The classification history · every date sourced
Are the fibreglass batts in my roof a cancer risk?
In 2001 the International Agency for Research on Cancer went back over glass wool and moved the whole category to Group 3 — not classifiable as a cause of cancer in humans. IARC Monographs Vol. 81 (2002), pp. 45–54 — Summary of Data & Evaluation ↗ That review covered the old fibre. The studies behind it followed thousands of factory workers in the United States and Europe who made and breathed the pre-1990s product for decades, and they did not show a clear excess of cancer. So we are not going to tell you the old batts in your roof are a proven carcinogen. The evidence says otherwise, and it says it about the old fibre specifically.
Here is the part that still earns respect: insulation batts made before the 2001 reformulation were never put through the biopersistence test today’s product passes, so when you disturb old batts, treat the dust with the care the manufacturers’ own paperwork asks for.
I’m Peter Johnson, a Brisbane insulation contractor since 1986. IARC gave two reasons for the change, and this page keeps both in view the whole way through: thirteen more years of factory-worker studies had shown no clear excess cancer risk, and manufacturers had changed the fibre chemistry to dissolve faster in lung fluid. IARC Monographs Vol. 81 (2002), General Remarks — “altered the chemical compositions of their products to enhance their solubility in biological systems” + “substantial improvements in the quality of the epidemiological information” ↗
Group 2B → Group 3
the 1988 rating and the 2001–02 rating
Before any history: where the rating stands today
The current rating on fibreglass insulation batts, in the regulators' and manufacturers' own words.
Read this box first. Everything below it is history, and history only makes sense against the current position. One definition before the documents: IARC’s Group 3 is “not classifiable as to its carcinogenicity to humans” — an absence of sufficient evidence, not a proven-safe stamp. IARC doesn’t use Group 3 to mean safe, so neither will I.
IARC — since the 2001–02 review
“Insulation glass wool, continuous glass filament, rock (stone) wool and slag wool are not classifiable as to their carcinogenicity to humans (Group 3).” IARC Monographs Vol. 81 (2002), Summary of Data & Evaluation ↗
Safe Work Australia — today
No carcinogen category is assigned to tested, biosoluble insulation glass wool. Both major Australian manufacturers state this on their own current safety data sheets, citing the biopersistence (Note Q) test their fibre passes. CSR Bradford FBS-1 SDS, 06/02/2024, §11 — “listed by Safe Work Australia as Man-made Vitreous Fibre (MMVF), which is Glasswool, biosoluble and of low biopersistence. It is considered non-hazardous.” ↗
Knauf’s own current SDS
“Results from a biopersistence test in line with the notes has shown that fibres in this product longer than 20 μm have a weighted half-life less than 40 days and meet the ‘Nota Q’ requirements, thus this product is not classified as a carcinogen.” Knauf Insulation Glasswool SDS (Australia), Rev 3.0, 30/07/2020, §11 ↗
CSR Bradford’s own current SDS
The FBS-1 glasswool product is classified “Non-Hazardous” — biosoluble, low biopersistence, per the same Note Q framework. CSR Bradford FBS-1 Glasswool Insulation SDS, 06/02/2024, §11 ↗
Those last two are my competitors’ own documents, quoted because they’re accurate. We sell against fibreglass batts on measured dust behaviour and coverage — see is fibreglass insulation safe and fibreglass dust in your house — not on a cancer claim their paperwork contradicts.
1988 → today, every step dated and linked
The paper trail on fibreglass batts: how the rating changed, document by document.
