DDVP Concentrations Research Articles

Acute Toxic Effects of Inhaled Dichlorvos Vapor on Respiratory Mechanics and Blood Cholinesterase Activity in Guinea Pigs

Using a modified noninvasive volume-displacement plethysmography system, we investigated the effects of inhaled dichlorvos (2,2-dimethyl dichlorovinyl phosphate, or DDVP) vapor on the respiratory mechanics and blood cholinesterase activity of guinea pigs. Data revealed significant dose-dependent changes in several pulmonary parameters. Animals exposed to a DDVP concentration of 35 mg/m3 did not show any significant changes in frequency, tidal volume, or minute ventilation. However, animals exposed to 55 mg/m3 DDVP showed significantly decreased respiratory frequency and significantly increased tidal volume with no significant changes in minute ventilation. Similarly, animals exposed to 75 mg/m3 DDVP showed significantly decreased respiratory frequency along with significantly increased tidal volume. The decreased respiratory frequency was large enough in the high exposure group to offset the increased tidal volume. This effect resulted in significantly decreased minute ventilation by the end of exposure, which remained attenuated 10 min after exposure. An analysis of whole-blood cholinesterase activity revealed significantly decreased activity for both acetylcholinesterase (AChE) and butylcholinesterase (BChE). Peak inhibition occurred for both enzymes at the end of exposure for all three concentrations and rapidly recovered within several minutes of exposure. Analysis of blood samples using gas chromatography–mass spectroscopy (GC-MS) revealed that minute ventilation may only play a minimal role in the dosimetry of inhaled DDVP vapor.

Clastogenic and mitodepressive effects of the insecticide dichlorvos on root meristems ofVicia faba

Plant bioassays are an important and integral part of the test battery used in detecting genotoxic/carcinogenic contamination in the environment. Highly sensitive biomonitoring of plant models have been developed, which enables the detection of hazards arising from pesticides, insecticides, industrial contamination, heavy metals and radiation. Root tips of Vicia faba ssp. minor were treated with 1-60 mM of the organophosphorus insecticide dichlorvos (DDVP) for 2 h, followed by a 20-h recovery period. Maleic acid hydrazide (MH) was used as a positive control for the mitotic index, micronucleus and chromosomal aberration assays performed on the Vicia model system. All treatments with DDVP significantly decreased the mitotic activity and increased the frequency of chromosomal aberrations at the metaphase. The frequency of micronuclei was significantly increased at DDVP concentrations starting from 10 mM. The results demonstrate clastogenic and mitodepressive effects of DDVP on Vicia faba cells.

Novel Piezoelectric DDVP Sensor Based on Self‐Assembly Method

A novel piezoelectric sensor was fabricated by depositing the films of polyvinyl pyrrolindone (PVP) and PVP with butyl cholinesterase (BuChE) (BuChE‐PVP), respectively, on the surface of quartz crystal microbalance (QCM) using self‐assembly method. The sensitive films were characterized with online examination and XPS technique. The obtained sensors were applied to measure o,o‐dimethyl‐o‐2,2‐dichlorovinyl phosphate (DDVP) pesticide concentration. It shows that BuChE‐PVP sensor has higher sensitivity than PVP sensor. There is a linear relationship between the shift of frequency and the concentration of DDVP in a range from 4.25 to 21.25 ppm. This highly sensitive sensor has also been shown to determine DDVP concentration in several samples, and the relative standard error is less than 3%. It also shows that CO, NO2, H2S, and SO2 with 10 times the concentration of DDVP have no interference with DDVP detection in the tested concentration range.

Polymer coated QCM sensor with modified electrode for the detection of DDVP

A quartz crystal microbalances (QCMs) based sensor was fabricated by modifying the geometry and size of the electrode to detect organophosphorus pesticide o, o-dimethyl- o-2,2-dichlorovinyl phosphate (DDVP). Both conductive and non-conductive polymers were characterized on the surface of the modified QCM electrode. Operating at the resonant frequency ranging from 10 to 20 Hz, the QCMs coated with non-conductive polymers, polyvinyl alcohol (PVA) and poly (acrylic acid) (PAA), were sensitive to DDVP. The results showed that the resonant frequency range of QCMs increased by the coating with conductive polymers, poly(3,4-ethylenedioxythiophene) (PEDOT) and a copolymer of PEDOT with poly(styrene sulphonic acid) (PEDOT/PSS), which was from 20 to 115 Hz and 18 to 60 Hz, respectively. The mechanism and corresponding equivalent circuit model of the QCM-based sensor were presented. The capacitance was calculated in the range of 0.199–0.194 pF for the PEDOT/PSS film and 0.198–0.187 pF for the PEDOT film. In the range of 6.5–32.5 ppm DDVP concentration, the relationship between the response of the sensor coated with PEDOT and the concentration was linear. The relative standard deviation of the modified sensor was less than 5%.

