Assessing airborne aflatoxin B1 during on-farm grain handling activities

The presence of aflatoxin in corn and corn dust during relatively normal years and the increased risk of Aspergillus flavus infestation during drought conditions suggest that airborne agricultural exposures should be of considerable concern. Liquid extraction, thin layer chromatography, and high pressure liquid chromatography were used for the analysis of aflatoxin B1 in grain dust and bulk corn samples. A total of 24 samples of airborne dust were collected from 8 farms during harvest, 22 samples from 9 farms during animal feeding, and 14 sets of Andersen samples from 11 farms during bin cleaning. A total of 14 samples of settled dust and 18 samples of bulk corn were also collected and analyzed. The airborne concentration of aflatoxin B1 found in dust collected during harvest and grain unloading ranged from 0.04 to 92 ng/m3. Higher levels of aflatoxin B1 were found in the airborne dust samples collected from enclosed animal feeding buildings (5-421 ng/m3) and during bin cleaning (124-4849 ng/m3). Aflatoxin B1 up to 5100 ng/g were detected in settled dust collected from an enclosed animal feeding building; however, no apparent correlation was found between the airborne concentration of aflatoxin B1 and its concentration in settled dust or bulk corn. The data demonstrate that farmers and farm workers may be exposed to potentially hazardous concentrations of aflatoxin B1, particularly during bin cleaning and animal feeding in enclosed buildings.

Respiratory symptoms and lung function abnormalities among machine operators in automobile production

This cross-sectional study was designed to assess differences in prevalence of respiratory symptoms and lung function between machine operators exposed to semisynthetic or soluble metal-working fluids (MWFs) and unexposed assemblers and to assess exposure-response relationships with MWF type, total aerosol, endotoxin, culturable bacteria and fungi. We evaluated 183 machine operators and 66 assemblers from one large automobile transmission plant using questionnaires, spirometry data, and cross-shift assessment of both lung function and respiratory symptoms. We found that airborne exposures to total aerosol, endotoxin, culturable bacteria and fungi were higher in machine operations than in the assembly area. There was a correlation between bulk and airborne culturable bacteria, but not between bulk and airborne culturable fungi. Machine operators had significantly more usual cough, usual phlegm, work-related chest tightness and post-shift symptoms of chest tightness, throat irritation, and cough compared with assemblers. We found exposure-response relationships between respiratory symptoms and total aerosol, as well as culturable fungi and bacteria. Associations with endotoxin were not strong or consistent, possibly because airborne levels were generally low. Cross-shift lung function decrements did not differ between machine operators and assemblers and there were no associations with MWF or specific exposures. The finding of respiratory symptoms at low levels of exposure in this study suggests the need to re-assess total aerosol thresholds. Associations between airborne fungal exposures and respiratory symptoms need further study to characterize sources of exposure other than MWF in machining operations.

The utility of preliminary surveys to detect the cause of acute metalworking fluid hazards

This paper describes preliminary studies undertaken to optimize a later epidemiologic study, the aim of which was to identify a causative agent of adverse respiratory effects and dermatitis among production machinists. Two methods were used to rate coolant system hazards. The results of a voluntary plantwide questionnaire with an 18% participation rate showed that both dermatologic and respiratory symptoms were higher among machine operators than among maintenance or assembly workers, that symptoms were not more prevalent early in the week, and that dermatitis may be associated with smoking status; however, the questionnaire was not helpful in rating individual coolant system hazards. The hazard ratings provided by an in-plant expert panel were strongly associated with particular synthetic coolant containing an ethoxylated phenol; however, the resulting design for a later epidemiologic study could not be implemented due to changes in coolants used at the plant.

