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Moutinho MF, de Almeida EA, Espíndola ELG, Daam MA, Schiesari L. Herbicides employed in sugarcane plantations have lethal and sublethal effects to larval Boana pardalis (Amphibia, Hylidae). ECOTOXICOLOGY (LONDON, ENGLAND) 2020; 29:1043-1051. [PMID: 32405782 DOI: 10.1007/s10646-020-02226-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 04/27/2020] [Indexed: 06/11/2023]
Abstract
The increasing demand for biofuels favored the expansion of sugarcane and, as a consequence, in the consumption of pesticides in Brazil. Amphibians are subject to pesticide exposure for occurring in or around sugarcane fields, and for breeding at the onset of the rainy season when pesticide consumption is common. We tested the hypothesis that herbicides used in sugarcane crops, although employed for weed control and manipulated at doses recommended by the manufacturers, can cause lethal and sublethal effects on amphibian larvae. Boana pardalis was exposed to glyphosate, ametryn, 2,4-D, metribuzin and acetochlor which account to up to 2/3 of the volume of herbicides employed in sugarcane production. High mortality was observed following prolonged exposure to ametryn (76%), acetochlor (68%) and glyphosate (15%); ametryn in addition significantly reduced activity rates and slowed developmental and growth rates. AChE activity was surprisingly stimulated by glyphosate, ametryn and 2,4-D, and GST activity by ametryn and acetochlor. Some of these sublethal effects, including the decrease in activity, growth and developmental rates, may have important consequences for individual performance for extending the larval period, and hence the risk of dessication, in the temporary and semi-permanent ponds where the species develops. Future studies should seek additional realism towards a risk analysis of the environmental contamination by herbicides through experiments manipulating not only active ingredients but also commercial formulations, as well as interactions among contaminants and other environmental stressors across the entire life cycle of native amphibian species.
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Affiliation(s)
- Mariana F Moutinho
- Programa de Pós-Graduação em Ecologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil
| | - Eduardo A de Almeida
- Instituto de Biociências, Letras e Ciências Exatas, Universidade Estadual Paulista, São José do Rio Preto, Brazil
- Fundação Universidade Regional de Blumenau, Blumenau, Brazil
| | - Evaldo L G Espíndola
- Centro de Recursos Hídricos e Ecologia Aplicada, Escola de Engenharia de São Carlos, Universidade de São Paulo, São Paulo, Brazil
| | - Michiel A Daam
- Departamento de Ciências Ambientais e Engenharia, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Lisboa, Portugal
| | - Luis Schiesari
- Escola de Artes, Ciências e Humanidades, Universidade de São Paulo, Avenida Arlindo Béttio 1000, São Paulo, 03828-000, Brazil.
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Dehnert GK, Karasov WH, Wolman MA. 2,4-Dichlorophenoxyacetic acid containing herbicide impairs essential visually guided behaviors of larval fish. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2019; 209:1-12. [PMID: 30684730 DOI: 10.1016/j.aquatox.2019.01.015] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2018] [Revised: 01/15/2019] [Accepted: 01/17/2019] [Indexed: 06/09/2023]
Abstract
Aquatic herbicides are used worldwide to eradicate nuisance and invasive plants despite limited knowledge of their toxicity to non-target organisms. 2,4-Dichlorophenoxyacetic acid (2,4-D) is a common active ingredient in commercial herbicide formulations, which triggers plant cell death by mimicking the plant-specific hormone auxin. Application practices of 2,4-D commercial herbicides typically coincide with yearly freshwater fish spawning periods. This practice exposes fish to xenobiotics at their vulnerable larval stages. The full impacts of 2,4-D on larval fish remains poorly understood, and hence, whether it may alter larval survival, larval behavior, fish populations, and ecosystem dynamics. In the present study, we exposed embryonic and larval zebrafish (Danio rerio) to the active ingredient 2,4-D (pure 2,4-D) or a 2,4-D containing commercial herbicide DMA4®IVM (DMA4) and evaluated morphology, survival, behavior, and nervous system function. At 2,4-D concentrations producing no overt morphological defects during embryonic or early larval stages, we observed reduced survival throughout a 21-day larval assay (4-8 ppm DMA4 and 0.75-4 ppm pure 2,4-D). Notably, prey capture, a behavior essential to survival, was reduced in 2,4-D-exposed larval zebrafish (4-8 ppm DMA4 and 0.75-4 ppm pure 2,4-D) and yellow perch (Perca flavescens) (4-20 ppm DMA4). In zebrafish, 8 ppm DMA4 exposure reduced prey capture when exposure was restricted to the period of visual system development. Consistent with these results, larval zebrafish exposed to 8 ppm DMA4 showed reduced neural activity within the optic tectum following prey exposure. Together, our results suggest that 2,4-D alters the development and function of neural circuits underlying vision of larval fish, and thereby reduces visually guided behaviors required for survival.
