Fluorescent tracer evaluation of chemical protective clothing during pesticide applications in central Florida citrus groves.

Chemical protective clothing (CPC) is often recommended as a method of exposure mitigation among pesticide applicators. This study evaluated four CPC regimens (cotton work shirts and work pants, cotton/polyester coveralls, and two non-woven garments) during 33 airblast applications of the organophosphorus insecticide ethion in central Florida citrus groves. CPC performance was determined by measurement of fluorescent tracer deposition on skin surfaces beneath garments with a video imaging analysis instrument (VITAE system), and by alpha-cellulose patches placed outside and beneath the garments. Non-woven coveralls allowed significantly greater exposure than did traditional woven garments, primarily because of design factors (e.g., large sleeve and neck openings). The greatest exposure occurred on the forearms beneath the non-woven garments. Fabric penetration was detected for all test garments; 5% to 7% of the ethion measured outside the garments was found beneath the garments. The clothing materials tested were not chemically resistant under these field conditions. Exposurepathways that would probably be undetected by the patch technique were characterized effectively with fluorescent tracers and video imaging analysis. However, the patch technique was more sensitive in detecting fabric penetration. CPC garments have been improved since this study was conducted, but performance testing under field conditions is not widespread. Workers conducting airblast applications would be better protected by closed cab systems or any technology that places an effective barrier between the worker and the pesticide spray.

Exposure to endosulfan in farmers: two case studies.

BACKGROUND: Endosulfan is not a restricted use organochlorine insecticide and is currently under re-registration review. In 1993, one confirmed case and one possible case of endosulfan poisoning in agricultural workers occurred in two southeastern states. METHODS: Two cases of suspected endosulfan poisoning were investigated utilizing record reviews, blood samples, a site visit, and clothing analysis. RESULTS: Case 1 was fatal; Case 2 resulted in permanent neurological impairment. Additionally, Case 1 mixed and applied two less toxic pesticides, acephate and maleic hydrazide to tobacco plants. Both farm owners had ample opportunity for endosulfan exposure while mixing concentrated endosulfan with water and applying the solution to tobacco with boom sprayers pulled by tractors. CONCLUSIONS: Estimates of the absorbed dose of endosulfan were not available because methods to determine actual personal exposure that would be found in fat or tissue samples were not used. Health and safety issues associated with endosulfan require a closer examination. A cooperative multi-disciplinary approach to providing timely accurate education is needed to prevent pesticide poisonings.

Use of historical uranium air sampling data to estimate worker exposure potential to airborne radioactive particulate in a uranium processing facility.

Historical industrial hygiene monitoring records from a uranium processing plant were collected and analyzed to characterize exposure potential to airborne radioactive particulate. More than 2,100 samples were collected during the period of 1954-1968. The data was organized by job title, plant number, and year of measurement. Laboratory analysis of air samples indicated a wide range of potential exposures to the alpha-emitting particulate. Logarithmic transformation of the data was necessary to approximate Gaussian distributions. Geometric Mean (GM) values were used as the measure of central tendency within years. GM values ranged from 23-49 disintegrations per minute per cubic meter of air sampled (dpm/m3) with the years 1963 and 1964 being significantly higher than other years (ANOVA: p < 0.05). When comparing exposure potential across plants, GM ranged from 20-68 dpm/m3, with plants 5 and 8 being significantly higher than the others (ANOVA: p < 0.05). Exposure potential for specific job titles across the plants varied widely. GM for clerks was the lowest (11 dpm/m3) while furnace operators were the highest (235 dpm/m3). Other job titles with potentially high exposures were chemical operators, forklift operators, machine operators, and furnace operators. This analysis indicates the magnitude and distributions of worker exposure to alpha-emitting airborne particulate. Additional analysis and epidemiologic studies are planned for this facility.

Hazard surveillance for industrial magnetic fields: I. Walkthrough survey of ambient fields and sources.

A walkthrough survey method was developed for measuring ambient magnetic fields (MFs) in industrial facilities as the first stage in hazard surveillance. This survey was designed to measure the mean and peak MF magnitudes at extremely low frequencies (ELFs), so that factories could be ranked by MF levels and prioritized for subsequent personal exposure monitoring. Sixty-two facilities from 13 Standard Industrial Classifications (SICs) with the highest monthly electric power usage were surveyed. To measure ambient MFs, a structured walkthrough survey with a special emphasis on workstations was conducted with an EMDEX-II meter in continuous operation, while MF sources were noted. The broadband MF data (40-800Hz) for each facility were summarized with the geometric mean (GM) and the average of the five highest readings (Hi-5). The range of the GM magnetic field magnitude was 0.04-1.61microT, where the maximum was measured at a steel mill operating large electric furnaces. Maximum values for specific sources were highly variable across and within facilities (Hi-5 range: 1.0-530 microT). Chemical and Allied Products (SIC 28) and Primary Metal Products (SIC 33) had facilities with GM and Hi-5 magnetic fields greater than any of the other industrial categories. However, the SIC categories were found to be poor predictors of the ambient MF in this sample of factories. A weak relationship was found between the facility-specific monthly electric power consumption and the GM magnetic field magnitude, but confidence limits were too broad to make meaningful exposure predictions from electric power data. Overall, 89% of the GMs were at or below 0.4 microT, consistent with most other studies that collected industrial MF exposure data. The walkthrough survey is a practical way of measuring ambient MFs in a large number of workplaces, and should be evaluated with personal measurements as a screening method for hazard surveillance.

