ASTM D6046 Standard Classification of Hydraulic Fluids for Environmental Impact
1. Scope
1.1 This classification covers all unused fully formulated hydraulic fluids in their original form.

1.2 This classification establishes categories for the impact of hydraulic fluids on different environmental compartments as shown in Table 1. Fluids are assigned designations within these categories; for example PwL, Pwe, and so forth, based on performance in specified tests.

1.3 In the current version of this classification the aspects of environmental impact included are environmental persistence of which biodegradability is one component and acute ecotoxicity. Although environmental persistence is discussed first, this classification does not imply that considerations of environmental persistence should take precedence over concerns for ecotoxicity.

1.4 Another important aspect of environmental impact is bioaccumulation. This aspect is not addressed in the present classification because adequate test methods do not yet exist to measure bioaccumulation of hydraulic fluids.

1.5 The present classification addresses the fresh water and soil environmental compartments. At this time marine and anaerobic environmental compartments are not included, although they are pertinent for many uses of hydraulic fluids. Hydraulic fluids are expected to have no significant impact on the atmosphere; therefore that compartment is not addressed.

1.6 This classification addresses releases to the environment which are incidental to the use of a hydraulic fluid. The classification is not intended to address environmental impact in situations of major, accidental release. Nothing in this classification should be taken to relieve the user of the responsibility to properly use and dispose of hydraulic fluids.

1.7 This classification does not cover any performance properties of a hydraulic fluid which relate to its performance in a hydraulic system.

1.8 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

2. Referenced Documents
2.1 ASTM Standards:
D5291 Test Methods for Instrumental Determination of Carbon, Hydrogen, and Nitrogen in Petroleum Products and Lubricants
D5864 Test Method for Determining the Aerobic Aquatic Biodegradation of Lubricants or Their Components
D6006 Guide for Assessing Biodegradability of Hydraulic Fluids
D6081 Practice for Aquatic Toxicity Testing of Lubricants: Sample Preparation and Results Interpretation
E 943 Terminology Relating to Biological Effects and Environmental Fate
E 1440 Guide for an Acute Toxicity Test with the Rotifer Brachionus

2.2 ISO Standards:
International Standard ISO Test 9439:1990, Technical Corrigendum 1, Water Quality - Evaluation in An Aqueous Medium of the "Ultimate" Biodegradability of Organic Compounds - Method by Analysis of Released Carbon Dioxide

2.3 OECD Standards:
OECD 301B, CO2 Evolution Test (the Modified Sturm Test)
OECD 301C, Modified MITI Test (I)
OECD 301F, Manometric Respirometry Test
OECD 201, Alga, Growth Inhibition Test
OECD 202, Daphnia sp., Acute Immobilisation Test and Reproduction Test
OECD 203, Fish, Acute Toxicity Test
OECD 207, Earthworm Acute Toxicity Test
OECD 208, Terrestrial Plants Growth Test

2.4 US EPA Tests:
Aerobic Aquatic Biodegradation Test, 40 CFR 796.3100. (Also available as EPA publication 560/6-82-003, number CG-2000)
Toxic Substances Control Act (TSCA), 40 CFR Parts 796 and 797 - Environmental Effects Testing Guidelines, Federal Register, Vol 50, No. 188, September 27, 1985, p. 39321

2.5 Environmental Canada Test Methods:
Biological Test Method: Acute Lethality Test Using Rainbow Trout, Report EPS 1/9, Environment Canada, July 1990
Biological Test Method: Reference Method for Determining Acute Lethality of Effluents to Rainbow Trout, Reference Method EPS 1/RM/13, Environment Canada, July 1990
Biological Test Method: Growth Inhibition Test Using the Freshwater Alga Selenastrum capricornutum, Report EPS 1/RM/25, Environment Canada, November 1992
Biological Test Method: Acute Lethality Test Using Daphnia spp., Report EPS 1/RM/11, Environment Canada, July 1990
Biodegradability of Two-Stroke Cycle Outboard Engine Oils in Water, CEC L-33-A-934, Co-Ordinating European Council, 1994 (Formerly L-33-T-82)
Toxic Substances Control Act (TSCA), Good Laboratory Practice Standards, Final Rule, U.S. Federal Register, 40 CFR Part 792, August 17, 1989

2.6 Other Standards:
MENVIQ 92.03/800 - D.mag. 1.1, March 1992
29 CFR 1910 OSHA Regulated Carcinogens and Potential Carcinogens

3. Terminology
3.1 Definitions:
3.1.1 acute ecotoxicity, n - the propensity of a material to produce adverse behavioral, biochemical, or physiological effects in non-human organisms or populations in a short period of time, usually not constituting a substantial portion of the life span of the organism.

3.1.2 aerobic, adj - (1) taking place in the presence of oxygen, (2) living or active in the presence of oxygen.

3.1.3 anaerobic, adj - (1) taking place in the absence of oxygen, (2) living or active in the absence of oxygen.

3.1.4 biodegradation, n - the process of chemical breakdown or transformation of a material caused by organisms or their enzymes.
3.1.4.1 Discussion - Biodegradation is only one mechanism by which materials are removed from the environment.

