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PubMed2002

Green fluorescent protein-labeled recombinant fluobody for detecting the picloram herbicide.

A green fluorescent protein-labeled fluobody was designed to develop a simple immunoassay method for detecting picloram herbicide in an environmental sample. The gfp gene was successfully inserted into the pSJF2 vector harboring the picloram-specific antibody fragment to yield pSJF2GFP. Picloram spiking in an environmental river sample could be indirectly detected by observing the fluorescence intensity value of the gfp-fluobody, exhibiting specific sensitivity to free picloram with an IC50 value of 50 ppb. Using the gfp-fluobody immunoassay avoids the enzyme-substrate reaction for calorimetric detection that is required in an enzyme-linked immunosorbent assay (ELISA).

Base Sequence↗
PubMed1970

Involvement of Ethylene in Picloram-induced Leaf Movement Response.

The relationship of root-applied 4-amino-3,5,6-trichloropicolinic acid (picloram) to ethylene production and the leaf movement response in honey mesquite (Prosopis juliflora [Swartz] DC. var. glandulosa [Torr.] Cockerell) and huisache (Acacia farnesiana [L.] Willd.) was studied in detail. The threshold and saturation levels of exogenous ethylene and root-applied picloram necessary to inhibit leaf movement were determined. Internal levels of ethylene in excess of those necessary to saturate the leaf movement inhibition response occurred in tops of treated plants before and after symptom expression. These internal levels of ethylene, while averages for the entire plant tops, probably occur at the specific site of action and thus account for the action of picloram in inhibition of leaf movement and related responses. Quantitative differences in the leaf movement response of both species to picloram and ethylene were observed. In huisache alone, a very small change in ethylene levels was necessary to produce a major blockage of the leaf movement response, suggesting that the gas may have a natural function in that species.

Journal Article↗
PubMed1986

Acute, 14-day repeated dosing, and 90-day subchronic toxicity studies of potassium picloram.

Potassium picloram was administered either by gavage (acute studies) or in drinking water to male and female Sprague-Dawley-derived rats (14-day and 90-day studies). The acute oral LD50 was 950 mg/kg (812-1120) for males and 686 mg/kg (599-786) for females. Depression, prostration, ataxia, tremors, and convulsions preceded death. There were no consistent biologically significant compound-related effects in rats that received 60, 190, 600 mg potassium picloram/kg/day for 14 days. In the subchronic study, rats received 60, 190, 600, or 1070 mg potassium picloram/kg/day in drinking water for 90 consecutive days. There were only 4 male and 2 female survivors out of 20 rats of each sex at the 1070 mg/kg dose and 16 male and 18 female survivors at the 600 mg/kg dose. Mortality was dose dependent. Administration of picloram appeared to exacerbate renal and hepatic lesions commonly noted in rats of this age. For example, at levels up to 1070 mg/kg mild lesions in the kidney of treated rats, especially in males at 600 mg/kg, were noted. Also noted were an increased incidence of mononuclear liver foci in male rats that received 190 and 600 mg/kg and an increased severity of mononuclear liver foci in females that received 600 mg/kg. There were no other consistent biologically significant compound-related effects. No specific organ site toxicity could be identified in these studies. Toxicity from exposure to picloram in drinking water is apparently low.

Animals↗
PubMed1985

Teratological evaluation of picloram potassium salt in rabbits.

The embryotoxic and teratogenic potential of orally administered picloram potassium salt was evaluated in New Zealand white rabbits. Artificially inseminated rabbits were given 0, 40, 200 or 400 mg picloram acid equivalent/kg body weight/day in the form of picloram potassium salt in aqueous solution on days 6 to 18 of gestation. The foetuses were removed for examination on day 29 of gestation. Transient weight loss was observed among rabbits given 200 or 400 mg/kg/day of the test material, though the total weight gain of the treated groups during gestation was comparable to that of controls. A few isolated, sporadic cases of foetal malformations were observed in the dosed groups, but there was no indication of a dose-related embryotoxic or teratogenic response to treatment.

