Case Note

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By Darrin Crouch, Special Counsel and Ella Crouch, Legal Assistant

In Knight v CPSM Pty Ltd [2021] QDC 3, the District Court of Queensland recently dismissed an unusual claim for damages by an employee at an aged care facility who claimed she suffered multiple chemical sensitivity (MCS) as a result of being continuously exposed to a chemical used by her employer as a sanitizer.

Background Facts

The plaintiff, Ms Knight, was employed by the defendant, CPSM Pty Ltd (CPSM), as a personal care assistant at one of their aged care facilities. As part of routine cleaning duties in the facility, particularly in spaces where food was prepared and consumed, cleaners would use a chemical known as D4 (containing the chemical Didecyldimethylammonium chloride) to wipe down and sanitize surfaces.

Around 3 years into Ms Knight’s employment with CPSM, she states she started to develop intermittent headaches during her shift whenever D4 was used in her presence, or when she entered a room where it had been recently used. Her alleged symptoms worsened to the point of incapacitating her for days after her shift, bed ridden with effects to multiple organ systems. In seeking to manage her complaints, the employer agreed that she was able to alert other staff to the effects that the use of the D4 chemical had on her, as well as ask that they warn her before its use so she could remove herself from the room. In over a year and a half of experiencing frequent symptoms, Ms Knight only ever filled out one incident form.

Eventually, shortly after a back injury unrelated to her issues with D4, Ms Knight’s employment ended with CPSM.

Ms Knight then sued CPSM and particularized that CPSM had breached their duty to her by failing to, amongst other things, ensure the chemical D4 was safe to use, training staff on the correct way to handle the product, and to prevent the plaintiff from being exposed to D4, including preventing other employees from using it in her presence, and providing proper PPE to the plaintiff.  The defendant denied the claim and provided evidence to suggest that they had gone out of their way to accommodate Ms Knight and ensure her safety while at work.

Medical Evidence

One of the main issues Her Honour Judge Sheridan found with the claim, was the validity and truthfulness of Ms Knight’s evidence, including the actual presence of the symptoms and disease itself. Four of the five experts that presented evidence during the trial all individually formed a very similar opinion on the nature of Ms Knight’s condition, or in fact, lack thereof. The evidence provided by these experts were based on physical pathology, and psychiatric issues.

Doctor Oliver, the only expert that provided evidence that aligned with Ms Knight’s claims, diagnosed Ms Knight with MCS. However, being based in the USA, Doctor Oliver never physically examined Ms Knight, and instead formed her diagnosis on several documents, such as the incident report and emails from Ms Knight, reports from other treating physicians, as well as a telephone consultation with Ms Knight’s GP, Doctor Gupta. Notably, Doctor Oliver also formed her diagnosis on the basis that the dilution of the D4 was allegedly 5 percent, a much higher amount than the actual 0.4 percent. In contrast, Dr Brandt expressed that the described exposure to D4 wouldn’t have led to any significant pathology further than a temporary or self-limiting mucous membrane irritation of the upper respiratory tract. Further, Dr Solley, an allergist, concluded that while he could not determine if Ms Knight was in fact hypersensitive to the chemical, if she was then simply moving away from direct exposure should be enough to cease the symptoms.

The presence of a possible psychiatric condition that could be causing these issues for Ms Knight was considered by several doctors. When originally providing evidence, Doctor Matthew wholeheartedly believed that Ms Knight had a “well represented … diagnosis of a somatoform disorder”[1]. He agreed with the evidence provided by Dr Brandt, where after the temporary physical condition ceased, her state of mind had become a significant cause of her ongoing symptoms.  However, some time into cross-examination, after being shown some two volumes of the plaintiff’s Facebook posts, Dr Matthew took an adjournment to reflect. When Dr Matthew returned to give evidence it was with a completely new opinion, which aligned with the opinion of Dr Shaikh, the second psychiatrist. Ultimately both psychiatrists stated that there was no evidence of any psychiatric condition present which renders Ms Knight unable to work but believed there to be some level of delusion or unexplained psychological disturbance.

Standard of Care

The raw chemical D4 was handled solely by the cleaning staff, who diluted the chemical by filling a spray bottle with 750ml of water, then pressing a button on a dispenser which would squirt 3ml of D4 into the bottle, to give a desired concentration of 0.4 percent. The use of the dispenser supplied by the suppliers ensured that no staff ever had to physically handle the raw chemical. Beside the dispenser was a Material Safety Data Sheet, and there were always gloves and masks available. The suppliers of D4 would visit the facilities on a monthly basis to ensure that chemicals were being handled and used safely, and to provide any further training to staff on safety.


Her Honour found there was no evidence capable of being relied on that shows the use of D4 could be harmful.  She relied on the dispensing system installed by the suppliers which ensured no handling of the raw chemical and the correct dilution of the chemical.

Her Honour stated that once CPSM became aware of the complaints Ms Knight had, they acted reasonably, ensuring no staff members used it in her presence, even though there was no evidence that D4 was harmful or that Ms Knight was genuinely vulnerable to its use.  She found that the evidence suggested that Ms Knight did not suffer chemical sensitivity, and that there was no expert evidence that was capable of persuading the court that the low levels of exposure could have resulted in the reported symptomology.

[1] Knight v CPSM Pty Ltd [2021] QDC 3

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