NIOSH 2024, WHMIS and hazardous drugs in compounding

By Dumitru Musteata, RPh, Pharmacy Compounding Compliance. Last reviewed October 1, 2026.

This guide is independent commentary. It has not been reviewed, approved or endorsed by NAPRA or by any pharmacy regulatory authority, and the interpretations in it are the author’s own, not NAPRA’s. Your provincial or territorial regulator sets the requirements that apply to your pharmacy. They may or may not be based on NAPRA’s model documents and can differ between provinces, so always check your regulator’s current documents.

A non-sterile compounding risk assessment starts by asking whether any ingredient is hazardous to the person handling it. Two sources answer that question: the NIOSH list of hazardous drugs and the WHMIS classification on the safety data sheet. This guide explains how each one works, where they disagree with the wording of the standards, and how “occasional small quantity” fits in.

The NIOSH list, 2024 edition

The current edition is the NIOSH List of Hazardous Drugs in Healthcare Settings, 2024, published in December 2024. It has two tables:

  • Table 1: drugs that have manufacturer’s special handling information in the package insert, or that meet the NIOSH definition of a hazardous drug and are classified as a known human carcinogen by the U.S. National Toxicology Program or as carcinogenic or probably carcinogenic to humans (Group 1 or 2A) by the International Agency for Research on Cancer.
  • Table 2: drugs that meet the NIOSH definition of a hazardous drug but do not meet the Table 1 criteria. Drugs whose only hazard is developmental or reproductive are flagged in a separate column of this table.

There is no third table in this edition. Examples from Table 1 include fluorouracil, methotrexate, azathioprine and tamoxifen. Examples from Table 2 include estradiol, progesterone and spironolactone. Table 2 drugs flagged as developmental or reproductive hazards only include finasteride, tretinoin and clonazepam. Always check the list itself for the ingredient in front of you.

NIOSH is clear about what the list is: hazard identification. It says a site-specific risk assessment is outside the scope of the list and depends on dose, potency and the potential for exposure. That is the pharmacy’s job.

The standards still speak of three groups

The Model Standards and guidance document were published in 2018 and refer to the 2016 NIOSH list, which had three groups: antineoplastic drugs (Group 1), non-antineoplastic hazardous drugs (Group 2) and drugs that primarily pose a reproductive risk (Group 3). The decision algorithm in the guidance document asks first whether a product is in “Table 1 of the NIOSH list – antineoplastic (cytotoxic) drugs”, and Level C is described in terms of Group 1.

The 2024 tables are built on different criteria, so an old group does not translate directly into a new table. Azathioprine is a useful example: the guidance document names it as a Group 2 drug, and the 2024 list places it in Table 1. The Ontario College’s 2026 risk assessment template asks about the 2024 list, describing Table 1 as hazardous drugs with carcinogenic properties and Table 2 as other hazardous drugs.

The practical approach is to record the drug’s place on the current list, note the kind of hazard it presents, and explain your reasoning for the level, without relying on the table number alone. Where the answer is uncertain, regulators direct pharmacies to the higher standard.

WHMIS and the safety data sheet

WHMIS is Canada’s hazard communication system for workplace chemicals. For compounding, the working document is the supplier’s safety data sheet:

  • Section 2, hazard identification, gives the classification. Health hazard classes include acute toxicity, skin corrosion or irritation, serious eye damage or irritation, respiratory or skin sensitization, germ cell mutagenicity, carcinogenicity, reproductive toxicity and specific target organ toxicity.
  • Section 8, exposure controls and personal protection, gives the recommended engineering controls and protective equipment.
  • Section 11, toxicological information, gives the detail behind the classification.

Three practical points. First, manufactured drug products with a DIN are exempt and do not have safety data sheets; consult the safety data sheet for the active ingredient and the product monograph. Second, check the date of each sheet and make sure you hold the supplier’s latest version. The guidance document speaks of updates every 3 years; under current WHMIS rules a supplier must update a sheet within 90 days of becoming aware of significant new data. Third, the two sources do not always agree: an ingredient can be absent from the NIOSH list and still carry a WHMIS health hazard. In the College’s first worked example, hydrocortisone acetate is not on the NIOSH list, but its safety data sheet shows reproductive toxicity and target organ toxicity.

“Occasional small quantity”

The decision algorithm lets a hazardous ingredient be handled with fewer precautions when it is compounded in an “occasional small quantity”. The standards give no number. According to the Ontario College:

  • What counts depends on the amount handled and how often, but those two cannot be considered in isolation.
  • They are not the only factors in the overall risk to staff and patients.
  • Cumulative exposure over time must be considered, even when preparations are made on different days.
  • A pharmacy that compounds many different products occasionally may need the same level of requirements as one that compounds a few products routinely.
  • The Designated Manager or the non-sterile compounding supervisor decides what is small or large, occasional or routine, and documents why.

To support the decision, record for each preparation the quantity made at a time and the frequency, and keep a periodic summary of the hazardous ingredients used across all preparations. If the total is growing, the answer to the question may have changed even though no single preparation has.

The hierarchy of controls

When a hazard is identified, the order in which controls are considered matters. NIOSH’s hierarchy of controls ranks them from most to least effective: elimination, substitution, engineering controls such as a ventilated containment device, administrative controls such as procedures and scheduling, and personal protective equipment. Gloves, gowns and respirators come last because they depend on being available, fitted and used correctly every time. A risk assessment that answers every hazard with protective equipment alone is worth a second look.

Putting it together

  1. For each ingredient, record its place on the NIOSH 2024 list and the health hazards in section 2 of its safety data sheet.
  2. Note the physical form and how it is handled. Powders, volatile liquids and crushed tablets raise exposure.
  3. Record quantity and frequency, and consider the pharmacy’s cumulative use.
  4. Choose controls in the order of the hierarchy, and write down why they are sufficient.
  5. Assign the level, sign, date, and review at least every 12 months.

The OCP risk assessment template, question by question

Sources

Need this documented for each preparation?

Our risk assessments record the NIOSH and WHMIS status of every ingredient, the quantity and frequency, and the reasoning for the level. About the risk assessment service

Request a quote
Call Now Button