Women who regularly use household cleaners and air fresheners are at double the risk of developing breast cancer than those who never use the products.
The study of more than 1,500 women found that solid slow-release air fresheners and anti-mould products had the biggest effect, according to a study published in Environmental Health, an international journal.
These chemicals are known to disrupt the endocrine (hormonal) system and are also considered breast cancer carcinogens.
The study’s authors questioned almost 800 women (787) with breast cancer diagnosed between 1988 and 1995 about the household cleaning products they used. They also interviewed 721 women that were breast cancer free. The women were asked about their beliefs about the causes of breast cancer.
Insect repellents, oven and surface cleaners also produced a slight increase.
"Women who reported the highest combined cleaning product use had a doubled risk of breast cancer compared to those with the lowest reported use," said Dr Julia Brody, from the Silent Spring Institute in the United States.
"Use of air fresheners and products for mold and mildew control were associated with increased risk."
Tests in laboratories have shown that some cleaning products, air fresheners and insect repellents have chemicals in them that may cause cancer.
They researchers found that overall women who used a combination of cleaning products were up to 110 per cent more likely to have developed breast cancer than those who never touched them.
The biggest effect was with solid air fresheners with those who replaced theirs more than seven times a year twice as likely to have developed breast cancer.
Using Mold and mildew removers more than once a week also seemed to double the risk.
Insect repellents, oven cleaners and furniture polish also had a slight increase in the risks.
"To our knowledge, this is the first published report on cleaning product use and risk of breast cancer," said Dr Brody.
The researchers said that although a link appeared to be made between cancer and the cleaning products more research was needed to be certain.
They found that women with breast cancer who believed that chemicals and pollutants contribute "a lot" to the risk of developing the condition were more likely to report high product usage.
The authors warned that “recall basis” may have altered the results. Meaning that patients who believed chemicals contributed heavily to the risk of developing breast cancers are more likely to report high use of cleaning products. Speaking about the potential bias to the study, Dr Brody said: "When women are diagnosed with breast cancer, they often think about what happened in the past that might have contributed to the disease.
"As a result, it may be that women with breast cancer more accurately recall their past product use or even overestimate it.
"Or, it could also be that experience with breast cancer influences beliefs about its causes.
"For example, women diagnosed with breast cancer are less likely to believe heredity contributes 'a lot', because most are the first in their family to get the disease."