Exposure to preservatives used in the industrial pre-treatment of timber.
OBJECTIVE: The research was to survey potential dermal exposure and inhalation exposure of operators to preservative fluids used in industrial timber pre-treatment. RESULTS: Surveys in 1996-98 produced 64 data points. These were taken from 54 sites, and involved 57 timber pre-treatment process operators. Of the data, 38 related to copper chromium arsenic preservative used in vacuum-pressure processes, 19 to solvent-based preservative in double vacuum processes and 7 to water-based preservative in double vacuum processes. Treatment cycle times, preservative concentrations, treatment load sizes and quantities of preservative used per cubic metre of timber are reported. Preservative deposition patterns were similar for all treatments, with about 90% on the legs, and most of the remainder on the arms and chest. The results are quoted as mg preservative preparation (as opposed to active substance), expressed as mg per treatment cycle and mg per minute. Water-based products in vacuum-pressure processes (38 data) showed potential dermal exposure in the range 547-132,000 mg per cycle with a median value 3960 mg per cycle (median cycle time 3 h). Water-based products in double vacuum processes (7 data) showed a range 59-8750 mg per cycle with a median value 4260 mg per cycle; and solvent-based products in double vacuum processes (19 data) showed a range 7.5-449 mg per cycle with a median value 119 mg per cycle (median cycle time 1 h for double-vacuum processes). Contamination of work clothing occurred in nearly all surveys, with around 10% penetration of the preservative as estimated by a sampling patch mounted inside the operator's coveralls. Contamination was measured inside the operator's gloves in nearly all surveys. Wearing fresh gloves was found to reduce exposure to arsenic by 71% and to permethrin by 37%. Contamination on socks was measured and found to be less frequent for double vacuum than for vacuum-pressure processes. Exposure by inhalation for vacuum-pressure processes expressed as preservative, showed a range of 0.06-7.96 mg/m3, with a median value of 1.07 mg/m3, time-weighted average exposure over one or two treatment cycles. Exposure was detected in 68% of the vacuum-pressure process surveys. There was evidence for aerosol generation on transporting timber treated with water-based preservative. For double vacuum processes, two non-zero results only were found, both for water-based preservatives. Aerosols within treatment vessels were found to have dispersed 2.5 min after opening the door. Pilotstudy biological monitoring data for urinary chromium, arsenic, and permethrin metabolites are quoted with reference to creatinine. There are tentative conclusions relating to up take via the skin. (+info)
Parkinson's disease mortality and pesticide exposure in California 1984-1994.
BACKGROUND: In the last two decades reports from different countries emerged associating pesticide and herbicide use with Parkinson's disease (PD). California growers use approximately 250 million pounds of pesticides annually, about a quarter of all pesticides used in the US. METHODS: We employed a proportional odds mortality design to compare all cases of PD recorded as underlying (1984-1994) or associated causes (1984-1993) of death occurring in California with all deaths from ischaemic heart disease (ICD-9 410-414) during the same period. Based on pesticide use report data we classified California counties into several pesticide use categories. Agricultural census data allowed us to create measures of percentage of land per county treated with pesticides. Employing logistic regression models we estimated the effect of pesticide use controlling for age, gender, race, birthplace, year of deaths, and education. RESULTS: Mortality from PD as the underlying cause of death was higher in agricultural pesticide-use counties than in non-use counties. A dose response was observed for insecticide use per county land treated when using 1982 agricultural census data, but not for amounts of restricted pesticides used or length of residency in a country prior to death. CONCLUSIONS: Our data show an increased PD mortality in California counties using agricultural pesticides. Unless all of our measures of county pesticide use are surrogates for other risk factors more prevalent in pesticide use counties, it seems important to target this prevalent exposure in rural California in future studies that use improved case finding mechanisms and collect pesticide exposure data for individuals. (+info)
Exposures and health effects from inorganic agricultural dusts.
