Environmental Engineering Reference
In-Depth Information
suggested that pesticide exposures can cause neuroblastoma, brain tumors,
and hematological abnormalities in children.
Leukemia in very young children has been epidemiologically associated
with the use of pest strips during the last 3 months of pregnancy, as well as
other exposure periods. Pest strip exposures have also been associated with
leukemia and brain cancer in older children. Dichlorvos, the pesticide used
in pest strips at the time of these studies, is a known animal carcinogen and
has been associated with leukemia in adult men. Lymphoma in children has
been associated with use of insecticides.
Childhood brain cancer has been linked with pesticide exposures in
some studies but not others. Recently, significant positive associations have
been observed between childhood brain cancer and the use of herbicides to
control weeds, as well as a variety of pesticides: bug bombs, termiticides,
flea collars on pets, Kwell (a lice control agent), and garden/orchard pesti-
cides (including carbaryl). Notably high statistical associations were
observed with potential infant exposures (particularly from birth to 6 months
of age) to pesticides used on pets.
d. Immunological effects.
Concern has been expressed that pyrethrins
and synthetic pyrethroids can induce allergic reactions. Such responses have
yet to be systematically investigated.
In case-control studies of very small populations, significant immuno-
logical effects at the cell level have been reported for apparent exposures to
PCP, chlordane/heptachlor, and chlorpyrifos. Individuals exposed to PCP-
treated log homes had activated T-cells, autoimmunity, functional immuno-
suppression, and B-cell disregulation. Activated T-cells, autoimmunity, and
functional immunosuppression have also been reported for exposure to chlo-
rdane/heptachlor. Immunological abnormalities have also been reported in
individuals apparently exposed to chlorpyrifos. Dose-response relationships
for these chemicals have yet to be demonstrated to establish a definitive link
between exposure and immunological changes.
The health significance of such changes is unknown. It may include an
increased risk of infection, development of sensitivity to a variety of aller-
gens, increased prevalence rates of chronic allergic rhinitis and asthma,
development of autoimmune diseases such as lupus, and cancer. Since a
number of studies have demonstrated a link between decreased immune
function and increased risk of cancer, this may explain, in part, the reported
increased risks of leukemia and lymphoma in children.
e. Other health concerns.
A new concern has recently been raised rel-
ative to chlorinated hydrocarbon pesticide exposures. These pesticides, as
well as other chlorinated substances such as dioxins and PCBs, have been
observed to be endocrine disruptors in animals; i.e., they mimic the action
of the female hormone, estrogen. Relatively low exposure levels of estrogen-
mimicking substances may cause reproductive changes in males and increase
