I have seen many posts recently about DE and decided to do a lit search. Here is what I found. Thought it may be of interst, and the papers reflect a variety of DE-related topics.
-------------------------------------------------------------------------------------------
Diatomaceous earths, a group of natural insecticides
Korunic, Z.
Journal of Stored Products Research
Volume 34, Issue 2-3, April 1998, Pages 87-97
Hedley Technologies Inc., 1540, 800 West Pender St., Vancouver, BC V6C 2V6, Canada
Abstract
Diatomaceous earth (DE) is a geological deposit consisting of the fossilised skeletons of numerous species of siliceous marine and fresh water unicellular organisms, particularly diatoms and other algae. Many of these fossilised sedimentary layers originated at least 20 million years ago in the lakes and seas of the Eocene and Miocene epochs. After quarrying, crushing and milling, a fine light dust is obtained, containing porous particles with certain abrasive properties and the ability to absorb lipids to about three or more times the particle mass. Any diatomaceous earth with high off absorbing capacity is a potential insecticide. Beyond the absorbing capacity, the size of particles, uniformity and shape of the particles, pH, and the purity of formulation affect the compound's insecticidal efficacy. Insecticidal diatomaceous earth should be a highly pure amorphous silica, having particles of equal diameter (< 10 μm), pH < 8.5, containing the least possible number of clay particles and less than 1% crystalline silica. The particles of diatomaceous earth are easily picked up by rough bodied insects. The particles damage the cuticle through hydrocarbon absorption and abrasion making the cuticle permeable to water which rapidly leaves the insect's body causing death from desiccation. In this paper the advantages and disadvantages of diatomaceous earth as an insecticide and its scope of use are discussed. Briefly, the description of DE application, the modes of action and its uses are described. Tests results show great variation in physical properties and efficacy against insects among DEs from different geographical locations. Environmental factors affecting efficacy and the potential scope of DE use are discussed.
---------------------------------------------------------------------------------------------
Development of a chronic inhalation reference level for respirable crystalline silica
Collins, J.F., Salmon, A.G., Brown, J.P., Marty, M.A., Alexeeff, G.V.
Regulatory Toxicology and Pharmacology
Volume 43, Issue 3, December 2005, Pages 292-300
Air Toxicology and Epidemiology Branch, Office of Environmental Health Hazard Assessment, California Environmental Protection Agency, 1515 Clay Street, Oakland, CA 94612, United States
Abstract
Chronic inhalation exposure of workers to crystalline silica can result in silicosis. The general public can also be exposed to lower levels of crystalline silica from quarries, sand blasting, and entrained fines particles from surface soil. We have derived an inhalation chronic reference exposure level for silica, a level below which no adverse effects due to prolonged exposure would be expected in the general public. Incidence of silicosis and silica exposure data from a cohort of 2235 white South African gold miners yielded a reference level of 3 μg/m3 for respirable silica (particle size as defined occupationally) using a benchmark concentration approach. Data from cohorts of American gold miners, Chinese tin miners, diatomaceous earth workers, and black South African gold miners yielded similar results with a range of 3-10 μg/m3. Strengths of the chronic reference exposure level include the availability of several large long-term studies of inhalation in workers at varying exposure concentrations, adequate histopathological and radiologic analysis, adequate follow-up of exposed workers, a dose-response effect in several studies, observation of a No Observed Adverse Effect Level in the key study, and the power of the key study to detect a small effect. Uncertainties include the general underestimation of silicosis by radiography alone and the uncertainties in exposure estimation.
2005 Elsevier Inc. All rights reserved.
------------------------------------------------------------------------------------------
Comparison of different silicas of natural origin as possible insecticides.
Mucha-Pelzer, T., Debnath, N., Goswami, A. Mewis, I.
Communications in agricultural and applied biological sciences
Volume 73, Issue 3, 2008, Pages 621-628
Department of Urban Horticulture, Institute for Horticultural Science, Humboldt University Berlin, Lentzeallee 55, DE-14195 Berlin, Germany.