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Affiliation(s)
- Gavin K Dehnert
- Department of Integrative Biology, University of Wisconsin - Madison, Madison, WI, USA
| | - William H Karasov
- Department of Forest and Wildlife Ecology, University of Wisconsin - Madison, Madison, WI, USA
| | - Marc A Wolman
- Department of Integrative Biology, University of Wisconsin - Madison, Madison, WI, USA.
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Lushchak VI, Matviishyn TM, Husak VV, Storey JM, Storey KB. Pesticide toxicity: a mechanistic approach. EXCLI JOURNAL 2018; 17:1101-1136. [PMID: 30564086 PMCID: PMC6295629 DOI: 10.17179/excli2018-1710] [Citation(s) in RCA: 92] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Accepted: 10/24/2018] [Indexed: 12/04/2022]
Abstract
Pesticides are known for their high persistence and pervasiveness in the environment, and along with products of their biotransformation, they may remain in and interact with the environment and living organisms in multiple ways, according to their nature and chemical structure, dose and targets. In this review, the classifications of pesticides based on their nature, use, physical state, pathophysiological effects, and sources are discussed. The effects of these xenobiotics on the environment, their biotransformation in terms of bioaccumulation are highlighted with special focus on the molecular mechanisms deciphered to date. Basing on targeted organisms, most pesticides are classified as herbicides, fungicides, and insecticides. Herbicides are known as growth regulators, seedling growth inhibitors, photosynthesis inhibitors, inhibitors of amino acid and lipid biosynthesis, cell membrane disrupters, and pigment biosynthesis inhibitors, whereas fungicides include inhibitors of ergosterol biosynthesis, protein biosynthesis, and mitochondrial respiration. Insecticides mainly affect nerves and muscle, growth and development, and energy production. Studying the impact of pesticides and other related chemicals is of great interest to animal and human health risk assessment processes since potentially everyone can be exposed to these compounds which may cause many diseases, including metabolic syndrome, malnutrition, atherosclerosis, inflammation, pathogen invasion, nerve injury, and susceptibility to infectious diseases. Future studies should be directed to investigate influence of long term effects of low pesticide doses and to minimize or eliminate influence of pesticides on non-target living organisms, produce more specific pesticides and using modern technologies to decrease contamination of food and other goods by pesticides.
