The death of a three year-old boy from organ failure was most likely linked to him drinking raw, unpasteurised bath milk, a Victorian coroner has found.

The boy had been placed on a gluten-free and organic diet in June 2014 on the advice of a naturopath, who said the boy was intolerant to certain foods including dairy, according to coroner Audrey Jamieson, whose findings were published on Friday.

His parents drank Mountain View Organic Bath Milk, labelled “not for human consumption” and “for cosmetic purposes only”, and occasionally added a small amount to their three-year-old’s drinks, Jamieson found.

Milk can become contaminated as soon as it touches the teat of a cow, which is located close to the animal’s bowel and is often in contact with faeces.

The Victorian health department website states unpasteurised milk increases the risk of contracting gastrointestinal illness because it can contain pathogens such as campylobacter, cryptosporidium, shiga toxin-producing E coli and listeria.

According to Jamieson’s findings, four other children had been identified who had become seriously ill after drinking Mountain View Organic Bath Milk, and three of them had developed haemolytic uraemic syndrome, associated with a toxic strain of E coli bacteria and which can lead to kidney failure. The other developed cryptosporidiosis, a parasitic infection commonly associated with gastroenteritis.

The three year-old’s parents took him to Frankston medical centre on 30 September 2014 after he began vomiting and suffered diarrhoea. The boy was diagnosed with viral gastroenteritis and when his condition worsened, his parents took him back to the doctor, on 2 October.

Doctors ordered tests and found the boy was not dehydrated, sending him home for monitoring. His parents took him to Frankston hospital emergency department on 4 October after he had blood in his stools.

Over the next week and a half, despite some periods of weight gain, the boy’s condition gradually worsened. He died of thrombatic microangiopathy, a rare but serious condition which can lead to organ failure, on 13 October, after a sudden and rapid deterioration in his condition.

Jamieson described the boy’s medical treatment as reasonable and appropriate, and made no adverse findings against the clinicians involved in his care. The boy had developed hemolytic uremic syndrome, Jamieson found, a rare and uncommon complication of gastro with a rapid onset and no cure.

The boy’s death was “most likely linked to the consumption of unpasteurised milk”, she found.

“I emphasise that at no point has prosecution been contemplated against Mountain View Farm, and the company was not considered to have breached any legislation at the time of [the child’s] death in 2014,” Jamieson found.

She added that it was a consumer’s choice to ignore regulations and drink unpasteurised milk, and noted that raw milk was a well-documented risk factor for gastrointestinal diseases and that the milk had been labelled as not for human consumption.

Since the 1940s it has been compulsory to pasteurise cow’s milk intended for consumption in Australia, which involves heating it for a very short time to kill pathogens. The sale of unpasteurised milk for human consumption is illegal in Victoria, but it is sold in health food shops for cosmetic purposes.

Following the death of the boy and outbreaks of illness in other children who had drunk unpasteurised milk, the Victorian government introduced new regulations that means Victorians who give family members raw milk to drink face now face fines of $60,000. The regulations also require a strong bittering agent be added to unpasteurised milk to deter people from consuming it.