The Open Loop Problem in Occupational Health: Why IARC Signals Expose System Failure—and How the Razavi Occupational Health Iceberg Closes the Loo

The International Agency for Research on Cancer (IARC) has released its 2025–2029 priority list for Monographs evaluation. This list is often read narrowly—as an academic exercise or an early warning of possible future classifications.

From a systems perspective, that reading misses the point.

The IARC list is not a verdict. It is a stress test of occupational health systems. It highlights agents with sufficient exposure prevalence and biological plausibility that, if systems are incomplete, harm will eventually surface.

The critical question for employers and industries is therefore not whether these agents are carcinogens today, but whether their occupational health system is closed or open.

Because an open loop system does not fail immediately.

It fails eventually.

Systems Thinking: Why Open Loops Always Fail

Any complex system that handles cumulative risk must be closed-loop. That is as true for engineering as it is for occupational health.

A closed loop requires:

• Measurement

• Interpretation

• Feedback

• Adjustment

• Verification over time

In occupational health, this loop can only be closed when exposure information is interpreted through human biology and fed back into work design, surveillance, and decision-making.

When that step is missing, the system remains open. Performance may appear acceptable for years. Compliance may be achieved. Metrics may look reassuring.

But biology continues to accumulate exposure silently.

Failure, under those conditions, is not hypothetical.

It is deferred.

The Occupational Health System — Properly Closed

When industries intersect with IARC-priority agents, effective governance requires the coordinated operation of three professional functions, with clear directionality of accountability:

• Occupational Medicine – the governing function that closes the loop by interpreting exposure data through human biology, integrating evidence across time, and translating risk into surveillance, accommodation, and prevention decisions

• Occupational Hygiene – the technical function that identifies hazards, measures exposure, analyzes trends, and reports findings into Occupational Medicine for clinical and biological interpretation

• Occupational Safety – the operational function that designs tasks and controls to prevent acute injury and process failure

This structure is not about hierarchy of importance. It is about systems logic.

Occupational Hygiene produces high-quality data.

Occupational Medicine determines what that data means for human health across a working life.

Without that interpretive step, the loop is open.

Why Occupational Medicine Is the Loop-Closing Function

Occupational Medicine is the only discipline designed to operate across:

• Exposure science

• Human physiology and susceptibility

• Time (years to decades)

• Health surveillance and early dysfunction

• Fitness for work and accommodation

• Causation when disease eventually appears

It answers the question no other function can:

“Given this exposure profile, what will happen to real humans over time—and how do we intervene before disease becomes inevitable?”

This role is especially critical for IARC-priority agents, where:

• Effects may be subclinical for long periods

• Risk is cumulative rather than acute

• Mixed exposures interact biologically

• Aging changes vulnerability

• Disease appears long after exposure decisions were made

Without Occupational Medicine in the loop, hygiene data remains technically excellent—but biologically mute.

The Razavi Occupational Health Iceberg (Successful System)

The Razavi Occupational Health Iceberg visualizes a closed-loop system.

Above the waterline are late outcomes—what organizations eventually see.

Below the waterline are the real determinants of health: cumulative exposure, biological interaction, work design, recovery, and governance.

A continuous Occupational Medicine thread runs through all submerged layers, closing the loop between:

• What is measured

• What is happening biologically

• What must change in work design and surveillance

Above the surface, older workers appear not as patients, but as healthy elders—men and women walking, playing, and engaging with their grandchildren.

These outcomes are not luck.

They are the visible result of a closed system.

Failure When Occupational Medicine Is Absent

Remove Occupational Medicine, and the loop opens.

Hygiene continues to measure.

Safety continues to control acute hazards.

Compliance continues to be reported.

But no one is interpreting cumulative exposure through biology. No one is closing the loop.

Below the waterline:

• Exposure is measured but not biologically interpreted

• Cumulative dose is not governed

• Mixed hazards are not integrated

• Early dysfunction is missed

• Surveillance starts only after disease

Above the waterline, the system finally reveals its failure:

hospital beds, medical dependency, late recognition.

Nothing went wrong suddenly.

The system was incomplete from the start.

The Inevitability Comparison

Closed Loop vs Open Loop

Placed side by side, the message becomes unavoidable.

Both systems often look identical early on.

Both may meet regulatory expectations.

Both may appear successful for years.

Only one is closed.

In the open-loop system, harm is not prevented—it is postponed. The question is never if the system will fail, but when the accumulated biological burden becomes visible.

Why the IARC Priority List Matters Right Now

It is true that:

Priority for evaluation does not equal carcinogenic classification.

But from a systems standpoint, that statement is irrelevant.

IARC priorities signal:

• Where exposure is widespread

• Where biological concern is credible

• Where future scrutiny is inevitable

Organizations that wait for certainty are not being cautious. They are leaving the loop open.

Organizations that embed Occupational Medicine early are not overreacting. They are closing the loop while prevention is still possible.

Closing the Loop — and the Legacy Question

Every employer already has an occupational health system.

The only question is whether it is closed or open.

So the real questions are:

Do you want a closed-loop system that governs health across time—or an open loop that guarantees late failure?

Which outcome are you designing for your workforce over a lifetime, not a quarter?

And when your employees reach the later years of their lives, what legacy will your system leave behind—healthy elders, or patients you never intended to create?

Because the loop is being built now.

And if it remains open, the outcome is not a surprise.