOELs) was compiled by screening oral toxicity studies. The substances recorded in each specific database were selected on the basis of their demonstrated adverse effects. For the neurotoxicity and developmental neurotoxicity databases, it was intended to cover all classes of compounds reported to have either a demonstrated neurotoxic or developmentally neurotoxic effect, or at least, on a biochemical or pharmacological basis were considered to have a potential for displaying such effects. For the immunotoxicity endpoint, it was ensured that only immunotoxicants were included in the database by selecting most of the substances from the Luster et al. database, provided that they satisfied the criteria for immunotoxicity defined by Luster. For the developmental toxicity database, substances were selected from the Munro et al. database that contained the lowest NOELs retrieved from the literature for more than 600 compounds. After screening these, substances showing any effect which could point to developmental toxicity as broadly defined by the US were recorded in the database. Additionally, endocrine toxicity and allergenicity were addressed as two separate cases, using different approaches and methodology. The distributions of NOELs for the neurotoxicity, developmental neurotoxicity and developmental toxicity endpoints were compared with the distribution of NOELs for non-specific carcinogenic endpoints. As the immunotoxicity database was too limited to draw such a distribution of immune NOELs, the immunotoxicity endpoint was evaluated by comparing immune NOELs (or LOELs-lowest-observed-effect levels-when NOELs were not available) with non-immune NOELs (or LOELs), in order to compare the sensitivity of this endpoint with non-specific endpoints. A different methodology was adopted for the evaluation of the endocrine toxicity endpoint since data currently available do not permit the establishment of a clear causal link between endocrine active chemicals and adverse effects in humans. Therefore, this endpoint was analysed by estimating the human exposure to oestrogenic environmental chemicals and evaluating their potential impact on human health, based on their contribution to the overall exposure, and their estrogenic potency relative to endogenous hormones. The allergenicity endpoint was not analysed as such. It was addressed in a separate section because this issue is not relevant to the overall population but rather to subsets of susceptible individuals, and allergic risks are usually controlled by other means (i.e. labelling) than the Threshold of Toxicological Concern approach. (ABSTRACT TRUNCATED)

Animals↗
PubMed2004

Cross-sectional study of cardiovascular effects of carbon disulfide among Chinese workers of a viscose factory.

OBJECTIVE: This cross-sectional study investigates the cardiovascular effects among Chinese workers who were occupationally exposed to carbon disulfide (CS2), and evaluates the protective value of the current Chinese Maximum Allowable Concentration (MAC) of CS2 against cardiovascular effects. METHODS: The measurements of exposure were performed by personal sampling and gas chromatography. The biological monitoring was performed by HPLC. Three hundred and sixty-seven exposed workers and 125 reference workers (never exposed to CS2,) were included in this study. The exposed workers were divided into 2 sub-groups according to their cumulative exposure indices, the cut-off point being at 100 which means 10 years exposure to the Chinese Maximum Allowable Concentration in the workplace (10 mg/m3). All subjects were examined using a self-administered questionnaire including medical and job history, clinical complaints in the previous three months, and underwent a clinical check-up and a 12 lead electrocardiography (ECG) at rest, coded according to the Minnesota code. Blood pressure (BP) was recorded and blood samples were collected for lipid measurements. RESULTS: The personal monitoring showed that the exposures levels (15.47 +/- 2.34 mg/m3) were below the Threshold Limit Value (TLV, 31 mg/m3), and most of the samples analyzed still showed higher values than the Chinese MAC (10 mg/m3). Clinical complaints and abnormal electrocardiograms were not significantly increased in exposed workers. No significant effect of CS2 on blood pressure, cholesterol, HDL and LDL cholesterol or triglycerides was found. Further studies are recommended to elucidate the mechanism of cardiac intoxication after CS2 exposure. CONCLUSION: This study showed that Chinese workers exposed to CS2 did not have more clinical complaints, nor more ECG abnormalities than controls and no adverse effects were found in their lipids at an exposure level below the current TLV. The present results indicate that differences of health effects reported worldwide are possibly due to different exposure levels. They also indicate that the current Chinese MAC (10 mg/m3) sufficiently protects workers against negative cardiovascular effects.