Abnormalities, Drug-Induced↗
PubMed1991

Effects of 2,4-dichlorophenoxyacetic acid and picloram on biotransformation, peroxisomal and serum enzyme activities in channel catfish (Ictalurus punctatus).

Channel catfish (Ictalurus punctatus) exposed to a mixture of picloram and 2,4-dichlorophenoxyacetic acid (2,4-D) for 10 days displayed increased activities of hepatic ethoxyresorufin O-deethylase (EROD), decreased serum chloride concentrations and decreased liver/body weight ratios. These changes were not observed in fish exposed to either compound alone. Neither compound, nor their mixture, increased hepatic peroxisomal catalase or lauroyl CoA oxidase activities. The results of this study indicate that 10-day exposure of 2,4-D or picloram does not induce peroxisomal enzymes in channel catfish; however, exposure to a mixture of 2,4-D and picloram may cause physiological effects to catfish not observed with either compound alone.

2,4-Dichlorophenoxyacetic Acid↗
PubMed2005

Heterogeneous photocatalytic degradation of picloram, dicamba, and floumeturon in aqueous suspensions of titanium dioxide.

Heterogeneous photocatalytic degradation of three-selected herbicide derivatives: (1) picloram (4-Amino-3,5,6-trichloropyridine-2-carboxylic acid, (2) dicamba (2-Methoxy-3,6-dichlorobenzoic acid, and (3) floumeturon (N,N-Dimethyl-N-[3-(trifluoromethyl)phenyl]-urea) has been investigated in aqueous suspensions of titanium dioxide under a variety of conditions. The degradation was studied by monitoring the change in substrate concentration employing UV spectroscopic technique and decrease in total organic carbon (TOC) content as a function of irradiation time under a variety of conditions. The degradation of the herbicide was studied under different conditions such as pH, catalyst concentration, substrate concentration, different types of TiO2, and in the presence of electron acceptors such as hydrogen peroxide (H2O2), potassium bromate (KBrO3), and ammonium persulphate (NH4)2S2O8 besides molecular oxygen. The degradation rates were found to be strongly influenced by all the above parameters. The photocatalyst Degussa P25 was found to be more efficient as compared with other photocatalysts in the case of dicamba (2) and floumeturon (3), whereas Hombikat UV100 was found to be better for the degradation of picloram (1). The herbicide picloram (1) was found to degrade faster as compared to dicamba (2) and floumeturon (3). The degradation products were analyzed by gas chromatography-mass spectrometry (GC/MS) technique, and plausible mechanisms for the formation of products have been proposed.

Dicamba↗
PubMed2002

A study of the potential for a herbicide formulation containing 2,4-d and picloram to cause male-mediated developmental toxicity in rats.

Male Vietnam veterans have repeatedly expressed concern that exposure to herbicides in Vietnam may have caused birth defects in their offspring. The second most used herbicide was a mixture of 2,4-D and picloram called Agent White. This study is an investigation into the possible male-mediated reproductive toxicology of this herbicide. Male rats were gavaged for 5 days per week for 9 weeks with a mixture of 2,4-D and picloram called Tordon 75D(R) (the Australian derivative of Agent White). Three doses were tested; the high dose was considered the maximum tolerated dose. Each male was mated with two untreated females during weeks 2 and 3, 4 and 5, and 8 and 9 of treatment, and with four untreated females after an 11-week recovery period. Negative controls were males dosed with distilled water, and positive controls were males dosed with cyclophosphamide at 5.1 mg/kg/day. All mated females were killed on day 20 of gestation, and the fetuses were weighed and examined for either structural malformations or skeletal development. Litter size, fetal weight, and malformation rate were all unaffected by treatment. The cyclophosphamide positive controls showed the expected large increase in postimplantation loss. In general, within the limitations of the power of the study, the results did not show any evidence that exposure to a herbicide formulation containing 2,4-D and picloram is likely to cause male-mediated birth defects or other adverse reproductive outcomes.