Most studies of respiratory disease from dust exposure in the agricultural workplace have focused on allergic diseases caused by inorganic dusts, specifically occupational asthma and hypersensitivity pneumonitis. Exposures to inorganic (mineral) dusts among farmers and farm workers may be substantial. Such exposures are most frequent in dry-climate farming regions. In such locations farming activities that perturb the soil (e.g., plowing, tilling) commonly result in exposures to farm operators of 1-5 mg/m(3) respirable dust and >= 20 mg/m(3) total dust. The composition of inorganic dust in agriculture generally reflects the soil composition. Crystalline silica may represent up to 20% of particles, and silicates represent up to 80%. These very high concentrations of inorganic dust are likely to explain some of the increase in chronic bronchitis reported in many studies of farmers. Pulmonary fibrosis (mixed dust pneumoconiosis) has been reported in agricultural workers, and dust samples from the lungs in these cases reflect the composition of agricultural soils, strongly suggesting an etiologic role for inorganic agricultural dusts. However, the prevalence and clinical severity of these cases are unknown, and many exposures are to mixed organic and inorganic dusts. Epidemiologic studies of farmers in diverse geographic settings also have observed an increase in chronic obstructive pulmonary disease morbidity and mortality. It is plausible that agricultural exposure to inorganic dusts is causally associated with chronic bronchitis, interstitial fibrosis, and chronic obstructive pulmonary disease, but the independent contribution of mineral dusts beyond the effects of organic dusts remains to be determined. (+info)
Patterns and problems of deliberate self-poisoning in the developing world.
Deliberate self-harm is a major problem in the developing world, responsible for around 600 000 deaths in 1990. The toxicity of available poisons and paucity of medical services ensure that mortality from self-poisoning is far greater in the tropics than in the industrialized world. Few data are available on the poisons most commonly used for self-harm in different parts of the world. This paper reviews the literature on poisoning, to identify the important poisons used for self-harm in these regions. Pesticides are the most important poison throughout the tropics, being both common and associated with a high mortality rate. In some regions, particular pesticides have become the most popular method of self-harm, gaining a notoriety amongst both health-care workers and public. Self-poisoning with medicines such as benzodiazepines and antidepressants is common in urban areas, but associated with few deaths. The antimalarial chloroquine appears the most significant medicine, self-poisoning being common in both Africa and the Pacific region, and often fatal. Paracetamol (acetaminophen) is used in many countries but in few has it reached the popularity typical of the UK. Domestic and industrial chemicals are responsible for significant numbers of deaths and long-term disabilities world-wide. Self-poisoning with plant parts, although uncommon globally, is locally popular in some regions. Few of these poisons have specific antidotes. This emphasizes the importance of determining whether interventions aimed at reducing poison absorption actually produce a clinical benefit, reducing death and complication rates. Future research to improve medical management and find effective ways of reducing the incidence of self-harm, together with more widespread provision of interventions proven to be effective, could rapidly reduce the number of deaths from self-poisoning in the developing world. (+info)
Using GIS and historical records to reconstruct residential exposure to large-scale pesticide application.
Investigation of pesticide impacts on human health depends on good measures of exposure. Historical exposure data are needed to study health outcomes, such as cancer, that involve long latency periods, and other outcomes that are a function of the timing of exposure. Environmental or biological samples collected at the time of epidemiologic study may not represent historical exposure levels. To study the relationship between residential exposure to pesticides and breast cancer on Cape Cod, Massachusetts, historical records of pesticide use were integrated into a geographic information system (GIS) to estimate exposures from large-scale pesticide applications between 1948 and 1995. Information on pesticide use for gypsy moth and other tree/vegetative pest control, cranberry bog cultivation, other agriculture, mosquito control, recreational turf management, and rights-of-way maintenance is included in the database. Residents living within or near pesticide use areas may be exposed through inhalation due to drift and volatilization and through dermal contact and ingestion at the time of application or in later years from pesticides that deposit on soil, accumulate in crops, or migrate to groundwater. Procedures were developed to use the GIS to estimate the relative intensity of past exposures at each study subject's Cape Cod addresses over the past 40 years, taking into account local meteorological data, distance and direction from a residence to a pesticide use source area, size of the source area, application by ground-based or aerial methods, and persistent or nonpersistent character of the pesticide applied. The resulting individual-level estimates of relative exposure intensity can be used in conjunction with interview data to obtain more complete exposure assessment in an epidemiologic study. While the database can improve environmental epidemiological studies involving pesticides, it simultaneously illustrates important data gaps that cannot be filled. Studies such as this one have the potential to identify preventable causes of disease and guide public policies. (+info)
The impact of endocrine disruptors on oocyte competence.
