Using Oil Spill Dispersants on the Sea (1989) / Chapter Skim
Currently Skimming:
3 Toxicological Testing of Dispersants and Dispersed Oil
3 Toxicological Testing of Dispersants and Dispersed Oil
Pages 81-164
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From page 81... ...
For example, are species' sensitivities to dispersed oils in New England waters applicable to Texan waters? This question, which is of concern to regulators and industry, is addressed in this chapter.
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From page 82... ...
The objectives of toxicity testing of dispersants and dispersed oils in the laboratory are: ~ to provide data on relative acute toxicities of effective products to commonly used test species under standardized conditions so that dispersant users have a basis for selecting effective and acceptably Tow toxicity products; · ~ . ~ ~ co assure anal c~lspersants do not significantly increase the acute and chronic toxicities of dispersed petroleum hydrocarbons; and .
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From page 83... ...
(1980, 19843, and McAuliffe (1986, 1987a) used the concept to compare laboratory bioassays that actuary measured the dissolved hydrocarbons in the water-soluble fraction and chemically dispersed of!
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From page 84... ...
Dispersant toxicity thresholds are most often reported as nominal concentrations total amount of dispersant or oil divided by the total volume of water in the experimental chamber- rather than measured concentrations of materials to which organisms are actually exposed. This can lead to major errors in some cases.
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From page 85... ...
Both criteria have already been considered together when evaluating dispersants for government agencies (Anderson et al., 1985; Aranjo et al., 1987; Environment Canada, 1984~. Screening tests should accurately evaluate and accommodate the possibly greater acute toxicity of more effective dispersants.
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From page 86... ...
. Yet most countries, out of concern about dispersed of} effects and joint toxicity of of} and dispersant constituents, have included both of!
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From page 87... ...
Regulatory considerations, acute toxicity test spp. Dispersant use decision-making methods Review, toxicity tests Policy on toxicity, fish, early reports Toxicity protocol Acceptability list, use guidelines Toxicity testing protocol Regulations on dispersant composition and use Dispersant policy Study for criteria for guidelines 87
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From page 88... ...
role of toxicity tests, registration and notification Methods, dispersant toxicity, sea and beach tests U.K. methods, dispereant toxicology Toxicity tests, rationale for choice Toxicity, 2S oil-dispersant mixtures, sea and beach tests U.K., MAFF toxicity approach U.K.
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From page 89... ...
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From page 96... ...
, it is important ~ , for ah countries to recognize Contemporary problems arising from the development of effective third-generation dispersants and more accurate methods for determining the toxicity of oils" in the design of their toxicity screening tests. There are significant advantages to screening only the dispersant formulation, but an international consensus on the key treatments to test has not yet been reached.
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From page 97... ...
Acute toxicity data of some surfactants used in current formulations (circa early 19SOs) are presented in Table 3-4 (WelIs et al., 1985~.
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From page 98... ...
S S Sulfosuccinate, Alkyl (C ~ sulfosuccinate salt, D S anionic surfactant 70% solution Amine surfactant Alkyl (C 3) sulfosuccinate salt, D D 70% solution Anionic surfactant Oxide ester of DDBSA in amine D D salts Aromatic surfactant Oxyalkylated (9 m)
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From page 99... ...
TOXICOLOGICAL TESTING OF OIL DISPERSANTS 99 1-Day EC50s (ppm) -' - ' Artemia 8p.
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From page 100... ...
Acute Toxicity of Formulations More than 100 studies have been conducted on acute lethal toxicity of dispersants alone, more than half of them on currently used second-generation dispersants (Doe and Weds, 1978; Doe et al., 1978; Dye and Frydenborg, 1980; Nelson-Smith, 1972, 1980, l9S5; Pastorak et al., 1985; Sprague et al., 1982; Wells, 1984~. Such an extensive data base of varying quality invites periodic critical analysis by dispersant, organism type and stage, and method of exposure before definitive statements can be made about the acute toxicity of any one formulation.
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From page 101... ...
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From page 106... ...
106 ._ v 1 of m UP US ~ _I OF C)
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From page 107... ...