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Affiliation(s)
- Volodymyr I. Lushchak
- Department of Biochemistry and Biotechnology, Vasyl Stefanyk Precarpathian National University, 57 Shevchenko Str., Ivano-Frankivsk, 76018, Ukraine
| | - Tetiana M. Matviishyn
- Department of Biochemistry and Biotechnology, Vasyl Stefanyk Precarpathian National University, 57 Shevchenko Str., Ivano-Frankivsk, 76018, Ukraine
| | - Viktor V. Husak
- Department of Biochemistry and Biotechnology, Vasyl Stefanyk Precarpathian National University, 57 Shevchenko Str., Ivano-Frankivsk, 76018, Ukraine
| | - Janet M. Storey
- Institute of Biochemistry, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario K1S 5B6, Canada
| | - Kenneth B. Storey
- Institute of Biochemistry, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario K1S 5B6, Canada
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Munro IC, Carlo GL, Orr JC, Sund KG, Wilson RM, Kennepohl E, Lynch BS, Jablinske M. A Comprehensive, Integrated Review and Evaluation of the Scientific Evidence Relating to the Safety of the Herbicide 2,4-D. ACTA ACUST UNITED AC 2016. [DOI: 10.3109/10915819209141893] [Citation(s) in RCA: 88] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The safety of 2,4-D to farm and forestry workers, commercial applicators and the general public has been of continuing concern because certain epidemiological studies of groups potentially exposed to 2,4-D have suggested a relationship between 2,4-D use and increased risk of soft tissue sarcoma, Hodgkin's disease or non-Hodgkin's lymphoma. This review on 2,4-D is unique in that the approach taken was to integrate data from worker exposure studies, whole animals, metabolic and other relevant laboratory studies with the epidemiological findings to assess the extent to which there is scientific support for the hypothesis that 2,4-D exposure is associated with any increased risk of human cancer. The case-control epidemiological studies that have been the source of the cancer risk hypothesis are inconclusive. Problems in assessing exposure based on patients' memories make these studies difficult to interpret. Cohort studies of exposed workers do not generally support the specific hypothesis that 2,4-D causes cancer. Taken together, the epidemiological studies provide, at best, only weak evidence of an association between 2,4-D and the risk of cancer. Importantly, the cancer hypothesis is not supported by other data. A critical evaluation of the exposure data indicates that exposure to 2,4-D in user groups is intermittent and much lower than the doses tested chronically in long-term animal studies that have not shown evidence of tumor induction. Moreover, the structure of 2,4-D does not suggest it would be a carcinogen. 2,4-D is a simple organic acid, that is largely excreted unchanged, and there is no evidence that it is metabolized to critically reactive metabolites or accumulates in tissues. This evidence is supported by a large body of negative studies on genotoxicity, which taken together with the metabolic studies, clearly indicates that 2,4-D is highly unlikely to be a genotoxic carcinogen. Furthermore, 2,4-D has no known hormonal activity and does not induce proliferative changes in any tissue or organ, indicating that it does not possess any of the characteristics of non-genotoxic animal carcinogens. Thus the available mechanistic studies provide no plausible basis for a hypothesis of carcinogenicity. In this review, data relating to potential neurotoxicity, immunotoxicity and reproductive toxicity also were evaluated. There is no evidence that 2,4-D adversely affects the immune system and neurotoxic and reproductive effects only have been associated with high toxic doses that would not be encountered by 2,4-D users. Historical exposures to 2,4-D by user groups, particularly farmers, forestry workers and commercial applicators, would be higher than those sustained under present rigorous standards for application which involve the use of protective clothing and other measures to reduce exposure. Proposed label changes indicate that in the future exposures will be even further reduced. Viewed in this context, the available data indicate that the potential public health impact of 2,4-D, including the risk of human cancer, was negligible in the past and would be expected to be even smaller in the present and future.
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Affiliation(s)
- Ian C. Munro
- CanTox Inc., 2233 Argentia Road, Suite 308, Mississauga, Ontario, Canada L5N 2X7
| | - George L. Carlo
- Health & Environmental Sciences Group Ltd., 1513 Sixteenth Street NW, Washington, DC 20036
| | - Joan C. Orr
- CanTox Inc., 2233 Argentia Road, Suite 308, Mississauga, Ontario, Canada L5N 2X7
| | - Kelly G. Sund
- Health & Environmental Sciences Group Ltd., 1513 Sixteenth Street NW, Washington, DC 20036
| | - Ross M. Wilson
- CanTox Inc., 2233 Argentia Road, Suite 308, Mississauga, Ontario, Canada L5N 2X7
| | - Elke Kennepohl
- CanTox Inc., 2233 Argentia Road, Suite 308, Mississauga, Ontario, Canada L5N 2X7
| | - Barry S. Lynch
- CanTox Inc., 2233 Argentia Road, Suite 308, Mississauga, Ontario, Canada L5N 2X7
| | - Maureen Jablinske
- Health & Environmental Sciences Group Ltd., 1513 Sixteenth Street NW, Washington, DC 20036
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Matviishyn TM, Kubrak OI, Husak VV, Storey KB, Lushchak VI. Tissue-specific induction of oxidative stress in goldfish by 2,4-dichlorophenoxyacetic acid: mild in brain and moderate in liver and kidney. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2014; 37:861-869. [PMID: 24657358 DOI: 10.1016/j.etap.2014.02.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2013] [Revised: 12/20/2013] [Accepted: 02/10/2014] [Indexed: 06/03/2023]
Abstract
This study investigated the effects of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) on free radical-related processes in tissues of goldfish given 96 h exposures to 1, 10 or 100 mg/L of 2,4-D as well as 96 h recovery from the 100 mg/L treatment. In liver, 2,4-D exposure increased levels of protein carbonyls and lipid peroxides by 36-53% and 24-43%, respectively, but both parameters reverted during recovery, whereas in brain glutathione status improved in response to 2,4-D. Lipid peroxide content in kidney was enhanced by 40-43% after exposure to 2,4-D with a decrease during recovery. Exposure to 2,4-D also reduced liver acetylcholinesterase activity by 31-41%. The treatment increased catalase activity in brain, but returned it to initial levels after recovery. In kidney, exposure to 100 mg/L of 2,4-D caused a 33% decrease of superoxide dismutase activity. Thus, goldfish exposure to 2,4-D induced moderate oxidative stress in liver and kidney and mild oxidative stress in brain.