1988
IARC rates glasswool Group 2B — “possibly” is the operative word
IARC’s Monographs Volume 43 evaluated man-made mineral fibres as a class and concluded: “Glasswool is possibly carcinogenic to humans (Group 2B).” The same Group 2B wording applied to rockwool, slagwool and ceramic fibres. That rating stood from 1988 to the 2001–02 re-review. IARC Monographs Vol. 43 (1988), Summary of Data & Evaluation ↗ IARC’s own caveat travelled with the finding, quoted verbatim in Australia’s 1990 code: the classifications “are based on a review of evidence that the disease could occur. They do not necessarily reflect the level of risk that is likely to exist in the workplace.” NOHSC:2006(1990), Appendix 2 — quoting the IARC Vol. 43 finding and caveat ↗
1990 · Australia
Australia’s code quotes the finding as background — and sets a workplace standard, not a pack warning
The National Code of Practice for the Safe Use of Synthetic Mineral Fibres, NOHSC:2006(1990), carried the 1988 IARC finding as background health-effects information. It set a workplace exposure standard and handling controls. Its labelling clause points to the general hazardous-substance labelling guidance — no cancer-warning label on the pack appears anywhere in the code. NOHSC:2006(1990), Appendix 2 (health effects) and §5.2 (labelling) ↗
1 July 1990 · California, USA
California lists glasswool under Proposition 65
California’s OEHHA listed “glasswool fibers (airborne particles of respirable size)” as “known to the State to cause cancer” — that phrase is California’s statutory Prop 65 formula, triggered automatically by the 1988 IARC finding, not a separate scientific verdict. OEHHA notice, 18 Nov 2011 — restating its own 1 July 1990 listing action verbatim ↗
By 1991 · USA
The American cancer-warning label on fibreglass batt packs, in the regulator’s own record
A 1991 OSHA compliance letter to Owens-Corning quotes the manufacturer’s own submitted US label text back to them: “Contains fiberglass wool. Possible cancer hazard. To avoid this possible cancer hazard, minimize breathing fiberglass wool dust.” US OSHA Standard Interpretation letter to Owens-Corning, 28 June 1991 ↗ This is US history. No Australian requirement for a cancer warning on insulation packaging has been found — and the US industry’s own association states the US “was the only jurisdiction in the world that required a cancer warning label on biosoluble fiberglass insulation.” NAIMA / Insulation Institute, Insulation Outlook Magazine, 2012 — “Cancer Warning Labels Removed from Fiberglass Building Insulation Products” ↗
1994 · USA
The US NTP lists glass wool, class-wide
“‘Glass Wool (Respirable Size)’ was first listed in the Seventh Annual Report on Carcinogens as reasonably anticipated to be a human carcinogen based on sufficient evidence from studies in experimental animals.” A blanket listing — it did not yet distinguish biopersistent from biosoluble fibre. US NTP, Report on Carcinogens, 15th ed., “Certain Glass Wool Fibers (Inhalable)” profile, p.1 ↗
January 2001 · Australia
The fibre in Australian-made insulation batts changes
WorkSafe WA, a state government WHS regulator, states it plainly: “All the fibreglass manufactured in Australia since January 2001 has been of the ‘biosoluble’ type.” WorkSafe WA, “Working with fibreglass” ↗ The industry’s own council, ICANZ, runs the certification mark behind that shift: “FBS-1 – Fibre Biosolubility is an industry trademark that has been operating in Australia since 2001.” ICANZ (the insulation industry's own council), “Fibre Biosolubility” ↗
October 2001, published 2002
IARC re-reviews and splits the category — insulation wool, old fibre included, moves to Group 3
A working group of 19 experts from 11 countries re-evaluated the whole class and concluded: “Insulation glass wool, continuous glass filament, rock (stone) wool and slag wool are not classifiable as to their carcinogenicity to humans (Group 3).” IARC Monographs Vol. 81 (2002), Summary of Data & Evaluation ↗ The human evidence in that review was of workers who manufactured and breathed the pre-reformulation fibre for decades — the downgrade covered the old fibre, not just the new one. Two categories stayed at Group 2B, “possibly carcinogenic to humans”: special-purpose glass fibres such as E-glass and ‘475’ fibres, and refractory ceramic fibres. Those are industrial products — aircraft and spacecraft insulation, battery separators, HEPA filter media, furnace and kiln linings. They have never been home ceiling insulation batts. IARC Monographs Vol. 81 (2002) — the Group 2B categories and their uses ↗
IARC gave two reasons for the downgrade. “There have been substantial improvements in the quality of the epidemiological information available for the evaluation of the carcinogenicity of glass fibres” — thirteen more years of factory-worker data with no clear excess cancer risk — and manufacturers had “altered the chemical compositions of their products to enhance their solubility in biological systems.” IARC Monographs Vol. 81 (2002), General Remarks ↗ Vol. 81 also carried its own limit: the newest special-purpose fibre types were too recently introduced for epidemiology to exist on them. The downgrade was a finding about the insulation-wool evidence, not a blanket all-new-fibres-are-fine ruling.
10 June 2011 · USA
The US NTP narrows its listing to biopersistent fibres only
In the Twelfth Report on Carcinogens, the NTP renamed and narrowed the 1994 listing. Its own profile: “The listing was changed in the Twelfth Report on Carcinogens to ‘Certain Glass Wool Fibers (Inhalable),’ which are listed as reasonably anticipated to be human carcinogens” — and the new definition is explicit that “only certain fibers within this class — specifically, fibers that are biopersistent in the lung or tracheobronchial region — are reasonably anticipated to be human carcinogens.” US NTP, Report on Carcinogens, 15th ed., “Certain Glass Wool Fibers (Inhalable)” profile, p.1 ↗ Federal Register, 23 June 2011 — 12th Report on Carcinogens announcement ↗ Since 2011 the NTP listing is, by its own definition, limited to biopersistent fibres. Ordinary biosoluble insulation wool falls outside that definition — which is why the Australian manufacturers’ own SDS cite their biopersistence test as the basis for “not classified.”
