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 145

5 Toxaphene

5.1 Levels in the Environment

The following sections present available toxaphene data for Newport Bay and
Watershed. Trends in toxaphene concentrations—particularly fi sh tissue concentra-
tions—are evident in data collected for 20 years in Newport Bay and Watershed.

5.1.1 Agricultural Soils

For toxaphene there were fewer agricultural soil data available than for DDT. As with
DDT data, samples from different years were taken in different locations since the
purpose of sampling was to assess site conditions for planning and development pur-
poses, not to establish concentration trends over time in the watershed. The majority
of toxaphene soil samples returned concentrations below detection limits (Table 32 ).
For example, for 2004 data, all 275 soil samples yielded concentrations below the
analytical detection limit of 0.1 ppm. Although no statistically clear trends in soil
toxaphene concentrations can be demonstrated from a data set in which roughly 90%
of samples have toxaphene concentrations below detection limits, and in which sam-
ples were not taken at the same locations over time, it appears from these data that the
mass of toxaphene in the watershed is currently quite small. This is consistent with
expectations based upon the half-life of toxaphene, as detailed below.

5.1.2 Sediments

Toxaphene was detected in only one of 42 sediment samples collected from 2005 to
2008. 8 The one sample had a toxaphene residue of 31.7 ppb. The detection limit for
all 42 samples was 10 ppb. The most recent analysis of sediments in 2011 (Orange
County Watersheds 2013 ) found no toxaphene above high detection limits that
ranged from 70 to 1,900 ppb.

Table 32 Toxaphene concentrations in agricultural soils in the Newport Bay Watershed

0-12 inch Sample Depth 12-24 inch Sample Depth

>24 inch Sample Depth

Range of
Detected
Toxaphene
(ppm)

Range of
Detected
Toxaphene
(ppm)

Range of
Detected
Toxaphene
(ppm)

Total Non-
detect
Samples

Total Non-
detect
Samples

Total Non-
detect
Samples

Detection
Limits
(ppm)

Year Total

Samples

Total
Samples

Total
Samples

1989 0.500 - 0.940 3 0 0.540 - 0.550 3 1 -- 3 3 0.25

1990 0.190 - 0.220 2 0 -- 1 1 -- 3 3 0.16

1995 -- 19 19 0.06

2000 -- 28 28 0.20 & 2.00

2002 0.340 - 2.300 174 125 0.210 - 0.300 27 24 --

2004 -- 230 230 -- 45 45 0.10 - 10.0

2006 -- 6 6 -- 6 6 0.10

Sources : Unpublished technical reports provided by The Irvine Company (1989-2006)
Data were not available for shaded areas

8 Personal communication from Amanda Carr at Orange County Watersheds.