Sir, I have followed the several letters to your journal editor relating to two articles which were published in the Journal of the Canadian Dental Association (J Can Dent Assoc 2005; 71 (10) and 2006; 72 (3)).

I was somewhat amused by one article titled Persuasive evidence that formocresol use in pediatric dentistry is safe – it appears he presumpes that the long standing formocresol (FC) controversy was solved by his follow-up letter to Dr Lewis. It seemed quite biased – and acerbic – as he referenced his two articles as proof of FC acceptability. Dr Lewis's strong academic past is well recognised – he is more than well published and versed in the great volume of formaldehyde (FA) and FC literature.

After rereading the 2006 Milnes article and his BDJ rebuttal, it reads as though he was attempting to fulfill – in writing – his own bias to support his clinical use of FC. Milnes' literature review covered a number of articles that discussed the dangers of FA, however, his persuasive justification for the paediatric use of FC is a bit weak, especially in light of the overwhelming number of studies reporting the biological dangers of aldehydes. It should be noted that the cresol component of FC is also known to cause irritation to the nose and throat, and has been associated with infant fatality to 20 mg of a 90% cresol solution.

It is a bit mystifying to understand how Milnes computed his measure of Buckley's 1:5 dilution of FC when placing an FC pellet for vital pulpotomy. He seems to have based his computation that 1 mg is equal to 1 ppm. Is not 1 mg a measure of weight and 1 ppm a measure of concentration? A bit like comparing apples to oranges. King reported in 2002 that many clinicians use full strength FC for pulpotomy, and placement of 190,000 ppm of FA on vital tissue would be toxic to the vital tissues – documented in many published studies.

A 2001 study ranked FA fourth on a list of environmental chemicals that produced significant brain damage. A 2004 publication on FA by the Director of Research of Champion Co. cited over 220 references – most of them since 2002 – noting chronic health effects from long-term low dosage FA exposure to health professionals and wood plant workers. The author cited physical complications ranging from seizures, memory loss, tremors, neurobehavioural impairment and neurotoxic symptoms.

Following recent public health concerns to FA contamination in portable housing trailers following hurricane Katrina, Johns-Manville Co, a major world wide wood construction company, has elected to completely eliminate all FA from all of their construction materials by 2010 – a step to correct their realisation of FA – demonstrating they are a socially concerned company.

Regarding biological concerns of carcinogenicity, FA is on the EPA's list of 10% of worst chemicals of overall hazards to human health. FA is one of the initial patch test protocols to confirm an individual's allergy – FA sensitisation is a known antigenic agent causing contact dermatitis, inhalation and asthmatic allergies and should be removed from clinician's treatment regimens around the world.