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PubMed2001

Biological monitoring of workers exposed to ethylbenzene and co-exposed to xylene.

OBJECTIVE: Ethylbenzene is an important constituent of widely used solvent mixtures in industry. The objective of the present study was to provide information about biological monitoring of occupational exposure to ethylbenzene, and to review the biological limit values corresponding to the threshold limit value of ethylbenzene. METHODS: A total of 20 male workers who had been exposed to a mixture of ethylbenzene and xylene, through painting and solvent mixing with commercial xylene in a metal industry, were recruited into this study. Environmental and biological monitoring were performed during an entire week. The urinary metabolites monitored were mandelic acid for ethylbenzene and methylhippuric acid for xylene. Correlations were analyzed between urinary metabolites and environmental exposure for ethylbenzene and xylene. The interaction effects of a binary exposure to ethylbenzene and xylene were also investigated using a physiologically based pharmacokinetic (PBPK) model. RESULTS: The average environmental concentration of organic solvents was 12.77 ppm for xylene, and 3.42 ppm for ethylbenzene. A significant correlation (R2 = 0.503) was found between environmental xylene and urinary methylhippuric acid. Urinary level of methylhippuric acid corresponding to 100 ppm of xylene was 1.96 g/g creatinine in the worker study, whereas it was calculated as 1.55 g/g creatinine by the PBPK model. Urinary level of mandelic acid corresponding to 100 ppm of ethylbenzene was found to be 0.7 g/g creatinine. PBPK results showed that the metabolism of ethylbenzene was highly depressed by co-exposure to high concentrations of xylene leading to a non-linear behavior. CONCLUSIONS: At low exposures, both methylhippuric acid and mandelic acid can be used as indicators of commercial xylene exposures. However at higher concentrations mandelic acid cannot be recommended as a biological indicator due to the saturation of mandelic acid produced by the co-exposure to xylene.

Benzene Derivatives↗
PubMed1997

Oncogenic risk in a chemical plant: a methological approach and preliminary results.

One of the major problems that occupational medicine has to deal with is cancer risk assessment. Recent Italian legislation requires the evaluation of occupational exposure to carcinogens in all workplaces, but a standardized method to be used in the environmental and biological criteria is generally lacking. The objective of this report is to identify a multidisciplinary approach to the research on this topic. The study is based on a chemical plant that produces pitch. The multidisciplinary approach is based on risk- and health-damage assessments. Ethical aspects are also taken into account, and the research design incorporates an informed consent for all employees. Some preliminary results are available. From the environmental point of view, all parameters provide an airborne concentration value below threshold limit values (TLVs), but biological monitoring demonstrates an increased urinary excretion of 1-OH-pyrene in all tested subjects. In conclusion, the first objective of our study is to demonstrate the carcinogenic risk of employees, searching for an agreement between environmental analysis, biological monitoring, and health effect data. A close collaboration between different professions is necessary.

Animals↗
PubMed1999

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.

Animals↗
PubMed2003

Multielement composition of wines and their precursors including provenance soil and their potentialities as fingerprints of wine origin.

The influence of the provenance soil and vinification process on the wine multielemental composition was investigated. For this purpose, two different vineyards from the Douro wine district, Portugal, were selected. Monovarietal grapes from a 10 year old vineyard were used to produce a red table wine, in a very modern winery. Polyvarietal grapes from a 60-70 year old vineyard were used to produce a red fortified wine, similar to Port, through a traditional vinification process. The multielement compositions (Al, As, B, Ba, Be, Ca, Cd, Co, Cr, Cs, Cu, Fe, Ga, Hf, Li, Mn, Mo, Nb, Ni, Pb, Rb, Sb, Sc, Sr, Ti, Th, Tl, U, V, W, Y, Zn, Zr, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu) of soil, grape juices (prepared in the laboratory), and samples collected in the different steps of each winemaking process were measured. Inductively coupled plasma mass spectrometry was used, after suitable pretreatment of the samples (by UV irradiation for liquid samples and high-pressure microwave digestion for soil). Both vinification processes influenced the multielement composition of the wines. Most of the elements presented similar or even lower concentrations in the wine as compared to that observed in the respective grape juice, probably as a result of precipitation or coprecipitation with suspended particles during fermentation and/or wine aging. Evidence of effective contamination during grape pressing, fermentation, and/or fining of wines (depending on the element) was observed for Cd, Cr, Cu, Fe, Ni, Pb, V, and Zn in the fortified wine and Al, Cr, Fe, Ni, Pb, and V in the table wine. Nevertheless, significant correlations were obtained between the multielement composition of the wine and the respective grape juice (R = 0.997 and 0.979 for the fortified and table wines, respectively, n = 31, P < 0.01), as well as between that in the wine (median of the two studied wines) and the provenance soil (R = 0.994, n = 19, P < 0.01), for the set of elements determined in common in the different types of samples. These results are promising concerning the usefulness of the elemental patterns of both soil and wine as fingerprints of the origin of the studied wines. Nevertheless, more wines from the same and other wine districts must be studied in order to consolidate this conclusion. The multielement compositions of the studied wines were compared with those of wines of different characteristics and origins, as well as with the respective legal threshold limit values, when available. Relatively low metal levels, below their threshold limit values, were found in all cases.

