The move has left scientists who advised Health Canada on the issue befuddled by the ban. So are many consumers who prefer natural bug sprays over ones with synthetic chemicals like DEET.
Repellents essentially fall into two categories. The first category is "chemical," which means that they're synthetic or man-made. The chemical repellents sold in the United States are DEET (N,N-diethyl-3-methylbenzamide) and IR3535. In a laboratory study that we did with a particular species of mosquito, DEET was found to be the most effective commercially available repellent.
The second category is the so-called plant-based insect repellent. The most common repellents that are botanical in origin are based on citronella. Oil of citronella, which has a somewhat lemony smell, was originally isolated from a couple of cultivated grasses. It is used in skin repellents as well as candles. It's been in used in this country as a repellent since about 1948, but very variable efficacy has been reported with its use.
Pharmacologist Mohamed B. Abou-Donia found frequent and prolonged use of DEET, the most often recommended and most common mosquito repellent ingredient, caused brain cell death and behavioral changes in rats.
The health threat posed by DEET (N,N-diethyl-3-methylbenzamide) to humans is still being studied, but Abou-Donia said his 30 years of research on pesticides' effects on the brain clearly indicate that people need to be cautious about their use of DEET.
Children are especially vulnerable to subtle brain changes caused by chemicals in the environment. That's because their skin more readily absorbs such chemicals, which have more of an impact on a child's developing nervous system.
Nevertheless, DEET is being given a pass while the harmless and natural essential oil of citronella is being banned.
No Basis For Ban
"It's the basis of the ban that I don't really understand," says toxicologist Sam Kacew.
Insect repellents are considered pesticides so they must meet strict safety standards. Small manufacturers who couldn't afford to submit detailed safety data saw their lines discontinued at the end of 2012. Those who submitted what data they could and tried to challenge the ban are now to see their products phased out at the end of this year.
In 2005, Kacew sat on an independent scientific panel to review Health Canada's position. He says the panel believed the study that led the government to question citronella's safety was flawed, in part because it examined what happened when rodents ingested the oil. "Humans are not going to drink citronella," he says.
The department told CBC that "the panel supported Health Canada's approach," but Kacew refutes that. He says the team of scientists concluded that citronella was safe as long as it didn't contain methyl eugenol, an impurity that could be a potential carcinogen. "In general, most of these citronella oils that were available for us to examine did not contain impurities, and they were regarded by us to be basically safe," he says.
Companies Pay the Price
Montreal company, Druide, has been selling government-approved citronella sprays and lotions since 1995.
"Where I am very sad is, in the end, [Health Canada] doesn't have anything against citronella, except questions about it," says Druide's owner, Alain Renaud.
He says he spent five years proving to Health Canada that his repellent didn't contain methyl eugenol.
But Renaud says that as soon as he won that battle the government "came back and said we still have questions and we need a complete toxicological report on many generations of animals."
That may be a standard approach, but Renaud eventually gave up his fight because his company doesn't believe in animal testing, and didn't have the estimated $1 million needed to fund a large-scale scientific study.
Druide's citronella-based bug spray was a bestseller for the company, which manufactures organic personal care products.
Renaud says he's had to lay off five employees because of the ban and has lost up to a million dollars spent on marketing his product and providing research for Health Canada. "At the end of maybe, five, 10 years of fighting, [Heath Canada] gets all our energy," he says.
DEET passed Health Canada's scrutiny because the manufacturers provided the required safety data. But citronella -- an extract from lemon grass -- has never been patented, which makes it an unattractive investment for costly studies.
"If the market was such that this product was generating millions of dollars, then the industry would have done something re-active to try and get [citronella] back on the market," said Kacew.
That's the problem withother essential oils as well. They may be effective as bug repellents, but no one has yet funded the studies to prove they're safe.
DEET Affects Successive Generations
The animal's DNA sequence remains unchanged, but the compounds change the way genes turn on and off -- the epigenetic effect studied at length by WSU molecular biologist Michael Skinner.
While Skinner's earlier research has shown similar effects from a pesticide and fungicide, this is the first to show a greater variety of toxicants -- including jet fuel, dioxin, plastics and DEET.
"We didn't expect them all to have transgenerational effects, but all of them did," Skinner said.
Biologists have suspected for years that some kind of epigenetic inheritance occurs at the cellular level. The different kinds of cells in our bodies provide an example. Skin cells and brain cells have different forms and functions, despite having exactly the same DNA. There must be mechanisms--other than DNA--that make sure skin cells stay skin cells when they divide.
This tells researchers that the ability to promote transgenerational disease is "not simply a unique aspect for a unique compound" but a characteristic of many environmental compounds.
When DEET and sunscreen agents are combined, there's a marked increase in the rate of absorption through the skin. University of Manitoba pharmaceutical researcher Dr. Xiaochen Gu says this could mean the side effects of the chemicals may be heightened when they're used together.
Natural Products Being Shut Down
Tracey TieF made and sold a natural bug spray with essential oils including lavender and rosemary for seven years before Health Canada shut her down recently.
The problem was that she hadn't registered her product and done any safety studies.
"I can't afford to run my own trial," says the certified health practitioner. "I feel afraid and I feel sick about it, actually, because for me, this is a passion."
TieF now puts that passion into teaching others how to make natural bug sprays. In a tiny room at Karma Co-op in Toronto, she passes out bottles, essential oils and recipes. "I'll teach people until [Health Canada] stops me," she vows.
Aimee Alabaster says she joined the class because she wants a natural bug spray for her children. "Everything out there for the most part contains DEET, and I don't want to put DEET on my kids."
Research has suggested DEET could be harmful to the central nervous system. But Health Canada states on its website that "registered insect repellents containing DEET can be used safely when applied as directed."
Come 2015, citronella bug sprays won't be entirely out of reach, you will just have to cross the border. The product will still be available in the U.S.
In 1998 the U.S. Environmental Protection Agency issued a re-registration standard for DEET, to ensure that it met newer, more stringent, safety requirements. After looking at the results of many studies that it required, the EPA did not feel that they had to change the labeling requirements based on the new data.
The vast majority of the DEET-based repellents that you see have a DEET concentration of between 5 percent and 15 or 20 percent. There are some products that go up to 35 percent concentration. And then, there are a few 100 percent DEET repellents still sold. When people go to buy DEET insect repellents, one of the biggest problems is the natural tendency to buy the highest concentration.
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Marco Torres is a research specialist, writer and consumer advocate for healthy lifestyles. He holds degrees in Public Health and Environmental Science and is a professional speaker on topics such as disease prevention, environmental toxins and health policy.