Adolescent↗
PubMed1981

[New aspects for the evaluation of health effects caused by exposure against halogenated hydrocarbons at the working place. A literature review (author's transl)].

Halogenated hydrocarbons with over 150 toxicological relevant substances represent a considerable group among the numerous noxes at the working-places. Tri- and perchloroethylene are industrially widely used solvents for cleaning, degreasing and extraction. At the workplace the main amount of intake occurs via lung. Hepato-, nephro-, neuro- and cardiotoxicological effects are important solvent-induced health impairments. If the valid maximum concentrations in the work area (MAK-value) for the specific substance is not exceeded, altogether health hazards are impropable. With information of the "Unfallverhütungsbericht" only 23 cases of intoxications at the workplace were indemnified in 1977 for the first time. The causes for this low number are: installation of closed equipments, automation of the procedures and improvement of the personal hygiene. However praxis in occupational medicine shows, that there is a great number of persons in small firms that has contact with these solvents. For the surveillance and judgement of these solvent-exposed persons exist two methods. First the airborne concentration of the chemical compound can be determined at the working area. Second the solvent and/or its metabolites can be quantitative analyzed in the biological material. This method, called "biological Monitoring (BM)" has important advantages. BM should be prefered in cases of non-continuous, short-term exposures to concentrations of high degree. The judgement has to be done in relation to biological permissible limits (Biologische Arbeitsstoff-Toleranz-Werte, BAT, biological threshold limit values, BTLV's). Based on our longtime experience this specific and sensitive method should be used with priority.

Cardiovascular Diseases↗
PubMed2006

Potential uses of petrochemical products can result in significant benzene exposures: MSDSs must list benzene as an ingredient.

According to 29 CFR1910.1200 (Hazard Communication Standard [HCS]), a material safety data sheet (MSDS) must list a carcinogen as an ingredient if its concentration in a product is 0.1% or more by weight. However, according to the HCS, when the concentration of a carcinogen in a product is less than 0.1% (by weight) it may not be necessary to list it as an ingredient on the MSDS. The standard stipulates that if potential uses of the product can result in exposures to the carcinogen that exceed the Occupational Safety and Health Administration (OSHA) permissible exposure limit or the ACGIH threshold limit value (TLV), then it must be listed. This article focuses on the failure of MSDSs to report benzene as a listed ingredient in products that incorporate petroleum-derived ingredients such as toluene and hexane. In the United States, approximately 238,000 people are occupationally exposed to benzene each year. Only rarely is benzene listed as an ingredient on MSDSs even though it often comprises more than 0.1% of petroleum solvents and, when its concentrations in petroleum-derived products are much less than 0.1%, inhalation exposures to benzene can be much higher that its OSHA PEL of one part per million (ppm) by volume (v/v) andACGIH TLV of/one-half ppm (v/v). As a consequence of benzene's omission from MSDSs as a listed ingredient, employers are frequently unaware of their requirement to implement 29 CFR 1910.1028 (Benzene Standard) and of the need to address employee exposures to benzene in the workplace. This article demonstrates that benzene should be listed as an ingredient on MSDSs, even at concentrations in benzene-containing products that are between one and two orders of magnitude below OSHA's 0.1% threshold. An exposure assessment methodology is presented that is applicable to employees whose conditions of exposure are similar to those in the published study. These workers make up a similar exposure group. The information and methodology presented here are germane to preparation of accurate MSDSs for benzene-containing products, employers who must comply with 29 CFR 1910.1028, and retrospectively estimating exposures to benzene.

Air Pollutants, Occupational↗
PubMed1990

Semen quality and sex hormones among mild steel and stainless steel welders: a cross sectional study.

