Ultra-clean homes linked to childhood leukaemia

An over-sterile germ-free environment in the first year of life is one of the major causal factors behind childhood leukaemia, a controversial study suggests.

Coupled with unlucky genetics, it can leave a child vulnerable to common infections such as flu triggering the disease, says a leading expert.

Professor Mel Greaves, from the Institute of Cancer Research in London, claims the most common form of childhood leukaemia – acute lymphoblastic leukaemia (ALL) – could be prevented by “priming” infants’ immune systems by exposing them to harmless bugs.

If the theory is backed by more evidence, a preventative treatment – possibly involving probiotic bacterial supplements – could be trialled in the next five years.

The research, published in the journal Nature Reviews Cancer, is based on a compilation of more than 30 years of work around the world investigating the origins of the disease.

At a press briefing in London, Prof Greaves said: “All the evidence is comprehensive. This is the bottom line for me – ALL is a paradox of progress in society.

“The research strongly suggests that ALL has a clear biological cause and is triggered by a variety of infections in predisposed children whose immune systems have not been properly primed.

“It also busts some persistent myths about the causes of leukaemia, such as the damaging but unsubstantiated claims that the disease is commonly caused by exposure to elecromagnetic waves or pollution.”

The theory could explain why ALL, which affects white blood cells, is more prevalent in affluent societies where infants are shielded from infection.

It may also be the reason why babies that are not breastfed, do not mix with other children in nurseries and are born by Caesarian section are more likely to develop the disease.

ALL is rare, affecting about one in 2,000 UK children per year, but can have a devastating impact on families despite a high cure rate.

Its likely causes have been debated for 100 years with a host of possible trigger factors proposed, including radiation, mobile phones, wi-fi, power lines and exposure to pollutant chemicals.

Prof Greaves said parents should “in no way” be blamed for children developing leukaemia but advised them to be “less fussy about common or trivial infections”.