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 133

Elliot et al. ( 1989 ) concluded that DDE levels were well below concentrations
known to reduce reproductive rates or survival in related species elsewhere.
With critical egg residue levels for hatching failure in the range of 3-4 ppm for
sensitive species, Wilson's storm petrel appears to be an inappropriate choice for a
protective rate of food intake. The protocol document lists many species that are
consumers of aquatic biota. In this list, the osprey appears to be the most sensitive
species. The daily food intake rate for the osprey is listed as 0.2 kg/kg body weight-
day. If one considers both the rate of food intake and reproductive effect threshold
to DDE as a measure of sensitivity to DDE, the osprey appears to be the most sensi-
tive among the listed species.
Using the Environment Canada method, the reference concentration can be cal-
culated directly from the ppm DDE in the sparrow hawk diet. If one divides the
3 ppm dietary level, a level that produced 15% shell thinning, by an uncertainty
factor of 10, the maximum NOEL for reproduction in the most sensitive species is
0.3 ppm or 300 ppb in the diet. Assuming the osprey is the most sensitive species,
with a food consumption rate of 0.2 kg/kg (Table 1 in the Protocol document) and
the sparrow hawk with a food consumption rate of 0.167 kg/kg (calculated from
data in Appendix 16 of the Assessment document), the reference concentration in
fi sh is 300 ppb × 0.167/0.2 = 250 ppb.
The reference concentration (which becomes the tissue reference guideline or
TRG) calculated above is 18 times higher than that recommended by Environment
Canada. Environment Canada's 18-fold lower TRG is due to the use of shell thin-
ning instead of hatching failure as the toxic endpoint and using data from an insensi-
tive species for estimating the maximum food intake rate.
The Canadian guidance is 11 times more protective than the 150 ppb fi sh residue
level that is the basis for the National criterion as well as a level protective of osprey
derived in this review. Not every community can afford a level of protection as high
as that provided by the Canadian guidance. Lower levels of protection have been
shown to provide healthy wildlife populations at far less expenditure of limited
resources. Continuing declines in fi sh residues of the DDTs will continue to increase
the degree of protection for wildlife.

3.2.5 US EPA Region IX BTAG Fish Guidance to Protect Wildlife

The Navy/US EPA Region 9 Biological Technical Assistance Group (BTAG) devel-
oped toxicity reference values (TRVs) for ecological risk assessments. BTAG TRVs
have been published by the California Department of Toxic Substances Control
( 2008 ). For the DDTs, the low TRV is 0.09 mg/kg-day. This value is borrowed from
the US EPA Great Lakes Criteria (US EPA 1995 ). The US EPA derived the TRV
from the Anderson et al. ( 1975 ) fi nding of a LOEL at 150 ppb DDTs in northern
anchovy. The TRV is three times more protective than the US EPA national water
criterion that also relies on the Anderson et al. ( 1975 ) study. The difference in the
two US EPA criteria is the use of an uncertainty factor of 3 in the Great Lakes crite-
rion to estimate a NOEL from a LOEL. This value for uncertainty was used despite
the authors acknowledging that DDTs in brown pelicans and northern anchovies