If Mrs. R. is typical, it’s a good thing there are no atomic bug bombs or thermonuclear mouse traps or our neighborhood would be a radioactive dead zone. In our case her malevolent vibrations are sufficient to sterilize the area of vermin (that and our dog) but many people resort to chemical bug bombs, called total release foggers (TRFs). These are canisters that release enough pesticide to fill a living area with chemical fog that kills bugs like cockroaches, fleas and flying insects. The pesticides are usually relatively non-toxic to humans, primarily pyrethrins, derived from chrysanthemums, or their synthetic counterparts, but they also contain additives like piperonyl butoxide that affect the insect detoxifying enzymes and could possibly affect the same systems in humans. The vehicles in which the pesticide is dissolved is often flammable and explosions and fires have been caused by area space heaters, pilot lights or sparking electrical circuits. Mostly, though, mishaps are less severe, although it is difficult to get a handle on how often these devices create problems for consumers. In CDC’s Morbidity and Mortality Weekly Reports (MMWR) eight states report the first systematic attempt to compile illnesses and injuries related to TRFs.
We begin with some typical case reports:
Case 1. In March 2008, a woman aged 38 years from Washington visited an emergency department with headache, shortness of breath, nausea, leg cramps, burning eyes, cough, and weakness after she was exposed to fumes from three TRFs (in 6-ounce cans) deployed nearly simultaneously by a downstairs apartment neighbor. One TRF each was set off in the crawlspace beneath the house, in the neighbor’s apartment, and in the hallway. The building was an old house converted into apartments, with a single ventilation system connecting all apartments. The neighbor had orally notified some of the tenants but not the patient. The patient recovered completely within 3 days, and the illness was classified as low severity. The TRF dispensed a toxicity category III pesticide product that contained permethrin and tetramethrin as active ingredients.
Case 2. In September 2007, a man aged 34 years who worked as a maintenance worker at an apartment complex in Michigan forgot to disarm the smoke detector before activating a TRF. Because the building elevator shuts down if a smoke detector is triggered, the maintenance worker (without respiratory protection) reentered the mist-filled apartment to disarm the detector. He had onset of cough and upper airway irritation approximately 1 hour after exposure, contacted a poison control center, and did not seek additional medical care. His symptoms resolved within 24 hours, and his TRF-related illness was classified as low severity. He was exposed to a toxicity category III pesticide product with pyrethrins, cyfluthrin, and piperonyl butoxide as active ingredients.
Case 3. In August 2007, a man aged 54 years in California simultaneously set off nine TRFs in his small 700 square foot (6,000 cubic foot) home. Each 1.5-ounce TRF can was designed to treat 5,000 cubic feet of unobstructed space and released a toxicity category III pesticide product containing cypermethrin. When the man returned 6 hours later, a strong odor prompted him to open the doors and windows and to vacate. Entering a second time 4 hours later, the man had onset of headache, dizziness, nausea, and vomiting. He visited an emergency department, where he was treated symptomatically for TRF-related illness with a nebulized anticholinergic bronchodilator, intravenous hydration, and intravenous medication for headache, nausea, and bradycardia. He completely recovered after 36 hours, and his illness was classified as moderate severity. (CDC MMWR)
None of these cases are dramatic but I think they can be taken as typical. In all, this preliminary surveillance system in eight states, using an ad hoc collection of poison control centers and other systems, found 466 cases of acute, pesticide-related illness or injury in 2001 – 2006. Three cases were pregnant women and 44 were in asthmatics. Most occurred in residences, not work places. Failure to get out of the area quickly enough, premature re-entry into the fogged area, accidental discharge and failure to notify others were the main factors contributing to the reported illnesses or injuries. Over 80% were low severity (cases 1 and 2 are typical), 18% moderate severity (case 3) and 2% high severity:
One death was classified by the Washington State Department of Health as suspicious. (This death occurred in a female infant aged 10 months who was put to bed the evening of the day her apartment was treated with three TRFs. The infant was found dead the next morning.) Twenty-one persons were hospitalized for 1 or more days (range: 1–35 days), and 43 persons lost time from work or other usual activities because of their illness or injury.
Pyrethrins and the added knockdown agents are of low acute toxicity in mammals, but can be irritants or sensitizers for some people. Over half the cases for which information was available involved the bug bomber him- or herself and involved the respiratory system. Anaphylactic reactions have been reported to these agents but were not present in this series. Burning or itching of the skin and eyes, gingling and numbness, dizziness, salivation, headache, fatigue, vomiting, diarrhea, seizure, irritability to sound and touch, and other central nervous system effects have also been associated with pyrethrins in some settings and the propellents and vehicles used in these bombs are capable of setting off reactions in some people.
These do-it-yourself bug bombs are a lower cost alternative to professional pesticide application. They are obviously less discriminating in where the pesticide is applied however and therefore have a greater potential for unintended or unaware exposure. As the MMWR report notes, appropriate usage requires some arithmetic calculation on the part of the resident about treatable volume. That requires not only the ability to do arithmetic (!?!) but the ability to measure or estimate a length, area or volume. Maybe I’m too cynical, but that’s a lot to ask of many people. There is also a tendency for some people to think that if one bug bomb is good, five bug bombs are even better.
Meanwhile, Mrs. R. is roaming the neighborhood with a twelve-gauge shotgun, looking for mice. We’ve been married so long she now thinks chemicals are dangerous.