Welding may be detrimental to the male reproductive system. To test this hypothesis, semen quality was examined in 35 stainless steel welders, 46 mild steel welders, and 54 non-welding metal workers and electricians. These figures represent a participation rate of 37.1% in welders and 36.7% in non-welding subjects. The mean exposure to welding fume particulates was 1.3 mg/m3 (SD 0.8) in stainless steel welders using tungsten inert gas, 3.2 mg/m3 (SD 1.0) in low exposed mild steel welders using manual metal arc or metal active gas (n = 31), and 4.7 mg/m3 (SD 2.1) in high exposed mild steel welders (n = 15). The semen quality of each participant was defined in terms of the mean values of the particular semen parameters in three semen samples delivered at monthly intervals in a period with occupational exposure in a steady state. The sperm concentration was not reduced in either mild steel or stainless steel welders. The sperm count per ejaculate, the proportion of normal sperm forms, the degree of sperm motility, and the linear penetration rate of the sperm were significantly decreased and the sperm concentration of follicle stimulating hormone (FSH) was non-significantly increased in mild steel welders. A dose response relation between exposure to welding fumes and these semen parameters (sperm count excepted) was found. Semen quality decreased and FSH concentrations increased with increasing exposure. Significant deteriorations in some semen parameters were also observed in stainless steel welders. An analysis of information from questionnaires obtained from the whole population including subjects who declined to participate indicated an underestimation of effects due to selection bias. Potential confounding was treated by restriction and statistical analysis. The results support the hypothesis that mild steel welding and to a lesser extent stainless steel welding with tungsten inert gas is associated with reduced semen quality at exposure in the range of the Danish process specific threshold limit values of welding.

Adult↗
PubMed1994

Xylene: its toxicity, measurement of exposure levels, absorption, metabolism and clearance.

Xylene is an aromatic hydrocarbon widely used in industry and medical technology as a solvent. Health and safety authorities in most countries, including Australia, recommend a threshold limit value (TLV) of 100 ppm in the working environment. Recently, the amount of the major metabolite of xylene, methylhippuric acid (MHA), in urine has been recommended as a better indicator of exposure. The American Conference of Governmental Industrial Hygienists has recommended an upper limit for this indicator, called a biological exposure index (BEI), of 2.0 g MHA/L urine (SG 1.016). Xylene vapour is absorbed rapidly from the lungs, and xylene liquid and vapour are absorbed slowly through the skin. Of the xylene absorbed, about 95% is metabolised in the liver to MHA and 70 to 80% of metabolites are excreted in the urine within 24 hours. However, the many variables which affect the absorption, metabolism and clearance of xylene include exercise, alcohol intake, cigarette smoking, co-exposure to other solvents, gender, and gastrointestinal, hepatic and renal pathology. Xylene in high concentrations acts as a narcotic, inducing neuropsychological and neurophysiological dysfunction. Respiratory tract symptoms are also frequent. More chronic, occupational exposure has been associated with anemia, thrombocytopenia, leukopenia, chest pain with ECG abnormalities, dyspnea and cyanosis, in addition to CNS symptoms. Concomitant exposure to xylene and other solvents, including toluene, affected hematological parameters, liver size, liver enzymes, auditory memory, visual abstraction, and vibration threshold in the toes. Normal metabolic pathways were altered and significant increases in some serum bile acids may reflect early liver damage.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorption↗
PubMed2005

Prognostic significance of low serum levels of Clara cell phospholipid-binding protein in occupational aluminium neurotoxicity.

The relationship between respiratory and neurological effects of exposure to aluminium (Al) was investigated in a group of foundry workers exposed to Al at concentrations below the threshold limit value (TLV) binding in Poland (2.0 mg Al2O3 m(-3)). Neurological and neurophysiological parameters indicated subclinical effects of Al exposure on the nervous system. The measurement of serum anti-inflammatory Clara cell protein (CC16) was employed as a peripheral marker of the lung epithelium function. There was a strong inverse relationship between serum Al (Al-S) and CC16 concentrations (p = 0.006). The lowest CC16 concentrations were found in serum of workers characterised by subjective symptoms of the central nervous system (CNS) and abnormal results of neurophysiological examinations (EEG and VEP). Low serum CC16 concentrations and enhanced Al and iron (Fe) levels were also observed in the younger age group of workers with the subjective CNS symptoms and abnormal VEP results, which suggests that Fe is implicated in strengthening of the neurotoxic Al potential. The results of our study support the hypothesis that subclinical neurological symptoms (especially abnormal VEP) are most likely associated with internalisation of Al ions with lipid fractions of the lung epithelium, which in turn may help Al ions overcome the blood-brain barrier. Low serum CC16 concentrations (<10 microg L(-1)) were noted in workers with the abnormal results of neurological (CNS) and neurophysiological (EEG and VEP) examinations as well as with Al body burden manifested by urinary excretion (Al-U) below 60 microg L(-1) and Al-S concentration of 2 microg L(-1). This concentration may be considered as a threshold allowable biological concentration of aluminium.