Organic air pollutants inside and outside residences in Shimizu, Japan: Levels, sources and risks

Concentrations of 38 organic air pollutants including aromatic hydrocarbons (AHCs), carbonyl compounds (CCs), volatile organic halogenated compounds (VOHCs), and organophosphorus compounds (OPCs) were measured in indoor and outdoor air in an industrial city, Shimizu, Shizuoka Prefecture, Japan. Levels of pollutants tended to be higher indoors than outdoors in both summer and winter except for benzene, carbon tetrachloride, trichloroethylene, tetrachloroethylene, and dichlorvos (DDVP). This trend was especially pronounced for CCs such as formaldehyde and acetaldehyde. For the organic air pollutants, the concentrations of AHCs and VOHCs substantially increased in winter, but not those of CCs and OPCs; the trends were similar for both indoors and outdoors. We investigated possible indoor sources of pollutants statistically. Multiple regression analysis of corresponding indoor and outdoor concentrations and the responses to our questionnaire showed that indoor concentrations of certain AHCs were significantly affected by their outdoor concentrations and cigarette smoking. For formaldehyde, indoor concentrations were significantly affected by house age and the presence of carpet or pets. For p-dichlorobenzene ( pDCB), the concentrations in bedroom trended to be higher than those in other indoors and outdoors, suggested that mothballs for clothes present in bedrooms are the principal indoor source of pDCB. We compared indoor and outdoor pollutant concentrations to acceptable risk limits for 11 organic air pollutants. In indoors without smoking samples, the geometric mean concentrations of benzene, formaldehyde, acetaldehyde, carbon tetrachloride, pDCB, and DDVP exceeded the equivalent concentration representing the upper bound of one-in-one-hundred-thousand (1 × 10 − 5 ) excess risk over a lifetime of exposure.

Weak Inhibitors Protect Cholinesterases from Stronger Inhibitors (Dichlorvos): In Vitro Effect of Tiapride

Metoclopramide is a benzamide dopamine receptor antagonist and serotonine receptor agonist widely used as an antiemetic and gastric prokinetic drug. In addition, metoclopramide is a weak and reversible inhibitor of cholinesterases. The authors have previously shown that metoclopramide has a cholinesterase protective effect against inhibition by organophosphates (OPs). The putative mode of protective action of metoclopramide is, when administered in excess, competion for the active site of the enzyme with the more potent OP. In the present paper the authors present their results using another benzamide with weak cholinesterase inhibitory properties, tiapride (TIA). The purpose of the study was to quantify in vitro the extent of TIA-conferred protection, using dichlorvos (dichlorovinyl dimethyl phosphate; DDVP) as an inhibitor. DDVP is a moderately toxic (LD50 in rats in the milligram range), non-neuropathic OP. The substance is responsible for a large number of accidental or suicidal exposures. Red blood cell (RBC) acetylcholinesterase (AChE) activities in whole blood and butyrylcholinesterase (BChE) activities in human plasma were measured photometrically in the presence of different DDVP and TIA concentrations and IC50 was calculated. Determinations were repeated in the presence of increasing TIA concentrations. The IC50 of DDVP increases with the TIA concentration in a linear manner. The protective effect of TIA on cholinesterase could be of practical relevance in the treatment of OP poisoning. The authors conclude that in vivo testing of TIA as an OP protective agent is warranted.

High-performance liquid chromatographic assay of dichlorvos, isocarbophos and methyl parathion from plant leaves using chemiluminescence detection

A high-performance liquid chromatographic (HPLC) method has been developed for the detection of organic phosphorous insecticides (dichlorvos(DDVP), isocarbophos and methyl parathion). In addition to a traditional method using UV detection, we developed an alternative method based on chemiluminescent reaction of organic phosphorous insecticides with luminol and hydrogen peroxide. The sample containing organic phosphorous insecticides was injected into a Hypersil ODS column (5 μm 4.6×100 mm) and eluted with methanol:water (60:40 (v/v)). The chemiluminescence (CL) response is linear to the concentration of DDVP, isocarbophos and methyl parathion, respectively. Most metal ions and organic compounds tested do not interfere with the determination.