To date, approximately 60 chemicals have been identified as endocrine disruptors: exogenous agents that interfere with various aspects of natural hormone physiology. The potential reproductive and health hazards of these environmental chemicals have recently generated concern among the scientific community, policy makers and general public. The present review presents and discusses the available evidence that environmental chemicals are causing ovarian toxicity in various species, with particular attention to farm animals. The impact of chronic exposure to endocrine disruptors via food and drinking water cannot be neglected when studying fertility problems in these species. This review focuses attention on the superfamily of organochlorine chemicals, persistent organic pollutants (POPs), because of their persistence in the environment, ability to concentrate up the food chain, continued detection in environmental matrices and ability to be stored in the adipose tissue of animals and humans. Published data clearly indicate that POPs disrupt mammalian oocyte maturation and follicle physiology in every species studied so far, including farm animals. However, as most of the data available still derive from experiments performed on laboratory species or in vitro models, great care should be taken when extrapolations to other species or environmental situations are attempted. (+info)
Controlled release urea as a nitrogen source for spring wheat in Western Canada: yield, grain N content, and N use efficiency.
Controlled release nitrogen (N) fertilizers have been commonly used in horticultural applications such as turf grasses and container-grown woody perennials. Agrium, a major N manufacturer in North and South America, is developing a low-cost controlled release urea (CRU) product for use in field crops such as grain corn, canola, wheat, and other small grain cereals. From 1998 to 2000, 11 field trials were conducted across western Canada to determine if seed-placed CRU could maintain crop yields and increase grain N and N use efficiency when compared to the practice of side-banding of urea N fertilizer. CRU was designed to release timely and adequate, but not excessive, amounts of N to the crop. Crop uptake of N from seed-placed CRU was sufficient to provide yields similar to those of side-banded urea N. Grain N concentrations of the CRU treatments were higher, on average, than those from side-banded urea, resulting in 4.2% higher N use efficiency across the entire N application range from 25 to 100 kg ha(-1). Higher levels of removal of N in grain from CRU compared to side-banded urea can result in less residual N remaining in the soil, and limit the possibility of N losses due to denitrification and leaching. (+info)
Effects of brash removal after clear felling on soil and soil-solution chemistry and field-layer biomass in an experimental nitrogen gradient.
Biofuels, such as brash from forest fellings, have been proposed as an alternative energy source. Brash removal may affect the sustainability of forest production, e.g., through a change in the availability of cations and N in the soil. We report initial effects of brash removal on inorganic N content in humus and mineral soil, soil-solution chemistry, and field-layer biomass after clear felling an N-fertilisation experiment in central Sweden. The experiment comprised six different fertiliser levels, ranging from 0 to 600 kg N ha(-1). Urea was given every 5th year during 1967 to 1982 to replicated plots, giving total doses of 0 to 2400 kg N ha(-1). Clear felling took place in 1995, 13 years after the last fertilisation. The removal of brash decreased the NO3- content in the humus layer after clear felling. A decrease in the NO3- concentration of the soil solution was indicated during most of the study period as well. No effect of the previous N fertilisation was found in the humus layer, but in the mineral soil there was an increase in NO3- content for the highest N dose after clear felling ( p = 0.06). The soil-solution chemistry and the field-layer biomass showed an irregular pattern with no consistent effects of brash removal or previous fertilisation. (+info)