, which has been used in much recent biological and tox~cological research on dispersants and dispersed oils (Nelson-Sm~th, 1985; PeakaD et al., 1987; Sergy, 1987; Wells, 1984; WeDs et al., 1984a)
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From page 108... ...
108 Vl a~ ~c a~ ._ c~ a' L' ~Q o e~ u, x o v o :^ v ._ x o v ._ ¢ 1 co m ¢ ~ V b.
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From page 109... ...
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From page 110... ...
. Factors Influencing Acute Toxicity A number of physicochemical and biological factors influence the toxicity of a dispersant formulation (Wells, 1984~.
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From page 111... ...
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From page 112... ...
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From page 114... ...
Biological Factors Biological characteristics of the exposed organisms were divided into three groups: species (phylogeny) , life history, and physiology.
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From page 115... ...
Young life stages of other organisms, such as echinoid sperm and larvae, and some species, such as copepods, appear to be particularly sensitive. Larval resistance of crustaceans increases with age, based on studies with surfactants only (Czyzewska, 1976~.
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From page 116... ...
Additional work on standardizing methods (WelIs, 1981; Wells et al., 1984b) and on studying sublethal effects and their causes should clarify the major influencing factors, the degree of their influence, and the implications of such variable responses to the field effects of dispersed oils.
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From page 117... ...
Thus, understanding these processes within exposed organisms is crucial to understanding why species sensitivities vary, which sublethal effects are significant, and whether dispersant-oi} combinations might be more harmful than either one by itself. It is also important to know whether toxicity is temporary or permanent.
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From page 118... ...
Sublethal Effects Many studies, performed mostly in the 1970s, have examined sublethal effects. Sublethal responses such as reproduction, behavior, growth, metabolism, and respiration usually occur at levels wed below lethal thresholds, and hence are the most sensitive biological
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From page 119... ...
Organisms from bacteria to algae and invertebrates to fish exhibited varied biological responses to dispersants in 50 to lOO sublethal laboratory studies (Wells, unpublished compilation; Nelson-Smith, 1985~. As with acute toxicity, the range of threshold concentrations is extremely wide, from less than 1 ppm to 106 (undiluted dispersant)
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From page 120... ...
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From page 121... ...
121 easel Go a~ ~ _' _ .OQ o ~ ~ :o =- ~: ~ ~ b.
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From page 122... ...
Hazard Assessment of D~spersant Alone Effects due to the dispersant solvent and surfact ants in the water column may be surmised only from laboratory studies, as field studies have not examined this question. A commonly accepted approach for laboratory and field comparisons and predictions does not yet exist.
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From page 123... ...
TOXICITY OF DISPERSED OIL This section addresses exposure assessment, comparative toxicity, and joint toxicity. Laboratory work is reviewed later in this chapter; field studies, which assess both toxicological and ecological
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From page 124... ...
Factors Affecting Comparative Toxicity Some of the physicochemical and biological factors influencing toxicity of dispersed oils and the magnitude of their effects are wed known (Mackay and Wells, 1981; NRC, 1985; Sprague et al., 1982~. Key biological factors to consider with chemically dispersed of]
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From page 125... ...
As discussed earlier, joint toxicity cannot be assessed by a straightforward comparison of of} toxicity with dispersed oil toxicity. In most experiments using of} alone, the of} remains primarily at the surface of the experimental tank, and only a small fraction the water-soluble fraction (WSF)
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From page 126... ...
LABORATORY STUDIES WITH DISPERSED OIL Since the Torrey Canyon spill in 1967, many studies of the effects of dispersed oils on marine organisms under laboratory conditions have measured toxicities and relative toxicities of various oils, of! with dispersants, and dispersants themselves.
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From page 127... ...
using nominal concentrations, the chemically dispersed of} appears to have a higher toxicity. For example, based on studies using nominal concentrations, it has been hypothesized that under natural field conditions, toxicity of oil-dispersant mixtures to organisms would be greater than that of untreated of!
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From page 128... ...