Fermentation↗
PubMed2000

[Methods for in vivo measurement of light transparency in the human crystalline lens].

A method for the in vivo measurement of light transparency of the human crystalline lens, based on the measurement of the blue and red light threshold radiance, in presented. The threshold limit values for radiances of 477 nm (blue) and 620 nm (red) were measured for people at age from 17 to 66 years old without cataract. The people recognised the geometric figures by left and right eye separately, after being adapted to darkness. The radiance of the figures was changed smoothly by ADM adaptometer. The threshold limit values were measured several times for each eye. For each eye the average of the threshold limit values for radiances of 620 nm and 477 nm and their quotient were calculated. Values of these quotients practically did not change for young eyes (to 32 years old) and they decreased for older eyes. These results indicate the increase of the threshold radiance of 477 nm in relation to threshold radiance of 620 nm for older people, and this means the reduction of the crystalline lens transparency for blue light in relation to red one as they grow old. It seems that the reduction should precede the development of cataractous changes and this fact may be used in the diagnostics of precataractous states.

Adolescent↗
PubMed1995

Occupational exposure and indoor air quality monitoring in a composting facility.

The objective of this study was to investigate indoor air quality in a completely covered enclosure used for the aerobic composting of organic wastes originating from vegetable, fruit, and garden refuse. Samples of gases and vapors were taken in the ventilation exhaust ducts. Volatile organic compounds (VOCs) were collected on Tenax absorbent; after thermal desorption they were analyzed by gas chromatography/mass spectrometry. Hydrogen sulfide was determined using Dräger test tubes. Microbial samplings were conducted on four sites inside the hall. Microbes were collected using a modified Anderson high-volume sampler, consisting of two impactor stages. Results indicate that the concentrations of VOCs were rather low; only the limonene level was elevated, but it was still well below the current Dutch provisional threshold limit value. Hydrogen sulfide levels found were also far less than the Dutch threshold limit value. Both total bacteria and gram-negative bacterial counts exceeded the provisional Dutch guideline of 10,000 cfu/m3 for indoor air in the work environment. Furthermore, the number of fungi, for the larger part consisting of the genera Aspergillus and Penicillium, which are known to cause respiratory tract disorders, approached the hazardous exposure level.

Air Pollutants, Occupational↗
PubMedDate not supplied

[Measurement of N-methylformamide in occupational exposure to N,N-dimethylformamide].

N,N-dimethylformamide (DMF) is a solvent that is widely used in industry. The major occupational sources of exposure results from production of synthetic leather. The main metabolite formed in both man and animals is N-hydroxymethyl-N-methylformamide. Demethylation leads to N-methylformamide (NMF) and formamide and also to a small extent to hydroxy-methylformamide. All the metabolites are excreted in urine, as are very small amounts of the unchanged substance. N-acetyl-S-(N-methyl-carbamoyl)-cysteine can be determined in urine as a further metabolite. We conducted this biomonitoring study with the aim of evaluating the correlation between the excretion of N-methylformamide (mainly from N-hydroxymethylformamide) and levels of exposure to N,N-dimethylformamide among occupationally exposed people. The mean time-weighted average (TWA) exposure was about half (13.5 mg/m3) of the current threshold limit value, the range of the values varying from 0.4 to 75.2 mg/m3. A linear equation existed between urinary NMF concentration and DMF concentration in the environment. The findings show that the urinary NMF concentration can be used as an appropriate biological exposure index. The authors suggest for occupationally exposed subjects, a urinary NMF concentration corresponding to the time-weighted average of the threshold limit value of 39.9 mg/l (37.2 mg/g creatinine) and a 95% lower confidence limit (biological threshold) of 23.4 mg/l (22.2 mg/g creatinine).

