Oakville's plan to combat Gypsy Moth infestation though an aerial spraying program is raising health and environmental concerns among a handful of local residents.

The Town will be spraying two applications of a biological treatment called Bacillus thuringiensis subspecies kurstaki (Btk) in mid-may. The use of Btk is permitted under Oakville's pesticide-bylaw. It's a soil bacterium used in crops, fruit trees, and forests and will be applied in the areas of North Park, Trafalgar Lawn Cemetery, 16 Mile Creek Park (north of Upper Middle Road), and Winston Woods in mid-May.

If Btk isn't sprayed, Oakville officials fear 1,000 trees could die this year and the damage would cost Oakville about a quarter of a million dollars.

Others, however, are wondering whether this is being done at the expense of public safety.

"I find the whole thing very disturbing. There is so little information [on Btk] and I'm worried that a lot of people are going to be sprayed upon and they won't really know what's happening to them. It's a very serious matter," said Edith Cunningham, who wrote a concerned letter to the mayor and council.

Once the pesticide is sprayed, it needs to be ingested by gypsy moths to become effective. The bacteria produce a protein that destroys the moth's gut, stopping their consumption and killing them within two to five days.

Since humans and other non-insects have acidic stomachs, Btk will not have the same affect on them, although, it might also target other lepidopterans larvae, such as butterflies and non-targeted moths.

Despite showing no human health hazards, Btk is worrisome to some residents.

"I'm a mother. I'm not a chemist and I just read about this and the hair in the back of my neck stands up," said Lisa Clegg, an Oakville resident.

Oakville will be spraying Foray 48B, a brand of Btk spray, provided by Valent BioSciences Corporation. The product has 75 per cent water; three per cent Btk and the remaining 22 per cent consists of inert ingredients, secret to the public, according to Joe Meating, president of Bioforest Technologies Inc., the forestry consulting company hired by Oakville.

Foray 48B's unrevealed ingredients causes concern. But Health Canada's Pest Management Regulatory Agency (PMRA), which has approved the use of Btk in Canada, is aware of all its ingredients, including non-active "secret" ones.

PMRA needs a list of all the ingredients within a product for testing and registration.

After exposing laboratory animals to considerably higher amounts of Btk than possible exposure at a spraying program, Health Canada's concluded Btk is safe for humans, dogs, or any non-lepidopterans larvae "when applied at registered label rates and approved application methods," according Véronik Levesque, spokesperson for Health Canada.

During current re-evaluation of Btk, Health Canada also tested the pesticide in relation to cancer, birth defects and other health problems and paid particular attention to children.

In a Halton Region Health Department report about Btk, Environmental Health Specialist Jacinth Miller stated," there have been some reports that Btk may cause temporary mild irritation to eyes, skin and nose in some people. It is believed that the irritation may be caused by various additives in the commercial formulation of Btk."

"There was an incident of when forestry workers, were exposed to over 500 times more than what the general public would be exposed to and they did experience some irritation," said Miller.

The report also quoted the World Health Organization (WHO), which conducted research on eight human volunteers, who were given Btk in a span of five days and didn't demonstrate any health concerns immediately after or four to five weeks later.

"I've done a lot of reading, a lot of research on Btk, specially Foray 48B and [the region's] literature didn't really convince me," said Cunningham.

"We should not be subjecting the people of Oakville to something that we don't know that much about because long-term studies have not been done. From all the literature we've looked at we can't find anything definitive. Another thing that worries me is that this is going to happen whether the people want it or not."

People who are exposed to Btk can also carry the bacteria in their system. It can be found in the spleen, liver and lung tissues of animals treated with superior levels of Btk, according to Health Canada. It is not considered a health hazard, however, since Btk is already deemed safe.

Miller could not provide a definitive answer on how long Btk could remain in human tissue.

The pesticide is also rumoured to increase or develop allergy symptoms in people with low immune systems or who already suffer from allergies.

A study from New Zealand "indicated that individuals, who have hay fever, may experience respiratory irritation, but not depression," while a study in BC with asthmatic kids "found that there weren't any increase in instances of kids having asthma attacks," according to Miller.

People with asthma or other health concerns "may follow the same precautions they would on poor air quality days. By staying indoors with doors and windows closed during the spray period and a few hours thereafter," stated Levesque.

It is recommended to the public to open windows after five to six hours for fresh air, since the amount of Btk indoors could exceed the concentrations outside by that time.

The Town has notified the homes within the vicinity of the spraying zone. The area of 16 Mile Creek Park has three-dozen homes nearby and Winston Woods has one industrial property. The notification included information about the project as well as an invitation to participate in public meetings.

"They are only notifying people within a certain block. Well I'm sorry, but it is moving and other people should be notified," said Clegg.

John McNeil, Oakville's Manager of Forestry and Cemetery Services, stated Btk will only travel a couple of hundred metres maximum; a fact supported by Bioforest Technologies' forestry expert, Meating.

Oakville isn't the only town applying Btk to its trees. Spraying projects will also be taking place in Toronto, Hamilton, Burlington, and Halton Region. Mississauga conducted spraying programs in 2006 and 2007.

The Town will be closing roads for five to 15 minutes to minimize potential accidents caused by a distracting low-flying helicopter.

Oakville and Bioforest Technologies will be spraying 63 hectares, four litres per hectare early in the morning between 5 a.m. and 8 a.m. and are waiting for perfect weather, making it impossible to give an exact spraying date. They will know when to spray 72 hours in advance.

Winds cannot exceed more than 16 km per hour. If winds exceed are higher than planned, the project stops to prevent drifting of Btk to non-spraying areas and maintain safety.

"They have these GPS system that will allow them to know where the material went," said Sandra Smith, a professor of Forestry from the University of Toronto who has worked with Btk. "They want a little bit of winds, not enough to move it, but enough to push it down."

Depending on humidity, wind and the height of the area, Btk can take up to an hour to drift all the way down, according to Meating.

"But usually most of it comes down in a matter of a few minutes," he said.

Health Canada however, could not say how long it would take for Btk to leave the air because no additional tests were necessary to register Btk-based pesticides.

"There are other ways of doing it, which of course our labour intensive, so I really feel that we should not be subjected to something unless there has been a much longer period of research on it. From everything I've read, nobody has come up with anything definitive," said Cunningham.

Although there are other alternatives to Btk- vacuuming egg masses, burrier bands, and burlap skirts-the severity of the infestation offers no other solution, according to Meating. Oakville's egg masses are above normal levels with thousands of egg masses.

"We look at all other options, which are typically scrapping egg masses of the trees. But if the tree is 70 feet high, it's pretty difficult. You can put bands around trees, but when you are looking at an outbreak that is covering such a large area, it's pretty hard to do this to 100,000 trees," said Meating.

There is a pheromone method available, attracted only to male moths but "they don't really do anything when populations are really high. Pheromone traps are usually used to detect building population."

There is also a virus aimed specifically at gypsy moths, unlike Btk, but it's not available commercially.

"If spraying is going to happen, the people that are going to sprayed upon should give their consent. There is no way that I could give informed consent because I'm not informed enough. That's my problem there," said Cunningham.

For more information regarding the spraying program and Btk visit www.oakville.ca/gypsymoth.htm. To be added to the contact list for exact spraying dates contact the town through Halton's 311 and provide your e-mail.