1984 - Dana Optima

On January 12, 1984, the Danish vessel M/S Dana Optima departed from North Shields in the U.K. for Esbjerg, Denmark. The 1,599grt vessel carried as a deck cargo 42 containers and trailers most of which were empty. One trailer carried 80 drums of the pesticide Dinoseb.

After departure from the U.K., the vessel encountered a heavy storm and on January 13, the main and auxiliary engines failed, causing 39 containers and trailers of the deck cargo to fall overboard, one of which contained the 80 drums of Dinoseb. During the night of January 13/14, the Dana Optima drifted among the various Danish offshore installations in the area but fortunately no collision took place. During January 14, control of the vessel was regained and it proceeded without assistance to Esbjerg arriving on January 15. The loss of the deck cargo was reported to the nearest Danish coastal radio station but the loss of the pesticide drums was not reported. On January 14, the officer-on-duty at the National Agency of Environmental Protection (NAEP) was informed by the Flag Officer Denmark (FOD) that the missing deck cargo did not contain substances harmful to the marine environment.

However, on January 16, the NAEP's officer on duty was informed by a private firm in Esbjerg that among the missing deck cargo was a truck-trailer with 80 drums, each containing 200 litres of Dinoseb. This was immediately confirmed by the owner.

Dinoseb is extremely toxic to marine organisms (in the range of ppb). It is not expected to bioaccumulate to a large extent because marine organisms will probably die before they are able to accumulate it. As a result, human consumption of contaminated fish should not constitute an acute risk. However, since the product is known to induce genetic changes and is considered carcinogenic, these effects could be induced in humans consuming contaminated fish. Laboratory investigations also show that the product is not easily biodegradable having a half-life of approximately 1 year in fresh water.

At the time of the accident, Dinoseb was used for weed control by farmers and gardeners in Denmark. Importation, sale and use of the product has been banned since September 1, 1984, following a re-evaulation of hazardous properties of the pesticide.

The risk of poisoning by the local population was considered high for anyone handling the product without appropriate protection equipment. Fishermen were considered at the highest risk since these could pick up leaking drums in their nets. At the same time, no immediate medical treatment would be available on their vessels should they be exposed.

In light of the information on the product's toxicity to human health, the Danish Minister for the Environment requested the NAEP to investigate if it was technically feasible to find and recover the drums. This was confirmed to be possible but certain conditions such as smothering by bottom sediments and movement of drums might complicate the operations.

On January 12, 1984, the Danish vessel M/S Dana Optima departed from North Shields in the U.K. for Esbjerg, Denmark. The 1,599grt vessel carried as a deck cargo 42 containers and trailers most of which were empty. One trailer carried 80 drums of the pesticide Dinoseb.

After departure from the U.K., the vessel encountered a heavy storm and on January 13, the main and auxiliary engines failed, causing 39 containers and trailers of the deck cargo to fall overboard, one of which contained the 80 drums of Dinoseb. During the night of January 13/14, the Dana Optima drifted among the various Danish offshore installations in the area but fortunately no collision took place. During January 14, control of the vessel was regained and it proceeded without assistance to Esbjerg arriving on January 15. The loss of the deck cargo was reported to the nearest Danish coastal radio station but the loss of the pesticide drums was not reported. On January 14, the officer-on-duty at the National Agency of Environmental Protection (NAEP) was informed by the Flag Officer Denmark (FOD) that the missing deck cargo did not contain substances harmful to the marine environment.

However, on January 16, the NAEP's officer on duty was informed by a private firm in Esbjerg that among the missing deck cargo was a truck-trailer with 80 drums, each containing 200 litres of Dinoseb. This was immediately confirmed by the owner.

Dinoseb is extremely toxic to marine organisms (in the range of ppb). It is not expected to bioaccumulate to a large extent because marine organisms will probably die before they are able to accumulate it. As a result, human consumption of contaminated fish should not constitute an acute risk. However, since the product is known to induce genetic changes and is considered carcinogenic, these effects could be induced in humans consuming contaminated fish. Laboratory investigations also show that the product is not easily biodegradable having a half-life of approximately 1 year in fresh water.

At the time of the accident, Dinoseb was used for weed control by farmers and gardeners in Denmark. Importation, sale and use of the product has been banned since September 1, 1984, following a re-evaulation of hazardous properties of the pesticide.

