Americas children today are generally healthier
and better nourished than at any time in history, but as research
in humans and animals progresses, scientists are beginning to verify
just how dangerous some synthetic chemicals are to human health
especially to children. While a great deal of uncertainty
remains, a growing body of peer-reviewed scientific literature strongly
suggests that the young are far more susceptible to toxic effects
- Children get heftier proportional
doses of pollutants because of their small sizes.
"Children eat, drink, and breathe more for their body weights
than adults do, so they get bigger proportional doses of whatever
is out there," explains University of Pittsburgh School
of Medicine psychiatrist Herbert Needleman, who pioneered studies
linking lowered intelligence with early childhood exposures
- Faster metabolisms in children
speed up their absorption of contaminants. Children
absorb a greater proportion of many substances from the intestinal
tract or lung, says pediatrician Dr. Philip Landrigan,
Chairman of Community and Preventive Medicine at the Mount Sinai
School of Medicine in New York, and a former senior adviser
to EPA on Childrens Health and the Environment. For
example, children take up approximately half of the lead that
they swallow while adults absorb only about one-tenth.
- Children live closer
to the ground, where the highest concentrations of many air
pollutants settle. They play in the dirt and on carpets
where they are exposed to contaminants that attach to dust particles.
In a 1998 study to investigate a possible association between
cancer risks and pesticides in house dust, the National Cancer
Institute found residues of 31 chemicals in carpet dust samples
from 15 Washington, DC area homes. The NCI found seven organochlorine
pesticides, including DDT, Methoxychlor, heptachlor, and chlordane,
three highly toxic carbamates, five types of PCBs and other
potentially toxic chemicals.
- Children spend a considerable
amount of time putting things in their mouths. In
1998, scientists at Rutgers University discovered that pesticides
sprayed in a home evaporate from floors and carpets, and then
re-condense on plastic and foam objects such as pillows and
plush toys. By observing how frequently a group of pre-schoolers
put clean toys in their mouths, the researchers calculated that
contaminated toys are likely to give young children much higher
doses of poison than adults would get in the same environment.
- Babies don't excrete contaminants
or store them away in fat in the same ways that adults do, making
the poisons more available to affect rapidly growing bodies.
Furthermore, because a babys immune system is not fully
functional, a babys body cannot counteract toxic effects
as well as an adult can. In an adult, a blood-brain barrier
insulates the brain from many of the potentially harmful chemicals
circulating through the body. But in a human child, that barrier
isn't fully developed until six months after birth.
- Many contaminants such as
dioxins and PCBs have an affinity for fatty tissue.
During pregnancy, women mobilize their amassed stores of body
fat to provide nourishment for their growing babies; the contaminants
in the fat are then passed to their children. Nursing mothers
also transfer a good portion of their lifetime accumulation
of chemicals to their babies.
- Children exposed in the
womb are at greatest risk of all.
Because cellular structures change so rapidly during embryonic
and fetal growth, a toxic exposure at the wrong moment can permanently
alter further development. According to Dr. Landrigan, the central
nervous system is especially vulnerable. To function properly,
the developing brain must lay down an intricate web of interconnecting
neurons. Small doses of neurotoxins during critical periods
of brain development can alter those crucial neural pathways
one mistake early on, and the brain may be forever changed
in subtle or serious ways. Government and university scientists
are currently investigating the possibility of a connection
between fetal exposures to toxics and developmental disabilities
such as attention deficit hyperactivity disorder (ADHD).
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