Environmental Engineering Reference
In-Depth Information
Pesticide use was observed to be high among Missouri households in
which a child had been diagnosed with cancer, as well as in a smaller number
of households in which no cancer was reported. Nearly 98% of approxi-
mately 240 families surveyed used pesticides at least once per year; 67% 5
times or more per year. Eighty percent used pesticides during pregnancy,
and 70% during the first 6 months of the child's life.
Though significant pesticide use was directed to controlling weeds (57%)
and to gardens and orchards (33%), the primary area for pesticide use was
inside the home itself (80%). Over 50% of surveyed families used flea collars
and/or shampoos to control fleas or ticks on pets. A limited number used
no-pest strips (9%) and Kwell (9%), a lice control product. The active ingre-
dients in these products were dichlorvos and lindane, respectively, both
suspected carcinogens.
Pesticide exposures of children in residences, not surprisingly, vary con-
siderably. They depend on the nature and extent of pesticide use in the home,
on lawn and gardens, and by occupants such as farm workers and commer-
cial applicators. They also depend on the type of pesticides that are used, as
they vary in volatility and persistence.
Like adults, children can be exposed to pesticides by inhalation, inges-
tion, and dermal contact. Toddlers are more likely to both ingest and der-
mally contact pesticide residues present in household dust and on surfaces
because they play on floors and engage in hand-to-mouth behavior. As
indicated in Chapter 2, such play and mouthing behavior (hands, toys, and
other objects and surfaces) is considered to be the major pathway for child-
hood lead exposures and elevated blood lead levels.
Uptake of pesticides based on mouthing behavior is inferred from stud-
ies on house dust/outdoor soil ingestion and blood lead. Though infant
children and toddlers spend more time indoors playing on dusty surfaces,
ingestion rates of household dust have not been determined.
An attempt was made in USEPA's NOPES study (described previously),
to assess pesticidal exposures to children by both inhalation and dust inges-
tion and to provide cancer risk assessments. The data suggest that dust
ingestion constitutes a substantial portion of a child's pesticide exposure in
some houses. It also suggests that many young children may be exposed to
a greater range of pesticides through ingestion than inhalation since more
pesticides are found in house dust than in air samples.
Many pesticides can be absorbed through the skin and move into the
bloodstream. Though the potential for significant dermal exposure for infant
children and toddlers exists, the magnitude of this exposure pathway has
received relatively limited scientific evaluation.
Most investigations of residential pesticide exposure have focused on
airborne concentrations based on fixed area sampling devices. Though some
have demonstrated differences in air concentrations as a function of height
(higher concentrations near the floor), such differences apparently do not
persist after pesticide application. If they did, children playing at floor level
would be expected to be exposed to higher air concentrations than adults.