This kind of model is useful for assessing the sources of toxicity in of} dispersions to different organisms over the crucial time periods after a major spill. It has been hypothesized that acute toxicity of chemically dispersed oils fans between that of the whole of]
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From page 129... ...
show that the apparently greater toxicity of chemically dispersed of} is generally a reflection of exposure, not a reflection of a greater inherent toxicity. The following discussion is devoted to a detailed survey of the current literature covering phytoplankton, marine plants, zooplankton, crustaceans, and other marine organisms.
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From page 130... ...
and chemically dispersed of} to phytoplankton. Macroscopic Algae and Vascular Plants As with phytoplankton, three of the five papers reviewed on macroscopic plants (Table 3-11)
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From page 131... ...
Zooplankton This section covers ad groupings that have been studied except crustacea, which are discussed later. Protozoa Little work has been conducted with protozoa and dispersed oils.
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From page 132... ...
~ O + D < Ail and dispersant toxicity is less than for oil alone. -CWater-soluble fraction.
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From page 133... ...
TOXICOLOGICAL TESTING OF OIL DISPERSANTS Toxicity Comparison O+D>Oa O+D |
From page 134... ...
In other studies, nominal concentrations were used and, as expected, chemically dispersed of} was reported to be more toxic. Six of these papers are compared in Table 3-12.
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From page 135... ...
eggs to the watersoluble fraction of Stati3ord A + B crude oil topped at 150°C and mixtures with Finasol OSR-5. To cause significant mortalities (98 percent)
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From page 136... ...
) NEOS AB 3000 Ekofisk 9 including crude Corexit 9527 Statfjord Finasol OSR-5 A+B, crude oil topped at 150 C NOTE: Uncertain information is noted by I?
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From page 137... ...
TOXICOL O GICA L TESTING OF OIL DISPERSA NTS Toxicity Comparison Biological Response O+D>Oa o+D |
From page 138... ...
OSR-2 and Finaso} SC, but comparisons were not reliable because only nominal concentrations were used. Venezia and Fossato (1977)
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From page 139... ...
Foy (1982) demonstrated that 96-hr I.C50s for Calanus hyperboreus, when based on hydrocarbon concentrations measured by fluorescence spectroscopy, were lower in Pru~hoe Bay crude oil-water mixtures than in oil-Corexit 9527 mixtures, that is, 73 (51 to 103)
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From page 140... ...
Prudhoe Bay crude Marcol 70 refined mineral oil Venezuelan crude Ekofisk crude BPllOOX Corexit 9527 Corexit 9527 Lethality, reproduction de~relopment Feeding Lethality Lethality Finasol SC, Sur~rival, lipid Finasol OSR-2 metabolism, · `. resp~ra`~on, swimming beha~rior Lethality Corexit 9527, Finasol OSR-5, Finasol OSR-7 Cran~on cran~on x Iraq Corexit 7664 Lethality, (shrimp)
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From page 141... ...
TOXICOL OGICA L TESTING OF OIL DISPERSA NTS Toxicity Comparison O+D>Oa O+D |
From page 142... ...
(1987) pointed out that toxicity indexes correlated with the presence of mono- and all-aromatics in the chemically dispersed of} and in the water-soluble fraction of physically dispersed oil.
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From page 143... ...
No conclusions can be drawn about the comparative effects of of} and of} dispersants since only nominal concentrations were reported. Depledge (1984)
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From page 144... ...
Capuzzo and Lancaster (1982) studied the physiological effects of physically dispersed and chemically dispersed Southern Louisiana crude of]
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From page 145... ...
ppm for physically dispersed oil, suggesting slightly more toxicity in the chemically dispersed oil. The toxicity curves are linear but nonparallel, suggesting that the mode of toxic action might be different in the two dispersion types.
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From page 146... ...
For gastropods (Table 3-14) , all studies used nominal concentrations, thus invalidating conclusions about the comparative effects of dispersed oils to oil alone, but showed that respiratory and behavioral responses were quite sensitive to oil or dispersant exposures.
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From page 147... ...
