12.Environment Effects
No ecotoxicity tests were provided during the assessment. The following toxicity results have been obtained from the Concise International Chemical Assessment Document (IPCS, 1998) on limonene. Test reports and figures are stated as reported and have not been sighted. No chronic testing on any trophic level appears to have been conducted.
The acute toxicity of d-limonene ranges from slight to high for aquatic organisms. The lowest acute toxicity values (EC50 or LC50) identified were approximately 0.4 mg/L for daphnia and 0.7 mg/L for fish. The no-observed-effect concentration (NOEC) for green algae is approximately 4 mg/L. The acute toxicity (EC50 or LC50) of dipentene to daphnia and fish is about 50-70 times lower than that for d-limonene. Results of ecotoxicity testing of aquatic organisms are summarised below.
12.1.1Toxicity to fish
Table 12.1 - Toxicity to fish (IPCS, 1998)
-
Species
|
Test Isomer
|
Test Duration
|
Test Conditions
|
Result (mg/L)
|
Fathead minnow
(Pimephales promelas)
|
d-Limonene
|
96 h
|
Flow-through
|
LC50 = 0.702
(0.619-0.796)
|
LC50 = 0.720
(0.618-0.839)
|
LC50 = 0.688
(0.606-0.782)
|
dipentene
|
96 h
|
Flow-through
|
LC50 = 38.5
(35.4-41.8)
|
LC50 = 28.2
|
Fish
|
n.s.
|
n.s.
|
n.s.
|
LC50 = 80
|
d-Limonene
|
n.s.
|
Flow-through
|
LC50 = 0.711
|
Golden orfe
(Leuciscus idus)
|
dipentene
|
48 hours
|
n.s.
|
LC50 = 32
|
The results of testing indicate that d-limonene can be considered highly toxic while the racemic mixture dl-limonene is slightly toxic to fish under acute exposure.
Table 12.2 - Toxicity to aquatic invertebrates
-
Species
|
Test Isomer
|
Test Duration
| Test Conditions |
Result (mg/L)
|
Reference
|
Water flea
(Daphnia magna)
|
d-Limonene
|
48 h
|
Flow-through
|
LC50 = 0.577
(0.496-0.672)
|
IPCS, 1998
|
EC50 = 0.421
|
n.s.
|
n.s.
|
n.s
|
LC50 = 39
|
dipentene
|
48 h
|
Flow-through
|
LC50 = 31
(27.5-34.8)
|
EC50 = 28.2
|
Water flea
(Daphnia pulex)
|
d-Limonene
|
48 h
|
Flow-through
|
LC50 = 0.730
|
n.s.
|
48 h
|
Static
|
LC50 = 69.6
|
Daphnia
|
d-Limonene
|
21 d
|
Structure-activity relationship (SAR) analysis
|
NOEC = 0.15
|
Mosquito fly
(Culex quinquesfasciatus)
|
n.s.
|
72 h
|
2nd-instar (23-33C), static
|
6.6-26.1
|
4th-instar (23-33C), static
|
7.8-30.6
|
Water hyacinth weevil (Neochetina eichhorniae, 60%, N. bruchi, 40%)
|
d-Limonene
|
n.s.
|
weevils dipped in limonene/
ethanol solutions
|
50% limonene
73% Mortality (range 40-100%)
|
Haag 1986
|
10% limonene
13.3% Mortality (range 0-20%)
|
The above results indicate that d-limonene can be considered highly toxic to aquatic invertebrates and the racemic mixture is slightly toxic. The racemate is also slightly toxic to mosquito fly.
12.1.3Toxicity to aquatic plants
Table 12.3 - Toxicity to aquatic plants
-
Species
|
Test Isomer
|
Test
Duration
|
Test Conditions
|
Result (mg/L)
| Reference |
Green algae
|
dipentene
|
96 h
|
Static
|
NOEC = 4.08
|
IPCS, 1998
|
Based on the results of this solitary test, the racemic mixture of limonene can be considered moderately toxic to aquatic plants.
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