Adult↗
PubMed1991

Acute behavioural comparisons of toluene and ethanol in human subjects.

A comparison of toluene and ethanol (EtOH) induced changes in central nervous system (CNS) function and symptoms were evaluated in two studies, and when possible the effects of toluene were expressed in EtOH equivalent units. The toluene concentrations were 0, 75, and 150 ppm, bracketing the American Conference of Governmental Industrial Hygienists threshold limit value (ACGIH TLV) of 100 ppm. The socially relevant EtOH doses were 0.00, 0.33, and 0.66 g EtOH/kg body weight, equivalent to two and four 3.5% 12 ounce beers. Forty two paid college students were used in each study. In the first study, subjects were exposed to toluene and an odour masking agent menthol (0.078 ppm) for seven hours over three days. In the second study EtOH or a placebo was administered at 1530 across three days also in the presence of menthol. Verbal and visual short term memory (Sternberg, digit span, Benton, pattern memory), perception (pattern recognition), psychomotor skill (simple reaction time, continuous performance, symbol-digit, hand-eye coordination, finger tapping, and critical tracking), manual dexterity (one hole), mood (profile on mood scales (POMS), fatigue (fatigue checklist), and verbal ability were evaluated at 0800, 1200, and 1600. Voluntary symptoms and observations of sleep were collected daily. A 3 x 3 latin square design evaluated solvent effects simultaneously controlling for learning and dose sequence. An analysis of variance and test for trend were performed on am-pm differences reflecting an eight hour workday and on pm scores for each solvent, in which subjects were their own control Intersubject variation in absorbance was monitored in breath. A 5 to 10% decrement was considered meaningful if consistent with a linear trend at p less than 0.05. At 150 ppm toluene, losses in performance were 6.0% for digit span, 12.1% for pattern recognition (latency), 5% for pattern memory (number correct), 6.5% for one hole, and 3% for critical tracking. The number of headaches and eye irritation also increased in a dose-response manner. The greatest effect was found for an increasing number of observations of sleep. A range of 2 to 7% decrements suggest the ACGIH TLV of 100 ppm toluene may be a good estimate of the biological threshold supporting a re-evaluation of the TLV. At 0.66 g EtOH/kg body weight symptoms and performance decrements were 6.6% for digit span, 9.2% for pattern recognition, 4.0% for continuous performance, 7.9% for symbol-digit, 16.5% for finger tapping, 6.2% for critical tracking, and 5.2% for the one hole test. The EtOH equivalents at 150 ppm toluene for digit span (0.56g EtOH/kg/body weight), the latency for pattern recognition (0.66 g EtOH kg body weight), and the one hole element "move" (0.37 g EtOH kg body weight) show that the first two measures would be affected at or above the 50 mg% blood alcohol concentration. This concentration is recognised as the lowest alcohol concentration associated with increased numbers of automobile accidents. The results suggest that EtOH may be a useful acute standard to compare the effects of various industrial solvents and support investigating an association between exposure to solvents and increased risk to safety in industry.

Adolescent↗
PubMed1997

In vivo measurements of lead in fingerbone in active and retired lead smelters.

