Assessment
Control Of Substances Hazardous to Health –
Risk Assessment
Identification of hazards | Estimation of Exposure | Overall Risk Rating | Carcinogens
Introduction
Making a COSHH assessment requires knowledge of chemical hazards and how the risk they pose can be controlled. This is why a COSHH assessment must be by a competent person which will be usually a manager or supervisor. The manger or supervisor may delegate the responsibility of the COSHH assessment to another person if they are considered to be suitably trained by the designated competent person. However, if the COSHH assessment has been made by another, the supervisor or manager must validate the conclusions of the risk assessment. Note that a written record of the assessment should be kept in all but the most trivial cases. Copies of the written record should be submitted to the Departmental COSHH adviser.
Substances and Identification of the Hazards.
The first part of the assessment involves the identification of the hazards related to the substances being used. This is outlined in the page Chemical Hazards .
In the Royal Society of Chemistry’s approach to COSHH assessment, the substance is given a hazard rating that is based upon its risk phrase . This rating is determined by using table 1, below:
TABLE 1 – HAZARD EVALUATION
| EXTREME HAZARD | Substances of known or suspected exceptional toxicity (e.g. carcinogens). |
| HIGH HAZARD | All substances whose toxicity exceeds that of the medium hazard category, except for those known, or believed to be so highly toxic as to merit special precautions (i.e. those in the extreme category). |
| MEDIUM HAZARD | Substances meeting criteria for CHIP classification as “Harmful” or “Irritant”. |
| LOW HAZARD | Substances not matching criteria for CHIP classification as “Harmful” or “Irritant”. |
Estimation of Exposure
The next part of the assessment involves quantifying the potential for exposure to the hazardous substance. Exposure depends on factors relating to the amount of the material to be used, the physical characteristics of the substance (e.g. a substance in a solid form poses less of an exposure problem than if it is a dust), and the characteristics of the activity (e.g. there will be a higher chance of exposure if an employee works in dusty environment rather than one where the dust is within a partially open container). The exposure associated with each factor is determined by using scoring system as shown in table 2. The overall exposure potential is estimated by taking the product of the three scores and is categorized as Low, Medium or High. As well as the tabulated exposure factors, exposure time (i.e. frequency and duration of the activity) should also be considered.Short duration tasks, involving a few seconds exposure at infrequent intervals should not effect the estimate, whereas continuous operations on a daily basis would probably raise the estimate to the next category (see table).
TABLE 2 – EXPOSURE POTENTIAL
| SCORE | 1 | 10 | 100 |
| (A)Quantity of Substance | <1g | 1-100g | >100g |
| (B)Physical Characteristics of Substance | Dense solids, non-volatile liquids, no skin absorption | Dusty solids, lyophilised solids, volatile liquids, low skin absorption | Gases, highly volatile liquids, aerosols, solutions that promote skin absorption |
| (C)Characteristics of Operation Activity | Predominantly enclosed system, low chance of mishap | Partially open system, low chance of mishap | No physical barrier, any operation where chance of mishap is medium or high. |
Exposure potential is estimated by multiplying the individual scores A*B*C
| A*B*C <1000LOW | 1000<(A*B*C)<10000MEDIUM | (A*B*C)>10000HIGH |
Overall Risk Rating
The overall risk associated with the activity is determined by referring to table 3.
TABLE 3 – OVERALL RISK
| HAZARD CATEGORY(From Table 1) | EXTREME | Risks presented by the handling of such substances are unsuited for this procedure and must be addressed on an individual basis. | |
| HIGH | 2 | 2 TO 3 | 2 TO 3 |
| MEDIUM | 1 | 2 | 2 |
| LOW | 1 | 1 | 1 |
| LOW | MEDIUM | HIGH | |
| EXPOSURE POTENTIAL (From Table 2) |
Hazard Containment
1. Open Bench 2. Fume Cupboard 3. Special Facility
Risk Controls
Once the risk has been determined it is then necessary to determine how the risk can be controlled. Table 3 can be used to determine the form of containment is suitable for the activity. In addition to these containment regimes, it may be necessary to specify personal protective equipment or other control measures, particularly where there may be exposure through the skin.
Replacement
It may be that the risk rating for the activity is high (i.e. 2 to 3 or “extreme”). In such a case the assessor should follow the first principle of COSHH: when faced with a hazardous substance is to replace it with a substance that is less hazardous or is in a less hazardous form e.g. pellets instead of powder. In fact, in all cases, where reasonably practicable, the replacement principle should be adopted.
Emergency Action
The written risk assessment should also include details of what is to be done in an emergency e.g. a chemical spillage.
Disposal of Waste
Disposal of chemical waste should follow the Department’s policy on waste disposal. Any special procedures that should be adopted should be included in the written risk assessment.
COSHH Assessment for Carcinogens,Mutagens and Substances Toxic to Reproduction.
Rules for the use of Category 1 and 2 carcinogens and to Category 1 and 2 Mutagens and Substances Toxic to Reproduction are as follows:
· No such material may be used by undergraduates at levels 1, 2 and 3.
· Level 4 undergraduates are strongly discouraged from using these materials. However, it may be necessary for level 4 students to work with such substances when no alternatives exist. In such cases no work may be carried out until it has been first approved by the Departmental COSHH Adviser and Head of the Department.
· Before use, a completed a special COSHH Assessment must be prepared, including a thorough justification for the use of such material, and approved by the Departmental COSHH Adviser.
· The procedures described in this COSHH Assessment must be strictly followed.
· A record must be kept of all user exposure to such material and returned to the Departmental COSHH adviser.
· Carcinogenic materials must be disposed of carefully and not via the waste solvents.