How does one prevent exposures?



baby walking

Neurobehavioural Effects

What is the concern regarding neurotoxic substances?

Substances that are neurotoxic alter the normal developmental path of a childís brain and nervous system. We have learned that even subtle changes in neurodevelopmental processes can permanently affect the way the nervous system functions and can produce changes in cognition and behaviour.

As recent reviews have suggested, the threat of exposure to neurotoxins is not merely hypothetical or potential, but is absolutely real and yet preventable. We know from both animal and human studies that a number of substances liberally emitted into our environment are neurotoxic. There is also evidence of adverse effects from some of these substances at current Canadian environmental concentrations.

Lastly, there is a great deal of uncertainty when it comes to neurodevelopmental effects. There appears to be an increasing prevalence of cognitive and behavioural problems in children. Researchers suggest this is linked to the considerable volumes of neurotoxins emitted regularly into the environment. There is an enormous societal cost in terms of the profound health compromise to the many children potentially exposed to environmental neurotoxins.

What substances can affect neurobehavioural development?

Among the major substances that are toxic to developing nervous systems and that are present in the Canadian environment at levels of some concern are:

  • Heavy metals such as lead, mercury, and manganese
  • Persistent organic pollutants such as PCBs, dioxins, DDT and other organochlorine pesticides
  • Pesticides of the organophosphate and carbamate type

How are children exposed to neurotoxic substances?

Most of our harmful exposures to neurotoxins come through the diet, through food and water, although in some cases they can be inhaled via air. In addition, children may be exposed in the womb, during infancy via breast milk and from consumer products that contain or harbour such contaminants.

What are the potential health effects from neurotoxins?

There is a spectrum of effects depending upon a) the dose and b) the timing of exposure. The range of neurotoxic effects includes fetal death, malformations, altered growth and functional abnormalities. Attention has been focused of late on the potential role of low levels of neurotoxins in contributing to subtle, yet important, functional changes such as developmental delays, behavioural problems, attention problems/hyperactivity, poor school performance and learning disabilities.

Why are children more vulnerable to effects from neurotoxins?

Children are more vulnerable due to a) developmental and b) behavioural differences. There are numerous, sequential windows of vulnerability for the brain and nervous system because of the complexity and distinct timing of the many processes involved. The most critical periods of exposure are in utero and during infancy. Childrenís exploratory and hand-to-mouth behaviours mean they are more exposed to environmental neurotoxins.

What can you do personally to prevent exposures?

Because of the broad window of susceptibility of the brain and nervous system and the brainís inability to readily repair cells after injury, once neurodevelopmental effects are apparent, they are unfortunately often permanent. Therefore, avoiding exposures before they happen and before they can do greatest harm is the key strategy for personal prevention. Physicians can counsel patients on choices in their diet and regarding personal activities, particularly if they are considering having children or are pregnant.

What do we do as a society to prevent these exposures?

Personal prevention strategies are only half measures at best, however. CAPE joins other health advocacy organizations in Canada and the United States in calling for precaution in health policies and environmental regulations to prevent harm to childrenís health from neurotoxic contaminants. This is crucial when there is a great deal of scientific uncertainty combined with the risk of exposure and harmful effects for considerable numbers of children.


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