OBJECT: The aim of this study was to determine the bone lead concentration in lead smelters and reference subjects, relate them to the lead concentration in blood (B-Pb) and urine (U-Pb), and to use the measured bone lead to calculate a biological half-life for lead in bone. METHOD AND DESIGN: The lead concentration in the second phalanx of the left index finger (bone-Pb) was determined in vivo using an X-ray fluorescence technique. The study population comprised 89 smelters with a history of long-term exposure to lead (71 active and 18 retired) and 35 reference subjects (27 active and 8 retired) with no known occupational exposure to lead. Bone-Pb was related to the previous lead exposure, estimated as a time-integrated B-Pb (CBLI). RESULTS: The retired smelters had the highest bone-Pb (median value 55 micrograms/g wet weight, as against 23 micrograms/g in active smelters) and 3 micrograms/g in the reference subjects. A strong positive correlation was observed between the bone-Pb and the CBLI among both active (rs = 0.73; P < 0.001) and retired (rs = 0.71; P = 0.001) smelters. The corresponding correlations between the bone-Pb and the period of employment were of the same magnitude. For retired workers, there were positive correlations between the bone-Pb and the B-Pb (rs = 0.58; P = 0.011) and U-Pb. (rs = 0.56; P = 0.02). Multiple regression analyses showed that bone-Pb was best described by the CBLI, which explained 29% of the observed variance (multiple r2) in bone-Pb in active workers and about 39% in retired workers. The estimated biological half-life of bone-Pb among active lead workers was 5.2 years (95% confidence interval 3.3-13.0 years). CONCLUSIONS: The high bone-Pb seen in retired workers can be explained by the long exposure periods, the higher exposure levels in earlier decades, and the slow excretion of lead accumulated in bone. The importance of the skeletal lead pool as an endogenous source of lead exposure in retired smelters was indicated by the associations between the B-Pb or U-Pb, on the one hand, and the bone-Pb, on the other. In active workers, the ongoing occupational exposure was dominant. The in vivo X-ray fluorescence technique is still mainly a research tool, and more work has to be done before it can be used more widely in clinical practice. However, over the next decade we can anticipate retrospective, prospective and cross-sectional epidemiological studies in which bone lead determinations reflecting the previous lead exposure in both occupationally and nonoccupationally lead exposed populations are related to various types of adverse health outcomes. Such studies will improve our knowledge of dose-response patterns and provide data that will have an impact on hygienic threshold limit values and prevention of lead-induced diseases.

Adult↗
PubMed2006

Axonal polyneuropathy after acute dimethylamine borane intoxication.

OBJECTIVE: To study a patient with axonal polyneuropathy due to acute dimethylamine borane (DMAB) intoxication. PATIENT: Confusion and drowsiness in the acute stage, followed by cognitive impairments and polyneuropathy, are reported in a chemical factory worker after acute exposure to DMAB. RESULTS: Nerve conduction studies indicated axonal polyneuropathy, particularly in the motor nerves. Sural nerve biopsy studies 3 months later revealed an axonal degeneration with a mild decrease of fiber density in the large myelinated fibers. Quantitative sensory testing also disclosed an impairment of pinprick, temperature, and touch sensations. Cutaneous nerve biopsy studies 9 months later demonstrated a moderate loss of epidermal nerves. During the follow-up period of 1.5 years, the clinical features and serial nerve conduction studies showed a steady improvement. CONCLUSIONS: Since DMAB is a new product and has been widely used recently in the manufacturing of semiconductors and electronics, we conclude that DMAB intoxication may produce motor-predominant axonal polyneuropathy and that the establishment of a threshold limit value is warranted.

Acute Disease↗
PubMed1999

Proactive approach for the evaluation of fetal safety in chemical industries.