2,4-Dichlorophenoxyacetic Acid↗
PubMedDate not supplied

Picloram and napropamide sorption as affected by polymer addition and salt concentration.

Polymer application to soil is a growing practice to improve soil physical properties and reduce soil erosion. Polymer addition can potentially influence herbicide and pesticide sorption in soil. The one-point distribution coefficient Kd values of two herbicides in the absence and presence of each of 10 polymers (7 polyacrylamides and 3 polysaccharides) were determined by the batch equilibrium method. The results showed that nonionic napropamide [2-(alpha-naphthoxy)-N,N-diethyl propionamide] sorption was essentially unaffected by the presence of any of the polymers. The influence of polymers on anionic picloram (4-amino-3,5,6-trichloropicolinic acid) sorption depends on the charge characteristics of polymers and salt concentrations in the solution. Electrostatic interaction and competition for sorption sites are two primary underlying mechanisms for the polymer influence. At low salt concentration, the increased picloram sorption in the presence of both cationic and anionic polymers was attributed to different electrostatic interactions and polymer partitioning between soil and solution phases. At high salt levels, the presence of polymers had either no influence or a slightly negative influence on the picloram sorption, which was attributed to competition for sorption sites. In field conditions, it is more likely that polymers have no or a slightly negative influence on herbicide sorption due to the presence of salts.

Adsorption↗
PubMed2001

Degradation of benomyl, picloram, and dicamba in a conical apparatus by zero-valent iron powder.

Reduction of some pesticides (benomyl, picloram, and dicamba) was studied in an aerobic batch conical pilot system to investigate the disappearance of these pesticides on contact with iron powder (20 g/l, 325-mesh). Aqueous buffered solutions of the compounds were added to the system followed by zero-valent iron powder (ZVIP), and the decline in the pesticide concentrations was monitored over time. HPLC analyses show a complete disappearance of picloram (1.20 mg/l) after 20 min of reaction. Benomyl (1.00 mg/l) and dicamba (1.25 mg/l) disappear after 25 and 40 min, respectively. The t50 values ranged from 3 to 5.5 min, and were about slightly less than the t1/2 values reported when the log of the relative HPLC peak area was plotted versus time, where the relative peak area was calculated by dividing the measured peak area by the initial peak area. Pathways for the degradation of the studied pesticides by ZVIP are proposed.

Benomyl↗
PubMedDate not supplied

Testicular changes induced by chronic exposure to the herbicide formulation, Tordon 75D (2,4-dichlorophenoxyacetic acid and picloram) in rats.

The second most used herbicide in the Vietnam war was Agent White, which contained the active components 2,4-dichlorophenoxyacetic acid (2,4-D) and 4-amino-3,5,6-trichloropicolinic acid (picloram). The herbicide formulation Tordon 75D is similar in terms of its active components to Agent White and is currently used by the agricultural industry in Australia. As part of an investigation into the possible adverse effects of this herbicide on male reproductive performance, groups of five male rats were gavaged 5 days a week for 9 weeks with either 0.125 ml/kg (low dose), 0.25 ml/kg (middle dose), or 0.5 ml/kg (high dose) Tordon 75D or water (controls). The high dose corresponded to 150 mg/kg body weight 2,4-D and 37.5 mg/kg picloram acid equivalents. At the end of the treatment period, the testes were collected, weighed, and examined histologically and blood samples were taken to determine serum testosterone. Groups of high dose animals were also examined after 1, 2, and 4 weeks treatment. The 9 weeks treatment with Tordon 75D caused severe reduction in testicular weight in some high dose animals. Histologically, the small testes showed shrunken tubules with germ cell depletion. This damage was still evident in some rats following a 21 weeks recovery period suggesting that the testicular damage was permanent. Testicular damage was not due to endocrine disruption as there were no significant differences in the serum concentration of testosterone in control animals compared to Tordon 75D-treated animals. Blood levels associated with the high dose were determined in a separate study and were much higher than those likely to be obtained by occupational exposure to this herbicide.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1987

Dietary toxicity of picloram herbicide in rats.