Adult↗
PubMed1989

[The actual state of occupational exposure to chlorpyrifos of termite control workers].

Chlorpyrifos, an organophosphorus insecticide, has been used as a termite control agent since regulatory measures against the use of chlordane were taken in September, 1986. In this study the actual state of occupational exposure to chlorpyrifos of termite control workers was investigated. The findings obtained were as follows. The concentration of chlorpyrifos in the air (near the mouth) was about 10 times higher (1.7-2.3 mg/m3) under the floor than the threshold-limit value (0.2 mg/m3) proposed by the ACGIH and rose close to the threshold-limit value even above the floor. Regarding the performance of the absorption can of the mask, generally satisfactory results were obtained. The adhesion of this compound to the work outfit was conspicuous during the spraying work under the floor, and it was often noted on the right forearm (12 micrograms/cm2), on the left knee (10 micrograms/cm2), on the right knee (9 micrograms/cm2) and on the face (5 micrograms/cm2). The rate of this compound penetrating through the work outfit amounted to an average of 40 percent, making it clear that a considerable amount of the compound penetrated the work outfit. Furthermore, direct adhesion of the compound to the neck was considered. These results suggested the dermal-exposure to chlorpyrifos of termite control workers. This compound was detected, though the quantity was very small, in blood after work, which was definitely indicative of exposure at the time of termite control work. The plasma cholinesterase activity in the termite control workers was within the normal range before the busy termite control season but fell off markedly when the full-scale termite control season set in. It is suggested that a decrease in plasma cholinesterase activity occurs due to chlorpyrifos exposure.

Chlorpyrifos↗
PubMed2006

Occupational endotoxin-exposure and possible health effects on humans.

BACKGROUND: Endotoxins are commonly found at workplaces where large amounts of bioaerosols are generated. In Germany, especially since the Ordinance on Safety and Health Protection related to work involving biological agents (Biostoff-Verordnung) became effective (1999), threshold limit values are widely discussed. Up to the present, endotoxin values are measured with non-uniform methods and therefore values are of limited benefit for classification of exposure groups. In Germany there is no threshold limit value for endotoxin. METHODS: Relevant literature of the last 20 years was selected from Medline and discussed. RESULTS: In this review we focused on the impact of endotoxin exposure on human health with special respect to the measurements on workplace and methodological aspects of endotoxin determination. Methods for sampling and endotoxin determination have to be validated, optimized, and standardized first. CONCLUSION: The adverse health effects of endotoxins are known, standardization of measurements is a necessary goal and protection measures should be established immediately.

Agriculture↗
PubMed1989

[Health care of workers engaged in waste water treatment. 1) The exposure conditions to organic solvents in workers engaged in waste water treatment].

In the investigation of the exposure conditions to organic solvents of workers in 35 waste water treatment facilities, it was found that these workers treated various kinds of solvents. Almost all of the facilities treated chloroform, acetone, n-hexane, methanol and carbon tetrachloride. The average exposure concentration of the workers was, however, low. Exposure concentration to organic solvents (chloroform, xylene and carbon tetrachloride) was evaluated in one of the facilities. The average concentration of the respective solvents in the workers did not exceed the threshold limit value of Japan, but the concentration calculated on the basis of combined exposure exceeded the threshold limit value. On the other hand, high concentrations of organic solvents were detected in the room where the solvents were introduced but not in the working rooms, indicating that the workers engaged in waste water treatment were mainly exposed to organic solvents in the former room where they sorted and mixed the solvents and placed them in the incinerator. In conclusion, improvement in working conditions and health care for workers engaged in waste water treatment facilities should be made in order to prevent workers from becoming intoxicated by organic solvents.

Acetone↗
PubMed2005

WBGT clothing adjustments for four clothing ensembles under three relative humidity levels.

