GULFTENE C16-18 ISOMERISED OLEFINS - NICNAS
GULFTENE C16-18 ISOMERISED OLEFINS - NICNAS
GULFTENE C16-18 ISOMERISED OLEFINS - NICNAS
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compound released with drill cuttings is likely to be adsorbed onto the surface of particles of<br />
drilling waste rather than being dispersed in the water column as in the laboratory tests.<br />
In respect of the general question of biodegradation in marine environments, a preliminary<br />
report (ECETOC 1993) has concluded that if a chemical exhibits ready biodegradation under<br />
aerobic conditions in a freshwater environment, the available evidence indicates that it will<br />
also be degraded in the marine environment. The mechanisms for degradation may be either<br />
aerobic or anaerobic, but marine degradation rates are likely to be substantially reduced in<br />
comparison because of the low bacterial population in the marine environment. Low<br />
temperatures at the benthic interface would also decrease the rate of degradation.<br />
8.2.1.c Anaerobic Conditions - Freshwater Studies<br />
Test Substance: <strong>C16</strong>/C<strong>18</strong> isomerised olefin<br />
This study (Environment & Resource Technology Ltd 1996) was conducted according to the<br />
protocol ISO/TC147/SC5/WG4 which may be similar to the ECETOC screening test<br />
(ECETOC 1988) whereby the test substance is incubated at 35°C over an extended period<br />
with sewerage digester sludge maintained under anaerobic conditions. The volume of<br />
evolved CO2 and methane is measured periodically throughout the test period. The results<br />
indicated that after 56 days incubation under the test conditions, only 10.6% of the original<br />
carbon in the test substance had been metabolised to CO2 and methane. Consequently, it was<br />
concluded that the material is only slowly degraded under anaerobic conditions.<br />
The notifier also provided a second summary report (Mather JI Latham M Tapp JF 1995) on<br />
anaerobic biodegradation performed on another sample of the same material by a different<br />
laboratory. The protocols used in this test were those of ISO/CD11734, and indicated 58%<br />
degradation after 56 days incubation with sewage sludge and around 62% degradation after<br />
77 days 2 . These results are significantly better than those of the first test, but since summaries<br />
only were provided for both studies, with no details of the test methods used, no further<br />
comment can be made. However, both tests indicated slow biodegradation, and as the tested<br />
material contained close congeners of the components of Gulftene 16-<strong>18</strong>, these components<br />
are likely to behave in a similar manner.<br />
In addition to the summary reports described above the notifier provided a copy of a paper<br />
(Steber 1995) dealing specifically with the anaerobic degradation of drilling fluids<br />
components, two of which were alpha olefins. These tests were conducted using the<br />
ECETOC screening procedure with C14 alpha olefin (test duration 98 days) and with <strong>C16</strong>-<strong>18</strong><br />
alpha olefin (test duration 84 days), and the two compounds were degraded by 48.3 % and<br />
22.4% respectively. Steber (1995) was of the opinion that these results indicate moderate<br />
potential for anaerobic biodegradation.<br />
Some supplementary summary data on the anaerobic biodegradation of a synthetic drilling<br />
mud (known as “Syn-Teq Mud”) containing C14-20 isomerised alpha olefins (present at<br />
between 3 30-50%) was also supplied by the notifiers (Croudace CP Tapp JF 1995). This test<br />
2 It should be noted that the Western Australian Department of Minerals and Energy requires that this test be<br />
performed on all drilling fluids which are to be used in drilling operations off the WA coast, Cobby (1999).<br />
3 The reference indicated that the drilling mud used in the test contained 35% carbon.<br />
FULL PUBLIC REPORT 26 April 2000<br />
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