Summary Report: SN/9

ChEster 306

Chevron Chemical Australia of 385 Bourke Street Melbourne VIC 3000 and Baker Hughes Inteq of 5 Stoneham Street Belmont WA 6104, in view of the availability of additional environmental data have submitted a secondary notification statement in support of their original application for which an assessment certificate was issued. ChEster 306 is used as a component of invert drilling muds for offshore drilling operations. An estimated 1000 tonnes of notified chemical will be imported per annum for each of the first five years.

ASSESSMENT OF PUBLIC, OCCUPATIONAL HEALTH AND SAFETY AND ENVIRONMENTAL EFFECTS

Based on the toxicological data for analogue substances, SDP and SOP, the notified chemical, ChEster 306, is expected to have low acute oral and dermal toxicity. ChEster 306 is not expected to cause any significant organ toxicity, neurotoxicity or reproductive or developmental effects based on the findings of a 90-day repeat oral dose study with SDP. ChEster 306 is not likely to be skin sensitising or genotoxic. However, it may cause some skin irritancy, including a skin drying effect upon repeated or prolonged exposure. The MSDS states that ChEster 306 is not expected to be harmful to internal organs if absorbed through the skin. The MSDS states contact with the eye may cause irritation, pain, reddening and impaired vision. Aspiration into the lung after oral ingestion is a potential hazard based on the measured kinematic viscosity of the analogues. On the basis of the potential aspiration hazard, ChEster 306 is considered hazardous under the ASCC Approved Criteria for Classifying Hazardous Substances and should carry the hazard classification Harmful (Xn) and risk phrase R65 - May Cause Lung Damage if Swallowed. Risk phrase R66 - Repeated Exposure May Cause Skin Dryness or Cracking, has recently being adopted by the European Commission. Although yet to be adopted by the ASCC, this risk phrase should be provisionally assigned based upon the observed skin defatting effects of SDP and SOP.

Occupational Health and Safety

Occupational exposure may occur during preparation of drilling mud, manipulation of contaminated drill bits and associated equipment and recycling of import containers. ChEster 306 is viscous and has low vapour pressure. Consequently, inhalation is not considered a significant route of exposure under normal use conditions. Eye and skin contact is expected to be the main route of exposure. ChEster 306 has low molecular weight, low water solubility and is lipophilic. The possibility of skin absorption cannot be excluded through normal intact skin. Furthermore, skin irritation and skin dryness may compromise the skin’s barrier function and subsequent exposure of damaged skin may promote skin penetration of the notified chemical.

During drilling mud preparation and use and container recycling, ChEster 306 will be handled in a manner that is automated/mechanised, intermittent and non-dispersive, with workers required to wear personal protective equipment, namely impervious protective clothing, safety glasses with eye shields and neoprene or nitrile gloves. In view of the frequency of contact, pattern of use and control measures, eye and skin contact is expected to be minimal and the risk of adverse health effects arising from the use of ChEster 306 is expected to be low. Aspiration into the lung after oral ingestion is a potential hazard; however, ingestion is not an expected route of occupational exposure.

During import and transport of ChEster 306 or prepared drilling mud, there is unlikely to be any worker exposure, except in the event of a spill. Exposure after a spill would be controlled by use of the recommended practices for spillage clean up given in the MSDS supplied by the notifier.

Public Health

Public contact will only occur following accidental exposure from a spill or with contact with water containing the notified chemical following cleaning of empty drums. Consequently, the potential for public exposure to the notified chemical during all phases of its life cycle is considered to be low. Based on the above, it is considered that ChEster 306 will not pose a significant hazard to public health when used in the proposed manner.

Environmental Effects

Almost all of ChEster 306 is expected to be released to the marine environment, and up to 1000 tonnes of the new chemical may be released each year from offshore drilling operations off the Western Australia coast. A small amount of the chemical may form a “slick” on the water surface after release in calm sea conditions, but this is expected to slowly evaporate and enter the atmospheric compartment. Here it will be degraded through reactions with hydroxyl radicals.

