Carbofuran

Carbofuran is one of the most toxic carbamate pesticides. It is marketed under the trade names Furadan, by FMC Corporation and Curater, among several others. It is used to control insects in a wide variety of field crops, including potatoes, corn and soybeans. It is a systemic insecticide, which means that the plant absorbs it through the roots, and from here the plant distributes it throughout its organs (mainly vessels, stems and leaves; not the fruits), where insecticidal concentrations are attained. Carbofuran also has contact activity against pests.

It has one of the highest acute toxicities to humans of any insecticide widely used on field crops (more toxic are only aldicarb and parathion). A quarter teaspoon ( 1 mL) can be fatal. Most carbofuran is applied by commercial applicators using closed systems with engineered controls, so that there is no exposure to the chemical through pouring or measuring. Toxic effects are due to its activity as a cholinesterase inhibitor (it is thus considered a neurotoxic pesticide).

Carbofuran is also known to be highly toxic to birds. In its granular form, a single grain will kill a bird. Birds often eat numerous grains of the pesticide, mistaking them for seeds, and then die shortly thereafter. Before it was banned by USEPA in 1991 ([1]), granular carbofuran was blamed for millions of bird deaths per year. The liquid version of the pesticide is less hazardous to birds since they are not as likely to ingest it directly, but it is still very hazardous.

Carbofuran usage has increased in recent years because it is one of the few insecticides effective on soybean aphids, which have expanded their range since 2002 to include most soybean-growing regions of the U.S.

The technical or chemical name of carbofuran is 2,3-dihydro-2,2-dimethyl-7-benzofuranyl methylcarbamate and its CAS number is 1563-66-2 and it is manufactured by reaction of methyl isocyanate with 2,3-dihydro-2,2-dimethyl-7-hydroxybenzofuran.

Oral LD50: Rats 8–14 mg/kg, Dogs 19 mg/kg.

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'killing Kenya lions'

By Adam Mynott BBC News, Kenya

Two Maasai Mara lions have recently died after carbofuran poisoning

Environmentalists in Kenya are worried that an insecticide is being used by farmers to kill lions and other predators.

Carbofuran is a very powerful and toxic insecticide.

Spread in the soil, it destroys bugs in the ground and is taken up by plants and kills insects which feed on the sap or foliage.

It is so powerful and toxic that it has been banned in Europe.

In the United States it cannot be used in granular form, and the US Environmental Protection Agency is seeking a total ban.

But in Kenya, carbofuran can be bought across the counter without restriction.

According to world-famous naturalist Dr Richard Leakey, it is being bought not by farmers wanting to control bugs and insects, but mainly by herdsmen who use it to kill lions, leopards and other predators.

Among the latest incidents two lions were poisoned and killed in the Maasai Mara game reserve after eating the carcass of a hippo that had ingested carbofuran.

Put down

Vets and wildlife rangers were called to watch the pathetic sight of the lions staggering and weakened from the effects of the poison.

(Carbofuran has) become known in rural communities in Kenya as an easy way to get rid of predators 

Naturalist Richard Leakey

One of the lions was shot to bring a quick end to its suffering.

Another lion died a few months ago from carbofuran poisoning on a private ranch in Laikipia.

In November last year, a dead camel was apparently found laced with carbofuran near Lewa Wildlife Conservancy.

The result was the death of at least two lions and 15 vultures which feasted on the carcass.

Also near Lewa, several lions from the nearby Samburu Wildlife Reserve were poisoned; again, it is thought carbofuran was responsible.

There are many other cases throughout Kenya of predators dying after eating meat contaminated with the chemical.

Dr Leakey says carbofuran is "deadly poisonous" and he has called for it to be banned in Kenya.

"It's become known in rural communities in Kenya as an easy way to get rid of predators: lions, leopards and hyenas," he says.

Dr Leakey says his research shows that Furadan, the trade name of the biggest-selling carbofuran insecticide in Kenya, is being bought not by farmers but by pastoralists who do not have any land for growing crops, and use the chemical to kill lions and leopards which threaten their herds.

There is no record for the number of predators killed in Kenya by poisoning, but many naturalists believe carbofuran is responsible for thousands of deaths, not just of big cats but all carrion eaters.

 I literally saw vultures dropping out of the sky 

Vulture expert Simon Thomsett

Simon Thomsett, a world renowned expert on vultures, eagles and other birds of prey, says there has been a "dramatic drop-off in the number of birds of prey in the past few years", and the finger of blame is being pointed at carbofuran.

He gives the example of 187 vultures that died when they fed on a carcass of an an animal that apparently laced with the deadly poison in an area by the Athi River.

Simon Thomsett says the poison cannot be detected when sprinkled on the carcass and is very fast to act.

"I literally saw vultures dropping out of the sky just a few minutes after they had eaten the poisoned meat," he said.

Easy to buy

Carbofuran comes in granular form, tiny dust-like purple pellets.

I went into several agricultural merchants in the capital, Nairobi, and found it easy to buy.

Vultures have died after feeding on laced carcasses

Three shops said it posed no health threat to animals or humans.

"It's safe, it's perfectly safe," one shop assistant told me.

Others warned it was poisonous and one shop-keeper even described carbofuran as a "lion-killer".

The container warns that it should be kept "locked away out of reach of children", but there is not a word on the label about a potential threat to wildlife.

Kenya's Pest Control and Products Board is carrying out research into carbofuran's dangers and toxicity, and say it is too early to come to a conclusion.

Dr Leakey says the evidence is there for all to see.

His worries are shared by Thomas Manyibe, a vet with the Kenya Wildlife Service who carried out post-mortem tests on the lions that were killed in the Masai Mara.

He says evidence shows that carbofuran is being used to target lions and leopards.

I spoke to pastoralists who said they had heard that Furadan was used to kill big cats.

On the edge of the Maasai Mara a young herdsman, Ndigwa, said he lost many cows every year to lions and leopards, but he said he would never resort to poison to take revenge on the predators.

 We take stewardship of our products very seriously and condemn any intentional baiting misuse of carbofuran 

FMC Corporation

Others do not hesitate.

Carbofuran comes from a number of different overseas suppliers, but the main producer is the US firm FMC Corporation.

The company said in a statement: "We take stewardship of our products very seriously and condemn any intentional baiting misuse of carbofuran.

"FMC is very concerned about reports of carbofuran (Furadan) being used to bait lions in Kenya and we have offered our services to the Kenya Pest Control Products Board in their investigation."

Concerns about the use of carbofuran are not new.

Fifteen years ago there were a number of cases of mass killings of birds in western Kenya; what is lacking is a comprehensive record of predators killed by poisoning.

There is lots of circumstantial evidence but few hard facts.

Detailed information is elusive, affected animals often disappear into the bush to die, and the evidence is then eaten by other carnivores.