Dermatitis among automobile production machine operators exposed to metal-working fluids

This cross-sectional study was designed to assess differences in prevalence of contact dermatitis between machine operators exposed to metal-working fluids (MWFs) and unexposed assemblers, and to assess potential risk factors for contact dermatitis among these machine operators. In their work, machine operators were exposed to either semisynthetic or soluble oil MWFs. We evaluated 158 machine operators and 51 assemblers from one large automobile transmission plant using questionnaires, dermatologist examination of the skin, and dermal dosimetry to measure wetness and metal exposures. We found that machine operators had more combined (definite plus possible) dermatitis (27.2% vs. 13.7%, chi(2) = 3.9, p = 0.05, 1 df) compared with assemblers. Among machine operators, risk factors significantly associated with (combined) dermatitis were subjective assessment of wetness of the work, exposure to semisynthetic as opposed to soluble oil MWF, current cigarette smoking, and increasing worker age. These risk factors suggested preventive and control measures including control of wet work, surveillance program including early self-report of dermatitis, consideration of replacement of semisynthetic with soluble oil MWFs, and strictly limiting smoking among machine operators exposed to MWFs.

Aflatoxin B1 in common Egyptian foods

Samples of common Egyptian foods (17 nuts and seeds, 10 spices, 31 herbs and medicinal plants, 12 dried vegetables, and 28 cereal grains) were collected from markets in Cairo and Giza. A portion of each sample was extracted with chloroform, and the concentrated extract was cleaned by passing through a silica gel column. Aflatoxin B1 was determined by reversed-phase liquid chromatography with UV detection. The highest prevalence of aflatoxin B1 was in nuts and seeds (82%), followed by spices (40%), herbs and medicinal plants (29%), dried vegetables (25%), and cereal grains (21%). The highest mean concentration of aflatoxin B1 was in herb and medicinal plants (49 ppb), followed by cereals (36 ppb), spices (25 ppb), nuts and seeds (24 ppb), and dried vegetables (20 ppb). Among nuts and seeds, the prevalence of aflatoxin B1 was highest (100%) in watermelon seeds, inshell peanuts, and unshelled peanuts. The lowest prevalence and concentrations were in hommos (garbanzo beans). The highest concentrations of aflatoxin B1 were detected in foods that had no potential for field contamination but required drying during processing and storage, such as pomegranate peel, watermelon seeds, and molokhia.

Exposures while applying commercial disinfectants

Measurements were made on 40 applicators applying chemical disinfectants to floors, walls, other hard surfaces, or carpeting by high-pressure spray, low-pressure spray, mopping, wiping, or aerosol spray. Inhalation exposure was assessed with air samples. Clothing and skin deposition was assessed with dermal gauze dosimeters attached both outside applicators' work clothing and inside their clothing against their skin. As is typical of agricultural pesticide applications, the airborne route of exposure was very low, usually below the chemical limit of detection. The primary route of exposure and dosing was to the skin. The normal work clothing worn by applicators consistently reduced clothing deposition to lower values reaching the skin. The effects of chemical detection limits and short use durations caused the analyte on many individual dosimeters to be below the method detection limit. Mean measured total dose of the active ingredient onto the skin (ranging from 0.1 to 26 mg per task) was converted to equivalent dose of the applied mixture (ranging from 0.1 to 2.7 g) to adjust for widely varying disinfectant concentrations. A discussion is also presented on the serious limitations of applying the assumption that undetectable samples are "one-half the detection limit" to a study of this nature where results are the sum of multiple measurements.

Exposure while applying industrial antimicrobial pesticides

Forty-three assessments were made of dermal and/or inhalation chemical exposure while applying industrial antimicrobial pesticide products, either by manually pouring or pumping liquids or by pouring a solid (powder or flake) product. Inhalation exposure was assessed via a personal air sample but was usually below the chemical limit of detection. Dermal exposure outside work clothing and dermal deposition inside the clothing was assessed via dermal gauze dosimeters. While dosimeters at discrete body locations often received exposures below the limit of detection, one or more dosimeters on individual applicators almost always showed measurable exposure. The median measured dose was between 30% and 70% of the maximum credible summed dose calculated by assuming that each dosimeter showed either the level of measurable deposition or one-half of the detection limit at locations where the chemical was unmeasurable. Because of differences in settings and the low level of control implicit in these application processes, measurable dermal doses were highly variable. Mean measurable dose rates were near 3, 8, and 10 mg product/hr, and daily total deposited doses were 2, 3.5, and 5 mg of product for pouring and pumping liquids and for pouring solids, respectively. Although the effect of gloves cannot be directly determined, wearers of gloves had geometric mean hand total doses 155- to 290-fold less than those not wearing gloves. Similar to the statistics for agricultural pesticides, the dermal route of exposure for these industrial pesticides exceeds the inhalation route by 5X to 100X, depending on assumptions regarding nondetectable values.

