Chemical Tankers / Day 2 / Day 2 Topic 1 USCG Chemical Guide

1.7 Health Hazard Data explanation

o The Third Rating (contd.)

0 - No likelihood or producing injury ;

1 - Minimum hazard. Includes most chemicals having threshold limits above 500 ppm;

1.7 Health Hazard Data explanation

o The Third Rating (contd.)

2 - Some hazard, typically having threshold limits of 100 to 500 ppm;

3 - Moderately hazardous chemicals;

4 - Severely hazardous chemicals usually having threshold limits below 10 ppm;

1.7 Health Hazard Data explanation

o Odour Threshold

The smallest concentration of gas or vapor, expressed in parts per million (ppm) by volume in air, that most people can detect by smell.

1.7 Health Hazard Data explanation

o Odour Threshold (contd.)

This is not an absolute value. It will vary among individual-and will vary from day to day for any one person.

The odor of a potentially dangerous vapor may be hidden by another odor.

In addition, certain vapors are likely to produce olfactory fatigue, which is deadening of the sense of smell.

1.7 Health Hazard Data explanation

o Odour Threshold (contd.)

For this reasons, the sense of smell alone is not a reliable indicator of the presence or absence of a dangerous vapor.

1.7 Health Hazard Data explanation

oPermissible Exposure Limits (PEL)

oThreshold Limit Value (TLV)

The PEL and TLV refer to airborne concentration of a product expressed in parts per million (ppm) by volume in air.

1.7 Health Hazard Data explanation

oPermissible Exposure Limits (PEL)

oThreshold Limit Value (TLV)

These are the Time-Weighted Average (TWA) concentrations believed to be safe for the average person during an 8-hour workday and 40-hour work-week for prolonged periods.

The sensibility of individuals will vary.

1.7 Health Hazard Data explanation

o “Skin”

The notation used to indicate that the product can be absorbed through the skin, including mucous membranes and eyes.

Prevent or reduce the exposure through the safety and personal protective equipment.

1.7 Health Hazard Data explanation

o Short Exposure Tolerance

Vapour concentration, expressed as parts per million (ppm) by volume in air, which should not be exceeded for the exposure times specified.

1.7 Health Hazard Data explanation

o Short Exposure Tolerance (contd.)

Other exposure information obtained from sources believed to be reliable is included.

In many cases little or no data on human exposure are available.