Growing up on a livestock farm increases the chances of developing cancer, according to scientists.

Researchers in New Zealand said living on livestock farms as children appeared to increase the risk of needing to be treated for blood cancers by one-fifth.

And they said the risk of developing a blood cancer was three times as high for people who had grown up on poultry farms.

In a report published on the British Medical Journal‘s website on Wednesday (28 July), scientists looked at the death certificates of more than 114,000 New Zealand residents aged between 35 and 85, who died between 1998 and 2003.

After looking at their jobs and those of their parents, scientists found of the 3,000 people who died of blood cancers, growing up on a livestock farm was associated with a higher risk of developing them.

The same association was not apparent for people who had grown up on arable farms, although working on them as an adult was associated with a higher cancer risk, they added.

The analysis showed that the overall risk of developing a blood cancer such as leukaemia, multiple myeloma and non-Hodgkin’s lymphoma was 22% higher for those growing up on livestock farm compared with those who had not.

Poultry farms posed a greater risk, with those who had grown up on them three times more likely to develop a blood cancer as those who had not.

Growing up on an arable farm resulted an almost 20% lower risk of developing a blood cancer, but crop farming as an adult was associated with an almost 50% increased risk, the researchers from Massey University in Wellington said.

Working on a livestock farm as an adult also seemed to lessen the risk by 20% – with the exception of beef cattle farming, where the risk was three times as high.

The reports authors said further research was needed before a “definitive cause and effect” could be established.

But they said their study “suggests that farming exposures in adulthood and childhood play independent roles in the development of haematological cancers”.

Exposure to particular types of virus in childhood may alter the immune system response, so increasing the risk of blood cancer in later life, they added.