Comparison of Laboratory Studies and Field Studies With Measured Hydrocarbons This section reviews and compares laboratory bioassays that measured dissolved hydrocarbons ACE to Clot in the water-soluble fraction from untreated and chemically dispersed crude oils with those measured in the field, and it also compares the Cal to CIO hydrocarbon fraction bioassays or behavioral studies of untreated crude of} with dispersed of} bioassays using the same organisms. Oil toxicity to organisms is thought to result principally from hydrocarbons that dissolve into water from crude oils or refined products (NRC, 1985~.
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From page 148... ...
b0+D |
From page 149... ...
O+D was not Nuwayhid et al., 1980 made; both WSFe and dispersants cawed damage to surface micro `,illi, cilia, and epithelial cell structure x Dispereant was considered Hargrave and responsible for decreased Newcombe, 1973 behavior and respiration rates 149
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From page 151... ...
151 o o : E ,, ~ c = _ _ _ _ _ _ _ ~ ~ ~ ~ ~ ~ ~ o _ ~ ~ . _ ~ ~ ~ ~ AS ~ US HIS HIS ° ~ ~ arch= ~ ° ~ o ° ~ ~ X .~.~.C)
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From page 152... ...
determined the exposures to dissolved hydrocarbons required to cause 50 percent mortality of chum salmon fry with untreated and chemically dispersed Pru~hoe Bay crude oil. The total Cat to Cal o hydrocarbon content of the water was measured ~ times during the 24-hr exposures.
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From page 153... ...
The field exposures in the water column for both untreated and chemically dispersed oils generally are much lower than exposures required to cause mortality or behavioral effects on a large number of species and life stages. · The dissolved hydrocarbons from the WSF of untreated oil and chemically dispersed oil produced similar organism mortalities.
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From page 154... ...
To date, laboratory studies have been most valuable in exploring the types of responses and the duration of effects under "high exposure" conditions, and offering guidance to the design and conduct of field studies on dispersed oils.
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From page 155... ...
and dispersant in the water column, which may have temporary toxic or inhibitory effects on the natural microbial populations. Creation of new surface area is the most important factor relating to biodegradation.
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From page 156... ...
As a result, knowledge of dispersed of! degradation is limited mainly to laboratory studies, pond and mesocosm studies, and information on physical and chemical changes that are known to occur mainly when dispersants act on spilled oil.
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From page 157... ...
Generally, inhibition has not been important in pond or mesocosm studies. The extent to which laboratory studies of biodegradation rate and extent can be extrapolated to the marine environment is severely limited.
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From page 158... ...
Microbial Field Studies Bunch (1987) studied the effects of chemically dispersed crude of} on bacterial numbers and microheterotrophic activity in the water column and sediments of selected bays at the BIOS experiment site, Cape Hatt, Northwest Territories, from 1980 to 1983.
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From page 159... ...
Effects on the water column were considered inconsequential or marginally deleterious, while effects on the sediment were indirect, long-term, and likely of marginal significance to microheterotrophic activity. Summary Some laboratory studies and all mesocosm studies have shown increased oil biodegradation rates when dispersants are used.
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From page 160... ...
Generally, crude oil and Corex~t 9527 mixtures and crude oil alone are similarly toxic to bird eggs, based on nominal concentrations. Work with other species, such as mallard ducks and herring gulls (Table 3-16)
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From page 161... ...
161 ~C~ _ ~ ~ ~ _ _ ~ e s~ t~ ~ ~ ~ ~ ~ s" s" oo ~ oo .
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From page 162... ...
Their evaluation of the toxicology, based on sublethal responses at the biochemical and physiolog~cal level, showed similar responses to of} components, with and without dispersants. Other studies have examined the toxicity of dispersed oils to seabirds; these include Butler et al.
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From page 163... ...
has addressed chemically dispersed oil effects. The critical work by the American Society for Testing and Materials (ASTM, 1987)
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From page 164... ...
Research on thermal responses was conducted by rubbing fresh oil or 5-day weathered Santa Barbara crude oil on adult California sea otter pelts (Hubbs Marine Research Institute, 1986~. Fresh oil alone, or with Correct, easily penetrated the fur, which quickly saturated upon immersion in water.
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