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Biomedical subjects

G Chester

Publications and source records attributed to G Chester.

12 recordsLinked to original sources
PubMed1994

Prescheduled neonatal return transports.

In 1990, increasing numbers of neonatal transports and high occupancy rates of neonatal beds statewide motivated our team to take a closer look at how to provide our services more efficiently. The neonatal transport medical director and team coordinator developed a system that addressed problematic issues in providing back or return transports to the community hospitals. This system was devised, implemented, and adjusted to provide a more organized approach to the overtaxed system already in place. With efficient use of supplies, human resources, and teamwork, the prescheduled neonatal return transport process was put into effect. The system provided an easier mechanism for the coordination of return transports and helped decrease frustration levels in community hospital staff, referring nursery staff, and transport personnel. All or portions of this plan can be utilized in other neonatal transport services that find their present resources inadequate to meet the referral region's needs.

Appointments and Schedules↗
PubMed1993

Biological monitoring for pesticide exposure--the role of human volunteer studies.

Predictions of human pesticide metabolism which are needed for the interpretation of biological monitoring data are frequently made from animal studies. Consequently, assumptions have to be made about the relationship between absorbed dose and metabolite excretion. The results from two human volunteer studies highlight the problems associated with extrapolating from animal studies in this way. The pyrethroid insecticide cypermethrin shows markedly different metabolite patterns when administered orally or dermally in man. Following dermal dosing the ratio of trans/cis cyclopropane acids is approximately 1:1, compared to 2:1 after oral administration. The ratio of total cyclopropane acids to phenoxybenzoic acids also differs depending on the route (dermal 1:4, oral 1:0.8). A knowledge of human metabolism by these two routes enables a much more meaningful interpretation of biological monitoring measurements. The herbicide molinate forms a mercapturate conjugate as a major urinary metabolite in the rat (35%). In volunteers at low dose levels this metabolite is present at insignificant levels (< 1%) and 4-hydroxymolinate is a much more abundant metabolite (39%). This shows that extrapolation between species can be very misleading. It is concluded that the benefits of using human volunteers for metabolism studies at low doses far outweigh the minimal risks involved. As a basis for biological monitoring such studies can lead to a greatly improved risk assessment for pesticides in use.

Administration, Cutaneous↗
PubMed1993

Evaluation of agricultural worker exposure to, and absorption of, pesticides.

The evaluation of the occupational exposure of agricultural workers to pesticides is an integral part of the risk assessment for product safety and regulatory purposes. At present, there is no internationally accepted, harmonized approach to this exposure evaluation. This paper reviews the currently available methods for the measurement of exposure to, and absorption of, pesticides by workers involved in their use and in associated agricultural activities. Biological monitoring is recommended as the most precise means of estimating the absorbed dose of a pesticide, particularly if supported by human metabolism and pharmacokinetic data. A 'whole-body' sampling method is recommended for the measurement of dermal exposure. For concurrent exposure and biological monitoring a refined 'whole-body' method is recommended which involves the use of clothing representing that which workers normally wear under the prevailing conditions. A personal air sampling method is recommended for the measurement of inhalation exposure, to collect the 'inspirable' fraction (and/or, where necessary, vapour component) of pesticide. These ambient exposure monitoring methods may be conducted simultaneously with biological monitoring. Guidelines are proposed for the conduct of field studies to evaluate exposure to, and absorption of, pesticides to satisfy the requirements of regulatory authority and other organizations.

Absorption↗
PubMed1993

Occupational exposure of Sri Lankan tea plantation workers to paraquat.

Absorption of the herbicide paraquat (1,1'-dimethyl-4,4'-bipyridinium) by mixer-loaders and spray operators on a Sri Lankan tea plantation was assessed over five consecutive days of spraying. Beginning on the day before spraying started and continuing for each of the five spraying days and for seven days after the last day of spraying, 24-hour urine samples were collected from each of the workers. Potential dermal exposure was assessed during further applications of paraquat on the day after the last day of urine collection. For this purpose two spraying replicates were conducted that involved the handling or spraying of an amount of paraquat equivalent to the maximum used per day in the assessment of absorption. The mixer-loaders and spray operators incurred, on average, approximately equivalent amounts of potential dermal exposure (66 mg and 74 mg paraquat ion, resp.); however, the distribution of the exposure differed. About 86% of the total exposure experienced by the mixer-loaders was to the hands, whereas about 90% of the exposure of the spray operators involved their hands, legs, and feet, in approximately equal proportions. In both cases, 90% or more of the total potential exposure involved parts of the body that were normally uncovered. Despite the evidence of dermal exposure, no paraquat was detected in the workers' urine. This probably was due to the very low concentration of paraquat in the solutions used for spot spraying on tea plantations (0.3-0.4 g paraquat ion per litre), the high standard of personal hygiene exercised by the workers, and the low permeability of human skin to paraquat.

Adult↗
PubMed1992

Exposure and health assessment during application of lambda-cyhalothrin for malaria vector control in Pakistan.