Most of ChEster 306 is expected to become associated with benthic sediments, and it is likely that the material would eventually be spread over a wide area of sea floor around each drilling platform. Marine sediments may be either aerobic or anaerobic. The new chemical is biodegradable under aerobic conditions and available information indicates that it is also likely to be biodegradable under anaerobic conditions. However, anaerobic degradation in benthic sediments may be a slow process.

Under aerobic conditions the compounds will degrade to water and carbon dioxide, while anaerobic processes will produce water, methane, carbon monoxide and carbon dioxide.

Based on the low water solubility and high value for the n-octanol/water partition coefficient, the potential for assimilation of ChEster 306 by aquatic organisms may be high, although this may be mitigated by the very low water solubility.

ChEster 306 is susceptible to biodegradation due to the presence of the ester group, and if assimilated by exposed aquatic biota is likely to be degraded and not bioaccumulate.

The results for the ecotoxicity tests submitted with the notification indicate that the chemical is non toxic to fresh water organisms up to the limits of its water solubility, and that formulated drilling muds containing ChEster 304 (see SN/8) show at worst slight toxicity to marine organisms. Toxic effects demonstrated against two species, Corophium volutator and Demoscaris tripsinosa, in two separate tests may have been due to physical effects or to toxic properties of other components of the drilling fluids. A study conducted in the North Sea found that discarded cuttings containing an ester based fluid initially disrupted marine populations within a radius of 1000 metres from the well. This was initially very severe close to the drill hole but a substantial recovery of the affected area had commenced within 12 months.

When used as a component of drilling muds on off shore drilling platforms, the available data indicates that ChEster 306 may present a temporary hazard to the marine environment when it is discarded with waste drill cuttings. However, the physical, chemical and biological processes occurring in deposits of marine drill cuttings are not well understood, and it is only recently that appropriate techniques for examination of the spoil piles have been developed. Consequently, while the present environmental hazard assessment has been based on all available data, it is possible that future studies may indicate other factors which should be considered in evaluating the environmental hazard of discarded organic based drilling fluids.

RECOMMENDATIONS

To minimise occupational exposure to ChEster 306 the following guidelines and precautions should be observed:

• Workers should be advised of the potential for occupational dermatoses following repeated skin exposure to ChEster 306 and to report any skin changes to the occupational health and safety officer at their workplace. When an occupational skin disease occurs, the employer should review work practices and opportunities for contact with the substance and instigate preventive measures to ensure other workers do not develop the same condition. Further guidance on preventing the occurrence of occupational skin diseases can be found in the ASCC guide Occupational Diseases of the Skin.
• Safety goggles should be selected and fitted in accordance with Australian Standard (AS) 1336 to comply with Australian/New Zealand Standard (AS/NZS) 1337;
• Industrial clothing should conform to the specifications detailed in AS 2919 and AS 3765.1;
• Impermeable gloves should conform to AS/NZS 2161.2. The notifier recommends neoprene or nitrile gloves;
• All occupational footwear should conform to AS/NZS 2210;
• Where exposure to airborne material may occur an organic vapour (Type A) filter respirator should be used. Respiratory protection should conform to AS 1715 and AS 1716;
• ChEster 306 is identified as a Class 2 combustible liquid and should be stored, handled and used in accordance with AS 1940;
• Spillage of ChEster 306 should be avoided. Spillages should be cleaned up promptly with absorbents which should be put into containers for disposal;
• Good personal hygiene should be practised to minimise the potential for eye and skin contact and ingestion; and
• A copy of the MSDS should be easily accessible to employees.

If the conditions of use are varied, then greater exposure of the public may occur. In such circumstances, further information may be required to assess the hazards to public health.

This assessment report be included in environmental management submissions where required under State or Commonwealth petroleum (submerged lands) legislation.

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