Commonwealth of Australia 2002
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- 12.3Summary of environmental effects
- 12.4Derivation of PNEC for aquatic organisms
- 13.Risk Characterisation
- 13.1.1Aquatic compartment
- 13.1.2Terrestrial compartment
- 13.1.3Atmosphere
12.2Terrestrial environmentThe toxicity of limonene has been studied in various terrestrial organisms (see Table 12.4). Limonene generally has moderate acute toxicity in insects and mites. The acute toxicity of d-limonene to earthworms (Eisenia foetida Savigny) was high (LC50 = 6.0 ppm) (33.4 mg/m3). Worms were exposed to limonene in capped 95 mL bottles containing filter paper (total surface area of paper = 115 cm3) wetted with limonene. Sublethal effects (i.e. abnormal rebounding of medial giant fibre pathway [MGF] impulses and spontaneous lateral giant fibre pathway [LGF] spiking) were observed following exposure of earthworms to 4.2 ppm (23.3 mg/m3) limonene (Karr et al., 1990). Limonene has low subacute toxicity to bobwhite quail (Colinus virginianus) exposed via the diet (LC50 > 5620 ppm) (31 247 mg/m3) (US EPA, 1994).
The limited results suggest invertebrates to be the most sensitive species in the aquatic system, with results for daphnia being 0.421 mg/L (48 h EC50). 12.4Derivation of PNEC for aquatic organismsd-Limonene Since several results for fish and invertebrates are available, an assessment factor of 100 is applied to the lowest acute toxicity result, that is, the EC50 of 0.421 mg/L for daphnia. This gives a PNEC of 4.21 g/L for d-limonene. Dipentene The data available for dipentene includes several results for fish and invertebrates and a chronic algal NOEC. Hence an assessment factor of 100 is applied to determine the PNEC from the lowest toxicity result (4.0 ppm for algae) (22.2 mg/m3) giving a value of 40 g/L for dipentene. 
Table 12.4 – Toxicity to terrestrial organisms 13.Risk Characterisation13.1Environmental riskLimonene is a volatile chemical with low water solubility. It has a range of uses in Australia, being used as a solvent, as a flavour in food, as a fragrance and in a host of cleaning products. Release is expected to be predominantly to the atmosphere although exposure to aquatic systems may also result. 13.1.1Aquatic compartmentThe major release of limonene to the aquatic compartment is expected to be through its use in cleaning compounds. The PEC for both d-limonene and dipentene were determined in Section 8.1.3. The PEC/PNEC ratios show that d-limonene should not cause adverse effects on the aquatic compartment. Table 13.1 - PEC/PNEC ratios determined for d-limonene and dipentene in the aquatic compartment
These values (worst case scenario) indicate that there will be no adverse effects on aquatic organisms arising from the formulation or end use of d-limonene or dipentene in Australia (see Section 8.1.3). This conclusion is in agreement with those outlined in the Concise International Chemical Assessment Document on limonene which concluded that because concentrations of limonene in surface waters of "polluted" and "unpolluted" areas are at least about 250 and 20 000 times lower than this acute toxicity value (0.4 mg/L; 48-h EC50 for daphnia), respectively, it is likely that limonene poses a low risk for acute toxic effects on aquatic organisms (IPCS 1998). No studies were identified on chronic effects, and therefore risks associated with chronic exposures of aquatic organisms to limonene in "polluted" waters cannot be determined. 13.1.2Terrestrial compartmentTerrestrial organisms are most likely to be exposed to limonene via the air. The few studies on terrestrial species (i.e. insects) using vapour exposure reveal effects of limonene at parts per million levels. Measured environmental concentrations from overseas are typically around 0. 1 to 2 ppb (0.6 to 11 g/m3), indicating a low risk for acute toxic effects on terrestrial organisms from direct exposure to limonene in air. At polluted sites, limonene concentrations in soil (up to 920 mg/kg soil in Florida) may exceed effect levels of soil-living organisms (e.g. earthworm, acute LC50 = 6.0 ppm) (33.36 mg/m3). 13.1.3AtmosphereLimonene and other terpenes are released in large amounts mainly to the atmosphere. When released to soil or water, limonene is expected to evaporate to air to a significant extent, owing to its high volatility. Thus, the atmosphere is the predominant environmental sink of limonene, where it is expected to rapidly undergo gas-phase reactions with photochemically produced hydroxyl radicals, ozone, and nitrate radicals. The oxidation of terpenes, such as limonene, contributes to aerosol and photochemical smog formation. Ozonolysis of limonene may also lead to the formation of hydrogen peroxide and organic peroxides, which have various toxic effects on plant cells and may be part of the damage to forests observed in the last decades. Emissions of biogenic hydrocarbons such as limonene and other terpenes to the atmosphere may either decrease ozone concentrations when oxides of nitrogen concentrations are low or, if emissions take place in polluted air (i.e. containing high oxides of nitrogen levels), lead to an increase in ozone concentrations (IPCS 1998). Limonene has not been identified as an air toxic in Australia and is not on the list of substances reported to the National Pollutant Inventory. Directory: data -> assets -> word doc -> 0019 0019 -> Commonwealth of Australia 2000 0019 -> Rail safety news issue 6 – October 2011 0019 -> Social and economic benefits of improved adult literacy: Towards a better understanding Robyn Hartley Jackie Horne 0019 -> From: Virginia Holt [mailto: (personal contact details deleted) 0019 -> By Yvonne Hillier Introduction 0019 -> Communications alliance 0019 -> Allocations Manual Homeless with Support Category 0019 -> Inquiry into Vulnerable Road Users Inquiry into Vulnerable Road Users Download 1.1 Mb. Share with your friends:
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