National Study Shows 82 Percent of U.S. Homes Have Mouse Allergens
Scientists at the National Institute of Environmental Health Science
(NIEHS), one of the National Institutes of Health (NIH), have found
that detectable levels of mouse allergen exist in the majority of
U.S. homes. NIEHS researchers analyzed dust samples, asked questions,
and examined homes in the first National Survey of Lead and Allergens
in Housing, a survey of 831 homes. Allergen levels were studied
and related to demographic factors and household characteristics.
82 percent of U.S. homes were found to have mouse allergens. The
findings by Cohn et al. appear in the June 2004 issue of the Journal
of Allergy and Clinical Immunology.
The survey was conducted using established sampling techniques
to ensure that the surveyed homes were representative of U.S. homes.
The homes were sampled from seventy-five randomly selected areas
(generally counties or groups of counties) across the entire country.
The 831 homes included all regions of the country (northeast, southeast,
midwest, southwest, northwest), all housing types, and all settings
(urban, suburban, rural).
The selection of homes was controlled to be a representative sample
of U.S. homes. For statistics derived from the 831 homes, the contribution
from each home was weighted as necessary to ensure that the statistics
are representative of the U.S. population.
Dust samples used in the study were collected from kitchen and
living room floors, upholstered furniture, beds, and bedroom floors.
Kitchen floor concentrations exceed 1.6 micrograms of allergens
per gram of dust in about one in five homes (22 percent). The amount
of these allergy-triggering particles on the kitchen floor is high
enough to be associated with allergies and asthma. Residents of
high-rise apartments and mobile homes are at greatest risk, but
the allergen is also present in all types of homes.
The NIEHS study, with collaborators at Constella Group, Inc. and
the Harvard School of Public Health, characterized mouse allergen
prevalence in a representative sample of U.S. homes and assessed
risk factors for elevated concentrations. The odds of having elevated
concentrations were increased when rodent or cockroach problems
Exposure to mouse allergen is a known cause of asthma in occupational
settings. Until now, exposure to these allergens had not previously
been studied in residential environments on a national scale. Clinicians
should consider these risk factors when treating allergy and asthma
NIEHS conducts and supports research to reduce the burden of human
illness and dysfunction from environmental causes by understanding
environmental factors, individual susceptibility and age and by
discovering how these influences interrelate.
For further information on study:
Dr. Darryl Zeldin, NIEHS scientist, 919-541-1169
Dr. Rich Cohn, Constella Group, 919-313-7700