POPs in Construction Waste: New Research & Risks

New UK Environment Agency research highlights the importance of identifying hazardous chemical additives before recycling construction and demolition waste.

How can a construction product that was perfectly legal to install in a building become a problem when that building is demolished decades later?

New research commissioned by the Environment Agency in the UK provides an important reminder that construction and demolition waste is not always as straightforward to recycle as it appears.

The study, undertaken by WRc, investigated persistent organic pollutants (POPs) and other potentially hazardous substances in discarded construction products.

More than 1,000 individual waste items were collected, including insulation, flooring, window and door frames, plastics, rubber products and expanding fillers.

The findings raise questions for demolition contractors, waste transfer stations, materials recovery facilities and businesses producing recycled construction products.

What Did the Researchers Find?

WRc used X-ray fluorescence screening, followed by more detailed chemical testing of selected samples.

According to its published findings:

• 13 samples contained POPs above relevant thresholds.
• Seven insulation samples contained polybrominated diphenyl ethers (PBDEs) above 500 mg/kg.
• One insulation sample exceeded the 1,000 mg/kg POPs waste limit for hexabromocyclododecane (HBCD).
• One expanding-filler sample contained short-chain chlorinated paraffins (SCCPs) above 10,000 mg/kg.
• Medium-chain chlorinated paraffins (MCCPs) exceeded 10,000 mg/kg in 20 samples.

Other findings included potentially hazardous concentrations of certain organophosphate flame retardants, lead and zinc in particular product categories.

These results do not establish the proportion of all UK demolition waste containing POPs. The study used targeted sampling and progressively more detailed analysis to investigate materials of concern.

Why Can Old Building Materials Contain POPs?

Many construction products contain chemical additives intended to improve performance.

Flame retardants, plasticisers, stabilisers and other compounds can make materials safer, more durable or easier to manufacture.

However, some substances used historically have subsequently been restricted because of their persistence, toxicity or potential to accumulate in the environment.

For example, certain brominated flame retardants were incorporated into insulation products to improve fire performance.

When buildings are demolished many years later, these additives may still be present.

The product's original suitability for construction does not automatically make the resulting waste suitable for unrestricted recycling.

The Recycling Problem: Contamination Can Follow the Material

One of the most interesting findings concerned traffic-management products manufactured using recycled PVC cable granulate.

WRc reported the presence of chlorinated paraffins in some of these products.

This illustrates a wider concern.

When waste plastics are recycled without sufficient understanding of their chemical composition, unwanted legacy substances can potentially be carried into new products.

Mechanical recycling does not necessarily destroy chemical additives.

Consequently, a process that successfully recovers valuable polymer material may also preserve substances that need to be controlled.

High material-recovery percentages are not enough. Recycled material must also be suitable for its intended use and comply with the applicable chemical and waste requirements.

Does This Mean Demolition Plastics Cannot Be Recycled?

No. That would be an unjustified conclusion.

Many construction products can be recycled safely when they are properly identified, segregated and assessed.

The challenge is distinguishing suitable materials from those containing substances that restrict recovery or require specific treatment.

Under the applicable POPs waste rules, waste containing regulated substances above relevant concentration limits may need treatment that destroys or irreversibly transforms those substances, subject to the legal requirements and permitted exceptions.

Importantly, hazardous-waste classification and POPs waste controls are related but separate assessments. A material should not be assumed to be non-hazardous simply because it is below a particular POPs concentration limit.

The results of this research should therefore support better product-specific waste classification rather than indiscriminate rejection of entire recycling streams.

What Should Waste Operators Learn from This?

In my view, there are three practical lessons.

First, know the material's origin. The age and original use of a building product can provide important clues about the additives it may contain.

Second, avoid unnecessary mixing. Segregating suspect insulation, PVC products, foams and other polymer-based materials can help prevent contamination of otherwise recyclable waste.

Third, use appropriate evidence. Screening methods such as X-ray fluorescence can be valuable, but elemental screening alone cannot always identify a particular organic pollutant or establish its concentration. Where necessary, suitable laboratory analysis is required.

Waste producers and operators should follow current Environment Agency guidance on waste classification, POPs and hazardous waste.

My View: Recycling Quality Matters as Much as Recycling Quantity

For many years, waste-management policy has rightly encouraged us to recover more material and send less waste to landfill.

But recovery should never become an end in itself.

If recycling transfers persistent hazardous substances from old products into new ones, we may simply be postponing the environmental problem rather than solving it.

There is also an important distinction between recovering material and producing a genuinely safe secondary raw material.

That distinction is becoming increasingly important as recycling technology improves and more complex waste streams enter recovery facilities.

The WRc research provides useful evidence to help regulators and waste businesses make more informed decisions.

The objective should be to recycle suitable materials with confidence while identifying and controlling the substances that should not be circulated indefinitely.

Further Reading and Sources

WRc: POPs and Hazardous Substances in Construction and Demolition Waste — project findings and links to both Environment Agency research reports.

Environment Agency: Construction and Demolition Waste — How to Classify.

CIWM Connect: Discussion of the WRc Research (may require CIWM login).

Commentary by Steve Last, Chartered Civil & Environmental Engineer (MICE), Chartered Waste Manager (MCIWM) and Chartered Environmentalist (CEnv), IPPTS Associates.