Threshold limit values for heat stress and strain are based on an upper limit wet bulb globe temperature (WBGT) for ordinary work clothes, with clothing adjustment factors (CAF) for other clothing ensembles. The purpose of this study was to determine the CAF for four clothing ensembles (Cotton Coveralls, Tyvek 1424 Coveralls, NexGen Coveralls, and Tychem QC Coveralls) against a baseline of cotton work clothes and to determine what effect relative humidity may have. A climatic chamber was used to slowly increase the level of heat stress by increasing air temperature at three levels of relative humidity (20%, 50%, and 70%). Study participants wore one of the five ensembles while walking on a treadmill at a moderate metabolic rate of 155 W m-2 (about 300 W). Physiological data and environmental data were collected. When the participant's core temperature reached a steady state, the dry bulb temperature was increased at constant relative humidity. The point at which the core temperature began to increase was defined as the inflection point. The environmental temperature recorded 5 min before the inflection point was used to calculate the critical WBGT for each ensemble. A three-way analysis of variance with ensemble by humidity protocol interactions and a multiple comparison test were used to make comparisons among the mean values. Only the vapor-barrier ensemble (Tychem QC) demonstrated an interaction with humidity level. The following CAFs are proposed: Cotton Coveralls (0 degrees C-WBGT), Tyvek 1424 Coveralls (+1), NexGen Coveralls (+2), and Tychem QC Coveralls (+10).

Adult↗
PubMed2004

Personal exposures to inorganic and organic dust in manual harvest of California citrus and table grapes.

The aim of this study was to determine characteristics of personal exposure to inorganic and organic dust during manual harvest operations of California citrus and table grapes. Personal exposures to inhalable dust and respirable dust were measured five times over a 4-month period of harvesting season. We analyzed components of the dust samples for mineralogy, respirable quartz, endotoxin, and total and culturable microorganisms. Workers manually harvesting were exposed to a complex mixture of inorganic and organic dust. Exposures for citrus harvest had geometric means of 39.7 mg/m(3) for inhalable dust and 1.14 mg/m(3) for respirable dust. These exposures were significantly higher than those for table grape operations and exceeded the threshold limit value for inhalable dust and respirable quartz. Exposures for table grape operations were lower than the threshold limit value, except inhalable dust exposure during leaf pulling. Considered independently, exposures to inhalable dust and respirable quartz in citrus harvest may be high enough to cause respiratory health effects. The degree of vigorous contact with foliage appeared to be a significant determining factor of exposures in manual harvesting.

Adult↗
PubMed1978

Methyl ethyl ketone polyneuropathy in shoe factory workers.

Three cases of polyneuropathy in shoe factory workers are described. The etiologic agent is felt to be methyl ketone, a substance previously thought to be a safe solvent. The concentration of this substance in the ambient air of the patients was below the threshold limit value. This suggests that there may be a cumulative effect and that we should reexamine the threshold limit values set for all the organic solvents with respect to inhalation and absorption from skin surfaces.

Adult↗
PubMed1977

Urinary chromium as an indicator of the exposure of welders to chromium.

Five welders working with high alloy Cr-Ni steel and one working with mild steel were followed during one work week. The chromium concentration in air was measured concomitantly with urinary chromium determinations. The water-soluble chromium concentrations in air exceeded 0.05 mg/m3 during welding with coated electrodes, but metal inert-gas (MIG) welding produced much lower concentrations. The proportion of water-soluble hexavalent chromium in the air was usually more than 50% of the total chromium concentration during welding with coated electrodes, whereas less than 10% of the chromium produced during MIG welding was in a water-soluble. Since water-soluble chromium (hexavalent) is the more important biologically, the determination of both water-soluble and water-insoluble chromium concentrations is emphasized instead of the measurement of the total concentration. The urinary chromium concentration proved to be a good indicator of short-term exposure to water-soluble chromium when exposure was above the current threshold limit value of 0.05 mg/m3, concentrations of more than 30 microgram/g of creatinine representing an exposure level higher than the threshold limit value.

Adult↗
PubMed1980

On site determination of Sulfotep air levels in a fumigating greenhouse.

Sulfotep air levels in a greenhouse were monitored continuously in real time, for 4-40 hours after fumigation, using a trace atmospheric gas analyzer system. Sulfotep air levels were below the threshold limit value of 15 ppb following overnight ventilation but, when ventilation was stopped to conserve heat, the Sulfotep air levels exceeded the threshold limit value. This study also showed that worker activity in the greenhouse significantly increased Sulfotep air levels. It is recommended, therefore, that ventilation of a greenhouse following Sulfotep fumigation should continue during the entire day and workers exposed to such conditions should wear appropriate protective equipment.

Air Pollutants↗
PubMed1985

Efficacy of the ejector flow-meter. A scavenging device for anaesthetic gases.

