Carbon Monoxide Poisoning arising during carriage of crude coconut oil


Published: 21 June 2001

The collapse of two workers, diagnosed with carbon monoxide poisoning while sweeping crude coconut oil in a tank on one of our member's ships, has provided a stark warning of a hitherto unknown hazard which can be associated with the carriage of this product. The workers fell onto the heating coils located at the bottom of the tank and suffered serious burns with the tragic result that one of them subsequently died from his injuries.

Carbon monoxide is a colourless, odourless, tasteless and non-irritating gas which is highly toxic. When inhaled the gas binds with the haemoglobin in the blood and thus prevents the uptake and distribution of oxygen to the cells of the body. Extended exposure or brief high level exposure to carbon monoxide can lead to unconsciousness (as evidently occurred in the current case), brain damage or death. Early warning signs of carbon monoxide poisoning are headaches, nausea, dizziness, shortness of breath and confusion.

The tank concerned had reportedly been ventilated, but the vessel was trimmed so that oil covered the heating coils at one end of the tank but was under the coil at the other when the workers entered. It is assumed that the dangerous concentration of carbon monoxide gas arose from thermal decomposition of the coconut oil over the hot coils. Normally carbon monoxide is produced from incomplete combustion of fuels,but it is also known that decomposition of vegetable oils under strong heat can lead to carbon monoxide formation. Nevertheless, scientists we have contacted have expressed surprise that crude coconut oil under the conditions that reportedly prevailed in the tank yielded dangerous levels of the gas. However, gas measurements in the tank immediately after the incident revealed that despite normal oxygen levels that the concentration of carbon monoxide was at a dangerously high level. Checks in an adjacent tank loaded with the same product, and which covered the heating coils, also revealed dangerously high concentrations of carbon monoxide, as indeed laboratory experiments later showed involving heating crude coconut oil to 60 degrees Celsius.

The association is aware that members have carried coconut and other vegetable oils safely for many years, but in view of the hazard that the above incident has shown can exist when crude coconut oil is carried, we recommend that ample safety precautions are taken before any personnel enters any tanks on ships having contained or still containing this or for that matter other vegetable oil products. The precautions should involve ample ventilation and gas checks to ensure not only safe oxygen levels, but also safe carbon monoxide levels. Carbon monoxide concentration can be monitored by using a gas concentration kit (pump and carbon monoxide gas detection tubes) or by a gas meter fitted with a carbon monoxide sensor. Gas sensors have practical advantage in that they obtain continuous readings, butthe sensors have a limited life. It is important when they are used that they are regularly calibrated in accordance with the recommendations of the manufacturer.

We welcome any comments that our readers might have on this subject.