Acute percutaneous paraquat poisoning

Paraquat poisoning in a burn patient

Paraquat is a bipyridyl compound widely used as a contact herbicide. Since its introduction in 1962, hundreds of deaths have occurred, usually after suicidal or accidental ingestion. Death after dermal absorption of paraquat is uncommon, but has occurred after either contact with undiluted paraquat, disruption of skin integrity, or prolonged exposure. It is the purpose of this case report to describe a patient who had fatal dermal paraquat absorption after a crop-dusting accident in which he sustained 37% TBSA burns. After 9.5 hours of cutaneous exposure, a paraquat level of 0.169 mg/ml was obtained at 20 hours, the standard lethal dose at 16 hours being 0.16 mg/ml. In light of the apparently irreversible pathophysiology of paraquat poisoning with plasma levels as low as 3 mg/L, prevention and early intervention are the best treatments. Our patient may have survived an otherwise routine thermal injury had his wounds been aggressively irrigated in the field.

Mixed diquat/paraquat-induced burns

BACKGROUND

Ducatalon is a bipyridylium herbicide containing a mixture of diquat and paraquat, and is used in agriculture. Adverse reactions due to contact of this compound with the skin have rarely been described.

CASE REPORTS

Two men were seen for severe pain due to extensive chemical burns in the perineal and scrotal regions, caused by leaking of Ducatalon from defective equipment used for spraying the herbicide. The lesions responded well to treatment with topical silver sulfadiazine, combined with systemic antibiotics. The damaged skin healed without scarring within a few days. The lesions have not recurred after the faulty spraying apparatus was replaced.

CONCLUSION

Direct contact of the skin with Ducatalon may lead to severe chemical burns. Proper precautions should be taken by the personnel handling this compound, with particular attention to the integrity of the equipment used for spraying the herbicide.

Exposure to paraquat through skin absorption: clinical and laboratory observations of accidental splashing on healthy skin of agricultural workers

Data concerning 15 consecutive cases of single exposures of the skin or eyes during work to paraquat solutions are presented. Urine and serum were analysed for paraquat in all these cases at the laboratory of the Israel Poison Information Center. From these data it is apparent that a single exposure of healthy skin to paraquat solutions caused only local lesions. No systemic effect was detected in these patients.

Toxicokinetics and bioavailability of paraquat in rats following different routes of administration

The toxicokinetics and bioavailability of [14C]paraquat were examined in rats which had received a single dose (11.6 micrograms/kg) of the herbicide by the iv, intragastric, dermal or pulmonary route. In the pulmonary route studies, rats were exposed to an aqueous solution or liquid aerosols of [14C]paraquat through a tracheal cannula or [14C]paraquat aerosols in a nose-only inhalation chamber. After intratracheal, intragastric, and dermal administration of [14C]paraquat to the rat, the average bioavailabilities were 0.45 +/- 0.22, 0.12 +/- 0.03, and 0.038 +/- 0.027, which corresponded to 20.3 nmol, 5.4 nmol and 1.7 nmol of [14C]paraquat, respectively. Since the dose administered to the rat in the [14C]paraquat aerosol studies was unknown, the bioavailability for this exposure route could not be determined. However, about 27.5 nmol of [14C]paraquat was observed into the systemic circulation of the rat after inhaling [14C]paraquat aerosols through a tracheal cannula. [14C]paraquat administered to the rat iv was eliminated from the blood with a half-life of about 68 min. Urine and feces were the major excretion routes. The radioactivity absorbed into the systemic circulation of the rat was approximately equal to that excreted in the urine; about 23.8 nmol, 8.5 nmol and 1.5 nmol of [14C]paraquat were recovered from the urine of the rat after inhalation of [14C]paraquat aerosols in a nose-only exposure chamber, intragastric injection and dermal absorption of [14C]paraquat, respectively. Tissue distribution studies showed that the bulk of the [14C]paraquat administered to the rat by the inhalation and dermal routes remained at the sites of administration.

