Challenges of the 21st Century - Science For Environmental Protection: The Road Ahead - page 18

technologies will be important in ensuring the net benefit of EPA's efforts. So-
cial-science and behavioral-science research will be critical in helping to design
and evaluate strategies for meeting that challenge.
Transport of Organisms
The geologically recent evolution of life occurred on isolated continents,
each of which evolved a distinctive biota. However, the ever-expanding move-
ment of people and goods has tended to homogenize Earth's biota and resulted
in two increasingly serious environmental problems: the spread of animal-
vectored diseases and the invasion of exotic species. Species are transported
around the world inadvertently on ships, airplanes, and automobiles. Others are
deliberately imported for agriculture, horticulture, biologic control, and recrea-
tion (such as pets or game animals). Most do not become established in the loca-
tions to which they are introduced, and few of the ones that do naturalize disrupt
the local ecologic communities seriously. However, some do become highly
invasive, dominating ecologic communities, spreading diseases, and diminishing
the ability of other species to survive. One example is the impact zebra mussels
have had in the Great Lakes region (Pejchar and Mooney 2009). Zebra mussles
compete with some fish for zooplankton prey, clog intake pipes and impair flow
at water treatment plants, contribute to the bioaccumulation of mercury and lead,
and change nutrient balances in the water resulting in increased phytoplankton
and cyanobacterial blooms. Few studies have been done to try to estimate the
total costs of nonnative invading species at a national level; however, one study
estimates that about $120 billion is spent in the United States per year due to
environmental damages and losses caused by nonnative invading species (Pi-
mentel et al. 2005; Pejchar and Mooney 2009). Increasingly, people are intro-
duced to new exposure pathways and vectors through other animals that are po-
tential carriers of diseases to which humans and other animals lack immunity.
ENVIRONMENTAL AND HUMAN HEALTH CHALLENGES
The patterns of change briefly described above have resulted in a suite of
current and emerging environmental and human health challenges for EPA, such
as
 Human and environmental exposure to increasing numbers, concentra-
tions, and types of chemicals. Factors contributing to human and environmental
exposures include energy choices, technologic change, and changing energy
consumption.
 Threat of deteriorating air quality through changes in weather (Jacob
and Winner 2009) and through the formation of more particles in the atmosphere
from allergens, mold spores, pollen, and reactions of primary air pollutants