Oil is not the only product transported by sea which poses a danger to wildlife. Other chemicals can also cause harm when accidents occur or when ships clean out their bulk tanks. For example the MV Rena was carrying, in addition to oil: aluminum trisodium hexafluoride (cryolite), ferrosilicon, alkyl sulfonic hydrogen peroxide, potassium nitrate trichloroisocyanuric acid.
All of these products are classified as hazardous or noxious substances under a variety of conventions, most notably the International Convention for the Safety of Life at Sea (SOLAS), the International Convention for the Prevention of Marine Pollution from Ships (initiated in 1973 and modified in 1978), known as MARPOL 73/78, and the OPRC-HNS Protocol. Under these conventions chemicals are rated for hazardous properties including flammability, toxicity, corrosiveness and reactivity. Ship design, construction, operation and equipment carried are regulated to minimise risks from spillage of hazardous materials. A further convention, the HNS Convention is waiting for ratification.
The hazardous and noxious substance list is constantly changing as new knowledge of potential hazards develops. For example, mineral oil, while not a hazard under most circumstances, can be dangerous to marine wildlife because it affects the feathers of birds and fur of mammals, impairing their waterproofing and thus their ability to thermo-regulate normally. Mineral oil is regulated under MARPOL’s Annex I, which also covers other types of oil.
Effects of HNS on wildlife need more study
Over the course of many years the effects of oil on wildlife have been carefully studied, resulting in a body of knowledge that allows responders to take steps to provide appropriate supportive care once the animals are taken into care. Cleaning procedures for various types of petroleum products have also been defined, allowing for faster restoration of feathers and fur for waterproofing.
This is not the case with most HNS incidents, partially because the chemical composition of the contaminant may not be known. A series of incidents in the North Sea and adjacent waterbodies involved birds covered in ‘a sticky substance’. Among the many substances identified during these incidents were nonylphenol, dodecylphenol, polyisobutylene (PIB), linseed oil or palm oil. Two incidents have since been confirmed as PIB spills or discharges.
Because the chemical make-up of the HNS was not known in these cases, it was difficult to predict the overall health consequences of the exposure. Standard washing procedures were also less effective and it took time to improve wash results. In the case of one spill in the North Sea which affected Northern gannets, personnel washing the birds experienced irritation of the eyes and respiratory tract.
Calciumdodecylphenolate, an additive used in ship engine lubricating oil, was found to be the source of the affects on the washers and the loss of many gannets from the toxic effects on the skin, respiratory and alimentary tracts, and central nervous system. Calciumdodecylphenolate breaks down in the presence of water to dodecylphenol and calcium hydroxide but this form of dodecylphenol is not specifically listed under MARPOL Annex II.
Even seemingly harmless products such as linseed oil can create problems for wildlife. When exposed to water, linseed becomes viscous and very difficult to clean, so while it is not toxic in and of itself, the need for aggressive cleaning agents contributed to the deaths of many birds. Palm oil is another oil listed as harmful under Category Y in Annex II, breaks down into diglycerids and triglycerids, which are not listed as harmful but which may impair digestion in birds when ingested.
Some HNS effects on wildlife are similar to those from exposure to oil:
- toxic effects from ingestion, inhalation or skin contact
- loss of waterproofing of feathers or fur
- impaired locomotion from adherent substances
- weight loss, starvation from inability to feed
- impaired immune function
- physiological damage
- endocrine disrupters
- liver and kidney damage from ingestion/inhalation
- blood disorders
Longer term effects can include:
- bioaccumulation through the food chain resulting in:
- immunological or physiological damage
- impaired reproduction
- impaired growth and/or development
For more information on the impact of hazardous and noxious substances on marine wildlife please see the 2011 European Science Foundation’s Marine Board Position Paper 16, Chemical Pollution in Europe’s Seas: Programmes, Practices and Priorities for Research, Chapter 5.