Mixed diquat/paraquat-induced burns

Human and experimental toxicology of diquat poisoning: Toxicokinetics, mechanisms of toxicity, clinical features, and treatment

Diquat (1,1'-ethylene-2,2'-bipyridinium ion; DQ) is a nonselective quick-acting herbicide, which is used as contact and preharvest desiccant to control terrestrial and aquatic vegetation. Several cases of human poisoning were reported worldwide mainly due to intentional ingestion of the liquid formulations. Its toxic potential results from its ability to produce reactive oxygen and nitrogen species through redox cycling processes that can lead to oxidative stress and potentially cell death. Kidney is the main target organ due to DQ toxicokinetics and redox cycling. There is no antidote against DQ intoxications, and the efficacy of treatments currently applied is still unsatisfactory. The aim of this work was to review the most relevant human and experimental findings related to DQ, characterizing its chemistry, activity as herbicide, mechanisms of toxicity, consequences of poisoning, and potential therapeutic approaches taking into account previous experience in developing antidotes for paraquat, a more toxic bipyridinium herbicide.

Systemic Poisoning after Mucosa and Skin Contact of Paraquat

Paraquat poisoning is associated with very high mortality and often results in severe complications including pulmonary fibrosis and multi-organ failure. Majorities of the reported cases had paraquat exposure from oral route either due to accidental intake or suicidal attempt. Systemic complications from dermal exposure were infrequently reported. We reported a patient suffering from acute renal failure and liver function derangement due to systemic absorption of paraquat from accidentally dermal and mucosal contact. The case has illustrated the danger of improper use of this high toxic substance as a household product.

Paraquat poisoning by skin absorption: Two case reports and a literature review

The present report describes two cases of paraquat poisoning by skin absorption. The cases involved contractual workers who were spraying paraquat in an orchard. Whilst spraying, some solution adhered to their skin. The skin developed erythema followed by blistering and hemorrhaging hemorrhagic diabrosis. Six days later the patients were admitted to the Department of Poisoning and Occupational Disease, Qilu Hospital of Shandong University (Jinan, China) with 3 and 2% total body surface area (TBSA) burns, respectively. Surgical debridement was performed and immunosuppressants were administered during the patients’ treatment. The patients were treated successfully and had made a complete recovery following 21 days. From these cases it was examined how paraquat may cause skin injuries and occasionally poisoning. To the best of our knowledge, cases of paraquat poisoning are rare in China. A review of the relevant literature was performed.

Spectra interference between diquat and paraquat by second derivative spectrophotometry

A rapid and accurate method, combining solid-phase extraction and second-order derivative spectrophotomety approaches, is developed for the simultaneous determination of diquat (DQ) and paraquat (PQ) in blood, tissue and urine samples. Supernatant resulting from the precipitation of protein (with trichloroacetic acid) in plasma and tissue or Amberlite IRA-401 resin treated urine are passed through a mini-column packed with Wakogel gel (Silica gel). Analytes are then eluted with a non-organic solvent, 0.2mol/l HCl solution containing 2mol/l NH(4)Cl. UV spectrum of the eluent in 220-350nm range provides effective screen to detect the presence of DQ and/or PQ. In the presence of DQ or PQ alone, the analyte present is quantitated by conventional zero- or second-order derivative spectrophotometry. The calibration curve in the 0.1-5.0mg/l range for either analyte obeys Beer's law. When both DQ and PQ are present, their concentrations are determined by the peak amplitudes of their respective second-derivative spectra after the addition of alkaline dithionite reagent. Interference is negligible when the DQ/PQ concentration ratio is within the 5.0-0.2 range. Using a 2-ml of sample size, the detection limits for DQ and PQ in plasma are 0.02 and 0.005mg/l. The corresponding detection limits for urine samples (10ml sample size) are 0.004 and 0.001mg/l. Recoveries of DQ and PQ in triplicate plasma and urine samples spiked with 0.5mg/l of analytes are 93 and 85%. The precision of the proposed method resulting from triplicate study of spiked urine samples varies from 3.2 to 4.6% at 0.5mg/l of DQ and PQ, respectively.

Vaginally applied diquat intoxication

CASE REPORT

We report the case of a woman who introduced 20 mL of diquat concentrate intravaginally. Abdominal pain, vomiting, diarrhea, burning chest pains, and somnolence appeared within the first 24 hours. The vulva and vagina were corrosively inflamed. Acute renal failure appeared on the third day and was treated by 6 hemodialyses over 6 days. The patient was dysarthric with spastic tetraparesis for 3 months. The electroencephalogram, diffusely slow on day 3, was normal on day 28. The electromyoneurogram was normal at all times. Biopsy of a peripheral nerve performed on day 57 following intoxication showed no myelin or axonal alterations.

Improving the solid-phase extraction of "quat" pesticides from water samples. Removal of interferences

A novel strategy, based on the addition of a cationic surfactant, for preventing the interferences associated with a diminution in the efficacy of solid-phase extraction (SPE) with silica cartridges of diquat, paraquat and difenzoquat in water is developed. Conditions for extraction are optimised with respect to pH, cationic surfactant and its concentration. Humic acids, anionic surfactants, inorganic salts and other organic contaminants like pesticides, phenols, polycyclic aromatic hydrocarbons and polychlorinated biphenyls produce the studied interferences. The best performance is shown in the improvement of the "quats" recovery from waters with high levels of humic acids and anionic surfactants (recovery is increased from ca. 30% to more than 80%). Unfortunately, the strong interference from inorganic salts remains. The presence in the water sample of other organic contaminants only affected the extraction efficiency of difenzoquat at high concentrations (more than 1 mg/l). Analytic utility is illustrated by selective measurements of the three herbicides, in real water samples. Overall, the results show that in spite of its drawbacks, SPE is a useful technique that allows the detection and quantification of the "quats" at limits below 100 ng/l as established by the European Union.