Abstract
Many insect-pests have developed resistances to pesticides. Therefore, there is always a need for new plant protection substances. For example the physically active insecticide diatomaceous earth (DE) gained much attention as an alternative insecticide in stored products. DE is a naturally occurring silica, which acts by destroying the insect's cuticle by absorbing the protective wax layer. This results in body water loss and ultimately the insect's death by desiccation. The silica-based materials tested were the commercial DE product Fossil Shield 90.0s, Advasan, and a formulation newly developed by the Urban Horticultural Department at Humboldt University, called Al-06. The trials were performed in small covered plastic boxes. Test substances were either dusted onto the surface of the boxes (E. vigintioctopunctata, S. litura) or mixed into rice medium (S. oryzae). The mortality was observed after 1, 2, 4, 7, 14, and 28 days. Untreated insects served as control. The first test series showed that some AL-06-formulations and FS90.0s were very effective against adults of S. oryzae and S. litura and larvae of E. vigintioctopunctata. For adult Epilachna beetles, we could not detect any differences between the treatments. The highest mortality rate in S. oryzae trials occurred with FS90.0s (100%) after 21 days. The same efficiency was achieved after 2 days with some AL-06 formulations against S. litura and E. vigintioctopunctata. The results of this study indicate that silica dusts can effectively control insect pests from different orders. At higher dosages, all materials resulted in higher insect mortality rates. It was also found that some substances did not perform well under higher rel. humidity; therefore, the conclusion was drawn that hydrophilic substances saturate with water from the surrounding air and lose their insecticidal efficacy. Earlier studies have proven that particles with a larger surface area are more effective than particles with smaller surfaces. As a result, the most effective substances in the field trials were the ones containing the small particles, since there is a larger surface area available to interact with the insects' cuticles. Further studies will be conducted to analyse the relevance of water saturation of substances in order to examine their effectiveness under greenhouse conditions. Greenhouse experiments are generally considered to study practicability of silica dusts in horticulture. Perhaps the silica dusts will show phytotoxic side effects.
------------------------------------------------------------------------------------------
Acid products adsorbed in diatomaceous earth beneficially influence the microbial environment in the gastrointestinal tract of piglets post-weaning
Mikkelsen, L.L., Virtanen, E., Jensen, B.B.
Livestock Science
Volume 108, Issue 1-3, 1 May 2007, Pages 222-225
a Danish Institute of Agricultural Sciences, Research Centre Foulum, DK-8830 Tjele, Denmark
b Kemira GrowHow Oy, Finland
Abstract
The effect of two acid products, CH01-141 and CH01-186 on the microbial ecosystem and on survival of the diarrhoea causing E. coli O149:K88 in the gastrointestinal tract of newly weaned four-week-old piglets was investigated. The results showed that piglets fed with the CH01-141 and CH01-186 products had a significantly lower pH and significantly higher concentration of lactic acid in the distal small intestine as compared with piglets fed the control diet without any acid product. The CH01-141 product also tended to increase the number of lactobacilli in the small intestine and decreased the number of yeasts throughout the gastrointestinal tract as compared with the control group. Besides this, the in vitro survival rate of E. coli O149:K88 tended to be lower in content from the distal small intestine of the CH01-141 fed piglets. In conclusion, the acid products, especially CH01-141, may have a beneficial effect on diminishing pathogenic bacteria, such as E. coli O149:K88, and thus improving gut health of piglets around weaning.
2007 Elsevier B.V. All rights reserved.
--------------------------------------------------------------------------------------------
-------------------------------------------------------------------------------------------
Diatomaceous earths, a group of natural insecticides
Korunic, Z.
Journal of Stored Products Research
Volume 34, Issue 2-3, April 1998, Pages 87-97
Hedley Technologies Inc., 1540, 800 West Pender St., Vancouver, BC V6C 2V6, Canada
Abstract
Diatomaceous earth (DE) is a geological deposit consisting of the fossilised skeletons of numerous species of siliceous marine and fresh water unicellular organisms, particularly diatoms and other algae. Many of these fossilised sedimentary layers originated at least 20 million years ago in the lakes and seas of the Eocene and Miocene epochs. After quarrying, crushing and milling, a fine light dust is obtained, containing porous particles with certain abrasive properties and the ability to absorb lipids to about three or more times the particle mass. Any diatomaceous earth with high off absorbing capacity is a potential insecticide. Beyond the absorbing capacity, the size of particles, uniformity and shape of the particles, pH, and the purity of formulation affect the compound's insecticidal efficacy. Insecticidal diatomaceous earth should be a highly pure amorphous silica, having particles of equal diameter (< 10 μm), pH < 8.5, containing the least possible number of clay particles and less than 1% crystalline silica. The particles of diatomaceous earth are easily picked up by rough bodied insects. The particles damage the cuticle through hydrocarbon absorption and abrasion making the cuticle permeable to water which rapidly leaves the insect's body causing death from desiccation. In this paper the advantages and disadvantages of diatomaceous earth as an insecticide and its scope of use are discussed. Briefly, the description of DE application, the modes of action and its uses are described. Tests results show great variation in physical properties and efficacy against insects among DEs from different geographical locations. Environmental factors affecting efficacy and the potential scope of DE use are discussed.
---------------------------------------------------------------------------------------------
Development of a chronic inhalation reference level for respirable crystalline silica
Collins, J.F., Salmon, A.G., Brown, J.P., Marty, M.A., Alexeeff, G.V.
