Common chemicals that people are routinely exposed to may be mixing together in the body to cause cancer, researchers say.

Chemicals deemed safe to humans may blend lethally together inside the human body to cause cancer, a report says.

Researchers, including New Zealand scientist Dr Linda Gulliver, have released findings into possible links between common chemicals and the development of cancer.

Their results, published in the journal Carcinogenesis, show mixtures of chemicals used in our environment may be acting in concert with each other inside the body to trigger the deadly disease.

Dr Gulliver, from Otago University's faculty of medicine, says on the back of the findings of the Halifax Project, "considerable attention" needs to be given to investigating the concerning links.

A high-profile task force was formed in 2013 by the international organisation Getting to Know Cancer, which was concerned that cancer research was focused primarily on the role of heritable and lifestyle factors as triggers.

This is despite evidence that as many as one in five cancers may be caused by chemical exposures in the environment that are not related to personal lifestyle choices.

Chemicals are tested for carcinogenic links, but only one at a time, leaving questions around the possibility that a fusion of these chemicals may instead be causing cancer.

The task force of 174 scientists in 28 countries investigated 85 prototypic chemicals that were not considered to be carcinogenic to humans, and they reviewed their effects against a long list of mechanisms that are important for cancer development.

Working in teams that focused on various hallmarks of cancer, the group found that 50 of those chemicals examined supported key cancer-related mechanisms at levels at which humans are routinely exposed.

The finding supports the idea that chemicals may be capable of acting in concert with one another to cause cancer, even though low-level exposures to these chemicals individually might not be carcinogenic.

Lead researcher William Goodson III, from San Francisco's California Pacific Medical Center, said his results show one-at-a-time testing is out of date and must be modernised.

"Every day we are exposed to an environmental 'chemical soup', so we need testing that evaluates the effects of our ongoing exposure to these chemical mixtures," he said.