18 November 2011 · California, USA
California matches the narrowing
OEHHA modified its Prop 65 listing to “Glass Wool Fibers (Inhalable and Biopersistent)” — the same narrowing logic as the NTP, applied to the state list that had driven the retail pack warning. OEHHA, “Modification of the Listing of Glasswool Fibers…”, 18 Nov 2011 ↗
2012 · USA
The US labels come off the batt packs
Per NAIMA, the US manufacturers’ association: “In 2012, the North American Insulation Manufacturers Association member companies removed cancer warning labels from fiberglass products.” NAIMA / Insulation Institute, Insulation Outlook Magazine, 2012 ↗
November 2025 · Australia
Australia’s current instrument keeps a test-gated split
The operative Australian document today — Safe Work Australia’s Workplace Exposure Standards for Airborne Contaminants, amended November 2025 — sorts man-made vitreous fibre into two buckets by one criterion: whether the fibre has passed the Note Q biopersistence test. The full detail, and what it means for untested insulation batts, is in the framework section below. Safe Work Australia, Workplace Exposure Standards for Airborne Contaminants, amended Nov 2025 — notes 3.2(h)–(o) pp.10–11 + Appendix A p.27 ↗
At the time of writing
The narrowed US listing still stands
The current edition of the NTP Report on Carcinogens at the time of writing (15th edition, 2021) keeps the same narrowed, biopersistence-gated definition. Last checked 19 August 2026 — editions get revised, so check ntp.niehs.nih.gov for the current one. US NTP, Report on Carcinogens, 15th ed., “Certain Glass Wool Fibers (Inhalable)” profile ↗
The mechanism behind the whole story
Why the rating changed: the fibre in the batts was engineered to dissolve in lung fluid.
The property every document in the timeline turns on is biopersistence— how long a fibre survives, undissolved, in lung tissue. The US government’s own toxicological history puts the product change on the record: “Since the early 1990s, manufacturers of synthetic vitreous fibers have been making modifications to new products in order to make them more biosoluble (i.e., less biopersistent) and potentially less hazardous than older products.” ATSDR, Toxicological Profile for Synthetic Vitreous Fibers, Sept 2004, p.145 ↗ Fibres that dissolve quickly clear out before they can drive the chronic-inflammation mechanism thought to cause fibre-related cancers — that is the regulators’ stated rationale, not a settled mechanism, so I’m quoting it rather than asserting it. ATSDR TP-161 (2004) + NTP 15th RoC glass wool profile — the stated biopersistence rationale ↗
The real threshold numbers
The legal pass mark is the EU’s “Note Q” test, which Australia’s framework adopts by name — see the framework section below. The operative text gives two alternative half-life ceilings for fibres longer than 20 μm: “a short term biopersistence test by inhalation has shown that the fibres longer than 20 μm have a weighted half-life less than 10 days” or “by intratracheal instillation… a weighted half-life less than 40 days.” Regulation (EC) No 1272/2008, Annex VI, Note Q — operative legal text ↗ Half-life means half the long fibres are gone by that day count — full clearance takes several half-lives. And 40 days is the maximum allowed, not a description of how tested modern fibre performs.
The before-and-after is measured, in one controlled dataset reprinted in the same government profile — 19 fibres tested side by side in the same lab under the same protocol. The row named “Traditional rock wool” cleared with a weighted half-life of 45 days — which would miss the 40-day ceiling. The rows named “New rock wool” came in at 13 and 6 days. For glass wool: the early-1990s reference insulation fibre MMVF10 sat at 37 days, inside the 40-day ceiling but nowhere near the 10-day one, while the two fibres labelled “New glass wool” both measured 4 days. ATSDR TP-161, Table 3-2, p.120 (data from Hesterberg et al. 1998a) — weighted half-times, fibres >20 µm, F344 rats ↗ By comparison the two asbestos rows in the same table read 418 and 817 days — quoted only to show what the man-made rows are not.
