CHRA

Purpose of CHRA

• Provides an evidence-based decision-making tool to ascertain:

  • Appropriate control measures.

  • Induction & training of workers.

  • Necessity of exposure-monitoring programme.

  • Necessity of a medical-surveillance programme.

• Ultimate goal: protect worker health when exposed to Chemical Hazardous to Health (CHTH).

Objectives of CHRA

• Identify hazards posed by each CHTH used on site.

• Evaluate the degree of exposure via inhalation, dermal, or ingestion routes.

• Evaluate adequacy of existing controls.

• Recommend and prioritise further risk-reduction measures.

Legal Compliance Requirements (USECHH Reg.)

• Assessment report must cover ⬇︎

  1. Potential risk to workers.

  2. Methods & procedures of use.

  3. Nature of the health hazard.

  4. Degree of exposure.

  5. Risk due to routine use and accidental release.

  6. Necessary control measures & emergency procedures.

  7. Need for exposure monitoring & medical surveillance.

  8. Training / re-training needs.

Assessment Strategies (Manual §1.4)

• Full Assessment (default approach)

  • Conducted strictly per CHRA Manual methodology.

  • Two deployment styles:

  • Site-Specific CHRA – each workplace assessed individually.

  • Generic CHRA – representative sites assessed; results extrapolated if work, risk & controls are similar.

• Simple Assessment (alternative, §1.4.2)

  • Permitted only when:

  • Chemical is on the site’s register.

  • NOT classified as Carcinogen Cat 1, Mutagen Cat 1, or Respiratory Sensitiser Cat 1.

  • Uses SIRAC (Simple Risk Assessment & Control) methodology.

Assessment Flow (Simplified Decision Tree)

1. Identify CHTH & associated hazards.

2. If criteria for §1.4.2 are met AND adequate data exist → conduct Simple Assessment.

3. Otherwise → perform Full CHRA.

4. Develop action plan → Implement → Verify adequacy.

5. If controls still inadequate → seek specialist advice.

Ten Steps of a Full CHRA

1. Gather information.

2. Define Work Units.

3. Determine Degree of Hazard.

4. Evaluate exposure (inhalation, dermal, ingestion).

5. Determine overall Risk Level.

6. Assess adequacy of existing controls.

7. Identify further actions & assign Action Priority (AP).

8. Conclude assessment & compile recommendations.

9. Prepare, present & submit report to management/DOSH.

Step 1 – Gathering Information

• Required documents / data sources:

  • Inventory of chemicals & Safety Data Sheets (SDS).

  • Plant layout, ventilation schematics & process flowcharts.

  • Workforce roster & tasks.

  • Existing engineering controls (LEV, enclosure, etc.).

  • Past accident / incident records involving chemicals.

  • Exposure monitoring & medical surveillance results.

  • PPE & training programmes, SOPs, safe-work procedures.

Step 2 – Defining the Work Unit

• Work Unit = group of workers with similar tasks and similar CHTH exposure.

• Categories: Routine vs Non-Routine.

• Can be defined by job, task, or process.

• Job-rotation rules:

  • If rotation ≤ monthly → treat combined tasks as a single work unit.

  • If rotation ≥ quarterly → assess tasks separately.

• Example: printing company with six operators rotating among mixing, machine operation & stamp printing every 6 months → treat each task as separate work units.

Step 3 – Determining Degree of Hazard

• Sources: SDS (Sections 2 & 11), GHS label, waste cards, databases.

• Hazard Rating (HR) – 1 (low) to 5 (high) based on inhalation toxicity:

  • Uses Table 1 (HR vs health effect / H-code / LC₅₀).

  • Carcinogens Cat 1A, mutagens Cat 1A, reproductive tox Cat 1A generally score HR = 5.

• Notes:

  • If the hazard statement does not specify route, assume all routes at risk.

  • Pesticides: consult Section 11 (LC₅₀).

  • Scheduled Waste: use Section A, item 4 of waste card.

Brief GHS Refresher

• Physical hazards (explosives, flammables, oxidisers, etc.).

• Health hazards (acute tox, corrosivity, STOT, carcinogenicity, etc.).

• Environmental hazards (aquatic tox, ozone layer).

• Nine pictograms indicate the classes; health-hazard pictogram depicts a silhouette with star-burst.

Step 4 – Evaluating Exposure (Inhalation)

4 A – Frequency Rating (FR) – Table 5

• 5 = Daily; 4 = > weekly; 3 = > monthly; 2 = > yearly; 1 = ≤ annually.

4 B – Duration Rating (DR) – Table 6

• 5 ≥ 7 h/shift; 4 = 4-<7 h; 3 = 2-<4 h; 2 = 1-<2 h; 1 < 1 h.

4 C – Frequency-Duration Rating (FDR) – Table 7

• Combine FR & DR via matrix (max = 5, min = 2).

4 D – Degree of Chemical Release / Presence – Table 8

• Low (1), Moderate (2), High (3) depending on volatility, dustiness, visible contamination, odour, etc.

4 E – Degree of Inhaled – Table 10

• Low, Moderate, High based on breathing rate & proximity of source.

• Breathing rate tied to Physical Activity (Table 11):

  • Light work → low.

  • Moderate work → medium.

  • Heavy work → high.

4 F – Magnitude Rating (MR) – Table 12

• Combine Degree of Release & Degree of Inhaled in a 3×3 matrix (scores 1-5).

4 G – Exposure Rating (ER) – Table 14

• Combine FDR & MR to obtain ER (1-5).

4 H – Risk Rating (RR)

• $RR = HR \times ER$ (not explicitly printed but implied by tables).

• Risk Levels (Table 16):

  • Low: $RR \in [1,4]$

  • Moderate: $RR \in [5,12]$

  • High: $RR \in [15,25]$

Step 5 – Dermal Exposure Evaluation

Extent of Contact

• Small (< 2 % body surface ≈ 0.04 m²) vs Large (> 2 %).

Duration of Contact

• Short < 15 min/shift; Long ≥ 15 min/shift.

Risk Matrix (Table 17)

• Cross-tabulates Hazard properties (irritant, corrosive, sensitiser, acute tox, carcinogen, STOT, etc.) with duration/extent to output risk level:

  • Low (L)

  • Moderate (M1, M2)

  • High (H1, H2)

• Combination effects (e.g. H310 + H314) escalate risk automatically.

• A robust CHRA integrates hazard data (intrinsic toxicity) with exposure reality (frequency, duration, intensity) to yield actionable risk ratings.

• Continuous review, worker engagement, and management commitment are crucial for effective chemical-risk governance.