Chemical and radiation hazards in healthcare

Most of the hazards covered in the earlier healthcare courses are easy to see: a heavy patient, a needle, a person who is angry. The hazards in this course are mostly invisible. A drop of a cancer drug dried on the outside of an IV bag, a trace of anesthetic gas breathed out by a patient in the recovery room, formaldehyde vapour above a specimen bucket, the scattered X-rays around a patient during a fluoroscopy procedure: none of them can be seen, and most cannot be smelled or felt. Some do their harm years later, which makes them easy to ignore and hard to connect to their cause.

This course is for everyone who meets these hazards: nurses who give hazardous drugs and care for patients afterward, pharmacy staff who receive and prepare them, laboratory and pathology staff who work with chemicals, imaging and nuclear medicine staff, operating room and recovery staff, and the porters, environmental services and laundry workers who handle the containers, waste, linen and spills that everyone else leaves behind. This first lesson maps the hazards, explains how they get into the body, introduces the exposure limits and the rules that apply, and shows how Northbridge Community Hospital built a register of them.

The main groups of hazard

Chemical and radiation hazards in a hospital fall into a handful of groups. Each is the subject of one or two later lessons.

The groups differ in where the hazard comes from, but they have a lot in common. All of them depend on the dose a worker receives. All of them can be controlled with the same hierarchy of controls taught in HSE-102: remove or substitute the hazard where you can, enclose or ventilate it, set procedures and training, and use personal protective equipment as the last line. And for all of them, the people with the least training are often the most exposed, because the cleaner who empties the waste or the porter who carries the bag was never told what was in it.

How chemicals get into the body

A chemical can only harm a worker if it reaches the body. There are four routes, and each calls for different controls.

• Inhalation: breathing in gases, vapours, mists or fine powders. This is the main route for anesthetic gases, formaldehyde, glutaraldehyde, ethylene oxide and aerosols from drug preparation. Ventilation, enclosures and respirators control it.
• Skin contact: absorption through skin, or damage to the skin itself. Hazardous drugs dried on surfaces, vials and bags reach many workers this way, and so do solvents and disinfectants. Gloves, gowns, cleaning and closed systems control it.
• Ingestion: swallowing the chemical, usually from contaminated hands touching food, drinks, gum, cosmetics or the face. This is why no one eats or drinks where drugs or chemicals are handled, and why hand washing after removing gloves matters.
• Injection: a needlestick or cut from a contaminated sharp, or a broken vial. The controls from HSE-392 apply.

Radiation is different. Ionizing radiation from an X-ray tube does not need to enter the body through any route; it passes through the body from outside, and it stops the moment the machine is switched off. Radioactive materials used in nuclear medicine can do both: they give off radiation from outside, and if they are spilled they can contaminate skin or be swallowed or breathed in, just like a chemical. Lessons 9 and 10 cover these differences.

Dose, time and the body's response

Every one of these hazards follows a basic rule of toxicology: the dose makes the harm. A small amount of formaldehyde vapour causes no symptoms; more causes stinging eyes and a sore throat; much more over years raises the risk of cancer of the nose and throat. Dose depends on two things: how much of the substance is present, and how long the worker is exposed to it.

Effects can be acute, appearing soon after exposure, or chronic, appearing after months or years of repeated exposure. Acute effects of hazardous chemicals include skin rashes, eye irritation, headaches, nausea and dizziness. Chronic effects include occupational asthma, contact allergy, damage to the liver or kidneys, harm to fertility and pregnancy, and cancer. Chronic effects are the hard ones to manage, because the worker feels fine at the time of exposure and the link to work is easily missed.

Some substances have no known safe level for certain effects. For carcinogens, and for drugs that damage genetic material, regulators and health agencies assume that any exposure carries some risk, so the goal is to keep exposure as low as reasonably achievable rather than just below a limit. The same idea, under the name ALARA, is the core of radiation protection.

Exposure limits

For many airborne chemicals, occupational exposure limits set the maximum concentration a worker may breathe. They come in three forms:

• A time-weighted average (TWA), the average concentration allowed over an 8-hour shift. Short peaks above it are allowed as long as the average stays below.
• A short-term exposure limit (STEL), the average allowed over any 15 minutes, which caps the peaks.
• A ceiling, a concentration that must never be exceeded at any moment.

In Ontario, exposure limits for most chemicals are set by Regulation 833, Control of Exposure to Biological or Chemical Agents, which adopts the limits published by the American Conference of Governmental Industrial Hygienists (ACGIH) with some Ontario changes. Eleven designated substances, including ethylene oxide, have their own regulation with stricter rules for assessment and control. Limits are written in parts per million (ppm) for gases and vapours, or milligrams per cubic metre for dusts and mists.

There is an important gap. Most hazardous drugs have no airborne exposure limit at all, because they are dangerous in tiny amounts and the main route is skin contact, not breathing. For these, the approach is to treat any contamination as unacceptable and to measure success by surface wipe testing and by how carefully procedures are followed. Lesson 2 explains why.

