were also made. A larger fraction of the population reported using pesticides
at the second interview than at the first interview, with only between
5.6 and 6.7% of individuals reporting use for both time periods.
The low levels of agreement could be due either to actual changes in
use patterns or due to differences in reporting andmay also be partially
responsible for the lack of correlation between questionnaire responses
and house dust concentrations.
Many previous studies have reported that residential pesticide use
questions were ineffective at identifying exposure levels (Sexton et al.,
2003). We also saw a lack of consistency in the relationships between
questionnaire data and measured levels of pyrethroids in the house
dust (Table 4). There was a positive correlation with reported outdoor
pesticide use and pyrethroid levels in the house dust. However there
was no relationship with indoor pesticide use. We found a slightly
negative correlation with outdoor traps and levels of indoor pyrethroids,
suggesting that families that use traps to reduce their pest
problems use less pesticide in their homes. A possible reason for
the lack of correlations between reported pesticide use (especially
indoor pesticide use) and pyrethroid levels found in the home is
that the questionnaire asked about any pesticide products used for
insect control, while we only measured five specific pyrethroid compounds.
It is very likely that products used contained other pyrethroids'
active ingredients as well. There are also likely to be large
discrepancies in the amount of pesticide applied, as well as cleaning
practices between participants. This information was not accounted
for in our questionnaire.
The most promising predictor of exposure was the pesticide inventory.
There was a significant correlation between the pesticide inventory
and the sum of pyrethroid concentrations found in the house dust.
With traditional questionnaires, it is often difficult for participants
to accurately recall pesticide use. The pesticide inventory on the other
hand is relatively easy data to collect, requiring only a few minutes
time for the interviewer to note the pesticide products present in the
participant's homes. Although neither method gives information on
what, or the concentrations of, specific pesticides that may be found
in the physical samples from the home, the pesticide inventory may
be a more useful tool to predict possible pesticide exposure than the
traditional participant recall.