The risk of poisoning by the local population was considered high for anyone handling the product without appropriate protection equipment. Fishermen were considered at the highest risk since these could pick up leaking drums in their nets. At the same time, no immediate medical treatment would be available on their vessels should they be exposed.

In light of the information on the product's toxicity to human health, the Danish Minister for the Environment requested the NAEP to investigate if it was technically feasible to find and recover the drums. This was confirmed to be possible but certain conditions such as smothering by bottom sediments and movement of drums might complicate the operations.

The following actions were taken as part of the countermeasures:

1) A warning to mariners as well as to the relevant authorities was issued a day after the private firm notified NAEP of the loss of the drums.

2) The NAEP issued a warning to fishermen about the Dinoseb as well as instructions about personal protection when handling drums containing Dinoseb. These were issued through the Fishermen's Association and the Association of the Danish Fishing Industry.

3) The NAEP recommended that the search for the drums should be carried out by an oil response vessel equipped with side-scan sonar and special navigational equipment as well as a remote operated vehicle equipped with a TV camera. Furthermore, divers should participate in the search.

The owners informed the NAEP that according to the information by the crew, the 80 drums of Dinoseb were lost during the time 06.45 to 13.00 of January 13.

The general strategy for the search of the drums involved establishing a search grid from the point of loss, followed by a systematic search (Figure 1). A rough survey was first made by sector-scanning sonars of the types used by fishing vessels and navy minesweepers. Suspect areas were then thoroughly searched by side-scan sonars.

After mapping these areas, all suspected objects were identified and examined by a submersible remote operated vehicle (ROV) equipped with a TV camera before salvage. In view of the fact that ordinary navigation equipment is not sufficiently accurate for searches where navigation lines are down to 50 metres from each other, the search vessels had to be fitted with special precision navigation equipment which gives more accuracy. In this operation, a system called "ARGO" supplemented by a system called "SYLEDIS" gave best accuracy but was rather sensitive to atmospheric changes causing functional problems at sunrise and sunset. The "PULSE/8" system was preferred because although less precise than "ARGO" (20 metres depth as opposed to 6 metres) was found to be sturdier.

The search for the drums took place in three phases:

Phase 1: January 22 - March 3 with the participation of a Danish oil response vessel, a Danish fishing vessel and four Dutch minesweepers. No drums were found.

Phase 2: March 31 - April 16 with the participation of a Danish oil response vessel, a Danish fishing vessel and a Dutch minesweeper.

Fifty-three drums were found. In the salvage operation (i.e. recovery operation), two Danish navy vessels participated as well as a Danish oil response vessel as well as a Danish fishing vessel.

Phase 3: April 26 - May 7 with the participation of a Danish oil response vessel. No drums were found although a Dutch fishing vessel found 1 drum on April 27.

In addition to the salvage of the 53 drums during the Phase 2 period, Dutch fishing trawlers recovered 13 drums of Dinoseb during the period March 27 - March 30 and 1 drum on April 27. Following the official termination of the search operation, 5 more drums had been recovered. A total of 72 drums out of 80 lost Dinoseb drums had been recovered. Figure 1 shows part of the grid system and the area of the spread of the drums on the sea bottom following loss overboard. An important factor that came to light after the accident was the bottom trawling carried out by fishermen could have contributed to a wider spread of the lost drums on the sea bottom.

The salvage operation itself was under the command of the Royal Danish navy assisted by a Danish oil response vessel and a Danish fishing vessel. A mobile laboratory was set up onboard the oil response vessel to monitor for any leaking drums in the environment. Two recovery methods were used: divers and the ROV which besides a TV camera and search sonar had a remote controlled grab. It was originally planned to recover the drums using divers during the day and using the ROV at night, however this procedure was changed and the ROV was mainly used to locate scattered drums since using divers was found to be more efficient. By the end of the recovery operation, a total of 34 drums were recovered by divers and 19 drums by the ROV. Recovered drums, which for the most part were found leaking as a result of damage by bottom fishing trawls or due to water pressure exerted at 40 metres, were placed in steel overpacks and sent to a disposal plant.

It has been assumed that the remaining drums not found had been scattered over a large area of the seabed by bottom fishing trawls. These drums will still constitute a potential risk for the crews of fishing vessels if the drums are caught in their nets. Leaking of the Dinoseb into the marine environment is not thought to constitute a high risk to marine flora and fauna due to the poor solubility of the product and the fact that affected areas will be quite small.