Chronic exposure to very low concentrations of benzene vapors in air of the order of
a few parts per million may cause leukaemia. In order to protect the health of seafarers
to the same level as that of shore-based workers performing comparable tasks, measures
should be taken for all ships carrying mixtures the benzene content of which is 0.5 per
cent or more. Such measures should include the following requirements:
1 Controlled tank venting system
Vapors displaced from the tank during loading and tank breathing should be emitted
through a controlled tank venting system complying with either Regulation II-2/59 of
SOLAS 74 or paragraph 8.3.2 of the IBC Code, or paragraph 2.14.2 of the BCH
Code, as applicable.
Whenever a vapor emission control system is available ashore, vapors displaced from
the tank during loading should be returned to that system.
2 Air quality monitoring
The airborne concentration of benzene vapor should be measured with an approved
instrument by a trained and properly protected person, before any other person is
authorized to work in a given area.
As an alternative, a programme of sampling and measurements should be carried out
covering all representative circumstances which may be found during cargo operations
and a record kept of such programme.
3 Operational exposure limits
Worker exposure to airborne concentrations of benzene vapors should be controlled
within the following limits:
- a Time Weighted Average (TWA) of one part of benzene per million parts of air,
over an eight hour period, which covers the time a man is assumed to work in
any 24 hour period.
- a Short Term Exposure Limit (STEL) of five parts of benzene per million parts
of air over any 15 minute period.
4 Personal protection equipment (PPE)
.1 Equipment for cargo operations on deck
Whenever direct or representative measurements indicate that the TWA or the STEL
are exceeded during normal cargo handling operations*, personnel required to work in the
affected area should wear appropriate respiratory equipment. Such equipment is indicated
below**, however a higher level of protection may be selected by the user.
- Half face piece: in areas where the airborne concentration of benzene vapors
exceeds 1 ppm but is less than 10 ppm;
- Full face (filter) piece with dual cartridge: operations other than emergency
response, spill response and clean-up, in areas where the airborne concentration
of benzene vapors exceeds 10 ppm but is less than 50 ppm;
- Air supplied respirators: operations in areas where the airborne concentration of
benzene vapors exceeds 50 ppm but is less than 100 ppm;
- Pressure demand breathing apparatus: in areas where the airborne concentration
of benzene is greater than 100 ppm or unknown; and
- Eye protection, impervious gloves and suitable protective apron should be
readily available to personnel while making or breaking cargo transfer
connections, sampling and gauging or when skin contact with the cargo is
likely.
.2 Equipment for entry into enclosed spaces when gas is present
Ships carrying mixtures the benzene content of which is 0.5 per cent or more should
carry not less than three complete sets of safety equipment each permitting personnel to
enter a gas filled compartment and perform work there for at least twenty minutes. Entry
must always be subject to adequate pre-entry criteria being satisfactorily complied with.
Such equipment should be in addition to what is required by regulation II-2/17 of
SOLAS 74.
One complete set of safety equipment should consist of:
- one self-contained air-breathing apparatus (not using stored oxygen);
- protective clothing, boots, gloves and tight-fitting goggles;
- fire-proof life line with belt resistant to the cargoes carried; and
- explosion-proof lamps.
Such ships should also comply with regulation 14.2.3 of the IBC Code.
5 PPE Maintenance
The personal protection equipment should be maintained and replaced in accordance
with manufacturers' instructions. Maintenance records should be kept on board.
6 Training
Each respirator wearer shall be given training (and retraining), which shall include
explanations and discussions of:
- the respiratory hazard and the effect on the wearer if the respirator is not used
properly;
- the engineering and administrative controls being used and the need for
respirators to provide protection;
- the reason for selecting a particular type of respirator;
- the function, capabilities, and limitations of the selected respirator; and
- the method of donning the respirator and checking its fit and operation.
7 Medical Monitoring
Ship personnel potentially exposed to benzene vapor inhalation should be submitted
to a programme of regular suitable medical checks on their health. The results of such
checks should be kept on record under normal confidential practices in the medical
profession.
8 Information on the benzene content of cargo
Prior to loading, the shipper should inform the master in writing if the cargo to be
loaded contains 0.5 or more percent benzene.
In order to comply with this requirement, the shipper might have to obtain this
information from the cargo manufacturer.
* These recommendations regarding air purifying masks apply to operational uses of respiratory equipment
for the purposes of protection during normal cargo handling operations and are be confused with those
provisions specified in 14.2.8 of the IBC Code.
** There are existing standards for respiratory protection equipment. These standards include:
- American National Standard for Respiratory Protection (ANSI Z88.2 - 1992)
- British Standard for Respiratory Protection Devices, Valved Filtering Half Masks to
Protect Against Gases or Gases and Particles (BS EN 405: 1993)