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Background: Toxicokinetics and recovery studies of dicamba dimethyl amine salt (DDAS) were conducted to obtain more information about its toxicity and tissue retention in farm animals., Results: The minimum oral toxic dose level of DDAS was determined as 1400 mg kg(-1) body weight. In the toxicokinetic study, blood DDAS concentration of 55.6 +/- 0.59 microg mL(-1) (mean +/- standard error) was detected at 0.08 h, which peaked to 102.3 +/- 5.03 microg mL(-1) at 0.25 h, and declined to a minimum of 4.1 +/- 0.06 microg mL(-1) at 36 h. In recovery studies, DDAS concentration in urine began to increase significantly (P < 0.05) from 12 h, peaked at 24 h and declined from 48 h onwards. Maximum excretion through faeces was at 24 h and was complete by 144 h. The residual level in tissues decreased significantly (P < 0.05) on day 7 as compared to day 4. In histopathological studies, cellular alterations in lungs, liver, kidney, adrenal gland and spleen were found., Conclusion: DDAS persists in the body for a shorter period and its major excretory route is through urine. DDAS has lower affinity to accumulate in tissues, and intensity of cellular alterations is not severe after single-dose oral administration., ((c) 2009 Society of Chemical Industry.)

Epidemiologic studies designed to assess the chronic effects of pesticides are limited by inadequate measurements of exposures. Although cohort studies have been initiated to evaluate the effects of 2,4-dichlorophenoxyacetic acid (2,4-D) and other pesticides in professional turf applicators, they may have limited power to detect significant health risks and may be subject to bias from exposure measurement error. In this study, the doses of 2,4-D, mecoprop [2-(4-chloro-2 methylphenoxy) propionic acid, MCPP] and dicamba (3,6-dichloro-o-anisic acid) were evaluated in a group of 98 professional turf applicators from 20 companies across southwestern Ontario. During a 1-week period (Saturday to Thursday), the volume of pesticide (active ingredient) applied was only weakly related to the total dose of 2,4-D absorbed (R(2)=0.21). Two additional factors explained a large proportion of variation in dose: the type of spray nozzle used and the use of gloves while spraying. Individuals who used a fan-type nozzle had significantly higher doses than those who used a gun-type nozzle. Glove use was associated with significantly lower doses. Job satisfaction and current smoking influenced the dose but were not highly predictive. In the final multiple regression models predicting total absorbed dose of 2,4-D and mecoprop, approximately 63-68% of the variation was explained. The future application of these models for epidemiologic research will depend on the availability of information and records from employers, the feasibility of contacting study subjects and cost.

Residues of toxic chemicals in human tissues and fluids can be important indicators of exposure. Urine collected from a subsample of the second National Health and Nutrition Examination Survey was analyzed for organochlorine, organophosphorus, and chlorophenoxy pesticides or their metabolites. Urine concentration was also measured. The most frequently occurring residue in urine was pentachlorophenol (PCP), found in quantifiable concentrations in 71.6% of the general population with an estimated geometric mean level of 6.3 ng/ml. Percent quantifiable levels of PCP were found to be highest among males. Quantifiable concentrations of 3,5,6-trichloro-2-pyridinol (5.8%), 2,4,5-trichlorophenol (3.4%), para-nitrophenol (2.4%), dicamba (1.4%), malathion dicarboxylic acid (0.5%), malathion alpha-monocarboxylic acid (1.1%), and 2,4-D (0.3%) were found, but at much lower frequencies. No quantifiable levels of 2,4,5-T or silvex were found. Preliminary analyses showed an apparent relationship between residue concentration and two measures of urine concentration (osmolality and creatinine). A large segment of the general population of the United States experienced exposure to certain pesticides, including some considered biodegradable, during the years 1976-1980.

The relation between blood chlorophenoxy herbicide and ioxynil concentrations and toxicity, and the effect of alkaline diuresis on outcome, have been studied in 41 patients. More than one herbicide was found in 38 cases. 6 of 30 patients who had ingested chlorophenoxy compounds alone died; 16 patients (mostly in grade 3-4 coma) had alkaline diuresis and 15 survived. 7 of 11 patients who had co-ingested ioxynil died; 3 had alkaline diuresis and all survived. Alkaline diuresis reduced plasma chlorophenoxy half-lives to values observed after doses that had no adverse effects (ie, below 30 h), but did not influence ioxynil clearance. Alkaline diuresis should be used to treat acute poisoning with chlorophenoxy herbicides or ioxynil in the presence of coma or other poor prognostic indicators, such as acidaemia, or if plasma total chlorophenoxy concentrations are 0.5 g/l or more.

Analytical procedures for the simultaneous determination of residues of 2,4-D and dicamba from polyurethane foam plug air samplers, ethylene glycol impregnated glass-fiber filter paper dermal samplers, 1% sodium bicarbonate hand wash solution, and urine are presented. Residues were derivatized with diazomethane and quantitated using electron capture gas chromatography. Recoveries were greater than 80% at the limit of detection in all substrates. The limits of detection for both herbicides were 0.1 microgram/foam plug and 0.5 micrograms/filter paper, and in the urine, 1.7 micrograms/100 mL and 5.0 micrograms/100 mL for dicamba and 2,4-D, respectively.

Potential respiratory and dermal exposure to applicators were estimated in a ground boom spray application of 2,4-D and dicamba. Time-weighted averages for airborne herbicide residues did not exceed 2.2 microgram/cu.m. in the cabs of application vehicles allowing only minor respiratory exposure. Dermal exposure was important as relatively large amounts of 2,4-D (1.2 - 18 mg) and dicamba (0.32-6.6 mg) were rinsed from applicators' hands. Urine analysis showed that the maximum elimination of herbicides occurred between 16 and 40 h after terminating exposure. A dicamba isomer (20% of the active material in the commercial formulation) was excreted in higher concentrations than dicamba in applicators' urine suggesting different toxicokinetic properties for the two compounds.