How many real kill 0.01 percent bromethalin rat poison bars is required to kill a larger animal such as a raccoon or fox the size of a medium sized dog?

Answer 1

I'm answering this question because I too wanted to know how dangerous 'Real Kill' 0.01% Bromethalin was to non-rodents, and found a lot of incorrect information on the internet.

So, I'll assume you're asking this question to AVOID accidentally killing a fox, raccoon, or other non-rodent, while using bromethalin rodenticide.

Note: Trying to kill a non-rodent is a misuse of this chemical, and is likely to be cruel and inhumane. Please do not misuse this, or any other pesticide!

The toxicity of poison is often expressed in terms of its "LD50" -- Lethal Dose 50. That's an estimate of the amount of a substance that will be fatal, on average, to 50% of animals exposed to that poison. The LD50 is usually adjusted for body weight, and so is often specified in terms of amount per body weight (e.g. mg/kg)

According to a University of Nebraska study (B. Jackson, et al; 1982), the oral LD50 of bromethalin in rodents (mice and rats) ranges from 2mg/kg to 8mg/kg.

But despite an oft-quoted "10 hour" latency, their data show that, once the rat or mouse has consumed a lethal dose, the average time til death ranges from 1.8 days to 10 days (depending on the amount ingested and the bait concentration.) For example, with a 100 ppm bait -- the same concentration as in "Real Kill" 0.01% -- rats and mice survived an average of2.6 days after ingesting a lethal dose ofbromethalin.

Within a particular species, it's safe to generalize that the larger the individual, the larger the dose of a given poison it can tolerate. But it's very difficult to generalize acrossspecies.

Fortunately, there have been some cross-species studies, such as Vanlier & Cherry, 1988, which investigated the LD50 of bromethalin for some other types of mammals.

In dogs, the LD50 appears to be about the same as for rodents, i.e. 5mg/kg. For rabbits the LD50 is 13mg/kg. The LD50 for cats is only about 1.0mg/kg, which implies that cats are at least 5 times more sensitive to bromethalin than are dogs.

Yet, while pigs are even more sensitive, with an LD50 of just 0.25mg/kg, guinea pigs are far more resistant, with an LD50 of greater than 1000 mg/kg! That's because guinea pigs lack the liver enzyme that creates the actual poisonous metabolite of bromethalin.

Unfortunately, there is not yet any experimental data on the toxicity of 0.01% bromethalin in foxes and raccoons; so it's impossible to know for sure how dangerous bromethalin is for them. But with some critical unverified assumptions, your question tentatively be answered.

If you assume a fox has the same tolerance to bromethalin as do dogs (LD50=5mg/kg), and assume your hypothetical fox weighs 30 lbs, the LD50 for a 30lb fox is approximately 68mg. (30lb * kg/2.2lb * LD50 5 mg/kg = 68mg bromethalin).

Since each tab of "Real Kill 0.01% Bromethalin" weighs about 14gms, there's about 1.4mg bromethalin in each tab.

That means, given all these unverified assumptions, if 100 30-lb foxes ate 48.5 tabs of 14gm 0.01% bromethalin, 50 of those foxes would die, on average. And if you assume 1/4 of the LD50 is the maximum non-lethal accidental ingestion limit, then as long as your hypothetical 30lb fox doesn't consume more than 12 Real Kill mouse bait tabs, it shouldn't fall ill.