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Affiliation(s)
- Tetiana M Matviishyn
- Department of Biochemistry and Biotechnology, Precarpathian National University named after Vassyl Stefanyk, 57 Shevchenko Str., Ivano-Frankivsk 76025, Ukraine
| | - Olga I Kubrak
- Department of Biochemistry and Biotechnology, Precarpathian National University named after Vassyl Stefanyk, 57 Shevchenko Str., Ivano-Frankivsk 76025, Ukraine
| | - Viktor V Husak
- Department of Biochemistry and Biotechnology, Precarpathian National University named after Vassyl Stefanyk, 57 Shevchenko Str., Ivano-Frankivsk 76025, Ukraine
| | - Kenneth B Storey
- Institute of Biochemistry, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario K1S 5B6, Canada
| | - Volodymyr I Lushchak
- Department of Biochemistry and Biotechnology, Precarpathian National University named after Vassyl Stefanyk, 57 Shevchenko Str., Ivano-Frankivsk 76025, Ukraine.
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Papaefthimiou C, Pavlidou V, Gregorc A, Theophilidis G. The action of 2,4-Dichlorophenoxyacetic acid on the isolated heart of insect and amphibia. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2002; 11:127-140. [PMID: 21782594 DOI: 10.1016/s1382-6689(01)00113-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2001] [Revised: 11/14/2001] [Accepted: 11/15/2001] [Indexed: 05/31/2023]
Abstract
The action of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) on the isolated heart of the frog (Rana ridibunda) and two insects, the honeybee (Apis mellifera macedonica) and the beetle (Tenebrio molitor), was investigated using basic electrophysiological methods. The results of this study showed that a concentration of 1 μM 2,4-D was required to reduce the force and the frequency of the isolated heart of the honeybee to about 70% of the initial contraction in less than 20 min. To cause the same effects on the atria of the frog, 45 μM 2,4-D was required and on the isolated heart of the beetle, over 1000 μM of 2,4-D. The presence of an extensive system of gap junctions found in the honeybee is most probably the cause of the unusual sensitivity of its heart to 2,4-D, compared with the heart of the beetle, where no gap junctions were identified.