Women, their families, and employers are concerned about potential fetal risks that may be associated with occupational exposure to chemicals. In an attempt to quantify potential fetal risks in the petroleum industry, we conducted a literature review of selected chemical compounds to which Imperial Oil Limited (IOL) female personnel may be exposed. Medline, Toxline, and Dissertation Abstracts databases were utilized to search for all research papers published in any language from 1966-1996. Chemical exposures in these papers were compared to IOL chemical exposure indices from a specific refinery and chemical plant. In total, 559 studies obtained from the literature search related to the chemicals used in a specific refinery and chemical plant. Of these, only 21 studies explicitly stated some sort of exposure level for the various chemicals. Most of the selected female reproductive toxicology studies summarized explicitly stated chemical exposure levels: either as parts per million, stratifying as to number of days of exposure, or as estimates of the percentage of the threshold limit value. On comparing the occupational literature that presented either actual or estimated values of chemical exposure dose with the IOL routine rating factors in IOL's Products and Chemicals Divisions, we found that IOL chemical exposure levels overall were lower than those reported in the literature to be associated with fetal risks. A new proactive approach is presented to inform female workers and their families of the relative safety/risk of routine occupational exposures. This approach allows for the mitigation of the misperception of teratogenic risk and unjustified fears associated with it.

Air Pollutants, Occupational↗
PubMed1997

Urinary excretion of specific mercapturic acids in workers exposed to styrene.

Styrene is an important chemical of wide industrial use, particularly in the manufacture of polymers and reinforced plastics. Environmental and occupational exposures to styrene occur predominantly via inhalation. Styrene undergoes biotransformation mainly by side chain oxidation catalyzed by cytochrome P-450 enzymes to its reactive metabolite, styrene oxide. The (R)- and (S)-enantiomers of styrene oxide can be conjugated with glutathione to both (R)- and (S)-diastereoisomers of specific mercapturic acids, N-acetyl-S-(1-phenyl-2-hydroxyethyl)-L-cysteine (M1) and N-acetyl-S-(2-phenyl-2-hydroxyethyl)-L-cysteine (M2). We conducted this biomonitoring study with the aim of evaluating the association between excretion of specific mercapturic acids (M1 and M2) and level of exposure to styrene among occupationally exposed people. The mean time-weighted average (TWA) exposure was about one-half the current threshold limit value, the range of the values varied from 44 to 228 mg/m3. Geometric mean (GM) concentrations of 650, 1,084, and 31.8 micrograms/g creatinine were measured, respectively, for M1-S, M2, and M1-R. The environmental styrene concentration exhibited a significant correlation with total specific mercapturic acid (Mtot = sum of M1-R, M1-S, and M2), making it possible for the first time to calculate the approximate relationship between styrene uptake and excretion of these substances. The M2 mercapturic acid had a better correlation (r = 0.56) with respect to M1-R and M1-S. Significant correlations were found also between the excretion of specific mercapturic acids and biological exposure indices (i.e., mandelic and phenylglyoxylic acids and urinary styrene).

Acetylcysteine↗
PubMed1997

Liver function alterations in synthetic leather workers exposed to dimethylformamide.

A cross-sectional study of the prevalence of chronic liver function alterations was performed in 75 workers employed in a synthetic leather factory, exposed to dimethylformamide (DMF) air concentrations below threshold limit values (30 mg/m3). Biological monitoring among workers revealed acceptable urine levels of monomethylformamide (NMF) on average, but the very wide range indicated that occasional overexposure was possible. The worker survey showed a high percentage of disulfiram-like symptoms (50%) and liver function abnormalities (22.7%), compared with a demographically similar group of unexposed workers. Covariance analysis (ANCOVA) revealed that enzyme levels were significantly higher in exposed workers than in controls after data were corrected for age, alcohol consumption, body mass index, and cholesterol levels. The authors conclude that DMF can cause liver diseases even if air TLVs are respected, because accidental contact with liquid DMF can significantly increase DMF uptake. In this situation, air monitoring is no longer sufficient to evaluate worker exposure.

Adult↗
PubMed1998

Was there sufficient justification for the 10-fold increase in the TLV for silica fume? A critical review.

In 1992, the Threshold Limit Value (TLV) for amorphous silica fume produced as a by-product of metallurgical processes was revised upwards from 0.2 mg/m3 (respirable dust) to 2.0 mg/m3. Comparison of the documentation justifying the lower TLV published by the ACGIH in 1989, with the subsequent documentation justifying the higher value published in 1992, does not support this increase. Following an outline of the problem areas existing in interpretational difficulties of experimental and review material in the silica fume bibliography, this paper provides a detailed examination of the six additional references cited in the 1992 documentation. All additional material suggests a need for extra caution, particularly with respect to recent experimental work in Australia on the sizing of silica fume. This paper concludes that the health evidence supports a TLV for silica fume closer to 0.3 mg/m3 rather than the current 2.0 mg/m3 now adopted in the U.S. and Australia.