Organophosphorus Compound O,O-Dimethyl-O-(2,2-dichlorovynyl)-Phosphate as Selective Inhibitor for Separate Determination of Acetylcholinesterase and Butyrylcholinesterase Activities in the Roach Rutilus rutilus

A comparative study is carried out on dependence of degree of activity inhibition of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) of a freshwater bony fish, the roach Rutilus rutilus L., on concentration of organophosphates: O,O-dimethyl-O-(2,2-dichlorovynyl)phosphate (DDVP) and tetraisopropylamidopyrophosphate (iso-OMPA). It has been shown that both in roach and in horse the both inhibitors are selective for BChE in comparison with AChE. Their selectivity degree was 2000-fold and 80-fold, respectively. The ranges of effective DDVP concentrations are overlapped for horse AChE and BChE, while they do not for the roach enzymes. A similar regularity is revealed at action of iso-OMPA. It is established that DDVP has a higher inhibitory potency and selectivity in relation to roach BChE, than iso-OMPA. It is suggested to use DDVP as a new selective inhibitor for separate evaluation of AChE and BChE activities in fish tissues.

Development, validation and application of assays to quantify metrifonate and 2,2-dichlorovinyl dimethylphosphate in human body fluids

Gas chromatographic procedures [GC with electron-capture detection (ECD) and GC–MS] for the quantitative analysis of metrifonate and its active metabolite 2,2-dichlorovinyl dimethylphosphate (DDVP) in human blood and urine were developed, validated, and applied to the analysis of clinical study samples. Analysis of metrifonate involved extraction of acidified blood with ethyl acetate followed by solid-phase clean-up of the organic extract. Acidified urine was extracted with dichloromethane and the residue of evaporated organic phase was reconstituted in toluene. ECD and diethyl analogue of metrifonate internal standard (I.S.) were used for quantitation of metrifonate. The metrifonate lower limit of quantitation (LOQ) was 10.0 μg/l. The DDVP metabolite was chromatographed separately after cyclohexane extraction of acidified blood and urine using d 6-DDVP I.S. and MS detection. The LOQ of DDVP was 1 μg/l. Stability studies have confirmed that the matrix should be acidified prior to storage at −20°C or −80°C to inhibit chemical and enzymatic degradation of the analytes and to avoid overestimation of DDVP concentrations. Metrifonate was found to be stable in acidified human blood after 20 months of storage at −20°C and after 23 months of storage at −80°C. Under these conditions DDVP was found to be stable after 12 months of storage. Both assay procedures were cross-validated by different world-wide laboratories and found to be accurate and robust during analyses of clinical study samples.

A Study of Optimal Experimental Conditions in the Photocatalytic Degradation of an Organophosphorous Insecticide

The photodegradation in aqueous solutions of dimethyl 2,2 dichloro vinyl phosphate (common name DDVP or Dichlorvos), which is an organophosphorous insecticide, was studied by using illumination with UV lamp and solar exposure. TiO2 was used as a photocatalyst. In photocatalytic degradation, different TiO2 amounts, different illumination times and different pH values were examined in order to determine the optimal experimental conditions. DDVP removals at different initial DDVP concentrations under these conditions were investigated. In the photocatalytic degradation experiments, DDVP and PO4 3− (as orthophosphate) concentrations were determined. pH, potential and conductivity values were measured.

Epiphytic invertebrate assemblages and dichlorvos usage at salmon farms

Dichlorvos (DDVP) is an organophosphate medicine, used to treat farmed salmon infested with ectoparasitic crustacean sea lice. Field evidence was sought for effects of DDVP usage on mid-tide level invertebrate assemblages associated with the macrophyte Ascophylllum nodosum on shores adjacent to salmonid cages. There was no evidence of impoverishment in Ascophyllum communities in general, and non-target crustacean populations in particular, that could be related to de-lousing operations. Acetylcholinesterase activity in Hyale nilssoni was progressively inhibited with increasing DDVP concentrations. There were indications of reduced AChE activity in Hyale and Carcinus maenas and greater resistance to DDVP in animals collected close to the fish farm with greater usage of DDVP.

