Selectivity in supercritical fluid extraction: recovery of pesticides from model matrices.
(17/1375)
Selected pesticides are spiked in an empty extraction thimble for use as a model system to study the solvating power of supercritical carbon dioxide and spiked in solid-phase sorbent materials to study the influences of matrix effects on the recoveries. Results from this study show that it is possible to identify supercritical fluid extraction conditions where the molecular structure of the analytes affect the extraction efficiency. The results also indicate that parameters other than solubility (e.g., volatility) have a marked influence on the extraction process, even under simplistic conditions (extraction from empty thimble). (+info)
Implementation of EPA's Worker Protection Standard training for agricultural laborers: an evaluation using North Carolina data.
(18/1375)
The US Environmental Protection Agency has promulgated a Worker Protection Standard which requires that farmworkers receive pesticide safety training. The implementation of these regulations has not been evaluated. Using data collected through personal interviews with 270 Hispanic farmworkers recruited from 35 labor sites in an eight-county area, the authors analyzed the extent to which farmworkers received pesticide safety training, characteristics of the training, and variations in knowledge and safety behavior. Approximately a third of the farmworkers reported having ever received information or training on pesticide safety, and 25.6% reported having received training in the year in which they were interviewed. Workers with H2A visas were significantly more likely to have received training than workers without these visas. The training received varied in location, duration, and language. Most included the use of a video, as well as verbal presentation, and most included printed materials. However, few workers knew the ways in which they could be exposed to pesticides or reported using any method to protect themselves from pesticide exposure. (+info)
Identification of determinants of pesticide exposure among Kenyan agricultural workers using empirical modelling.
(19/1375)
The influence of factors such as type of pesticides used, use of personal protective devices and hygienic behaviour on acetylcholinesterase inhibition and activity levels in red blood cells of agricultural workers was studied in four areas in Kenya. Empirical modelling techniques were used to identify and quantify factors affecting acetylcholinesterase inhibition and activity. Use of personal protective devices was almost non-existent in areas 3 and 4 where mainly subsistence farmers were studied. Differences in hygienic behaviour between areas were relative small. WHO Class I pesticides were mostly found in area 1 (mainly large farms growing flowers) which also had highest amounts of pesticide use and highest frequency of pesticide spraying. Despite widespread use of protective devices in this area significant inhibition occurred. It became unclear whether acetylcholinesterase inhibition occurred as a result of protective clothing soaked with pesticides, thereby increasing dermal exposure, or because of other (unmeasured) factors. Inhibition, however, could have been much worse without protective devices. In area 1, most workers wore boots, which were found to be protective only when combined with an overall; wearing boots alone led to increased inhibition. Access to a washing facility or bathing facility had a positive effect on acetylcholinesterase levels. However, washing of hands and bathing immediately after spraying seemed reactive behaviour rather than proactive behaviour. Spraying was found to lead to more profound acetylcholinesterase inhibition than mixing. Workers who sprayed WHO Class III pesticides had less acetylcholinesterase inhibition than workers spraying more toxic pesticides. (+info)
Identifying populations potentially exposed to agricultural pesticides using remote sensing and a Geographic Information System.
(20/1375)
Pesticides used in agriculture may cause adverse health effects among the population living near agricultural areas. However, identifying the populations most likely to be exposed is difficult. We conducted a feasibility study to determine whether satellite imagery could be used to reconstruct historical crop patterns. We used historical Farm Service Agency records as a source of ground reference data to classify a late summer 1984 satellite image into crop species in a three-county area in south central Nebraska. Residences from a population-based epidemiologic study of non-Hodgkin lymphoma were located on the crop maps using a geographic information system (GIS). Corn, soybeans, sorghum, and alfalfa were the major crops grown in the study area. Eighty-five percent of residences could be located, and of these 22% had one of the four major crops within 500 m of the residence, an intermediate distance for the range of drift effects from pesticides applied in agriculture. We determined the proximity of residences to specific crop species and calculated crop-specific probabilities of pesticide use based on available data. This feasibility study demonstrated that remote sensing data and historical records on crop location can be used to create historical crop maps. The crop pesticides that were likely to have been applied can be estimated when information about crop-specific pesticide use is available. Using a GIS, zones of potential exposure to agricultural pesticides and proximity measures can be determined for residences in a study. (+info)
The dead zones: oxygen-starved coastal waters.