Air Pollutants, Occupational↗
PubMed2000

Occupational airway sensitizers: an overview on the respective literature.

BACKGROUND: Worldwide, there is rigorous scientific activity concerning the further development of work safety regulations involving airway-sensitizing substances. Technical directives on hazardous substances are enforced in several countries and are being continuously updated. The European Union has established a code for several occupational substances, now labeled R 42 ("may cause sensitization by inhalation"). METHODS: We present an overview of the literature dealing with allergic occupational asthma. The literature was selected according to criteria of study design and diagnostic test methods. Approximately 300 publications were reviewed including both epidemiological studies and individual case reports. RESULTS: Airway sensitizers are systematically arranged and separately listed according to chemicals and their origin from animals, plants, and microorganisms. The clinical data as well as threshold limit values (TLV) and R 42 labeling of 250 airway-sensitizing substances are presented. CONCLUSIONS: The most common sensitizing substances causing occupational asthma were dust of cereal flours, enzymes, natural rubber latex, laboratory animals as well as low molecular substances such as isocyanates and acid anhydrides.

Asthma↗
PubMedDate not supplied

Subchronic inhalation neurotoxicity study of amyl acetate in rats.

An inhalation toxicity study was conducted with rats to examine the potential for amyl acetate vapor to produce alterations in nervous system structure and function following repeated exposure. The study was performed as part of a USEPA Toxic Substances Control Act (TSCA) Section 4e Enforceable Consent Agreement for amyl acetate. Rats (CD) were exposed to amyl acetate vapor at concentrations of 0, 300, 600 or 1200 ppm, 6 h per day, 4 or 5 days per week, for at least 65 exposures. Treatment groups consisted of 15 rats per gender for the control and 1200 ppm groups and 10 rats per gender for the 300 and 600 ppm groups. Evaluations included clinical observations before, during and after each exposure, weekly detailed clinical examinations, weekly body weight and food consumption measurements and monthly functional observational battery and motor activity measurements conducted on non-exposure days. Neuropathology examination of the central and peripheral nervous system was performed at the end of the study. Exposure to amyl acetate did not result in overt clinical signs of toxicity or changes in body weight or food consumption. Transient, subtle decreases in general activity level during the 6-h exposure period were noted for animals in the 600 and 1200 ppm groups during the first 2 weeks of the study. Functional observational battery evaluations, automated motor activity measurements and neuroanatomy were unaffected by exposure. The no observed-effect level for subchronic neurotoxicity for this study was at least 1200 ppm, which is greater than an order of magnitude above the occupational threshold limit value (8-h, time-weighted average) for amyl acetate (100 ppm).

Administration, Inhalation↗
PubMed2001

Respiratory diseases caused by occupational exposure to 1,5-naphthalene-diisocyanate (NDI): Results of workplace-related challenge tests and antibody analyses.

BACKGROUND: 1,5-naphthalene-diisocyanate (NDI) is an aromatic diisocyanate with a very low vapor pressure which is mainly used in the automotive industry. METHODS: In the present study we described five cases with workplace-related asthma and one case with extrinsic allergic alveolitis associated with pulmonary hemorrhage after NDI exposure. RESULTS: Corresponding to case histories, extrinsic alveolitis on asthmatic reactions in three subjects and a rhinitis reaction in one patient could be reproduced by inhalative challenge tests to NDI at a concentration of 10 ppb. Preliminary IgE and IgG antibody analyses in patients' sera did not produce significantly positive results. CONCLUSIONS: According to the outcome of our tests and in comparison with several other studies, we conclude that NDI should be classified as potent airway-sensitizing substance. Improved workplace conditions and decrease in threshold limit values should therefore be recommended.

Adult↗