The toxicity of orally administered technical-grade picloram was evaluated in male and female Fischer 344 rats. Dietary dose levels were up to 2000 mg/kg body weight (bw) X d for 2 wk, 500 mg/kg bw X d for 13 wk, or 200 mg/kg bw X d for 12 mo. Routine indices of toxicity were evaluated at all of the respective time periods. Body weight, food consumption, clinical chemistries, urinalyses, and hematological determinations were considered unaffected by treatment. The only treatment-related effect, regardless of the duration of exposure, was in the liver of both male and female rats. This was generally manifested as an increase in the liver-to-body weight ratio and slight hypertrophy and pallor of the centrilobular hepatocytes. These effects were consistently present in rats receiving 1000 mg/kg bw X d for 2 wk, 300 mg/kg bw X d for 13 wk, or 200 mg/kg bw X d for 6 or 12 mo. Similar effects were marginally evident for rats receiving 500 mg/kg bw X d for 2 wk, 150 mg/kg bw X d for 13 wk, or 60 mg/kg bw X d for 6 or 12 mo. At 60 mg/kg bw X d, the effects were not progressive from 6 to 12 mo. The no-observable-effect level (NOEL) was 20 mg/kg bw X d for male and female rats fed picloram for 12 mo.

Administration, Oral↗
PubMedDate not supplied

Anionic polyacrylamide effects on soil sorption and desorption of metolachlor, atrazine, 2,4-D, and picloram.

Polyacrylamide (PAM) treatment of irrigation water is a growing conservation technology in irrigated agriculture in recent years. There is a concern regarding the environmental impact of PAM after its application. The effects of anionic PAM on the sorption characteristics of four widely used herbicides (metolachlor, atrazine, 2,4-D, and picloram) on two natural soils were assessed in batch equilibrium experiments. Results showed that PAM treatment kinetically reduced the sorption rate of all herbicides, possibly due to the slower diffusion of herbicide molecules into interior sorption sites of soil particles that were covered and/or cemented together by PAM. The equilibrium sorption and desorption amounts of nonionic herbicides (metolachlor and atrazine) were essentially unaffected by anionic PAM, even under a high PAM application rate, while the sorption amounts of anionic herbicides (2,4-D and picloram) were slightly decreased and their desorption amounts increased little. The impact mechanisms of PAM were related to the molecular characteristics of PAM and herbicides. The negative effects of PAM on the sorption of anionic herbicides are possibly caused by the enhancement of electrostatic repulsion by presorbed anionic PAM and competition for sorption sites. However, steric hindrance of the large PAM molecule weakens its influence on herbicide sorption on interior sorption sites of soil particles, which probably leads to the small interference on herbicide sorption, even under high application rates.

2,4-Dichlorophenoxyacetic Acid↗
PubMedDate not supplied

Gas chromatographic determination of picloram in fish.

A simple method for determining picloram in fish is described. The sample is homogenized with ethyl acetate, acidified with 1N HCl, and extracted twice more with ethyl acetate. Ethyl acetate fractions are pooled, derivatized with diazomethane, cleaned up by column chromatography, and analyzed by electron capture gas chromatography. Rainbow trout exposed to 14C-picloram were used to evaluate the efficiency of 2 methods of extraction and to provide data on the rate of uptake and the bioconcentration factor. The detection limit for this method is 5 ng/g, using a 4 g sample.

Animals↗
PubMed1993

Reductive dechlorination of the nitrogen heterocyclic herbicide picloram.

