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Feb. 3, 2005
Published March 24, 2005


Human Exposure and Health Hazards - Pt. 1

by Anne Steinemann*

United States environmental regulations, intended to protect human
health, generally fail to address major sources of pollutants that
endanger human health. These sources are surprisingly close to us and
within our control, such as consumer products and building materials
that we use within our homes, workplaces, schools, and other indoor
environments. Even though these indoor sources account for nearly 90%
of our pollutant exposure, they are virtually unregulated by existing
laws. Even pollutant levels found in typical homes, if found outdoors,
would often violate federal environmental standards.

This article examines the importance of human exposure as a way to
understand and reduce effects of pollutants on human health. Results
from exposure studies challenge traditional thinking about pollutant
hazards, and reveal deficiencies in our patchwork of laws. And results
from epidemiological studies, showing increases in exposure-related
diseases, underscore the need for new protections. Because we cannot
rely solely on regulations to protect us, and because health effects
from exposures can develop insidiously, greater efforts and innovative
policies are needed to reduce and prevent significant exposures before
they occur.

Pollutant Exposure Studies: Surprising Results

Numerous studies on personal exposure to pollutants have revealed some
startling results (Wallace, 1987, 1991, 1993; CDC, 2001, 2003; EWG,

We are regularly exposed to many toxic chemicals and carry them in our
bodies, as evidenced by samples of human blood, breath, hair, tissue,
and body fluids.

Most of our exposures to these chemicals are not from sources
traditionally regulated, such as remote waste sites and factories.
Rather, the primary sources are close to us: within our indoor
environments, and the personal activities, products, and materials
inside those environments.

Of more than several hundred pollutants regulated by federal laws, all
but a few are higher indoors than outdoors, due to indoor sources.

The sources of these pollutants are largely unregulated -- meaning
that our environmental regulations, designed to protect and promote
human health, are missing major sources of health risks.

The public is generally unaware of these types of everyday exposures,
their health consequences, and the relatively simple and cost-
effective actions that could reduce health risks.

Exposure Science: Measuring Pollutants that Affect Humans

The science of human exposure emphasizes an important but often
overlooked fact: The pollutants that affect human health are those
that come in contact with humans (Ott, 1985). In this way, exposure
science differs from traditional approaches to environmental
management. Instead of identifying a pollutant source and then trying
to trace emissions through the environment to see who or what might be
affected, exposure science starts with the receptor of those
pollutants -- humans. It identifies and measures the pollutants that
have reached humans, and then traces the pollutants back to their
sources. If a goal of environmental regulations is to protect and
promote human health, then we need to address not only the pollutant
sources but also the receptors.

Advances in the science of exposure assessment have enabled
researchers to measure, with great accuracy, the types,
concentrations, durations, and locations of human exposure to
environmental pollutants. These advances are technological, such as
the use of highly sensitive analytic instruments and portable exposure
monitors, and methodological, such as the use of sophisticated
probability sampling designs in large-scale field studies (Ott and
Roberts, 1998).

In the 1980s and 1990s, the U.S. Environmental Protection Agency (EPA)
and other researchers conducted the landmark TEAM (total exposure
assessment methodology) studies that measured personal exposures to
pollutants. These studies monitored more than 3,000 participants, in
18 U.S. urban and suburban cities and one Canadian province, for
exposure to volatile organic compounds (VOCs) (Wallace, 1987; Wallace
et al., 1991; Wallace, 1993), pesticides (Immerman and Schaum, 1990;
Whitmore et al., 1994), carbon monoxide (Akland et al., 1985),
particles (Ozkaynak et al., 1996a,b; Pellizzari et al., 1993),
phthalates (plasticizers) and polycyclic aromatic compounds (PAHs)
(Sheldon et al., 1993), among other pollutants. The participants
carried around personal exposure monitors that indicated what, how
much, and where pollutants were affecting them. In addition, the VOC
and CO studies measured breath levels of 2000 participants to detect
the chemicals in their bodies (Wallace et al., 1986; Wallace et al.,

These studies produced a compelling finding: Most of our exposure to
pollutants occurs indoors, and from products that we choose to use.
This result contradicted conventional thinking, and conventional
regulation, that focus on outdoor sources of emissions rather than
indoor and personal sources of exposures.

What and where are these pollutant sources? Studies identified the

** consumer products, such as air fresheners, deodorizers, cleansers,
disinfectants, personal care products, laundry supplies, moth
repellants, cosmetics, dry-cleaned clothes, solvents, and pesticides.

** building materials and furnishings, such as paints, varnishes,
adhesives, solvents, carpets, vinyl flooring, pressed wood products,
and combustion appliances.

** individual activities, such as bathing and washing in chlorinated
water, burning firewood and candles, refueling an automobile tank, and
cigarette smoking.

Specific results include the following.

** VOC exposures indoors are typically 5 to 50 times higher than
outdoors, even in cities with relatively high levels of outdoor
pollution and heavy industry. New buildings often contain VOC levels
that are hundreds of times higher than outdoor levels (Sheldon et al.,
1988b; Wallace 2001). Common VOCs cause both acute and chronic health
effects, ranging from sensory irritation and headaches, to
neurological damage and cancer (Pierson et al., 1990; Otto et al.,
1990, NIH, 2003).