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Affiliation(s)
- Chrisovalantis Papaefthimiou
- Department of Zoology, Laboratory of Animal Physiology, School of Biology, Aristotle University, Thessaloniki 54006, Greek Macedonia, Greece
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Dickow LM, Podell M, Gerken DF. Clinical effects and plasma concentration determination after 2,4-dichlorophenoxyacetic acid 200 mg/kg administration in the dog. JOURNAL OF TOXICOLOGY. CLINICAL TOXICOLOGY 2001; 38:747-53. [PMID: 11192461 DOI: 10.1081/clt-100102387] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
OBJECTIVE To investigate the clinical effects and to determine the 2,4-dichlorophenoxyacetic acid plasma concentrations after a dose of twice the reported LD50 (100 mg/kg) was administered orally to dogs. Investigation included electromyographic evaluations and biochemical parameter determinations, as well as observable clinical signs. METHODS Six beagle dogs were administered 2,4-dichlorophenoxyacetic acid 200 mg/kg orally. Dogs were monitored for the development of clinical signs and were anesthetized at 24 hours for needle electromyography. Blood was collected pre- and 24-hours postadministration. Plasma was analyzed for total and unbound 2,4-dichlorophenoxyacetic acid by high-performance liquid chromatography with fluorescence detection. Serum was submitted for clinical chemistry parameter analysis. Statistical analyses of the chemistry parameters were performed using paired t-tests. RESULTS All 6 dogs survived after oral administration of twice the reported LD50. Clinical signs observed were vomiting in 33% and diarrhea in 100% of the dogs. No gait abnormalities were seen in awake dogs. Electromyographic findings revealed predominantly insertional myotonia with 1 dog having spontaneous fibrillations. Decreases from baseline measurements were seen in serum calcium, potassium, and total bilirubin. The mean total and unbound plasma 2,4-dichlorophenoxyacetic acid concentrations were 511 mg/L and 129 mg/L, respectively. CONCLUSIONS This study demonstrates that the beagle dog is less sensitive to the acute effects of 2,4-dichlorophenoxyacetic acid than previously reported. The main clinical effects seen after oral administration of twice the reported LD50 were vomiting and diarrhea. Total and unbound plasma 2,4-dichlorophenoxyacetic acid concentrations may be a useful indicator of toxicity.
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Affiliation(s)
- L M Dickow
- The Ohio State University, College of Veterinary Medicine, Columbus, USA
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Pereira LF, Campello AP, Silveira O. Effect of Tordon 2,4-D 64/240 triethanolamine BR on the energy metabolism of rat liver mitochondria. J Appl Toxicol 1994; 14:21-6. [PMID: 8157865 DOI: 10.1002/jat.2550140105] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Tordon herbicide, which is a mixture of 4-amino-3,5,6-trichloropicolinic acid (picloram) and 2,4-dichlorophenoxyacetic acid (2,4-D), depresses the phosphorylation efficiency of the rat liver mitochondria, as inferred from the decrease of the respiratory control coefficient and the ADP/O ratios when NAD(+)-dependent substrates were used; NADH oxidase and NADH cytochrome c reductase were also inhibited, without any effect on the other enzymatic complexes of the respiratory chain. Tordon (66.2 nmol picloram + 270 nmol 2,4-D mg-1 protein) affected the amplitude of swelling induced by glutamate, succinate, (N,N,N',N'-tetramethyl-p-phenyldiamine + sodium ascorbate and ATP. These results characterize an interaction of Tordon with complex I of the respiratory chain and also a partial collapse of the proton motive force of the mitochondrial inner membrane without affecting its elasticity.
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Affiliation(s)
- L F Pereira
- Departamento de Bioquímica, Universidade Federal do Paraná, Curitiba, PR Brasil
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Kuntz DJ, Rao NG, Berg IE, Khattree R, Chaturvedi AK. Toxicity of mixtures of parathion, toxaphene and/or 2,4-D in mice. J Appl Toxicol 1990; 10:257-66. [PMID: 2391407 DOI: 10.1002/jat.2550100406] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The toxicity of the mixtures of parathion (PA), toxaphene (TOX) and/or 2,4-dichlorophenoxyacetic acid (2,4-D) was studied in ICR male mice (21-24 g) by oral intubation, in corn oil, daily for up to 14 days. On Day 15, the exposure was discontinued, and animals were monitored for an additional period of 7 days for the possible reversibility of the toxicity. The body weight gain decreased with the mixtures, as well as with the individual agricultural chemicals (ACs), during the 14-day period. The cholinesterase (ChE) activity in the serum and brain was inhibited in the animals of the groups of PA (1-10 mg kg-1) and PA (5 mg kg-1)-containing mixtures. TOX (50-200 mg kg-1) caused initial inhibitory effects of 20-65% on the serum ChE (Day 1) before producing increases of 53-64% in the enzyme activity by Day 15, with little effects on the brain ChE levels. 