Carbaryl, Carbofuran, and Methomyl - National Marine Fisheries ...

Monitoring Data from California Department of Pesticide Regulation
We evaluated monitoring data available from the CDPR, which maintains a public database of
pesticide monitoring data for surface waters in California (CDPR 2008). Data were available for
carbaryl, carbofuran, methomyl and 3-hydroxycarborfuran (a degradate of carbofuran), but not 1napthol.
Data in the database (http://www.cdpr.ca.gov/docs/emon/surfwtr/surfdata.htm) are from
multiple sources, including monitoring conducted by CDPR, USGS (data from the NAWQA
program as well as other studies), state, city, and county water resource agencies; and some nongovernmental
or inter-governmental groups such as Deltakeeper. The CDPR requires a formal
QA/QC protocol for data submitted or does a separate QA/QC review, thus only data subject to
appropriate QA/QC procedures are included in the surface water database. Unlike the USGS
NAWQA data set, the CDPR database may contain whole water samples as well as filtered
samples. If whole water concentrations are reported for compounds that sorb significantly to the
particulate phase, concentrations would appear higher than in a filtered sample, which represents
only the dissolved phase. The majority of the studies, which are described in metadata available
from CDPR, are not targeted at correlating water concentrations with specific application
practices, with the exception of some studies evaluating rice pesticides.
Summary information for carbaryl, carbofuran, methomyl, and 3-hydroxycarbofuran is reported
below (Table 55). No monitoring for 1-napthol was reported in the database. The database, last
updated in June 2008, consists of approximately 270,000 data records. Each record reports a
specific sampling site, date, and analyte. The number of records associated with a particular
compound is indicative of monitoring intensity rather than actual occurrence in surface waters.
In this database, detections below the LOQ are reported as 0 μg/L. Summary statistics were
calculated on samples with values above the LOQ.
Carbaryl (5,265 records) and carbofuran (5,864 records) were the subject of greater monitoring
intensity than either methomyl (1,982 records) or 3-hydroxycarbofuran (1,149 records).
Quantifiable amounts of methomyl appeared in 11.0% of the samples. Carbaryl (3.6%) and
carbofuran (5.9%) were quantifiable less often, and 3-hydroxycarbofuran (0.3%) was only rarely
quantifiable. Quantifiable concentrations ranged from 0.0030 – 8.4 μg/L for carbaryl, 0.0066 –
294