Paraquat poisoning: clinical features and immediate general management

In contrast to 10-15 years ago most cases of paraquat poisoning are now due to deliberate self-poisoning with parasuicidal or suicidal intent rather than to accidental ingestion. Less commonly, poisoning may follow careless handling of paraquat during occupational use. Although paraquat can be absorbed through the skin if improperly handled, poisoning usually follows ingestion and has rarely been reported after subcutaneous, intravenous or intraperitoneal injection. Clinically, three degrees of intoxication may be distinguished. Mild poisoning occurs after the ingestion or injection of less than 20 mg of paraquat ion/kg body weight. In these cases patients are either asymptomatic or symptoms are confined to the gastrointestinal system. All patients recover fully. Moderate to severe poisoning usually follows the ingestion (rarely injection) of 20-40 mg of paraquat ion/kg body weight. Non-specific symptoms of ill health together with local gastrointestinal symptoms precede the development of renal failure (which may recover spontaneously) and pulmonary fibrosis which may not be manifest for days or weeks. Death occurs in the majority of cases but is usually delayed for 2-3 weeks. Acute fulminant poisoning follows the ingestion of substantial quantities of paraquat (greater than 40 mg of paraquat ion/kg body weight). In addition to local symptoms, multiple organ (cardiac, respiratory, hepatic, renal, adrenal, pancreatic, neurological) failure occurs. Death may supervene within hours and is never delayed for more than a few days. Initial general management has four priorities.(ABSTRACT TRUNCATED AT 250 WORDS)

Sequential bilateral lung transplantation for paraquat poisoning. A case report. The Toronto Lung Transplant group

A 31-year-old nurseryman developed progressive respiratory failure secondary to paraquat poisoning after repeated and prolonged exposure. Ventilatory assistance proved inadequate to maintain satisfactory oxygenation, and extracorporeal membrane oxygenator support was instituted. A right lung transplantation was performed, but the transplant subsequently was damaged when lethal levels of paraquat entered the bloodstream from muscle reservoirs. Membrane oxygenation was reinstituted for 19 days during which time charcoal hemoperfusion reduced paraquat levels to the undetectable range. A left lung transplantation was then performed, after which pulmonary gas exchange no longer posed a problem. The patient subsequently developed a progressive, severe, toxic myopathy with generalized weakness and inability to maintain spontaneous ventilation. Death occurred from a cerebrovascular accident after a trachea-innominate artery fistula, 93 days after the initial lung transplantation and 71 days after the second one. The development of progressive toxic myopathy following severe Paraquat poisoning has not been previously recognized, presumably because most victims of fatal paraquat poisoning survive only a brief period.

Near fatal percutaneous paraquat poisoning

A fatal paraquat poisoning can occur when relatively large areas of skin are contaminated with a concentrated solution of paraquat (Gramoxone). A paraquat absorption takes place of the same magnitude as that with an equal dose per os. In the presence of mechanical or chemical lesion of the skin the percutaneous paraquat absorption is distinctly enhanced.

Paraquat poisoning: evidence of systemic toxicity after dermal exposure

Exposure of the scrotal skin to a concentrated paraquat solution led to renal and respiratory failure and to hepatic damage with eventual recovery of the patient. Dermal exposure to paraquat, especially to the scrotum may produce serious systemic toxicity.

Fatal paraquat poisonings after skin absorption

This paper reports five cases of fatal paraquat poisoning after skin absorption in adult Papua New Guinea men. Three incidents followed occupational accidents, one victim used paraquat concentrate to treat a scabies infestation, and one used it to treat head lice. All had marked blistering and excoriation, and all died from respiratory failure. In developing countries, reporting on poisoning incidents is very limited, and treatment of paraquat poisoning is, for practical purposes, nonexistent. As paraquat is not essential for tropical agriculture, its continued use should be critically reviewed.

Hepatic injury associated with paraquat toxicity in humans

Thirteen patients are reported who developed evidence of hepatic damage after exposure to paraquat and subsequently died. At autopsy, the main changes involved the bile excretory pathways. Ten of the thirteen cases had cholestasis, usually localized to the centrilobular zone. There was cholangiocellular injury involving the small and medium-sized bile ducts in portal areas. It consisted of shrinkage of cells, poor definition of outline, separation from the basement membrane, desquamation of cells into the lumen, infiltration of the wall by neutrophils and possible loss of integrity of the basement membrane. These bile duct lesions have not been previously described in association with paraquat toxicity. On the basis of the overall histologic findings in this study and extrapolation from experimental studies, it is hypothesized that paraquat injury to the liver is biphasic; it is initially hepatocellular but becomes cholangiocellular after the first 2 days.