The rules that apply

Several layers of law cover these hazards in Ontario. The Occupational Health and Safety Act sets the general duty to take every precaution reasonable in the circumstances. Regulation 67/93 for health care facilities requires written measures and procedures, developed with the JHSC, for hazards including chemical agents, and specifically requires measures and procedures for the safe handling of antineoplastic drugs. WHMIS rules, under Regulation 860 and the federal Hazardous Products Act, require labels, safety data sheets and training. Regulation 833 sets exposure limits, and the designated substance regulation covers ethylene oxide. For radiation, X-ray machines are covered by Ontario's X-ray Safety regulation under the OHSA, while radioactive materials used in nuclear medicine are licensed federally by the Canadian Nuclear Safety Commission (CNSC). Pharmacy compounding of hazardous drugs follows the NAPRA model standards, adopted by the Ontario College of Pharmacists.

Northbridge's chemical and radiation register

When Joanne Pelletier reviewed last year's injury data with the JHSC, chemical exposures looked small: 11 reports, 2 claims and 1 lost-time case. But Joanne knew that number missed most of the story. Chronic effects rarely produce an injury report, and nobody reports breathing anesthetic gas in the recovery room or touching a contaminated IV bag. She proposed a register: a list of every chemical and radiation hazard in the hospital, the departments and jobs exposed, how many workers, how bad the possible harm, and what controls were in place.

The committee spent two months on it. Priya Shah listed the hazardous drugs used in pharmacy and their dosage forms. Daniel Okafor listed the laboratory chemicals and the pathology grossing station. The diagnostic imaging manager listed the X-ray rooms, the portable machines, the fluoroscopy suite, the CT scanner, the nuclear medicine department and the MRI. Marta Kowalski walked the routes environmental services takes with waste and linen, and found that the cytotoxic waste bins on the oncology day unit were emptied by the same staff who cleaned the cafeteria, with no specific training.

To decide what to tackle first, the committee scored each hazard by severity of the possible harm and by how many workers were exposed, and adjusted the score down for strong controls already in place.

# Northbridge chemical and radiation register: a simple ranking
# severity: 1 (irritant) to 5 (cancer, reproductive harm)
# workers: number of staff regularly exposed
# control: 1.0 (no controls) to 0.2 (strong engineering controls)
register = [
    ("Hazardous drugs, oncology day unit", 5, 34, 0.6),
    ("Hazardous drugs, pharmacy compounding", 5, 9, 0.3),
    ("Cytotoxic waste and linen", 5, 41, 0.9),
    ("Formaldehyde, pathology grossing", 4, 6, 0.5),
    ("Glutaraldehyde, endoscopy", 3, 8, 0.6),
    ("Anesthetic gases, recovery room", 3, 22, 0.7),
    ("Fluoroscopy scatter", 4, 18, 0.5),
    ("Portable X-ray on wards", 2, 60, 0.4),
    ("MRI magnetic field", 4, 25, 0.5),
    ("Latex and glove sensitizers", 3, 900, 0.3),
]

def score(sev, n, ctrl):
    # severity counts most; worker numbers grow slowly (square root)
    return round(sev * sev * (n ** 0.5) * ctrl, 1)

ranked = sorted(register, key=lambda r: -score(r[1], r[2], r[3]))
print(f"{'hazard':40}{'sev':>4}{'staff':>6}{'ctrl':>6}{'score':>7}")
for name, sev, n, ctrl in ranked:
    print(f"{name:40}{sev:4}{n:6}{ctrl:6.1f}{score(sev, n, ctrl):7}")

hazard                                   sev staff  ctrl  score
Cytotoxic waste and linen                  5    41   0.9  144.1
Hazardous drugs, oncology day unit         5    34   0.6   87.5
Latex and glove sensitizers                3   900   0.3   81.0
MRI magnetic field                         4    25   0.5   40.0
Fluoroscopy scatter                        4    18   0.5   33.9
Anesthetic gases, recovery room            3    22   0.7   29.5
Hazardous drugs, pharmacy compounding      5     9   0.3   22.5
Formaldehyde, pathology grossing           4     6   0.5   19.6
Glutaraldehyde, endoscopy                  3     8   0.6   15.3
Portable X-ray on wards                    2    60   0.4   12.4

The ranking surprised people. Pharmacy compounding, the area everyone thought of first, ranked lower than expected because Priya's team already worked in a negative-pressure room with a biological safety cabinet and closed-system devices. At the top were the workers with the weakest controls: the environmental services and laundry staff handling cytotoxic waste and linen, and the nurses on the oncology day unit. Latex ranked high because of the sheer number of glove users, even though most of the hospital had already switched to nitrile.

A score like this is a tool for discussion, not a measurement. The weights are judgements, and the committee changed them twice during the review. Its value was in forcing everyone to look at every hazard on the same page, and in pointing the first year of work at waste handling and the oncology day unit, which became the subject of the hazardous drug safety plan in Lesson 12.

Pregnancy, fertility and these hazards

Several hazards in this course can harm fertility or a developing pregnancy: many hazardous drugs, some anesthetic gases at high levels, some laboratory solvents and ionizing radiation. Workers who are pregnant, breastfeeding or planning a pregnancy, of any gender, need clear information so they can make choices, and employers need a policy for alternative duties. The policy should let a worker ask for a temporary change of duties without having to explain why, and should not push workers out of jobs they want and can do safely with good controls.

Northbridge's policy offers any worker who is pregnant, breastfeeding or trying to conceive the option of not preparing or giving hazardous drugs and not working in the fluoroscopy suite, with no loss of pay or seniority, and it treats the request as confidential medical information handled by the Occupational Health and Safety office. It follows Ontario's human rights duty to accommodate.