3.1.5 ecotoxicity, n - the propensity of a material to produce adverse behavioral, biochemical, or physiological effects in non-human organisms or populations.

3.1.6 effect load XX (ELXX), n - a statistically or graphically estimated loading rate of test material that is expected to cause one or more specified effects in XX % of a group of organisms under specified conditions for a specified time.
3.1.6.1 Discussion - This terminology should be used for hydraulic fluids instead of the standard effect concentration (ECXX) when the hydraulic fluid is not completely soluble under test conditions.

3.1.7 environmental compartment, n - a subdivision of the environment based on physical or chemical properties, or both.
3.1.7.1 Discussion - Examples of environmental compartments are aerobic fresh water, aerobic marine, aerobic soil, and anaerobic media. The results of test procedures may be applied to environmental compartments, but the test systems do not constitute an environmental compartment.

3.1.8 fresh water environment, n - the aerobic, fresh water environmental compartment.

3.1.9 good laboratory practices (GLP), n - guidelines for the management of laboratory experiments which are published by regulatory agencies or other recognized groups and are concerned with the organizational process and the conditions under which laboratory studies are planned, performed, monitored, recorded, and reported.
3.1.9.1 Discussion - The major GLPs used are USE-PA-TSCA, USFDA, OECD, and to some extent the MITI version from Japan for submissions in Japan.

3.1.10 inhibition load XX (ILXX), n - a statistically or graphically estimated loading rate of test material that is expected to cause a XX % inhibition of a biological process (such as growth or reproduction) which has an analog as opposed to a digital measure.
3.1.10.1 Discussion - An example of a digital measure would be alive or dead. This terminology should be used for hydraulic fluids instead of the standard inhibition concentration (ICXX) when the hydraulic fluid is not completely soluble under test conditions.

3.1.11 inoculum, n - spores, bacteria, single-celled organisms, or other live materials that are introduced into a test medium.

3.1.12 lethal load XX (LLXX), n - a statistically or graphically estimated loading rate of test material that is expected to be lethal to XX % of a group of organisms under specified conditions for a specified time.
3.1.12.1 Discussion - This terminology should be used for hydraulic fluids instead of the standard lethal concentration (LCXX) when the hydraulic fluid is not completely soluble under test conditions.

3.1.13 loading rate, n - the ratio of test material to aqueous medium used in the preparation of a water accommodated fraction (WAF) and in interpretation of the results of a toxicity study with a poorly water soluble lubricant or lubricant component.

3.1.14 mechanical dispersion, n - a mixture produced by the application of mechanical shearing forces to a multi-phase system, one component of which is water, so as to distribute one or more of the materials uniformly throughout the mass of the water with the water existing as a continuous phase.

3.1.15 pre-adaptation, n - the pre-incubation of an inoculum in the presence of the test material and under conditions similar to the test conditions.
3.1.15.1 Discussion - The aim of pre-adaptation is to improve the precision of the test method by decreasing variability in the rate of biodegradation produced by the inoculum. Pre-adaptation may mimic the natural processes which cause changes in the microbial population of the inoculum leading to more rapid biodegradation of the test material but not to a change in the final extent of biodegradation.

3.1.16 primary biodegradation, n - degradation of the test material by microorganisms resulting in a change in its physical or chemical properties, or both.
3.1.16.1 Discussion - The extent to which the results of a primary biodegradation test correspond to the biological conversion of the test material will depend on the attribute which is being measured.

3.1.17 primary biodegradation test, n - a test which follows the disappearance of a test material by measuring some attribute of the material.
3.1.17.1 Discussion - The extent to which the results of a primary biodegradation test correspond to the biological conversion of the test material will depend on the attribute which is being measured.

3.1.18 terrestrial (or soil) environment, n - the aerobic environmental compartment which is found in and on natural soils.

3.1.19 theoretical CO2, n - the amount of CO2 which could in theory be produced from the complete oxidation of all the carbon in a material.

3.1.20 theoretical O2, n - the amount of oxygen which would theoretically be required to completely oxidize a material.

3.1.21 ultimate biodegradation, n - degradation achieved when a material is totally utilized by microorganisms resulting in the production of carbon dioxide (and possibly methane in the case of anaerobic biodegradation), water, inorganic compounds, and new microbial cellular constituents (biomass or secretions or both).

3.1.22 ultimate biodegradation test, n - a test which estimates the extent to which the carbon in a material is converted to CO2 or methane, either directly by measuring the production of CO2 or methane, or, for aerobic biodegradation, indirectly by measuring the consumption of O2.
3.1.22.1 Discussion - The measurement of new biomass is usually not attempted.

3.1.23 water accommodated fraction (WAF), n - the predominately aqueous portion of a mixture of water and a poorly water-soluble material which separates in a specified period of time after the mixture has undergone a specified degree of mixing and includes water, dissolved components, and dispersed droplets of the poorly water soluble material.
3.1.23.1 Discussion - The chemical composition of the WAF depends on the ratio of poorly soluble material to water in the original mixture as well as the details of the mixing procedure.

3.1.24 wppm - an abbreviation for part per million by weight.

3.1.25 Definitions and terms not given in this classification may be found in the Compilation of ASTM Standard Definitions, 1990 or Terminology E 943.