When the government of Halifax, Nova Scotia, researched a citywide pesticide ban, they faced conflicting evidence and many questions. Some people argued that pesticides, when used properly, are safe, effective, and beneficial. However, recent science has linked pesticides to health problems, especially in children. With the science still unclear in some areas, should the government take a narrow approach, protecting only people with severe symptoms? Or should it take a broad approach, protecting the entire population?

Scientists understand that people can get sick from pesticides. Acute and allergic effects, like those suffered by Jamie Armstrong, are short-term illnesses caused by one or more exposures to pesticides. Acute effects can be minor or very severe, including seizures, an abnormal heartbeat, and anaphylactic shock (a potentially fatal allergic reaction that involves the whole body). Humans vary widely in their susceptibility to pesticides: some people get sick from one exposure while others do not seem to be affected. However, there is no doubt that pesticides can cause acute and allergic effects.

Chronic, or long-term, effects are more complicated, because it can be difficult for scientists to prove that pesticides, rather than some other environmental factor, caused disease over years of exposure. Some studies, however, show a small risk of cancer, impaired fertility, and birth defects from long-term pesticide exposure, and there is evidence that children and pregnant women are the most vulnerable. Elizabeth Guillette, an anthropologist who studied the effects of chronic pesticide exposure in Mexico’s Yaqui Valley, found that children who were exposed to pesticides had multiple developmental deficits. Similarly, a study by the Canadian Pediatric Society on the herbicide 2,4-D—commonly used to kill dandelions and clover—found that it was “persuasively linked to cancers, neurological impairment and reproductive problems.” Denmark, Norway, and Sweden have all banned it.

In the end the government of Halifax took a broad approach, instituting a citywide ban on the outdoor application of certain pesticides. People can use a number of natural materials to control pests, and pesticides can be used in certain circumstances when insects have infested a property or are dangerous for humans. Since this video was taped, the Canadian provinces of Quebec, Ontario, Prince Edward Island, and New Brunswick have instituted similar bans province-wide.

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