Hazard surveillance for industrial magnetic fields: II. Field characteristics from waveform measurements.

Magnetic field characteristics have been surveyed systematically in six factories with the Multiwave(R) II waveform capture instrument. These six facilities manufactured plastics, pharmaceuticals, cement, liquid air products, aluminum parts, and aluminum-framed filters. The study goals were to survey the physical characteristics of magnetic fields that may be related to biological effects under various interaction mechanisms and to relate those characteristics to the field's sources. From 59 waveform measurements at worker locations near sources, we calculated the extremely low frequency (ELF) and static field magnitudes, their frequency characteristics, and spatial characteristics of the 60Hz component. The RMS vector magnitude of the ELF magnetic field (the usual exposure metric in most studies) had medians ranging from 0.53 to 12.83 microT in the six factories. The static magnetic field magnitudes had medians of 24.2-46.2 microT, which is well below the geomagnetic reference field of 55.0 microT because of shielding from steel structures. The maximum static field was 128.6 microT near a DC motor. The frequency spectra of the most common fields is dominated by 60Hz, and has a median total harmonic distortion equal to 14.8%. The most common higher frequencies are the third, fifth, and second harmonics of 60Hz. However, magnetic fields in these workplaces had many other 60Hz harmonics and non-harmonic frequencies due particularly to electric motors and computer monitors. The 60Hz component magnetic fields have elliptical polarization with median axial ratio of 25.4%. The average proportion of the 60Hz component parallel to the static field vector was 51.5+/-3.0%, which indicates a significant trend towards perpendicular orientation between these two field components. In this survey of only six factories, the Multiwave(R) II measurements documented a wide diversity of complex magnetic field characteristics and non-sinusoidal waveforms. Although these characteristics are important to the various mechanisms postulated to explain biological effects, they are overlooked by the popular exposure assessment methods which only measure the ELF magnitude. Therefore, spot measurements with the Multiwave(R) II or similar waveform capture instruments are necessary for a complete magnetic field exposure assessment.

Identification of potential hazards associated with new residential construction.

There were several advantages and limitations of this observational study. The most important advantage of this study was the opportunity to observe residential construction workers performing their jobs. By observing work practices, valuable information was gathered about specific trades and their potential exposure to various chemical and physical agents. This information will be useful in guiding subsequent exposure assessments. Probably the greatest limitation of this study was the lack of participation by homebuilders. Ideally, observations of construction processes would have been more objective if the study included the participation of more than one homebuilder. Aside from one worker who was observed to wear safety glasses, leather gloves, and a dust mask, virtually no personal protective equipment (PPE) was observed onsite. Often small contractors do not have the financial resources necessary to procure the appropriate PPE and issue these items to the workers. Based on hazard prevalence, professional judgement, and the degree of hazardous product use, potential exposures that warrant quantitative sampling efforts during Phase 2 of this study are: bulldozer/backhoe operators--noise, vibration, diesel exhaust; concrete workers--naphtha, mineral spirits, Portland cement; asphalt workers--petroleum hydrocarbons, asphalt, mineral spirits; plumbers--methylethyl ketone, acetone, tetrahydrofuran, cyclohexanone; drywall finishers--total and respirable dust, hexane, acetone; painters--ethylene glycol, VOCs; masons--dust (during the preparation of mortar); floor preparation technicians--total and respirable dust; and ceramic tile installers--toluene, naphtha, silica (from grout powder).

Potential exposure and health risks of infants following indoor residential pesticide applications.

Air and surface chlorpyrifos residues were measured for 24 hours following a 0.5 percent Dursban broadcast application for fleas inside a residence. Two of the three treated rooms were ventilated following application. Maximum air concentrations were measured 3-7 hours post-application. Peak concentrations in the infant breathing zone were 94 micrograms/m3 in the nonventilated room and 61 micrograms/m3 in the ventilated room, and were substantially higher than concentrations in the sitting adult breathing zone. Concentrations of approximately 30 micrograms/m3 were detected in the infant breathing zone 24 hours post-application. Surface residues available through wipe sampling were 0.7-1.6 micrograms/cm2 of carpet on the day of application and 0.3-0.5 micrograms/cm2 24 hours post-application. Estimated total absorbed doses for infants were 0.08-0.16 mg/kg on the day of application and 0.04-0.06 mg/kg the day following application, with dermal absorption representing approximately 68 percent of the totals. These doses are 1.2-5.2 times the human No Observable Effect Level (NOEL). Exposures to cholinesterase inhibiting compounds following properly conducted broadcast applications could result in doses at or above the threshold of toxicological response in infants, and should be minimized through appropriate regulatory policy and public education.