Painters are at a “significantly” increased risk of developing bladder cancer and the risk increases the longer their career continues, according to a meta-analysis carried out by the International Agency for Research on Cancer (IARC).

 

Even when taking smoking into account, the study showed a 25% increased risk of bladder cancer compared with various groups of unexposed people, which the authors say supports the IARC’s classification of painting as an occupation that is “carcinogenic to humans”.

 

More than 130,000 people die each year worldwide from bladder cancer, with 330,000 cases emerging every 12 months, according to the IARC.

 

Researchers at the IARC in Lyon, France — along with colleagues in Italy and the United States — analysed 41 studies stretching back to the 1950s, which together covered about 2900 cases of or deaths from bladder cancer.

 

 “Because several million people are employed as painters worldwide, even a modest increase in the relative risk is remarkable,” write Neela Guha and colleagues this month in Occupational and Environmental Medicine.

 

The study found that those who worked as painters for more than 10 years had “a higher risk” than those exposed to paint for less than 10 years.

 

Although the report notes that paint composition and working environments could differ between countries, the results did not vary across the regions covered by more than one study, such as Europe, North America and Oceania.

 

As well as painters, workers in a number of allied trades were included in the study — such as plasterers, wallpaper hangers and artists — because the authors believed they shared the same working environment.

 

Cigarette smoking has been identified as the most significant risk factor associated with bladder cancer, accounting for some 66% of cases. But an increased risk of the disease has also been associated with certain industries, such as rubber manufacturing and painting.

 

Nuha and colleagues say the increased risk associated with smoking is probably due to the presence of aromatic amines in cigarette smoke. While “the specific agents causing the increased risk of bladder cancer in painters have not been identified”, the authors highlight that painters are exposed to similar chemicals during the course of their work.

 

Future studies should be designed to assess the classes or quantities of chemicals to which painters are exposed in order to identify the underlying carcinogenic agents, the authors suggest.