DDT, Chlordane, Toxaphene and PCB Residues in Newport Bay and Watershed: Assessment of Hazard to Wildlife and Human Health - Reviews of Environmental Contamination and Toxicology - page 146

5.1.3 Water Column

Ninety water samples collected from 2002 to 2009 have been analyzed for toxa-
phene (Bay and Greenstein 2003 ; Orange County Watersheds (see footnote 8)).
Only one sample contained detectable toxaphene. The detected level was 5.5 pptr,
which was less than the stated detection limit of 10 pptr.

5.1.4 Fish and Mussels

In the case of red shiner, toxaphene tissue concentration data dating from 1983
show a substantial decline (see Figs. 29 and 30 ). Red shiner may be taken as an
indicator of toxaphene concentrations in receiving waters within the watershed, as
red shiners are a local, short-lived species. The primary statistical approach to estab-
lishing the declining trend in toxaphene concentrations in the watershed has been to
derive fi rst-order decay constants using historical toxaphene data for red shiner fi sh
tissue. The equations of these curves are indicated in Fig. 29 .
When all red shiner data are considered together, a statistically strong (R 2 value
of 0.671) downward trend in toxaphene concentration is evident. The statistical
analysis that characterizes these trends was confi rmed by splitting the data set for
red shiners into two separate sets consisting of the fi rst 10 years of data (1983-1992)
and the second 10 years of data (1993-2001). Calculated fi rst-order decay rates for
the red shiner toxaphene data are statistically similar for the full data set and for the
sub-sampled datasets. The decay rate (−0.00055 per day or −0.20 per year) obtained

9000

8000

7000

6000

5000

4000

3000

2000

1000

0

Jan-80 Jan-85 Jan-90 Jan-95 Jan-00 Jan-05

Date

y = 2E+11e -0.0006x
R 2 = 0.2377

y = 3E+09e -0.0005x
R 2 = 0.4879

y = 8E+13e -0.0008x
R 2 = 0.5181

Red Shiner (1983-1992) Red Shiner (1993-2001) Red Shiner (1983-2001)

Expon. (Red Shiner (1983-1992)) Expon. (Red Shiner (1993-2001)) Expon. (Red Shiner (1983-2001))

Fig. 29 Toxaphene concentrations in red shiner, San Diego Creek and Peters Canyon Wash
(1983-2001). Source : California Toxic Substances Monitoring Program ( 1983 -2002). Red shiner
data from 2002 to the present are not available