In late August 2009, patrons of Mi Ranchito restaurant in Lenexa, Kansas, began falling ill.
Their symptoms included severe nausea and vomiting. Part of the mystery surrounding the outbreak of illnesses was that the victims’ symptoms came on so quickly after dining at the restaurant–sometimes just after eating the meal.
The reason, as investigating health authorities recently discovered, was that the outbreak was not caused by a common foodborne pathogen like E. coli O157:H7 or Salmonella, which typically take a lot longer to incubate before causing illness. It was caused by the ingestion of a dangerous pesticide called methomyl, which causes illness much more quickly in human beings than do its bacterial and viral counterparts
Methomyl is a highly toxic compound in EPA toxicity class I. It was introduced in 1966 as a broad spectrum insecticide to be applied to the surface of plant foliage. Methomyl effectively kills target insects by direct contact, or by what is known as “systemic poisoning” or absorption of the insecticide by the target insects.
Oral ingestion by human beings is the quickest, most efficient delivery route, and produces the most severe symptoms.
Typically, symptoms of methomyl poisoning include weakness, blurred vision, headache, nausea, abdominal cramps, chest discomfort, constriction of pupils, sweating, muscle tremors, and decreased pulse. Cases of severe poisoning may also cause apparent neurological dysfunction including twitching, giddiness, confusion, lack of muscle coordination, slurred speech, low blood pressure, heart irregularities, and loss of reflexes.
In the most severe cases, paralysis and death may occur. In addition to ingestion orally, people may become sick from methomyl poisoning by inhalation of aerosolized or dustborne particles, and even by skin contact with the pesticide.
For the Mi Ranchito outbreak, the remaining mystery is how, or for what reason, a pesticide would have contaminated the restaurant’s salsa, which was identified as the contaminated food vehicle.
Given the nature of the contaminant involved one conclusion would be that a particular ingredient in the salsa was treated with a heavy dose of methomyl, which was not adequately washed off prior to processing or service.
Another theory, according to Rulber Dela Torre, one of the restaurant’s founders, is that the methomyl contamination was a deliberate act.
Understandably upset about his restaurant’s association with the public health crisis, Dela Torre stated ” If this did happen, it was a deliberate act by somebody who wants to hurt my business.”
State officials cleared the restaurant to open last week after it passed a safety inspection and its employees passed a safety test.