Summary
In short
- The assessment covers the task, not the substance. Quantity, method, duration, frequency and ventilation determine exposure, and none of them appear on a data sheet.
- Skin is an exposure route that assessments routinely underweight. Wet work and dermal absorption cause a large share of occupational ill health and are absent from most chemical assessments.
- OSHA's 2024 final rule aligned the Hazard Communication Standard with GHS Revision 7, the first realignment since 2012, and took effect on 19 July 2024.
- On 15 January 2026 OSHA extended the compliance dates by four months. Substances moved from 19 January to 19 May 2026 for manufacturers, and employers handling substances now have until 20 November 2026.
- Mixtures follow later: manufacturers to 19 November 2027, and employers handling mixtures to 19 May 2028.
- The updated standard changes label elements and safety data sheet content, which means employer training obligations follow rather than being optional.
What it is
What it is
What is a chemical risk assessment?
An assessment of the risk to health from a substance as it is actually used: the quantity, the method, the duration and frequency, the ventilation, the routes by which exposure could occur, and who else is nearby. It concludes with the controls required and whether health surveillance or exposure monitoring is warranted.
Is a safety data sheet an assessment?
No, and treating it as one is the most common error in this area. The data sheet describes the substance's intrinsic hazards and gives general handling advice written without knowledge of your process. The assessment describes exposure arising from your use of it, which is what determines the controls.
When to use it
When to use it, and when not to
This assessment covers a task involving substances. Where a specific regime applies, it takes precedence rather than being replaced by this.
Use it for
- Any task involving a hazardous substance, assessed as the task is actually performed
- Introduction of a new substance, supplier, formulation or method
- Change in quantity, frequency, duration, location or ventilation for an existing task
- Following a reported symptom, spill, or exposure incident
- Where exposure monitoring or health surveillance results indicate controls are not adequate
Not for
- The safety data sheet, which describes the substance and is an input to this assessment
- The substance register, which lists what is held on site and where
- Dermatitis and skin assessment where wet work dominates, which needs its own treatment
- Process safety management for covered highly hazardous chemicals, which is a distinct regime
- Fire and explosion assessment under DSEAR or equivalent, which addresses a different consequence
Standards
What it is built against
Chemical control is governed by a duty to assess and control in most jurisdictions, alongside a communication regime that has just been substantially updated in the United States.
| Clause | Requirement | Where it lands |
|---|---|---|
| COSHH reg.6 | Suitable and sufficient assessment of health risks from substances before work begins | Header |
| COSHH reg.7 | Prevention or adequate control, with PPE only after other measures have been applied | Controls |
| COSHH reg.9 | Maintenance, examination and test of control measures, including LEV every 14 months | Controls |
| COSHH regs 10-11 | Exposure monitoring and health surveillance where required by the assessment | Result |
| OSHA 1910.1200 | Hazard communication: labels, safety data sheets and training, updated to GHS Revision 7 in 2024 | Related records |
| OSHA 1910.1200(h) | Employee training on new label elements and SDS format following the 2024 update | Related records |
| OSHA Subpart Z | Permissible exposure limits for specific substances with their own monitoring requirements | Exposure routes |
| EU CLP and REACH | Classification, labelling and packaging, and exposure scenarios in extended safety data sheets | Related records |
What it does not cover
- The safety data sheet, which describes intrinsic hazards and is an input to this assessment rather than a substitute.
- Dermatitis and skin assessment, which addresses wet work and barrier damage that a general chemical assessment usually omits.
- Process safety management, for covered highly hazardous chemicals, which is a distinct and far more prescriptive regime.
- DSEAR or explosive atmosphere assessment, which addresses fire and explosion rather than health.
- Health surveillance, which is a clinical activity triggered by this assessment and recorded separately.
Filling it in
Filling it in well
Four things separate an assessment that changes controls from one that reproduces a data sheet.
Quantity used per occasion, method of application, duration of exposure, frequency per shift, and the room and its ventilation. Those five values determine exposure, and an assessment without them cannot support a control decision or be compared against an exposure limit.
Inhalation is assessed reliably. Skin absorption, skin contact causing local damage, ingestion through hand-to-mouth transfer and eye contact are routinely thinner. Skin is the route most often underweighted and, across occupational ill health, one of the largest contributors.
Elimination, substitution with a less hazardous product, enclosure, local exhaust ventilation, then administrative measures, then PPE. Recording why each higher level was rejected is what makes the assessment defensible and is what a regulator asks about after an exposure incident.
Where exposure may approach a limit, or where a substance can cause an identifiable disease with a valid detection technique, the assessment should say so and name the trigger. Health surveillance decided informally later, or not at all, is a common gap that surfaces years after the exposure.