(21/1375)
After the great Mississippi River flood of 1993, the hypoxic (or low-oxygen) "dead zone" in the Gulf of Mexico more than doubled its size, reaching an all-time high of over 7,700 square miles in July of 1999. Scientists attribute the Gulf of Mexico dead zone largely to nutrient runoff from agriculture in the Mississippi River basin. During the warm months, these nutrients fuel eutrophication, or high organic production, causing large algal blooms. When the algae decay, the result is hypoxia. Reports of such hypoxic events around the world have been increasing since the mid 1960s. Eutrophication and hypoxia have resulted in mortality of bottom-dwelling life in dozens of marine ecosystems and have stressed fisheries worldwide. Some algal blooms can alter the function of coastal ecosystems or, potentially, threaten human health. Anthropogenic nutrient loading from sources such as agriculture, fossil fuel emissions, and climate events is believed to be related to the global increase in frequency, size, and duration of certain algal blooms. (+info)
Farming from a new perspective: remote sensing comes down to earth.
(22/1375)
Farmers strive to increase the yield of their fields by adding nutrients and water to the land, and using pesticides to control insects and disease. In addition to bountiful harvests, the results of their endeavors may include elevated amounts of fertilizers in surface waters and aquifers and potential risk to themselves and their neighbors from exposure to pesticides. Precision agriculture is the use of modern information technologies such as geographic information systems, the global positioning system, and remote sensing from the air to reduce the environmental effects of these chemicals while enhancing the productivity of farming. By combining crop yield maps with soil survey maps and remote sensing output, farmers can identify areas that need more or less fertilizer, water, or pesticide. (+info)
Fatal aluminum phosphide poisoning.
(23/1375)
A 39-year-old man committed suicide by ingestion of aluminum phosphide, a potent mole pesticide, which was available at the victim's workplace. The judicial authority ordered an autopsy, which ruled out any other cause of death. The victim was discovered 10 days after the ingestion of the pesticide. When aluminum phosphide comes into contact with humidity, it releases large quantities of hydrogen phosphine (PH3), a very toxic gas. Macroscopic examination during the autopsy revealed a very important asphyxia syndrome with major visceral congestion. Blood, urine, liver, kidney, adrenal, and heart samples were analyzed. Phosphine gas was absent in the blood and urine but present in the brain (94 mL/g), the liver (24 mL/g), and the kidneys (41 mL/g). High levels of phosphorus were found in the blood (76.3 mg/L) and liver (8.22 mg/g). Aluminum concentrations were very high in the blood (1.54 mg/L), brain (36 microg/g), and liver (75 microg/g) compared to the usual published values. Microscopic examination revealed congestion of all the organs studied and obvious asphyxia lesions in the pulmonary parenchyma. All these results confirmed a diagnosis of poisoning by aluminum phosphide. This report points out that this type of poisoning is rare and that hydrogen phosphine is very toxic. The phosphorus and aluminum concentrations observed and their distribution in the different viscera are discussed in relation to data in the literature. (+info)
Leukemia and non-Hodgkin's lymphoma in childhood and exposure to pesticides: results of a register-based case-control study in Germany.
(24/1375)
Previous studies have suggested an association between exposure to pesticides and different types of childhood cancer. This paper presents results from a population-based case-control interview study of parents of children less than 15 years of age, which was conducted in the states of West Germany from 1993 to 1997. Cases were 1,184 children with leukemia, 234 with non-Hodgkin's lymphoma, and 940 with a solid tumor; 2,588 controls were also included. Parental occupational exposures were found to be related to childhood cancer regardless of the time period of exposure and the type of cancer. This finding might partially be explained by different recall of past exposures by the parents of cases and controls. Residential use of insecticides was associated with childhood lymphoma: both extermination of insects by professional pest controllers (odds ratio (OR) = 2.6, 95% confidence interval (CI): 1.2, 5.7) and frequency of parental use of household insecticides (p for trend = 0.02) were significant risk factors for this diagnosis. The use of pesticides on farms was weakly related to childhood leukemia (OR = 1.5, 95% CI: 1.0, 2.2), while their use in gardens was not associated with childhood leukemia (OR = 1.0, 95% CI: 0.8, 1.2). The major strengths of this study were the population base and the large number of cases and controls included; a drawback was assessment of exposure on the basis of parental interviews. The data provide some evidence for an increased leukemia risk for children living on farms and for an association between use of household pesticides and risk of childhood leukemia or lymphoma. (+info)