Bromophos toxicity

An advantageous property, characteristic of both compounds, is their very low toxicity to warm-blooded animals. The oral ld,o of bromophos for rats is 3750-6100 mg/kg. This, together with the fact that it injures neither the skin nor the mucous membranes, has made possible its use also against the ectoparasites of domestic animals. 

One of these is the phosphonate analogue of cyanophos (43), cyanofenphos (109), O-ethyl-O-p-cyanophenyl-benzenephosphonothioate, developed by Ku-ramoto et a/. (1961). Its for mice is 46 mg/kg, i.e. it is about twenty times more toxic than cyanophos. The phosphonate analogue of bromophos (39) is known under the trade name Phosvel (110). 

OP insecticide-induced intermediate syndrome (IMS) was reported for the first time in human patients in Sri Lanka in 1987 (Senanayake and Karalliede, 1987). Since then, this syndrome has been diagnosed in OP-poisoned patients in South Africa (1989), Turkey (1990), Belgium (1992), the United States (1992), Venezuela (1998), France (2000), and elsewhere. IMS is usually observed in individuals who have ingested a massive dose of an OP insecticide either accidentally or in a suicide attempt. IMS is clearly a separate clinical entity from acute toxicity and delayed neuropathy. A similar syndrome has also been observed in dogs and cats poisoned maliciously or accidentally with massive dosc.s of certain OPs. OPs that are known to cause IMS include bromophos, chlorpyrifos, diazinon, dicrotophos, dimethoatc, fenthion, malathion, merphos, methamidophos, methyl parathion, monocrotophos, omethoate, parathion, phosmet, and trichlorfon. These compounds and IMS are discussed further in Chapter 26. 

An established and well understood interaction. The organophosphorus pesticides are potent anticholinesterases used in agriculture and horhcul-ture to control insects on crops, and in veterinary practice to control various ectoparasites. They are applied as sprays and dips. Anyone who is exposed to these toxic pesticides may therefore show changes in their responses to neuromuscular blockers. Widely used organophosphorus pesticides include azamethiphos, bromophos, chlorpyrifos, clofenvinfos. 

The very high mammalian toxicities of TEPP, parathion and dimefox can be contrasted with the very low toxicities of malathion and ronnel, and the almost non-toxic properties of bromophos and avenin (Table 12.31). Malathion and trichlorphon are particniarly suitable for domestic nse becanse of their relatively low mammalian toxicity. 

---