Audit findings
Common audit findings
Chemical assessment findings concentrate on what the assessment describes rather than on missing paperwork.
| Finding | Clause | What fixes it |
|---|---|---|
| Assessment reproduces the safety data sheet without describing the task. | COSHH reg.6 | Record quantity, method, duration, frequency and ventilation; those determine exposure. |
| Skin route not assessed. | COSHH reg.6 | Assess absorption, contact and hand-to-mouth transfer; skin is systematically underweighted. |
| PPE specified without higher controls being considered and rejected. | COSHH reg.7 | Record why elimination, substitution and engineering control were not used. |
| LEV relied on with no examination and test record. | COSHH reg.9 | Examine and test at least every 14 months in Great Britain; an untested system is an assumption. |
| Assessment not updated after a supplier or formulation change. | COSHH reg.6 | Trigger review on any change to product, supplier, method or quantity. |
| Employee training not updated for the 2024 HazCom label and SDS changes. | 1910.1200(h) | Train on the new label elements and SDS format; employer deadlines run to November 2026 and May 2028. |
| Exposure monitoring or health surveillance triggers not stated. | COSHH regs 10-11 | Name the trigger in the assessment rather than deciding informally later. |
| Substances present on site with no assessment because they arrived via maintenance or contractors. | COSHH reg.6 | Control the entry route; unregistered substances arrive through non-procurement channels. |
| Assessment covers the user but not others nearby. | COSHH reg.6 | Include adjacent workers, cleaners and anyone entering afterwards. |
| Emergency and spill arrangements not addressed in the assessment. | COSHH reg.13 | Cover foreseeable accidents and incidents alongside routine use. |
Worked case
Case in point: the same product, two very different exposures
A plant used a solvent-based cleaner in two places. In the workshop it was decanted into a bottle and wiped onto components in a bay with local exhaust ventilation, perhaps twenty minutes a shift. In a plant room it was sprayed onto overhead pipework, arms raised, for around ninety minutes during a quarterly clean, in a space with no mechanical ventilation.
One assessment covered both, because it was written per product. It reproduced the data sheet hazard statements, specified nitrile gloves and safety glasses, and was reviewed annually. Both uses were recorded as adequately controlled.
The exposures were not comparable. Spraying overhead into an unventilated space produces inhalation exposure orders of magnitude higher than wiping in a ventilated bay, and the raised-arm posture puts the breathing zone directly in the aerosol. The assessment described a product; only one of the two tasks was actually controlled.
Definitions
Definitions and key terms
- Exposure route
- How a substance reaches the body: inhalation, skin absorption or contact, ingestion, eye contact and injection.
- Local exhaust ventilation
- Engineering control capturing contaminant at source, requiring examination and test at least every 14 months in Great Britain.
- Permissible exposure limit
- The OSHA airborne concentration limit for a substance, typically as an eight-hour time-weighted average.
- Workplace exposure limit
- The equivalent limit in Great Britain, published in EH40 and used to judge adequacy of control.
- GHS
- The UN Globally Harmonized System of classification and labelling. OSHA's HazCom aligned with Revision 3 in 2012 and Revision 7 in 2024.
- Sensitiser
- A substance that can cause an allergic response, after which very small exposures provoke a reaction that is not reversible.
- Extended safety data sheet
- An SDS with exposure scenarios attached, produced under REACH for substances registered above a tonnage threshold.
- Adequate control
- The COSHH standard: exposure prevented, or where not reasonably practicable, controlled below the limit with good practice applied.
FAQ
Frequently asked questions
Is a safety data sheet enough?+
No. The sheet describes the substance's intrinsic hazards and offers general handling advice written without knowledge of your process. The assessment describes what happens when someone uses a stated quantity, by a stated method, for a stated time, in a stated place. The same product can require very different controls in two areas of one site, and the sheet gives identical advice for both.
What changed with OSHA HazCom in 2024?+
The final rule published in May 2024, effective 19 July 2024, aligned the Hazard Communication Standard with GHS Revision 7, the first realignment since the 2012 update to Revision 3. Changes cover hazard classification, label elements including provisions for small containers, safety data sheet content in several sections, and trade secret disclosure of concentration ranges.
When do the HazCom deadlines fall?+
OSHA extended them by four months on 15 January 2026. Manufacturers, importers and distributors evaluating substances now have until 19 May 2026, and employers handling substances until 20 November 2026. For mixtures the dates are 19 November 2027 for manufacturers and 19 May 2028 for employers. During the transition period compliance with the updated rule, the 2012 standard, or both is permitted.
Why is skin exposure so often missed?+
Because inhalation is what exposure limits are written for and what monitoring measures. Skin absorption, local damage and hand-to-mouth transfer have no equivalent limit to compare against, so they are harder to assess and easier to omit. Across occupational ill health, skin routes are a large contributor, and wet work in particular is rarely treated as a chemical exposure at all.
What triggers review?+
Any change to the substance, supplier, formulation, quantity, method, frequency, location or ventilation, plus any reported symptom, spill or monitoring result suggesting control is inadequate. The supplier change trigger is missed most often, because a like-for-like substitution on price can alter the formulation without anyone treating it as a change.
The agents
What the agents do with it
The assessment is short once the task is described. What fails is the substance that arrived through maintenance and the assessment written per product rather than per task.
Holds assessments against tasks rather than substances, and links each to the data sheet, the controls specified and the people who perform it.
Watches supplier and specification changes for formulation differences, and raises reassessment rather than waiting for the annual review.
Carries exposure monitoring and health surveillance triggers from the assessment into scheduled activity, including skin surveillance where wet work applies.
Schedules LEV examination and test against the systems the assessment relies on, since an untested extraction system is an assumption rather than a control.
This template lives in KnowSafe — safety and compliance. Incidents, hazards, permits, inspections and the critical controls behind them.
Meet KnowSafe→Sources
Sources
- Control of Substances Hazardous to Health Regulations 2002, regulations 6, 7, 9, 10, 11 and 13
- 29 CFR 1910.1200, Hazard Communication Standard, as amended May 2024, OSHA
- HCS 2024 compliance date extension notice, OSHA, 15 January 2026
- 29 CFR 1910 Subpart Z, toxic and hazardous substances, OSHA
- HSE EH40 workplace exposure limits (GB)