Dealing With the Impact of Rodenticides on Children, Pets and Wild Animals.
Controlling rodents is essential for sanitation and health but when habitat management and traps fail to control the problem, poison baits are often used. This can have a far-reaching effect on pets, such as cats and dogs, wildlife species, and on humans. Thousands of children in the US are exposed to rodenticides each year, with around 76% of the hospitalizations due to brodifacoum and other second-generation anticoagulants. According to the EPA, rat poisons are the leading cause of pesticide related visits to health care providers amongst children 6 years and younger and the second leading cause of emergency hospitalization. While most children are not seriously injured, they can experience consequences ranging from bloody stools and urine, bleeding gums, nosebleeds, internal bleeding, coma and anemia.
Added to that, around 74% of pet poisonings are due to rat poisons. Symptoms that your dog or cat may have been impacted by exposure to rodenticides include: difficulty breathing, blood in the animal's stool, lack of appetite, vomiting, blood in the pet's urine, bleeding gums or nose bleeds, weakness, bruising found in the animal's skin, eyes or ears, or a ghostly pallor. Pets exposed to rodenticides may succumb to death caused by bleeding into the animal's chest cavity. If your pet consumes a rodenticide, vomiting should be induced immediately. Get your pet and the product package to a vet immediately. Vitamin K1 treatment should be initiated within 24 hours, whenever possible.
Rodenticides and Accidental Wild Life Animal Poisoning
There are two types of poisoning, both of which can be lethal. Primary poisoning occurs when a non-target animal directly eats the rat bait. Secondary poisoning happens when a predator eats a poisoned rodent. Both primary and secondary poisoning has been seen in a variety of species of wild birds and mammals. Foxes, raccoons, coyotes, opposums, squirrels, bobcats, wild pigs, deer, even mountain lions have been killed by rodenticides (Stone et al. 1999; Hosea 2000; Eason et al. 2002).
The Lethal Impact of Rodent Management on Wild Birds.
Owls, hawks and eagles are a natural form of pest control as they hunt rodents. However, these wild birds or "raptors" are dying from secondary poisoning after consuming their prey, which have eaten bait such as brodifacoum and bromadiolone (Albert et al. 2010; Stone et al. 2003; Walker et al. 2008).Added to that, Brakes and Smith (2005) found that woodmice, field voles, and bank voles were also being poisoned by rat bait boxes. So, not only are raptors experiencing secondary poisoning, but, their populations are dropping as their food supply shrinks.
Raptors show a particular sensitivity to anticoagulants. A study by Rattner et al. (2011) found that kestrels were 20-30 times more sensitive to the lethal effects of diphacinone than other species of birds tested. The study also calculated that the secondary poisoning risk associated with a single day exposure to diphacinone would be low for hawks and owls. The risk is low because diphacinone is quickly eliminated. However, hawks could show effects of sublethal exposure by as little as 3.5g of liver from diphacinone poisoned rats (Rattner et al. 2011).
These sublethal amounts make raptors more susceptible to disease and accidents (Lemus et al. 2011; Stone et al. 2003), because sublethal hemorrhage may interfere with locomotion, predisposing animals to predation, accidental trauma, and reduced food intake. There is also the possibility of toxic injury to the liver.
Sublethal amounts also seem to cause birth defects in raptors. A study by Naim et al. (2010) showed nestling barn owls weighed 13% less in test areas baited with brodifacoum compared to those in untreated areas. Other points to note were shorter wingspans and tail lengths, as well as malformed feathers in one animal. We know that birth defects in humans can be caused by anticoagulants so it is worth exploring the effects secondary poisoning may have on reproduction in raptors (Stevenson et al. 1980).
Current EPA Rodenticide Regulations
As a result of the numerous poisonings in humans, pets, and wildlife, the United States Environmental Protection Agency (EPA) reviewed the problems with rodenticides in 2008. As of June 2011, rules were implemented banning the sale of second generation anticoagulants on the consumer market, with bait stations also made compulsory for all rodenticides sold in this market. However, there are some companies fighting these regulations (EPA 2008, EPA 2011).
These rules do not affect the professional market or the use of rodenticides on farms. Farmers may use second generation anticoagulants for the control of rats and mice around structures, but not for pests such as gophers and voles (EPA 2011).
Rodenticides should be used as a last resort because children, pets,
and wildlife can be accidentally killed or injured. To put this into perspective, let's look at the numbers; each year 13,000-20,000 people in the U.S. are poisoned by rodenticides, most of whom are children under the age of five. Added to that, around 95,000 pet poisonings due to rodenticides were reported to American Poison Control Centres in 2010, with 75% of those being dogs (Bronstein et al. 2011).
These numbers should diminish with the 2011 EPA regulations currently in place, as consumers are now no longer able to buy rodenticides in the form of grain or loose bait. Manufacturers must now produce tamper resistant bait stations for use in the consumer market (EPA 2011).
This does not, however, solve the problem of wildlife poisoning – in particular raptors – where secondary poisoning is a real issue. In fact, raptors should be encouraged as an organic form of rodent pest control. There are studies to show that increasing the use of barn owl boxes can make a difference in reducing the numbers of rats and the damage they can cause (Basri et al. 1996, Mohamad and Goh 1991).
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