What these numbers are NOT
No published biopersistence number exists for any specific historical Australian retail batt — the table above is class-level test fibre data, not a reading off anything that was on a Brisbane shelf in 1995. And the lab dissolution rate (Kdis) is a screening tool, not the legal test: in the NTP’s own words, “As of 2010, no regulatory agency in the United States or the European Union had adopted the dissolution constant as a predictor of fiber carcinogenicity.” US NTP, Report on Carcinogens, 15th ed., glass wool profile, p.2–3 ↗
The two measurements, defined (for the technically minded)
In-vivo weighted half-time (WT1/2, days): after a test animal inhales the fibre, lung tissue is sampled over time and the fibres longer than 20 μm are counted; WT1/2 is the fitted day count at which half of them are gone. Fibres longer than about 15–20 μm are too long for a lung macrophage to engulf, so they can only leave by dissolving and breaking — which is why regulators test that size fraction. ATSDR TP-161, pp.119–120 — method description, verbatim ↗
In-vitro dissolution rate (Kdis, ng/cm²/hour): fibres sit in flowing simulated lung fluid and the shrinkage of their diameter is measured directly; a bigger number means faster dissolution. Useful lab proxy, not the regulatory pass/fail line — see the callout above. ATSDR TP-161, p.119 — Kdis formula and units ↗
The current Australian framework, read precisely
Where untested insulation batts sit under Australia’s current classification framework.
The operative Australian instrument today is Safe Work Australia’s Workplace Exposure Standards for Airborne Contaminants, amended November 2025. It splits man-made vitreous fibre into two buckets on a single criterion — a lab test, not a calendar. Its note (l) covers “Any MMVF which have not been tested according to the test protocol” of the 1999 European method “and Note Q in EC Regulation No. 1272/2008… or fibres which have been tested and failed to comply with these tests” — that bucket is labelled High Biopersistence MMVF, listed in the same table row as refractory ceramic fibres, with an advisory classification of Carcinogenicity Category 1B, which the document defines as “presumed to have a carcinogenic potential for humans” based largely on animal evidence. Fibre that has been tested and passed sits in the Low Biopersistence bucket — Category 2 or exempt from carcinogen classification altogether. Safe Work Australia, Workplace Exposure Standards for Airborne Contaminants, amended Nov 2025 — notes 3.2(h)–(o), pp.10–11 + Appendix A table, p.27 ↗
SafeWork NSW ties the tested bucket to the 2001 reformulation: glasswool and rockwool products containing low-biopersistence fibre “have been manufactured in Australia since 2001” and “have undergone toxicology testing resulting in being classified as non-hazardous under the Globally Harmonized System.” SafeWork NSW, “Man-made vitreous fibre insulation products” — hazard guidance ↗ Insulation batts made before 2001 were made before that test protocol existed, so no batch of them ever produced a pass certificate — and under the framework’s either/or gate, fibre with no test result defaults to the untested bucket.
Now read that for exactly what it is, because the two halves of this page have to be kept straight. The untested-fibre default is a classification-framework rule about missing test paperwork— where a substance lands when nobody can produce a pass result. It is not a scientific finding that old batts cause cancer, and in the same breath: the scientific review points the other way. IARC’s 2001 re-evaluation covered the old fibre, rested on decades of workers who made and breathed it and moved the whole insulation-wool category to Group 3. IARC Monographs Vol. 81 (2002), pp. 45–54 — Summary of Data & Evaluation ↗ Both statements are true at once. The framework runs on test certificates; the monograph runs on epidemiology. This page quotes each in its own lane and does not swap their labels.
The gate is the test, not the age or the brand
The framework’s split is biopersistence testing — not manufacture date and not brand. A current import that no one has run through the Note Q protocol sits in the same untested bucket as a 1995 batt, and a tested-and-passed product is exempt whoever makes it. So the practical takeaway is narrow and fair: the reassurance on a current Australian data sheet was earned by tested current fibre. An untested batch has no equivalent paperwork — which is a reason for dust discipline when old insulation batts get disturbed, and nothing more.
Read this bit twice
We are not saying modern fibreglass batts cause cancer. Here’s the position, plainly.
The manufacturers say today’s biosoluble fibre is safe to breathe because it dissolves before it can persist in the lung — that is their claim to make, it’s printed on their own data sheets and the current classifications back their right to print it. Knauf Glasswool SDS Rev 3.0, 30/07/2020, §11 — the Note Q result ↗ The strongest thing I can say without overreaching runs like this: the specific fibre property regulators tied the higher rating to — biopersistence — is a property today’s biosoluble insulation wool is tested not to have, and every current classification reflects that.
You can weigh that claim and buy fibreglass batts with a clear conscience. Or you can take the simpler path we build our own product around: choose an insulation with no particle size that reaches the deep lung at all. Of the three product documents we compared in August 2026, the glasswool paperwork is the only one carrying a skin and respiratory irritation statement. The polyester manufacturer’s MSDS states any free fibres present are “not of respirable size.” Autex polyester MSDS (Australia) — “not of respirable size” ↗ The US government’s study of cellulose fibre products measured under 0.1% of installation dust at respirable size — and found that trace fraction was fire-retardant mineral, not cellulose fibre. US NTP TOX-74 (2006), plain-language summary p.5 + abstract p.8 ↗
Same standard applied to ourselves: our own Cellulose Fibre Insulation guidance recommends dust masks during installation too — installation dust is installation dust, whatever the product. The difference we sell on is what’s left behind for the life of the house, and you can read that case with every number cited on the dust page and cellulose fibre vs polyester.
