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Better Living Through Chemistry, Unless You’re Blattella germanica Y
es, this is an Editorial about a cockroach—a member of the 3500-strong roach family known as the German cockroach (GrCh). I know that this is a weird topic for an Editorial in Analytical Chemistry, but it is a good example of chemistry applied in service to society. GrCh is a home-dwelling pest from antiquity whose prospects were magnified in the 20th century by indoor plumbing, central heating, and the human habit of storing food. Food markets and warehouses provided comfortable harborages that promoted the prodigious reproductive capacity of GrCh, which moved on to infest homes and apartment dwellings. Imagine 106 GrCh in one home (1979 data)! Besides the unappealing aesthetic of cockroach goo between your toes, the debris of cockroaches is—for the 9–12 million asthma sufferers in the United States (1994 data)—well established as a serious source of indoor allergens, competitive with the dust mite. In the 1970s and 1980s, the insecticide ingredient hydramethylnon was introduced in a baited formulation that GrCh loves. Hydramethylnon works by inhibiting ATP synthesis, so it is a slow killer, allowing a foraging GrCh time to return to the colony nest and feed its fellows either through its droppings or through GrCh’s innate cannibalism. This “recycling” of the poison can yield a 44:1 lethality multiplier. It is such an effective system that its commercial value for GrCh control may be shrinking—a sign of possible victory. Analytical chemists played a crucial role in the development of hydramethylnon and the testing of its environmental consequences. The widely applied standard residue analysis for hydramethylnon involves HPLC with UV detection (limit of detection 0.2 ppb). Also important have been investigations of allergenic problems caused by GrCh—mostly using immunoassay strategies—that have established a clear correlation between cockroach infestation and asthmatic reactions. Allergy testing for GrCh is a recommended procedure in diagnosis of origins of chronic asthmatic symptoms. None of the analytical chem-
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istry I read about broke any new fundamental ground, but it illustrated the deep impact of applied analysis in establishing the general safety of this potent insecticide. Considerable environmental information has become available about hydramethylnon, and in terms of uses for GrCh control, I saw nothing that could project a concern for human health either in our homes and businesses or in their immediate environment. I did see, on the other hand, that hydramethylnon is also heavily used for wide-area control of fire ants in the United States. Fire ants are also a serious pest as well as a hazard (as you’ll know if you step on a mound!). The recommended broadcast dosage is 4–10 g/acre. Hydramethylnon has been thoroughly studied for this use, and considerable toxicity information is available. LD50 for rats is about 1.3 ppt of body mass—that’s a relatively safe number. Toxicity for fish is high (160 ppb for rainbow trout); fortunately, hydramethylnon has a low persistence (a few days to weeks) and low water solubility. Nonetheless, I believe that the invitation to large-area usage on ants needs continued environmental monitoring and investigation for possible problems. I’ve never written an Editorial about killing, and I hope that I am not attacked by the Roach Protection Society and that I do not unduly insult entomological scholars or my German colleagues (hey, I didn’t name it!). But I have not found any article defending the GrCh’s place in society—it seems to have negligible popularity, and its demise seems to be appreciated by all. We must thank chemistry for that. I hope that someday, through clear-headed, factual education about its benefits, the word “chemistry” will become less of an epithet in informed society.
© 2004 AMERICAN CHEMICAL SOCIETY