The anaerobic biodegradation of picloram (3,5,6-trichloro-4-amino-2-pyridinecarboxylic acid) in freshwater sediment was favored under methanogenic conditions but not when sulfate or nitrate was available as a terminal electron acceptor. Under the former conditions, more than 85% of the parent substrate (340 muM) was removed from nonsterile incubations in 30 days, following a 50-day acclimation period. Concomitant with substrate decay, an intermediate transiently accumulated in the sediment slurries. By liquid chromatography-mass spectrometry, the intermediate was identified as an isomer of dichloro-4-amino-2-pyridinecarboxylic acid. Proton nuclear magnetic resonance evidence suggested that a chlorine was reductively removed from the parent substrate at the position meta to the nitrogen heteroatom. Upon continued incubation, the dechlorinated product was transformed into an unidentified compound which accumulated and resisted further decay. The addition of sulfate or bromoethanesulfonic acid to sediment slurries inhibited picloram dehalogenation, but molybdate reversed the inhibitory effect of sulfate on pesticide metabolism. These findings help clarify the fate of a halogenated nitrogen heterocyclic herbicide in anaerobic environments.

Journal Article↗
PubMed1978

Hatching success and early performance of chicks from eggs sprayed with 2,4-D,2,4,5-T and picloram at various stages of embryonic development.

Aqueous solutions of 2,4-D, 2,4-5-T and picloram were sprayed on hens' eggs at 10x normal rate (11.2 kg/ha). Eggs used were stored prior to incubation over a 24 day period and application on each age egg occurred at the start as well as 4 and 18 days after the onset of embryonic development. No adverse effects on any parameter used to evaluate either incubation or subsequent live performance could be attributed to either spray treatment or embryonic age when applied. Although extended preincubation storage significantly reduced hatching success, it was independent of herbicide contact and germ stage when contaminated. Chicks derived from eggs stored 1--2 and 23--24 days before incubation performed comparably and were uninfluenced by all treatments during incubation.

2,4,5-Trichlorophenoxyacetic Acid↗
PubMed2004

Adsorption, separation, and thermochemical data on the herbicide picloram anchored on silica gel and its cation interaction behavior.

The herbicide 4-amino-3,5,6-trichloropicolinic acid (picloram), chemically anchored on silica gel surface (SiPi), has been used for divalent cation M(2+) (Cu, Ni, Zn, and Cd) adsorption from aqueous solutions at room temperature. The series of adsorption isotherms were adjusted to a modified Langmuir equation from data obtained by suspending the solid with MCl(2) solutions, which gave the maximum number of moles adsorbed as 9.27, 7.54, 5.12, and 1.54 x 10(-4) molg(-1) for Cu, Ni, Zn, and Cd, respectively. The minimum cation retention capacity from aqueous solution was observed at pH 1, increasing up to pH 4, and was maintained constant at pH 5 for all cations. The maximum retention capacity followed the sequence Cu>Ni>Zn>Cd. SiPi-M (Cu, Ni) interactions presented endothermic enthalpic values, which contrasted with exothermic values for SiPi-M (Zn, Cd) interactions. The anchored herbicide was also used to separate the cations when loaded in a column. Their resolutions were determined as the ability of this surface to separate cations, to give Rs(Cd-Zn)=2.33, Rs(Cd-Ni)=3.16, Rs(Cd-Cu)=7.21, Rs(Zn-Ni)=1.31, Rs(Zn-Cu)=2.55, and Rs(Ni-Cu)=0.72.

Adsorption↗
PubMed1976

[Ultrastructural changes caused by a herbicide, picloram in technical dosage (70,4%), in a plankton alga, Dunaliella bioculta (Volvocales)].

A study on the effects of an auxin-like herbicide-picloram (techinical grade 70,4%)--was carried out on a planktonic green Alga, Dunaliella bioculata. At concentrations about 250 mug/ml, the cellular growth decreases while at 400 mug/ml it is completely inhibited. Concentrations of 250-300 mug/ml induce the fall of flagella and an increase of the cellular volume; granulous inclusions-nuclear bodies-are observed inside the nucleus; Golgi apparatus is abnormally developed. The vascuolar system is particularly disturbed: its volume increases; vesicles, cytoplasmic and membrane fragments and osmiophilic granulations can be observed inside vacuoles under the electron microscope.

Cell Division↗