The practical bit — a tradesman’s advice, not a law
If your roof holds fibreglass batts from before 2001, here’s how I’d treat them.
Get the frame right first. Batts installed before the 2001 reformulation predate the biosoluble fibre chemistry and were never put through the Note Q test today’s product passes. That does not make them a proven carcinogen — IARC’s Group 3 covered insulation glass wool as a category, old fibre included, on the strength of the worker studies. IARC Monographs Vol. 81 (2002), Summary of Data & Evaluation ↗ What it does mean is that the reassurance on a 2024 data sheet was earned by a 2024 fibre. An older product has no equivalent paperwork, so the sensible response is dust discipline.
Every classification and exposure standard in this story is about airborne dust during manufacture and handling. None of them is about insulation lying still in a ceiling. The time to think about any of this is when you disturb it — and that’s a dust-mask-and-long-sleeves job per the manufacturers’ own data sheets, not an emergency.
My advice from forty years on roofs
- Don’t rip old batts out yourself. Hand-pulling dry old batts through a manhole is the dustiest possible way to do the dustiest job in the house. Our removal-reality page shows what actually comes off the material when it moves.
- Have it done professionally, with extraction and sealed bags.Not because a law says so — check your state WHS regulator’s guidance and your council’s disposal rules — but because dust control is equipment and habit, and weekend hire gear has neither.
- My preference: don’t be home while removal happens. The house gets opened up, the roof space gets worked hard and the dust settles fastest with nobody stirring the air downstairs.
- Don’t leave old insulation batts in an open skip out the front for days. Wind does to a skip full of loose old fibre exactly what you’d expect. Bag it, seal it and get it gone.
- Wear the gear their own paperwork asks for.The manufacturers’ SDS and WorkSafe WA’s fibreglass guidance line up: respirator, long sleeves, gloves, eye protection, keep dust generation down and bag offcuts — never blow dust around with compressed air. Knauf Glasswool SDS Rev 3.0, 30/07/2020, §8 — exposure controls / PPE ↗ WorkSafe WA, “Working with fibreglass” — handling guidance ↗
Removing old fibreglass batts in full PPE and a Sundström SR100 respirator
Removing settled old fibreglass batts means full suit, full PPE and a proper silicone respirator — every bit of it goes to landfill full of rodent mess.
Read the transcript
Just here removing some fibreglass batts that are all degraded over time and so they actually all settle down, they start out a lot thicker than that and over time they just sink down and you don't have anywhere near the R value that you bought in the first place. These are about 30 years old, these ones. So we're just rolling them up, pulling them out and then we're going to put in some cellulose fibre. It's just like this, I'm going to roll every bit up. There we go. We're going to put it right in.
The option most people haven’t been offered
The pump-over: leave the old insulation batts undisturbed and seal them under a dense blanket.
Removal isn’t the only answer, and for plenty of roofs it isn’t the best one. Where the old material is dry and sound we can leave it exactly where it lies and pump a heavy, dense blanket of Cellulose Fibre Insulation straight over the top. The old fibre ends up sandwiched between the new blanket above and the plaster below — pinned down, out of the moving air, with a seamless layer over every gap the old batts left.
The logic follows from everything above: the standards in this story are about airborne dust during handling, so the option that involves no handling of the old material at all — and then stops it circulating — deals with the practical concern without a removal bill. You also come out the other side with a properly insulated roof instead of just an empty one. How we decide between removal and top-over, case by case, is written up in the removal-vs-top-over FAQ, and the removal service itself — dust-controlled, machine-assisted, sealed disposal — is on the insulation-removal page.
Why the dense blanket does the sealing job: our product is pumped as one continuous layer at a heavier applied density than a laid batt, which is the same property that makes it seal gaps on a normal install. The grades and how they differ are on the coarse-vs-fine grades page.
One more label worth decoding
“Low-itch” fibreglass batts — compared to what? Their own older product.
