by the rising numbers of asthma and allergy-addled kids, some
researchers are pointing the finger at too-clean home environments and
overzealous parenting practices.
Generally referred to as the “Hygiene Hypothesis,” the theory that kids’
immune systems need to interact with harmless bacteria in order to
develop properly has been around since the late eighties.
After finding that households with large families recorded fewer
instances of atopic disorders (asthma and allergies) epidemiologist David
Strachan of the London School of Hygiene and Tropical Medicine concluded
that “unhygienic” sibling traffic may be good for a child’s immune
system.
The theory posits that when forced to take a defensive position against
infection, a child’s immune system receives essential early training on
how to process irritants and may be less likely to overreact to allergens
like dust, animal dander and pollen later on. Taking his findings
further, Dr. Strachan theorized that smaller family sizes and
consequently higher standards of cleanliness in the modern household
might hinder this necessary training.
As a consequence of the work of Dr. Strachan and others, some now believe
that early exposure to innocuous bacteria boosts immune system tolerance
and reduces the risk of a child developing allergies.
“Children’s exposures early in life may influence which way their immune
system develops, although not necessarily a ‘healthy immune system’.
Cleaner environments appear to foster the development of allergies, as
opposed to children in ‘dirtier’ environments. A child’s genetic
background has an influence on this as well. Homes with pets, or living
on farms with close contact to farm animals appears to decrease the
development of allergies. It appears that the immune system requires
exposure to bacteria in order to develop properly. Exposure to cleaning
agents and other strong fumes, or to dust, may cause irritation of the
respiratory system, but doesn’t appear to adversely affect the immune
system directly,” says Dr. Paul V. Williams, allergist/immunologist at
the Northwest Asthma and Allergy Center in Mount Vernon, Washington.
Dr. Williams is quick to point out, however, that kids who suffer from
allergies do not have “bad” immune systems.
“It is a common misconception that people with allergies have a ‘weak
immune system’ and they need to do something to ‘strengthen’ their immune
system. In fact, their immune system is quite healthy, it just responds
in a different fashion to common environmental exposures that ordinarily
would not induce any response at all in those with a non-allergenic
disposition. Children with allergies are not more prone to infections or
more severe infections on the basis of an altered immune system.”
Many in the scientific community emphasize that the hygiene hypothesis is
only theory. In fact, researchers are engaged in looking at a variety of
factors, including diet and environmental pollution, to explain the
increased numbers of asthma and allergy cases. Moreover, others see the
idea as an oversimplification, claiming that while exposure appears to be
a significant factor in building a better working immune system,
determining what is an appropriate level of cleanliness is problematic.
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