The deadliest animal in the world isn't a lion or shark. It's a mosquito. The World Health Organization attributes 1 million deaths every year to the mosquito, mostly as a result of the spread of malaria. Recently, one particular species of mosquito, Aedea aegypti (also known as the yellow fever mosquito), was also linked to a wave of birth defects in Brazil and elsewhere.

Commonly, mosquitoes are the source of untold annoyance because their saliva causes an irritating rash upon contact with human skin. But some species of mosquitoes such as the Aedea aegypti act as "vectors" - that is, they transmit harmful diseases such as malaria, yellow fever and the Zika virus that causes birth defects.

As a result over concerns about the Zika virus, U.S. sales of insecticides and bug sprays soared in early 2016, reaching an annual rate of $516 million. Sales of some popular products rose as much as 150% over the previous year. Unfortunately, many insecticides and bug sprays contain dangerous chemicals that pose new dangers to human health

Potential dangers of mosquito repellants

Most bug repellents, including mosquito sprays, contain a chemical known as DEET (or N,N-diethyl-mtoluamide). DEET is designed for application directly to the skin. It does not kill insects, it keeps them away from human contact by making it hard for them to smell us.

DEET may not be a health concern under normal circumstances and when used correctly. But DEET is toxic to human beings. Military personnel and others who apply DEET to their skin for sustained periods of time can develop blistering and even permanent scars on the skin. Exposures to small amounts of DEET can cause stomach irritation, nausea and vomiting. This can happen when small amounts of the chemical are swallowed or accidentally sprayed into the eyes, nose or mouth, especially with small children.

When the exposures to DEET are greater, neurological damage, seizures, coma and death can occur. Although these exposures are rare, they do happen.

A safer alternative

In some cases, the dangers of DEET may be outweighed by the risks of the vector-borne diseases that mosquitoes and other insects transmit. This can be true even in sensitive populations such as pregnant women. That's why DEET, when used as directed in low doses, is considered "relatively not harmful" by the U.S. National Institutes of Health.

And while DEET is especially effective and recommended by government authorities for repelling mosquitoes, there are safer, less toxic alternatives. One natural alternative, oil of lemon eucalyptus (also known as PMD), has received the recommendation of the U.S. Centers for Disease Control and Prevention (CDC). Researchers at New Mexico State University found that oil of lemon eucalyptus was as effective as DEET for repelling mosquitoes.

Tips on using bug sprays safely

Because so many bug sprays and repellents contain potentially toxic ingredients, it's important to consider options and always use products carefully. Here are a few tips:

1. Always consider natural alternatives to chemical products.Oil of lemon eucalyptus has been shown to be as effective as popular chemical repellents such as DEET. The natural oil can be purchased at major department stores and pharmacies.
2. Never spray repellent in closed areas.Always spray chemical bug repellent outside so chemicals and ingredients do not become aerosolized indoors.
3. Use caution when using repellents on children.Apply the product onto your own hands first and then rub the repellent onto the child's skin with your hands. This is because children frequently put their hands in their eyes and mouth.
4. Avoid "fogging" products if possible.So-called "fogging" products that are insecticides sprayed into the air to kill mosquitoes are considered by the CDC to be the least effective method of mosquito control. They also contain toxic chemicals that can be harmful to breathe if not used correctly. Indoor spaces must be vacated, typically for 2-4 hours, after spraying.

If you live in an area where mosquitoes are a problem, especially in summer, a bug repellent can help make outdoor living more pleasant. But by choosing the right repellent, and avoiding potentially dangerous and unnecessary exposure to toxins in some products, you can avoid annoying mosquito bites without putting your health at risk.