2,4-D (50-200 mg kg-1) resulted in significantly elevated levels of the serum ChE, with substantial decreased in the brain ChE activity. The serum glutamic pyruvic transaminase level was up (38-630%) in TOX (50 mg kg-1), 2,4-D (50 mg kg-1) or their mixture group. No pathological changes at the light microscopic level in the brain and liver were noticed. TOX and TOX-containing mixtures significantly increased the liver/body weight ratio and decreased the pentobarbital (60 mg kg-1, i.p., in saline)-induced sleep.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- D J Kuntz
- Department of Pharmaceutical Sciences/Toxicology, North Dakota State University College of Pharmacy, Fargo 58105
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Steiss JE, Braund KG, Clark EG. Neuromuscular effects of acute 2,4-dichlorophenoxyacetic acid (2,4-D) exposure in dogs. J Neurol Sci 1987; 78:295-301. [PMID: 3585404 DOI: 10.1016/0022-510x(87)90043-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
2,4-Dichlorophenoxyacetic acid (2,4-D) was administered once orally to adult female mongrel dogs at 0, 25, 50, 75, 100 or 125 mg/kg of body weight (n = 4 per group). Clinical neurological examinations, electromyography (EMG) and motor nerve conduction velocity measurements were carried out before exposure, and on days 1, 3, 7, 14, 21 and 28 post-exposure. On day 7, two dogs per group were killed. Samples of the medial and lateral plantar nerves were removed for teased fiber and semi-thin section analysis; samples of appendicular muscles were removed for histology and histochemistry. Necropsy included histopathological examination of the brain and spinal cord at multiple levels. Remaining dogs were killed on day 28 and their tissues were processed similarly. Transient generalized myotonic discharges were found in skeletal muscles of dogs receiving 50 mg/kg or more of 2,4-D. A few dogs in the higher dosage groups also had mild muscle stiffness, myotonic dimpling and/or lethargy, lasting up to 3 days post-exposure. Other parameters remained within normal limits.
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11
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Toyoshima E, Mayer RF, Max SR. Effects of 2,4-dichlorophenoxyacetic acid (2,4-D) on the contractile properties of reinnervated rat skeletal muscle. Exp Neurol 1985; 90:601-10. [PMID: 4065276 DOI: 10.1016/0014-4886(85)90158-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
2,4-Dichlorophenoxyacetic acid (2,4-D), a common herbicide, was administered to rats (100 mg/kg, i.p.) during 24 days to determine whether or not it is toxic to regenerating peripheral nerve and reinnervating muscle. The peroneal nerve was crushed 1 cm proximal to the extensor digitorum longus muscle and recordings made in vivo after 1 to 24 days. Functional reinnervation was observed by day 10 and recovery was similar in rats receiving 2,4-D or vehicle. Distal motor latencies and muscle action potentials returned toward normal during the 24 days in a similar manner in 2,4-D and controls. Isometric twitch tensions per muscle weight on indirect stimulation returned to intact values by 17 days, but in the 2,4-D animals they became larger (P less than 0.01) than controls by day 24. The twitch:tetanus ratios were increased at day 10 and returned toward normal values in the controls but remained increased (P less than 0.01) in the 2,4-D animals at 24 days. Similar results were obtained on direct muscle stimulation. The data suggest that 2,4-D is not toxic to nerve during regeneration or muscle reinnervation in the rat, but that it does affect both twitch and tetanus tensions suggesting proliferation as well as disruption of myofibrils.
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12
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Toyoshima E, Mayer RF, Max SR, Eccles C. 2,4-Dichlorophenoxyacetic acid (2,4-D) does not cause polyneuropathy in the rat. J Neurol Sci 1985; 70:225-9. [PMID: 2997403 DOI: 10.1016/0022-510x(85)90089-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
2,4-Dichlorophenoxyacetic acid (2,4-D), a component of Agent Orange, was injected intraperitoneally into adult male Fisher rats for 3-12 weeks. During the period of study gait and toe-spreading reflexes remained normal and distal motor latencies, motor and mixed nerve conduction velocities and amplitudes remained similar (P greater than 0.05) in animals receiving 2,4-D or vehicle. This study suggests that 2,4-D is not toxic to peripheral nerves in the rat.
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