** Fragranced and scented products represent significant sources of
human exposure to toxic VOCs (Wallace et al, 1986, Wallace et al,
1988); specifically, synthetic fragrances that are found in numerous
consumer products , such as air fresheners, deodorizers, laundry and
dishwashing detergents, chlorine bleach, dryer sheets, and personal
care products such as shampoo, soap, lotions, hairspray, after-shave,
nail polish and remover (EPA 1989b; Sack and Steele, 1992; Cooper et
al., 1992). More than 95% of chemicals used in fragrances are
synthetic compounds derived from petroleum, including benzene
derivatives, aldehydes and many other known toxics and sensitizers
capable of causing cancer, birth defects, central nervous system
disorders and allergic reactions (USHR, 1986; NIH, 2003).

** Pesticide levels can be 5 to 10 or more times higher indoors than
outdoors, even though some pesticides are used only outdoors (Whitmore
et al., 1994). Reasons are that pesticides used outdoors, such as
termiticides, can seep indoors or be tracked inside by shoes; plus,
pesticides can persist much longer indoors where they are protected
from degradation. In addition, past applications of pesticides can
persist in the environment and in human bodies for decades after the
initial application. For instance, the pesticide
dichlorodiphenyltrichloroethane (DDT), which was banned in 1972, was
nonetheless found in carpets of 25% of 362 Midwestern homes (Camann et
al., 2000). In addition, polycyclic aromatic compound concentrations
found in carpet dust of 89% of these homes were more than seven times
the Superfund preliminary remediation goal for outdoor soil. This
implies that an average urban infant, consuming an average of 100 mg.
of dust containing 100 nanograms of benzo(a)pyrene a day, could be
exposed to an amount equivalent to smoking 2.8 cigarettes a day (Ott
and Roberts, 1998).

Partly influenced by the TEAM Study findings, several national and
regional task forces attempted to compare a wide selection of
environmental risks. The consensus was that the risk from indoor air
pollution and consumer products was far greater than most of the other
risk factors surveyed, including hazardous waste sites and outdoor air
pollution (EPA 1987, 1988a, 1989a; Omenn, 1997).

The U.S. Centers for Disease Control and Prevention (CDC) recently
conducted two nationwide assessments of human exposure to toxic
chemicals in air, water, food, soil, dust, and other media (such as
consumer products). The First National Report on Human Exposure to
Environmental Chemicals (CDC, 2001) presented exposure data for 27
chemicals (lead, mercury, cadmium, and other metals; metabolites of
organophosphate pesticides; cotinine; and phthalates). The Second
National Report (CDC, 2003) included these 27 chemicals and added 89
more, including polycyclic aromatic hydrocarbons; dioxins, furans, and
coplanar polychlorinated biphenyls (PCBs); non-coplanar PCBs;
phytoestrogens; organophosphate, organochlorine, and carbamate
pesticides; herbicides; pest repellants; and disinfectants.

Results showed some success in dealing with prior problems, such as
exposures to lead and environmental tobacco smoke. But they also
revealed new problems. One is exposure to phthalates, which virtually
all Americans now carry in their bodies. Phthalates are found in
numerous consumer products such as soft plastics, pesticides,
pharmaceuticals, lotion, children's toys, adhesives, detergents,
lubricants, food packaging, soap, shampoo, hairspray, nail polish, and
products made from polyvinyl chloride (PVC). Levels of phthalates were
highest in children and women of reproductive age, posing risks of
developmental and reproductive abnormalities, such as infertility,
precocious thelarche (onset of breast development before age eight in
girls), sperm damage, and birth defects (Raloff, 2000; NTS, 2000;
CERHR, 2000). Another is the prevalence of pesticides and the levels
of pesticides, especially in children. Metabolites of the pesticide
chlorpyrifos were nearly twice as high in children (age 6-11) than as
in adults. Metabolites of the organochlorine pesticide DDT were
clearly measurable in young adults ages 12 to 19, even though they
were born after the U.S. ban (CDC, 2003). [For a report on known and
potential health effects of chemicals in these CDC studies, see PSR

A recent exposure study, led by Mount Sinai School of Medicine in New
York, in collaboration with the Environmental Working Group and
Commonweal (EWG, 2003) evaluated nine adult subjects, none of who work
with chemicals, and all of whom were regarded as leading healthy
lives. The study found 167 industrial compounds (average of 91
compounds) in the blood and urine of these subjects, including
breakdown products from organochlorine and organophosphate pesticides,
polychlorinated biphenyls, dioxins, furans, and phthalates. These
chemicals are associated with cancer, brain damage, hormonal
disruption, birth defects, developmental abnormalities, reproductive
system defects, and immune system damage (EWG, 2003; NIH, 2003). Among
the chemicals tested, the most prevalent were 77 semivolatile and
volatile organic chemicals, present in common consumer products,
solvents, cleaners, and paints. None of these 77 compounds was tested
in the CDC studies, and each of them was found in at least one subject
in this study.

Next week: What are the health consequences of these chemicals in our
bodies, and what might we do about them?


* Anne Steinemann holds the title of Professor in the Department of
Civil & Environmental Engineering, and in the School of Public
Affairs, at the University of Washington in Seattle, where she is also
director of the Center for Water and Watershed Studies. This article
is a slightly modified version of "Human exposure, health hazards, and
environmental regulations," Environmental Impact Assessment Review
Vol. 24 (2004), pgs. 695-710.

References for Part 1

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