The reformulation story explains the modern marketing too. In every manufacturer page we checked in August 2026 that names a comparison, the comparison is with that manufacturer’s own earlier glasswool: Knauf’s Earthwool FAQ asks why it is “softer and less itchy than traditional glasswool” Earthwool FAQ, “Why Earthwool?” — checked August 2026 ↗, its ECOSE page reports customers finding it less itchy than product “made with traditional binders” Knauf Insulation, “The ECOSE Difference” — checked August 2026 ↗, while its own comfort-and-handling page carries the plainer statement that mineral wool fibres “may cause mechanical irritation (discomfort) for some people upon contact with skin.” Knauf Insulation, “Comfort and Handling” — checked August 2026 ↗ CSR Bradford’s Gold ceiling batts page says “low-itch” with no comparator stated CSR Bradford, Gold Ceiling Batts product page — checked August 2026 ↗, and its Comfort Touch wall-batt page cites “external testing conducted September 2025” without naming the laboratory, method, standard or result. CSR Bradford, Gold with Comfort Touch Technology page — checked August 2026 ↗ None of the five compares against polyester batts or Cellulose Fibre Insulation.
In my view, “low-itch” means less itchy than their old product — not not-itchy, and not measured against anything else. That’s my opinion sitting on the checked pages above; make your own read of them. The one numbered test we did find sits in an Owens Corning patent, which ran the wool-textile industry’s prickle test (Wool Comfort Meter, standard IWTO-66) on its engineered fine fibre: conventional fibreglass scored 150–267 and the new fibre 57–140 — roughly half the prickle, not zero. Owens Corning US Patent 12,297,342 B2, Col. 24 / Table 6 — IWTO-66 Comfort Factor data ↗ We could find no Australian standard or WHS classification that defines “low irritant” as a threshold — the governing 1990 code describes the mechanical-irritation mechanism without any product pass/fail scheme. NOHSC:2006(1990) — describes SMF mechanical irritation; no low-irritant classification exists ↗
The products we install make no skin-irritation claim for a simpler reason: their own paperwork carries no skin-irritation statement to soften. Polyester’s MSDS states its free fibres are “not of respirable size,” Autex polyester MSDS (Australia) — checked August 2026 ↗ and the US government study of cellulose fibre products put respirable dust under 0.1% with the trace being fire-retardant mineral rather than cellulose fibre. US NTP TOX-74 (2006), plain-language summary p.5 ↗ Neither sheds the fraction the 1990 Australian code recorded for the coarser 5–8 µm glasswool fibre of that era — “in the order of 10 to 20 per cent” of fibres under the 3-micron respirable size. That figure belongs to the 1990 product; no equivalent modern percentage is published, so we don’t quote one. NOHSC:2006(1990), Schedule 3 §7 — the 1990-era figure, for the 1990-era fibre ↗
Suiting up in full PPE to install fibreglass batts
Peter putting on the disposable suit and respirator before a fibreglass batt job, because of the fibres.
Read the transcript
Yeah, yeah, yeah, that's right mate. Just suiting up to do this job. So, putting on all the PPE. Yeah, stop all the fibreglass fibres making you too itchy while you're in the job.
Straight answers
Fibreglass batts and the cancer question — what I get asked.
Do the fibreglass batts in my roof cause cancer?+
No regulator classifies any home insulation batt — old or new — as a carcinogen today, and this page doesn't either. Since IARC's 2001–02 review, insulation glass wool has sat at Group 3, "not classifiable as to its carcinogenicity to humans," and the worker studies behind that review were of people who made and breathed the old fibre. Safe Work Australia assigns tested biosoluble glass wool no carcinogen category, and the current Australian safety data sheets from both major manufacturers state "not classified as a carcinogen" and "Non-Hazardous." What this page covers is the documented history of how that rating changed between 1988 and 2011, and the practical point that insulation batts made before the 2001 fibre reformulation were never put through the biopersistence test today's product passes — which matters when you disturb them, not while they lie still.
Why did IARC change the cancer rating on fibreglass batts in 2001?+
IARC gave two reasons, and both matter. First, thirteen more years of factory-worker studies had accumulated since 1988 and showed no clear excess cancer risk — and those workers had been making and breathing the old, pre-reformulation fibre for decades. Second, manufacturers had changed the fibre chemistry so it dissolves faster in lung fluid — IARC's own general remarks say manufacturers "altered the chemical compositions of their products to enhance their solubility in biological systems." The 1988 Group 2B rating — "possibly carcinogenic to humans," which applied from 1988 to 2001–02 — became Group 3, "not classifiable as to its carcinogenicity to humans," for insulation glass wool. Group 3 is an absence of sufficient evidence, not a proven-safe stamp — IARC doesn't use it to mean safe.