Development and Validation of an Analytical Method for Naled and Dichlorvos in Air

A new gas chromatographic method for analysis of the thio organophosphate pesticide naled and its transformation product dichlorvos (DDVP) was developed and validated. Naled and DDVP in air were trapped on XAD-4 resin. The pesticides were recovered from the resin with ethyl acetate. Ethyl acetate extract was analyzed for naled and DDVP by using a gas chromatograph equipped with a DB-5 Megabore capillary column and a nitrogen−phosphorus detector. The limits of quantitation for naled and DDVP were 0.05 and 0.10 μg/sample, respectively. Naled and DDVP trapped on the resin were stable over 21 days at −20 °C. Trapping efficiencies of naled and DDVP in the air samples were 74.5 ± 3.5% and 49.7 ± 3.3%, respectively. The newly developed method showed excellent results for the air samples collected at the application sites. Maximum observed concentrations of naled and DDVP at the application sites were 6.30 and 0.99 μg/m3, respectively. Keywords: Air sample; naled; dichlorvos; gas chromatography

Tissue distribution of DDVP after fatal ingestion

Tissue distribution of dichlorvos (DDVP) was determined in a case of fatal ingestion using a rapid and simple gas chromatographic (GC) assay. Remarkable autopsy findings were congestion of the lung and kidneys and bleeding ulcer extending from the dorsum of the tongue to the upper pharynx. The serum cholinesterase activity was 2 IU/l, however, miosis was not observed. In the stomach, 250 ml of volatile fluid was found. Tissue distribution of DDVP was determined using a newly developed simple and rapid GC method. DDVP was found in the spleen and heart at higher concentrations (3340 and 815 μg/g, respectively), and also detected in the urine at the lowest level (4.5 μg/ml). The DDVP concentrations in blood, brain, lung, kidney and liver were 29, 9.7, 81, 80 and 20 μg/ml or g, respectively.

Lethal and sub-lethal effects of the salmon delousing agent dichlorvos on the larvae of the lobster ( Homarus gammarus L.) and herring ( Clupea harengus L.)

A series of toxicity tests was conducted on larvae of lobster, Homarus gammarus, and herring Clupea harengus, to determine their sensitivities to dichiorvos (DDVP), the active ingredient of Aquagard R (Ciba-Geigy Agrochemicals, Cambridge, UK), a product administered m bath treatment to farmed fish as a treatment for sea lice ( Lepeophtheirus salmonis Krøyer and Caligus elongatus Nordmann) infestation. The respective 96-h LC50 values of 5.7 and 122 μg 1 −1 reflect the greater sensitivity of crustaceans to this organophosphorus compound. Whilst lobster larvae were sensitive to extended exposure at low concentrations of DDVP they were able to recover from extended exposure to sublethal concentrations. They were also able to tolerate and recover from repeated 1-h exposures to concentrations of up to 100 μg 1 −1. Lobster acetylcholinesterase activity was sensitive to inhibition by DDVP at sub-lethal concentrations. The environmental implications of the available data are discussed.

Effects of dichlorvos on blood cholinesterase activities of cattle

SUMMARY Inhibitory effects of dichlorvos (2,2-dichlorovinyl dimethyl phosphate, ddvp) inhibitory effects on erythrocyte acetylcholinesterase (AChE) and plasma cholinesterase (ChE) activities of steers were characterized after treatments in vitro and in vivo (cutaneous application). The rates of in vitro inhibition were markedly influenced by ddvp concentration and incubation time. The activities of inhibited enzymes failed to reactivate spontaneously and had little response to treatment with 2-pyridine aldoxime methiodide (2-pam). After gel-filtration chromatography, however, the inhibited enzymes had remarkable spontaneous reactivation and reactivation by 2-PAM treatment, indicating interference of excess unreacted ddvp in the reactivation process. Repeated cutaneous applications of a ddvp-containing livestock spray caused marked and characteristic decreases of AChE and ChE activities in blood of treated steers; however, the effects were transient because activities of both enzymes regenerated gradually. The nature of these in vivo trends suggests that spontaneous and de novo synthetic mechanisms could be responsible for complete recovery of both enzyme activities.

Relationship between toxicity and acetylcholinesterase inhibition of some thiono- and oxo-form organophosphates in tiger shrimp larvae at different stages.