A method for monitoring dermal exposure to volatile chemicals

Absorptive pads of charcoal cloth were developed and tested for monitoring the deposition of volatile toxic materials on skin. The dosimeters can retain over 60% of volatile deposits such as toluene or dichloropropene droplets over an 8-hr workday. Evaporation from liquid deposits and vapor adsorption onto the dosimeters are factors which can complicate the interpretation of exposure data. Evaporation was inversely proportional to the log of the deposit size (volume), vapor pressure, and the air humidity. Vapor adsorption was proportional to the vapor concentration, exposure duration, and the log of air velocity. A procedure is offered for estimating the initial size of the liquid deposit from retained mass. The charcoal cloth dosimeter's accuracy and precision are optimal in situations involving possible dermal exposure to toxic materials with low to moderate volatility or with low vapor concentration, i.e., those where dermal exposure may be equal to or more significant than respiratory exposure.

Characterization of dusts collected from swine confinement buildings

As part of a project to evaluate health hazards for workers in swine confinement buildings, the air in 21 different buildings was sampled with 37 mm cassette filters with and without cyclone preselectors and with cascade impactors. Filter results yielded a mean total aerosol of 6.3 mg/m3, a mean respirable aerosol of 0.5 mg/m3; the geometric mean diameter was 2.9 microns. Cascade impactor measurements revealed a mean total aerosol of 7.6 mg/m3, a respirable aerosol of 2.5 mg/m3 and a mass median diameter of 9.6 microns. The two major constituents in these aerosols were grain particles and dried fecal matter. The grain particles were larger than fecal particles and proportionately more abundant in finishing buildings where 50 kg X 100 kg animals are housed. Therefore the respirable fraction was less in finishing buildings than in farrowing and nursery buildings. Culturing of settled dusts yielded six different mold species, with the highest counts for Verticillium sp. (5 X 10(2) cfu/mg dry dust) grown at 37 degrees C. Thermophilic Actinomycetes and both gram negative and gram positive bacteria were isolated. Azocasein proteinase activity was found in most dust samples analyzed. This dust had a protein content of about 23% and a mean adsorbed ammonia content of 0.4%.

The delivery of therapeutic aerosols through endotracheal tubes

We used an in vitro model system to examine the sites of deposition of aqueous therapeutic aerosols administered through 3-mm, 6-mm, and 9-mm endotracheal tubes (commonly used in infants, children, and adults) at clinically relevant inspiratory flow rates. Aerosol was delivered to the endotracheal tube via a "T" piece and a 90 degree elbow. Aerosol exiting the endotracheal tube passed through an appropriately sized Plexiglas model of the trachea and mainstem bronchi, and then into an 80-liter bag. Aerosol deposited in the "T" and elbow, endotracheal tube, large airway model, and collection bag was quantitated separately using 0.1% uranine as a tracer. Study of a conventional aerosol typical of those in common clinical use (aerodynamic mass median diameter = 3.95 microns) showed that most of the aerosol delivered into each endotracheal tube was deposited before leaving the mainstem bronchi. Substitution of an alternative nebulizer that produced a much smaller aerosol particle size (aerodynamic mass median diameter = 0.54 micron) dramatically decreased aerosol deposition in the "T" and elbow, endotracheal tube, and large airway model, and increased the quantity of aerosol penetrating beyond the mainstem bronchi up to ninefold. The mass median particle diameter of the conventional aerosol was reduced during endotracheal tube and large airway passage by poorly defined aerodynamic mechanisms that selectively removed larger particles. The smaller submicron aerosol was not similarly affected. Thus, conventional therapeutic aerosols appear to penetrate poorly through endotracheal tubes. Use of smaller particle size aerosols in treatment of intubated patients may be an effective way to circumvent this problem.

Health effects of organic dusts in the farm environment. Report on agents

Recommendations were formulated on sampling strategies and characteristics of different sampling methods. Microbiological products, such as endotoxins and proteases were suggested to be included apart from traditional dust measurements. It was recommended that priority should be given to establishing dose-response relationships and that the importance of anaerobic organisms be evaluated. A summary of components within organic dust suspected of contributing to respiratory disease was presented.

