November 21, 2008
From the Hamilton Spectator

by Tom Muir

"SAFE ... (provided label directions are followed)"

I realize everyone is getting ready to put their lawns and gardens to sleep for the winter, but come next spring we may be waking to a new dawn in how we have to deal with weeds and bugs.

The Ontario government has just issued draft pesticide regulations for public comment. But obstacles loom large. Dow Chemical, maker of the common herbicide 2,4-D, might challenge the pesticide regulations under the North American Free Trade Agreement (NAFTA).

Perhaps the biggest obstacle we face in this hotly contested issue is that Health Canada tends to shoot us in the foot with the way it regulates all chemicals, pesticides included. They assess chemicals one at a time, even when there are many chemicals that act in the same way or have the same effects. They ignore the real-life human exposures to hundreds of such chemicals and pesticides on a cumulative daily basis.

They did it to us in the NAFTA challenge by Ethyl Corp. on the gas additive MMT. Then environment minister Sheila Copps was embarrassed to find Health Canada statements that there was no neurological health threat at the levels of expected exposure to MMT, and did not support her proposed ban. Ethyl won its case and Canada had to pay a substantial sum in penalty. Health Canada ignored all the other neurotoxic chemical exposures superimposed on MMT and cumulative effects. They have done the same thing with 2,4-D.

If the World Antidoping Agency monitored the use of performance-enhancing drugs by athletes in this way, ignoring the possibility of multiple drug use, each at low levels, the agency's mission would be an obvious farce and the cheaters would go undetected.

Making matters worse with Health Canada regulation is the disingenuous way that "safety" is asserted -- pesticide safety requires that the label directions be followed. Logically then, if the label directions are impossible to follow in practice, it is also impossible to declare a pesticide safe. There are the makings of fallacy in this kind of regulatory definition of safety.

So what does "label directions" or "used as directed" really mean in practice? According to the industry "master label" for 2,4-D, there are a great many restrictions and directions across a wide variety of applications. Of particular interest to local pesticide bylaw debates are label directions for various kinds of turf or grasses, such as parks, lawns, sports fields, cemeteries and golf courses.

As health effects require a mode of exposure, the use directions aim at preventing exposure associated with pesticide application. So there are directions that forbid applications that will contact, or expose, any person or pet, either directly, indirectly or by drift.

These instruct to keep people and pets away from the area during application, and to not allow entry until wet sprays have dried, or dry dust has settled. There is a short time restriction on entry for residential uses that contrasts with numerous commercial applications, including seed and sod grasses, where there are 12 to 48 hour re-entry restrictions, despite similar applications rates.

No more than two applications a year, including spot treatments, are allowed, while directions advise application when weeds are young and actively growing for effectiveness.

For spray applications, the factors of wind direction, wind speed, temperature and relative humidity must be evaluated. Use directions forbid applications at wind speeds above 15 mph.

At wind speeds below 3 mph, applications are not allowed during temperature inversions or stable atmospheric conditions. As well, 2,4-D may volatilize during conditions of low humidity and high temperature, so directions say don't apply during such conditions.

Directions indicate that all local laws and requirements must be followed, and if they are more restrictive they must be observed.

That all these label directions are followed in practice is the assumption that justifies the defined safety and acceptability of use. But what's the reality?

It's impossible to keep all people and all pets out of, and off, pesticide-treated areas. Pets in turn track it into the house and spread it around. So do children at play.

It's common to see ordinary people and commercial lawn care companies apply pesticides in all manner of weather, temperatures and wind conditions. It's also common to smell the evaporation of the applied pesticide wet solutions, or granules, drifting through the neighbourhood.

The lawn companies keep to their appointed rounds, just like the proverbial mailman, through wind, heat, rain or storm. They need to in order to stay in business.

The direct exposure from being around the applications areas are not the only ones. Indirect exposures abound. 2,4-D has been measured in indoor air and on surfaces inside homes, including carpets, and is associated with dust.

As well, 2,4-D contaminates rain, sometimes exceeding guidelines, and is observed in urban and agricultural streams and rivers, and in urban stormwater retention ponds. Other exposures can be from food and drinking water.

Human and animal exposure certainly occurs, and has been measured in the urine of adults and children in the general population. Higher levels in urine and semen are detected in occupational herbicide and agricultural workers, and their children. According to the most recent data from the Centers for Disease Control and Prevention in the U.S., these general population exposures have been increasing.

The group of chemicals that includes 2,4-D is considered possibly carcinogenic in humans by the International Agency for Research on Cancer. This chemical group has been associated since the 1970s with increased cancer risks from soft tissue sarcoma, malignant lymphoma, non-Hodgkin lymphoma, prostate cancer and a variety of other cancers, in exposed populations.

These chemicals have also been associated with increased rates of birth malformations and other adverse birth outcomes in U.S. wheat-producing states. The rates were the highest for births conceived in the spring, peak time for herbicide application.

There are other suspected health effects also associated with 2,4-D, and all the other co-exposures to hundreds of other pesticides and industrial chemicals. But that evidence is beyond the present space.

The bottom line is that the claim by Health Canada and industry that 2,4-D use is "safe" (provided the label directions are followed), still puts the exposed populations in the red.

Are you feeling safe yet?

Tom Muir is an environmental economic scientist retired from Environment Canada and living in Burlington.

© 2008 Torstar Corporation