1.1 MB pdf - Bolsa Chica Lowlands Restoration Project

SECTION 4: RISK CHARACTERIZATION
with HQs of 5 and 8.4, respectively. Chemicals exceeding chronic LOECs included
14 inorganics and 3 organics with HQs ranging from 1 for cadmium to 480 for lead. These
chemicals are considered to pose a possible risk to terrestrial plants (Category B). Of those
chemicals exceeding chronic LOECs, 4 were evaluated using an exposure point
concentration that was ½ the reporting limit for a non-detect.
Aquatic Invertebrates
Evaluation of potential toxicity to aquatic invertebrates (Table 4-3) indicated that 9 inorganic
and 21 organic chemicals had probable (Category A) risk based on exceedance of an acute
RTV (ER-M or LC 50 ). Only two chemicals, nickel and zinc, exceeded both the ER-M and the
LC 50 . The HQs for these were similar between the two RTVs. All HQs for ER-M and LC 50
exceedances were less than 10 with the exception of lead (44), chlordane-technical (18), and
total PCBs (16) for ER-M and endrin aldehyde (14), endrin ketone (200), fluorene (32), TPHdiesel
(17), waste oil (13), and combined TPH-diesel plus waste oil (14 ) for the LC 50 .
Chemicals with possible risk (Category B) included 4 inorganics and 6 organics. Chrysene was
the only chemical that exceeded both the ER-L and LC 20 . Cadmium, mercury, anthracene,
benzo(a)anthracene, and naphthalene exceeded the ER-L but not the LC 20 . HQs among this
group ranged from 1.2 (benzo[a]anthracene) to 4.4 (mercury). Chemicals that exceeded the LC 20 ,
but not he ER-L included beryllium, vanadium, benzo(b)fluoranthene, and total PAHs. HQs
among this group ranged from 2.0 (vanadium) to 13 (benzo[b]fluoranthene).
Some possible risk (Category C) was estimated for silver, benzo(a)pyrene, fluoranthene,
pyrene, and high MW PAHs based on exceedance of the no-effect level (Nereis NOEC) but
not exceeding a low-effect level. The NOEC HQs for these chemicals ranged from 5.8 to 78.
Similarly, there were several chemicals that have uncertain risk (Category U) based on
exceedance of the Nereis NOEC. However, there was no other RTVs available for these
chemicals so the risk estimates may be overestimated.
Two toxicity bioassays were conducted using the marine amphipod (Eohaustorius estuarius)
with sediment collected from the Muted Tidal area (Table 3-14). One sample was significantly
different from controls for survival. Neither was significantly different for reburial.
Two sediment bioaccumulation studies were conducted using the clam worm Nereis viriens.
None of the samples were significantly different from controls for survival, but they were
significantly different for bioaccumulation of nickel in Cell 60, and lead and zinc in Cell 67.
Semi-Aquatic Birds
Risk estimates for semi-aquatic birds indicate that metals and pesticides pose the greatest
potential for adverse effects (Table 4-2). The tern was the most sensitive receptor in all cases.
Chemicals with possible risk (Category B) included cobalt, lead, zinc, and 4,4’-DDE for both
heron and tern); and copper and Aroclor 1254 for tern. The NOAEL HQs for these chemicals
ranged from 3.5 for copper to 273 for lead, both for tern. The LOAEL HQs for these
chemicals ranged from 1.3 for cobalt (heron) to 80 for 4,4’-DDE (tern). Three chemicals
showed some possible risk (Category C), cobalt (stilt), copper (heron), and lead (stilt).
Several chemicals had uncertain risks (Category U) because although they exceeded the
NOAEL, LOAELs were not available. These included barium, chromium, selenium,
vanadium, 4,4’-DDD, 4,4’-DDT, and dieldrin. The NOAEL HQs for these chemicals ranged
from 1.1 for chromium (stilt) to 243 for selenium (tern).
SAC/143368(004.DOC) 4-13 ERA REPORT
7/31/02