A synopsis of agricultural respiratory hazards

This report summarizes the current state of both knowledge and programs concerning a wide range of respiratory hazards facing agricultural producers including cotton dust, grain dust, agricultural chemicals, organic and inorganic dusts, and microbiologic and immunologic agents. Comparisons and criticisms are made among the hazards on the basis of their epidemiology, their occurrence within the agricultural setting, and current approaches, interest, and support for evaluating and controlling the hazard. This report was prepared as both an overview of the technical issues and as a focal point of organizational concern for what appears to be a very broad and largely underrecognized spectrum of occupational health hazards affecting large segments of the agricultural industry. The difficulties confronting research and human health in these areas are at once technical, sociological, and organizational in nature, and remain a challenge to the industry, to government, and to the health profession.

Vapor pressure and solvent vapor hazards

This paper discusses applications of vapor pressure to industrial hygiene. Vapor pressure is the quantitative term characterizing solvent volatility; it is also equivalent to the concentration of solvent vapor at the liquid surface. The ratio between this concentration at the source and the acceptable concentration at the breathing zone is an intrinsic property of each chemical but varies over 6 orders-of-magnitude among common organic chemicals. The name Vapor Hazard Ratio (VHR) is introduced quantifying this ratio; and its logarithm is termed the Vapor Hazard Index (VHI). Thus, while vapor pressure is directly relatable to the economic effects of solvent evaporation and to airborne concentrations, the VHI has the added component of occupational toxicity. To be used safely and/or acceptably within the workplace, vapors must be diluted from concentrations at the source by a ratio equal to or greater than the Vapor Hazard Ratio, either by general or local exhaust ventilation. It is argued that the VHI can be used currently to predict the relative hazards of vapor concentrations of proposed substitute solvents to be used in similar settings and in hazard communication programs, and in the future with vapor dilution profiles to anticipate achieving quantitative compliance levels with new processes, work practices or ventilation controls. A review of the pertinent vapor pressure literature is also provided.

Urinary Excretion of theN-Acetyl Cysteine Conjugate of Cis-1,3-Dichloropropene by Exposed Individuals

A gas chromatographic-mass spectrometric assay was developed to identify and measure the N-acetyl cysteine conjugate of cis-1,3-dichloropropene. The assay was used to show that individuals exposed to 1,3-dichloropropene vapor during field applications excrete this conjugate in their urine. The recoveries of the conjugate were correlated with the product of airborne concentrations and the duration of exposure (r = 0.83).

Exploring citrus harvesters' exposure to pesticide contaminated foliar dust

The results of measurements in 32 citrus groves indicate that available and dislodgeable foliar dust measurements can predict aerosol mass concentrations produced during harvest with regression r2 values of 0.41 and 0.25, respectively. The pesticide content of these foliar measurements correlates with whole-body dermal dosing via the deposition of pesticide containing aerosols with similar regression r2 values of 0.63 and 0.75. Several lines of argument suggest that the wide range of particle size (< 1 microns to > 200 microns) underlies differences in foliar residue, aerosol, and dermal pesticide measurements. Significant implications of this report include the magnitude of the aerosols to which these workers are exposed (10-80 mg/m3) and the potential ability to set re-entry intervals based upon these predictable dermal dose estimates.

Chrysotile asbestos in a California recreational area

Dustfall along roads and trails being used recreationally in the Clear Creek area of San Benito County, California, located in the New Idria serpentinite, was found to be 90 percent or more chrysotile asbestos. Personal samplers worn by motorcyclists using one of the trails showed concentrations of airborne fibers ranging from 0.3 to 5.3 fibers per milliliter, according to methods prescribed for monitoring occupational exposures. The present workplace standard for brief exposures to asbestos is 10 fibers per milliliter; 5 fibers per milliliter is the proposed standard. The average total dust concentration estimated from personal samplers was approximately 20 milligrams per cubic meter of roughly 90 percent chrysotile. To our knowledge, this is the first demonstration of asbestos exposures of this magnitude, in size ranges known to be pathogenic, resulting from natural deposits not associated with mining, milling, or industrial use.