Are old fibreglass batts from before 2001 still rated as possibly carcinogenic?+
Not by IARC. Its 2001–02 review downgraded insulation glass wool as a whole category to Group 3, and the worker studies behind that downgrade were of people exposed to the older fibre. The products that stayed at Group 2B — special-purpose glass fibres like E-glass and refractory ceramic fibres — are industrial materials for aircraft, battery separators and furnace linings. They were never home ceiling insulation batts. Separately, Australia's current workplace exposure standards run a lab-test gate: glass wool that has passed the Note Q biopersistence protocol is exempt from carcinogen classification, while fibre that has never been through the test defaults to the untested High Biopersistence bucket. Batts made before 2001 predate that test, so no test paperwork exists for them. That default is a rule about missing test results, not a scientific finding that old batts cause cancer — and it is a solid reason to respect the dust whenever you disturb old insulation batts.
Did fibreglass batt packs in Australia ever carry a cancer warning?+
We could find no Australian requirement for a cancer warning on insulation packaging — the 1990 national code set a workplace exposure standard, not a warning label on the pack. The warning-label story is American. California listed "glasswool fibers (airborne particles of respirable size)" under Proposition 65 from 1 July 1990, and by 1991 Owens-Corning was printing "Contains fiberglass wool. Possible cancer hazard" on US packs under OSHA's hazard-communication rules. The US industry's own association later stated the US "was the only jurisdiction in the world that required a cancer warning label on biosoluble fiberglass insulation," and its member companies removed the labels in 2012 after the US listings were narrowed in 2011.
Should I remove old fibreglass batts or top over them?+
Both are real options and we quote both. Removal takes the old insulation batts out of the house for good — done with proper dust control, sealed bags and a machine-assisted process rather than someone ripping batts out by hand. The pump-over option leaves the old insulation undisturbed and pumps a heavy, dense blanket of Cellulose Fibre Insulation over the top, sealing the old fibre between the new blanket and the plaster so it stops moving with the air. Every exposure standard in this story is about airborne dust during handling — insulation lying still under a dense blanket isn't being handled. Which one suits your roof depends on the condition of the old material, and our removal-vs-top-over FAQ walks through how we decide.
What does 'low-itch' mean on fibreglass batts?+
In every manufacturer page we checked in August 2026 that names a comparison, the comparison is with that manufacturer's own earlier glasswool — "traditional glasswool," "traditional binders." None compares against polyester batts or Cellulose Fibre Insulation. In my view, low-itch means less itchy than their old product — not not-itchy, and not measured against anything else. An Owens Corning patent that did run a numbered prickle test (the wool industry's IWTO-66 Wool Comfort Meter) scored its engineered fine fibre at roughly half the prickle of its conventional fibre — half, not zero. We could find no Australian standard or WHS classification that defines "low irritant" as a threshold a product passes or fails.
This page is general information, not medical, legal or occupational-hygiene advice. Every classification, date and quote is read from the primary document linked beside it. Last verified 19 August 2026 — classifications, report editions and safety data sheets get revised, so check the current version of any document before relying on it. For handling questions, follow the manufacturer’s SDS and your state WHS regulator’s guidance; for disposal, check your local council’s rules.
Got pre-2001 insulation batts in your roof? We quote both paths — dust-controlled removal or the pump-over that seals them in place under a dense blanket of Cellulose Fibre Insulation — online, fixed price, no inspection visit needed.
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Angela M.
SE Queensland
“The fact that I can't even tell it's 6 degrees outside when I wake up in the morning speaks for itself. Have wasted so much money attempting to heat and cool an uninsulated home. Worth every $.”
- Phipages
P Peter
Alstonvale, 2024
“Connected with Comfort Zone Insulation and would recommend them”
- J
Jessa B.
Brisbane
“It dropped about 4 degrees straight away, and we added another 3 with the second job. I appreciate Peter's honesty, and the team showed pictures before and after.”
- Nhipages
Nola M
Birtinya, 2024
“They were courteous and competent.”
- I
Iain V-B.
Brisbane
“Quick and polite service. Great follow-up advice and photos sent for our records. Above and beyond what we expected. Would highly recommend.”
- Jhipages
Jennifer's E
Upper Caboolture, 2024
“Excellent customer service. Highly recommended. Has a profound knowledge of insulation products and has the best interest of his customer.”
- G
Gerry S
Fitzgibbon, 2023
“I used Comfort Zone and they have a done an excellent job.”
- Jhipages
Jennifer
Upper Caboolture, 2024
“Excellent customer service. Highly recommend. Has a profound knowledge of insulation products and has the customer best interest.”
- J
Jung K
Riverhills, 2023
“An experienced family operation. Highly recommend. Thank you for the great job!”
- Dhipages
Diane A
Ormeau, 2024
“Peter and crew did a great job I would definitely recommend them”
- D
David H
Sunshine Coast, 2021
“Completed the job as quoted and to a high standard. Great personal service. Would highly recommend Comfort Zone for ceiling installation work.”