A study was made regarding the relationship between the toxicity and acetylcholinesterase (AChE) inhibition of three organophosphorothionates (fenitrothion, FS; diazinon, DIN; phenthoate, PAP) and three oxo-forms (fenitrooxon, FO; diazoxon, DOX; dichlorvos, DDVP) in tiger shrimp Penaeus japonicus at different larval stages. The shrimp larvae at nauplius and zoea stages showed relatively high resistance to FS, DIN and PAP, i.e., the respective 24-h LC50 values were 1.84, 10.5 and 5ppm. However, the toxicity of these thiono-form phosphates increased abruptly with the progress of the larval stages, especially after metamorphosis into the postlarva, resulting in the increase by ca. 2, 600, 1, 200 and 850 times respectively to that of nauplius stage. On the other hand, the toxicity of FO and DDVP to the larvae was almost unchanged throughout these stages, at the levels of ca. 7ppb and 5.6ppm as the 24-h LC50 value, respectively.The susceptibility of the larval AChE to the tested phosphates was almost unchanged from zoea to postlarva. The concentrations of FO, DDVP, DOX, FS, PAP and DIN producing 50% inhibition (I50) of the AChE activity were approx. 0.015, 0.35, 1.27, 200, 650 and 1, 200μm, respectively. Although FS showed the highest AChE inhibition among the thiono-forms; its oxon (FO) displayed 12, 000 times high AChE inhibition compared to FS. The high AChE inhibition of FO was in good correlation with its high toxicity to the larvae even at the early stage.

DDVP residues in air following application to a tobacco-storage warehouse

A 10% solution of DDVP was sprayed until a total volume of 20.9 liters of the solution had been released into the air in a tobacco-storage warehouse. Air samples were taken at various times after application in three different experiments to measure DDVP levels with time and to determine if DDVP concentrations exceeded the threshold limit (TVL). In the three experiments, residue levels were highest initially in the center of the warehouse compared to a corner, but residue levels tended to equalize over the sampling period. The data indicated that workers entering storage warehouses after application of DDVP would not encounter hazardous levels of this material.

New method for the determination of saturation concentration of Dichlorvos

Saturation concenrtation of DDVP at room temperature (28°) has been determined by a colorimetric method. The saturation concentration at 28° are 9.39 and 8.55 mg/l for AR and technical grade samples respectively. The method consists of coupling DDVP vapours in gas-tight tubes with alkaline resorcinol at a water bath of 60–65°, when a yellow chromophore with an absorption maximum at 490 nm is formed. The linear relationship between the concentration of DDVP and absorbance at 490 nm holds good in the range of 1 to 20μg DDVP. The method has been checked with a gas Chromatographie method for accuracy. These values are also verified by a physical method based on Dalton's Law of partial pressures in a gaseous mixture.

Sister chromatid exchange frequencies in cultured human cells exposed to an organophosphorus insecticide: Dichlorvos

Sister chromatid exchange (SCE) frequencies in human cells grown in the presence of bromodeoxyuridine were determined after a 72-h exposure to concentrations of 2.5, 5 and 10 μg/ml dichlorvos (DDVP). A decrease occurred in lymphocytes and increase in fetal fibroblasts with increasing concentrations of DDVP. While differences were statistically significant (0.05 > P > 0.01), they were insufficient to be of biological significance.

Effects of dichlorvos (DDVP) inhalation on the activity of acetylcholinesterase in the bronchial tissue of rats.

The experiments presented here deal with the effects of the inhalation of dichlorvos [dimethyl-(2,2 dichlorvinyl)-phosphate, DDVP] vapor on acetylcholinesterase (ACHE) activity in rat bronchial tissue. Exposure to DDVP concentrations of 0.8 and 1.8 micrograms/l for 3 days reduced ACHE activity in the bronchial tissue (62.8 +/- 0.8 and 51.6 +/- 1.6% of the control), but did not elicit any changes in blood ACHE activity (101 +/- 4.5% of the control each). Higher concentrations (4.3 micrograms/l) induced a decline in ACHE activity also in the blood (38.2 +/- 1.1% of the control). In the histochemical preparations used to demonstrate ACHE activity in bronchial tissue (thiolacetic acid method), a staining of the bronchial glands and smooth muscles characteristic of the enzyme activity was strongly reduced after exposure of the animals to even the lowest dose applied (0.2 microgram/l). The question of whether localized inhibition of ACHE in the bronchial tissue might cause increases in airway resistance due to activation of a broncho-bronchial reflex is discussed. This efferent cholinergic mechanism has been found to be at least partly responsible for maintenance of bronchospasm and hypersecretion in chronic obstructive diseases of the respiratory system.