Bulletin No.: 07/1998

Date (Y-M-D): 1998-05-21
 

Subject: Mercury (Hg) Contamination

During a recent inspection of a Canadian flag ship, elevated levels of elemental mercury, also known as quicksilver, were identified in the ballast control room.

It would appear that this contamination had occurred through the overflow of ballast control gauges. Mercury may also be found in such devices as thermometers, barometers and electrical/mechanical equipment.

It should be noted that hazards to crew are posed only upon exposure to release of mercury outside the containing vessel. Mercury contained within the instruments, where all parts are sealed to open atmosphere, poses no health concerns.

Mercury is a silvery-white, heavy, mobile metal which is liquid at ordinary room temperature and pressure. The main routes of entry to the body are ingestion (by mouth) and inhalation (through the lungs). The effects of mercury contamination are dependent on the route of entry to the body and the level and duration of exposure. Limits of exposure are prescribed by the Marine Occupational Safety and Health Regulations, made pursuant to the Canada Labour Code, Part II. Summarized information regarding the properties and safety precaution requirements for mercury are included on the Material Safety Data Sheet ( MSDS ) found on board each vessel with mercury present in the work environment. More detailed information may be obtained from subject-matter publications in most municipal libraries or from the Canadian Center for Occupational Safety and Health.

The presence of mercury can usually be detected by sight or by vapor test. Should mercury be detected through either of these tests, it is highly recommended that a marine chemist, industrial hygienist or other qualified person measure the environment, record observations and make recommendations, in accordance with paragraphs 8.3 (2) and 8.4 of the Marine Occupational Safety and Health Regulations. Where these tests indicate that exposure limits have been exceeded, immediate implementation of remedial action and medical assessments of employees that may have been exposed is required.

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