Measurements of air concentrations of nitrous oxide and halothane in the breathing zone of the anaesthetist and the operating-room nurse were carried out during inhalation anaesthesia with a Mapleson D system. Gas removal was performed from inside the breathing system at the same rate as that of the fresh gas inflow by means of an ejector flow-meter. The concentrations of nitrous oxide and halothane were maintained below the Danish Threshold Limit Values of 100 and 5 parts per million, respectively, by using this type of scavenging. When these anaesthetics were used simultaneously, the reduced Threshold Limit Values were not exceeded during endotracheal anaesthesia.

Air Pollutants, Occupational↗
PubMed2002

Perceived odor and irritation of isopropanol: a comparison between naïve controls and occupationally exposed workers.

OBJECTIVES: To assess sensory irritation levels from isopropanol (IPA) unconfounded by subjective evaluations of odor for comparison against the recommended exposure limits (400 ppm threshold limit value (TLV); American Conference of Governmental Industrial Hygienists). METHOD: The lateralization method was used to assess intra-nasal irritation thresholds for IPA, while odor detection thresholds were also measured. Thresholds for 1-butanol and phenyl ethyl alcohol (PEA) were obtained as positive and negative irritant controls. To compare potency and hedonic characteristics, subjects provided subjective ratings of odor, irritation and annoyance intensity for three concentrations of each chemical. Workers occupationally exposed to IPA ( n=26) were compared with previously unexposed controls ( n=26). RESULTS: The (geometric) mean odor detection threshold for IPA was slightly higher among exposed workers than controls (39 ppm vs. 11 ppm). Lateralization thresholds measuring intra-nasal irritation were elevated when compared with controls (6,083 ppm in exposed workers vs. 3,361 ppm in naïve controls), with a significantly higher proportion of phlebotomists being unable to lateralize the maximum concentration regarded as safe, than controls. Calculations of the 6th percentile for lateralization thresholds revealed that 95% of the sample did not experience sensory irritation below 512 ppm. Thus, while odor detection thresholds were well below the current recommended exposure limits, the irritation thresholds were well above these values. The odor, irritation and annoyance from IPA was perceived, on average, as between weak and almost strong, from lowest to highest concentration. CONCLUSIONS: The results indicate that current exposure guidelines would be adequately protective of the acute adverse effect of nasal sensory irritation, as operationally defined by the intra-nasal lateralization threshold. Exposures to higher concentrations should perhaps be evaluated on the basis of existing knowledge about systemic, rather than local (e.g., irritation), toxic effects. IPA appears to be a weak sensory irritant and occupational exposure to IPA appears to elicit small changes in sensitivity that do not generalize to other odorants (e.g., PEA and 1-butanol) and are likely to be reversible.

2-Propanol↗
PubMed2003

Sensory irritation due to methyl-2-cyanoacrylate, ethyl-2-cyanoacrylate, isopropyl-2-cyanoacrylate and 2-methoxyethyl-2-cyanoacrylate in mice.

The expiratory bradypnoea indicative of upper airway irritation in mice was evaluated during a period of 60 min of nasal exposure to methyl-2-cyanoacrylate, ethyl-2-cyanoacrylate, isopropyl-2-cyanoacrylate and 2-methoxyethyl-2-cyanoacrylate vapors using nose only exposure. Irritation of the upper respiratory tract caused a concentration-dependent decrease in the respiratory rate. The maximum effect occurred within the first 10 min of exposure and was followed by a drop-off in the response during the remainder of the exposure period. The airborne concentration resulting in a 50% decrease in the respiratory rate of mice (RD(50)) was calculated for each chemical. The results show that the four chemicals had similar irritant potencies. The RD(50) values of methyl-2-cyanoacrylate, ethyl-2-cyanoacrylate, isopropyl-2-cyanoacrylate and 2-methoxyethyl-2-cyanoacrylate were 1.4, 0.7, 0.6 and 1.0 p.p.m. Tentative estimates of threshold limit values showed that 0.1 RD(50) was closer to the values recommended by the American Conference of Governmental Industrial Hygienists for methyl- and ethyl-2-cyanoacrylate than 0.03 RD(50). On the basis of a threshold limit value for short-term exposure limit (TLV STEL) equal to 0.1 RD(50), the TLV STELs for the four cyanoacrylates should not exceed 0.1 or 0.2 p.p.m.

Animals↗