- Thipages
Timea
Highland Park, 2023
“I was extremely satisfied with the service they provided. They gave a very thourough explanation of the materials used, the way the work will be carried out and the price I had to pay was the exact amount quoted, no hidden costs included. They arrived on time, well prepared and workwas carried out exactly how they said it would be, they were super efficient, well prepared and were kind enough to even clean up after themselves. The services they provided was second to none! I don't hesitate to recommend them for any insulation job!”
- B
Benjamin H
Carseldine, 2019
“Very good explanation about their works. Advice of existing problems with the roof. Clean work. Very professional.”
- Mhipages
Mark
Pottsville, 2017
“Michelle, we are done - Peter from comfort zone insulation was very helpful. very honest with his recommendations - in fact he told me that the product my daughter had if installed correctly was superb. Thanks Peter you are a champion and i would recommend you to any person that was wanting professional advice and old school service.”
- I
Ian G
Burnside, 2019
“Good information, communication and professionalism.”
- Jhipages
Jessica
Pottsville, 2016
“This business offers a fantastic product that other businesses did not. Pump in ceiling insulation. Knowledge of the industry second to none.”
- D
Danny D
Boondall, 2018
“He explained everything he was going to do and the different types of insulation they used. He talked through the different options but made a recommendation for the one most people use, which is the one I chose. He was very understanding towards what I needed and not about himself.”
- Jhipages
Jack
Pottsville, 2023
“Excellent communication and informative. Professional.”
- G
Graham R
Riverhills, 2018
“Comfort Zone. Turned up ahead of time, completed in about 2 hours, cleaned up. All good. Very motivated installation team.”
- Thipages
Tony P
Redland Bay, 2023
“Very knowledgeable about insulation”
- A
Alex B
West Ipswich, 2018
“Fast, friendly, efficient.”
- Shipages
Steve
Redland Bay, 2017
“Excellent job and reasonable price.”
- L
Luke D
Mcdowall, 2017
“Peter did a good job. It was a quick and clean service. I'm happy to recommend!”
- Bhipages
Bruce H
Kuluin, 2023
“Prompt and efficient quoting.”
- B
Brendon
Brays Creek, 2016
“Peter supplied and installed roof insulation for me. He was very informative and provided good advice.”
- Ghipages
Gerry S
Fitzgibbon, 2023
“I used Comfort Zone and they have a done an excellent job.”
- T
Trevor G
Brookside Centre, 2016
“Excellent tradesmen from Comfort Zone Insulation. They were punctual and cleaned up after. Highly recommended.”
- Thipages
Tamara
Underwood, 2023
“Peter is honest, hard-working and came on time. Knew excally what he was talking about and answered my questions. Would 100% recommend”
- J
John G
Beaudesert, 2019
“Peter is an honest person who provided me with the information I wanted then performed a good job with great results for the benefit of myself and my family.”
- Shipages
Sterling G
Ashgrove, 2023
“Comfort Zone were very knowledge with great communication and follow up”
- Ghipages
Graham R
Riverhills, 2018
“Comfort Zone. Turned up ahead of time completed in +- 2 hours cleaned. All good. Very motivated installation team”
- Jhipages
Jung K
Riverhills, 2023
“An experienced family operation. Highly recommend. Thank you for the great job!”
- Khipages
Kathy A
North Lakes, 2023
“We connected with Peter through HiPages and he was prompt, professional and even came back after the job was complete to assist with a question we had. We would highly recommend Peter for further insulation works.”
- Dhipages
David H
Sunshine Coast, 2021
“Completed the job as quoted and to a high standard. Great personal service. Would highly recommend Comfort Zone for ceiling installationn work.”
- Shipages
Sue H
Sunshine Coast, 2021
“Incredible customer service”
- Ehipages
Eileen C
Cedar Vale, 2021
“Quality work, good customer service, prompt”
- Chipages
Craig M
Woody Point, 2021
“Called within 5 minutes of request. Very knowledgeable and explained job in great detail, provide great advice in prior preparation for works required. Very friendly and helpful.”
- Jhipages
Jenny C
Plainland, 2021
“Although I did not hire Peter I was impressed with the initial contact and the knowledge he was willing to impart. I was treated with respect which I appreciated. I would have hired but I received a lower quote.”
- Qhipages
Quinton
Coomera, 2020
“Professional installation without any short cuts. True to their word with high integrity. Response from Comfort Zone Insulation”
- Ghipages
Gary P
West Kempsey, 2020
“Came & Gave a free quote”
Old insulation batts sorted properly — removed or sealed in, your call.
Send us your address and roof type for a fixed-price quote within 48 hours for most houses. Servicing Brisbane, SE QLD and Northern NSW.
Peter Johnson
Owner / installer · Comfort Zone Insulation Team® · Since 1986