Icon 10 WP insecticide, a wettable powder formulation containing 10% lambda-cyhalothrin, was evaluated for possible adverse effects on the health of spraymen and villagers during treatment of dwellings for malaria vector control. Skin sensory effects and occasional coughing and sneezing in confined spaces were the only symptoms noted by the workers resulting from the handling and spraying of the insecticide. Absorption of lambda-cyhalothrin was estimated by determining its metabolites in urine and serum. The average amount of lambda-cyhalothrin absorbed by the workers per day (54 micrograms) represents less than 0.0001% (< 1 micrograms.kg-1.day-1) of the average daily amount of the substance handled. Only a small proportion of villagers showed detectable levels of lambda-cyhalothrin metabolites in their urine. Absorption of lambda-cyhalothrin from the formulation tested was therefore very low and, apart from the nuisance of skin sensory effects, there should be no risk to the health of workers or to the villagers whose dwellings are treated.

Aerosols↗
PubMed1987

Worker exposure to a herbicide applied with ground sprayers in the United Kingdom.

This study was designed to measure potential dermal and respiratory exposure of agricultural workers during the application of a typical herbicide, 2,4-dichlorophenoxy acetic acid, with five types of application equipment commonly used in the United Kingdom. The workers were monitored during filling and loading operations and during spray application. Potential dermal exposure was higher during mixing and loading all tractor-powered sprayers than during spraying. Potential dermal exposure from tractor-powered sprayers fitted with conventional hydraulic nozzles was lower than from knapsack sprayers, with exposure from a tractor-powered sprayer fitted with controlled-droplet application equipment intermediate in this regard. There was no difference in potential dermal exposure between tractor-mounted and tractor-drawn sprayers fitted with conventional hydraulic nozzles. The hands were the most highly exposed part of the body during mixing and loading operations for all sprayers, and during spraying with tractor-powered sprayers. The lower legs of the workers were exposed principally when knapsack sprayers were used. For all five sprayers, potential respiratory exposure, where detectable at all, was negligible compared with potential dermal exposure.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1986

Biological monitoring of a herbicide applied through backpack and vehicle sprayers.

Field studies have been done with the herbicide, fluazifop-butyl, to assess exposure and systemic absorption following application by backpack and vehicle sprayers. The data have been used to assess the usefulness of a model for predicting the systemic absorption of a pesticide. The model uses the concept of the 'rate of absorption' through skin and this model is compared with the 'percent absorption' concept in their ability to predict systemic absorption following application with vehicle sprayers. The field study of vehicle sprayers showed that the 'rate of absorption' model was a better predictor of systemic absorption.

Administration, Oral↗
PubMed1982

Studies of the occupational exposure of Malaysian plantation workers to paraquat.

Studies carried out on the occupational exposure to paraquat of plantation workers in Malaysia comprised quantitative estimates of dermal and respiratory exposure of knapsack spray operators, carriers, and rubber tappers operating under their normal working conditions. Spray operators have been shown to be dermally exposed to paraquat by walking through recently sprayed vegetation and into their own spray, regular adjustment and unblocking of spray nozzles and leakage, and overfilling of knapsack spray tanks. Carriers also received measurable dermal exposure from walking through recently sprayed vegetation and accidental spillage when carrying and loading. The infrequent and negligible dermal exposure of tappers resulted from walking through recently sprayed vegetation. Determinations of the total airborne paraquat concentrations in the breathing zone show that spray operators and carriers are exposed to an order of 1% or less of the current TLV for respirable paraquat. No paraquat was detected in the breathing zones of tappers working in simultaneously sprayed blocks. The calculated ranges of dermal and respiratory exposures, when compared with published data on both the exposure to, and the toxicity of, paraquat, indicate that there should be no toxicological risk to any of the three groups studied as a result of using paraquat.

Agriculture↗
PubMedDate not supplied

Field evaluation of protective equipment for pesticide operators in a tropical climate.

In order to extend the practical advice and information on personal protection when using pesticides in tropical climates, a GIFAP-FAO Working Group carried out a study on protective equipment worn by pesticide workers in hot and humid conditions in Thailand. Items assessed included protective garments worn by workers mixing and loading the organophosphorus insecticide formulation Tamaron and by spraymen applying the diluted formulation for several hours per day to a cotton crop with knapsack sprayers. The mixer-loaders also wore nitrile rubber gloves and a faceshield. The protective garments were made up of two pieces, an upper garment of a double apron design and separate trousers. Garments made up of different materials were assessed for their acceptability to the workers, their comfort and durability and their protectiveness against the insecticide. As a result of the study it is considered that cotton protective garments are appropriate for pesticide workers in these conditions if additional protection is necessary. The nitrile rubber gloves and faceshield were also found to be suitable for mixer-loaders in these circumstances. It is emphasized that the effective use of protective equipment must go hand in hand with safe handling precautions and the adoption of good personal hygiene.

Evaluation Studies as Topic↗