Regulatory Toxicology and Pharmacology
Volume 43, Issue 3, December 2005, Pages 292-300
Air Toxicology and Epidemiology Branch, Office of Environmental Health Hazard Assessment, California Environmental Protection Agency, 1515 Clay Street, Oakland, CA 94612, United States
Abstract
Chronic inhalation exposure of workers to crystalline silica can result in silicosis. The general public can also be exposed to lower levels of crystalline silica from quarries, sand blasting, and entrained fines particles from surface soil. We have derived an inhalation chronic reference exposure level for silica, a level below which no adverse effects due to prolonged exposure would be expected in the general public. Incidence of silicosis and silica exposure data from a cohort of 2235 white South African gold miners yielded a reference level of 3 μg/m3 for respirable silica (particle size as defined occupationally) using a benchmark concentration approach. Data from cohorts of American gold miners, Chinese tin miners, diatomaceous earth workers, and black South African gold miners yielded similar results with a range of 3-10 μg/m3. Strengths of the chronic reference exposure level include the availability of several large long-term studies of inhalation in workers at varying exposure concentrations, adequate histopathological and radiologic analysis, adequate follow-up of exposed workers, a dose-response effect in several studies, observation of a No Observed Adverse Effect Level in the key study, and the power of the key study to detect a small effect. Uncertainties include the general underestimation of silicosis by radiography alone and the uncertainties in exposure estimation.
------------------------------------------------------------------------------------------
Comparison of different silicas of natural origin as possible insecticides.
Mucha-Pelzer, T., Debnath, N., Goswami, A. Mewis, I.
Communications in agricultural and applied biological sciences
Volume 73, Issue 3, 2008, Pages 621-628
Department of Urban Horticulture, Institute for Horticultural Science, Humboldt University Berlin, Lentzeallee 55, DE-14195 Berlin, Germany.
Abstract
Many insect-pests have developed resistances to pesticides. Therefore, there is always a need for new plant protection substances. For example the physically active insecticide diatomaceous earth (DE) gained much attention as an alternative insecticide in stored products. DE is a naturally occurring silica, which acts by destroying the insect's cuticle by absorbing the protective wax layer. This results in body water loss and ultimately the insect's death by desiccation. The silica-based materials tested were the commercial DE product Fossil Shield 90.0s, Advasan, and a formulation newly developed by the Urban Horticultural Department at Humboldt University, called Al-06. The trials were performed in small covered plastic boxes. Test substances were either dusted onto the surface of the boxes (E. vigintioctopunctata, S. litura) or mixed into rice medium (S. oryzae). The mortality was observed after 1, 2, 4, 7, 14, and 28 days. Untreated insects served as control. The first test series showed that some AL-06-formulations and FS90.0s were very effective against adults of S. oryzae and S. litura and larvae of E. vigintioctopunctata. For adult Epilachna beetles, we could not detect any differences between the treatments. The highest mortality rate in S. oryzae trials occurred with FS90.0s (100%) after 21 days. The same efficiency was achieved after 2 days with some AL-06 formulations against S. litura and E. vigintioctopunctata. The results of this study indicate that silica dusts can effectively control insect pests from different orders. At higher dosages, all materials resulted in higher insect mortality rates. It was also found that some substances did not perform well under higher rel. humidity; therefore, the conclusion was drawn that hydrophilic substances saturate with water from the surrounding air and lose their insecticidal efficacy. Earlier studies have proven that particles with a larger surface area are more effective than particles with smaller surfaces. As a result, the most effective substances in the field trials were the ones containing the small particles, since there is a larger surface area available to interact with the insects' cuticles. Further studies will be conducted to analyse the relevance of water saturation of substances in order to examine their effectiveness under greenhouse conditions. Greenhouse experiments are generally considered to study practicability of silica dusts in horticulture. Perhaps the silica dusts will show phytotoxic side effects.
------------------------------------------------------------------------------------------
Acid products adsorbed in diatomaceous earth beneficially influence the microbial environment in the gastrointestinal tract of piglets post-weaning
Mikkelsen, L.L., Virtanen, E., Jensen, B.B.
Livestock Science
Volume 108, Issue 1-3, 1 May 2007, Pages 222-225
a Danish Institute of Agricultural Sciences, Research Centre Foulum, DK-8830 Tjele, Denmark
b Kemira GrowHow Oy, Finland
Abstract
The effect of two acid products, CH01-141 and CH01-186 on the microbial ecosystem and on survival of the diarrhoea causing E. coli O149:K88 in the gastrointestinal tract of newly weaned four-week-old piglets was investigated. The results showed that piglets fed with the CH01-141 and CH01-186 products had a significantly lower pH and significantly higher concentration of lactic acid in the distal small intestine as compared with piglets fed the control diet without any acid product. The CH01-141 product also tended to increase the number of lactobacilli in the small intestine and decreased the number of yeasts throughout the gastrointestinal tract as compared with the control group. Besides this, the in vitro survival rate of E. coli O149:K88 tended to be lower in content from the distal small intestine of the CH01-141 fed piglets. In conclusion, the acid products, especially CH01-141, may have a beneficial effect on diminishing pathogenic bacteria, such as E. coli O149:K88, and thus improving gut health of piglets around weaning.
--------------------------------------------------------------------------------------------
