Two new studies have found that two chemicals used in areas including food and personal care packaging are absorbed by the body, and can be a cause of fertility problems in women.

A study by the University of Rochester Medical Center has challenged the assumption that bisphenol A, the chemical found in food packaging, is rapidly metabolized in the human body, and claims that exposure may come from non-food sources.

These findings were published online ahead of print in the journal Environmental health Perspectives.

Bisphenol A (BPA) is used in certain packaging materials such as polycarbonates for baby food bottles. It is also used in epoxy resins for internal protective linings for canned food, infant formula and metal lids.

BPA has been declared as safe, in part, by the US Food and Drug Administration (FDA) and the European Food Safety Authority (EFSA), on the assumption that it was excreted quickly from the body.

The authors of the study looked at levels of the chemical in the urine of 1,469 US adults who took part in Center for Disease Control's National health and nutrition Examination Survey (NHANES).

While it had been thought that BPA was rapidly eliminated from the body through urine, this study found people who had fasted for even a whole day still had significant levels of the chemical.

The researchers said this suggested BPA may linger in the body longer than previously known or that it may get into the body through sources other than just food, such as tap water or house dust.

They added that BPA may get into fat tissue, from where it might be released more slowly.

A recent study by a team of UK researchers found that higher concentrations of the chemical in urine were linked with heart disease, type 2 diabetes and liver enzyme abnormalities, while the US National Toxicology Programme (NTP) said that effects on reproductive development from BPA in packaging cannot be ruled out.

Chemicals in Packaging Linked to Infertility

Another study has found that perfluorinated chemicals (PFCs), which are used in areas like food packaging, pesticides, clothing, carpets and personal care products, may be linked to infertility in women.

The University of California Los Angeles (UCLA) study of 1,240 women has found that those with higher levels of PFCs in their bloodstreams tend to take longer to become pregnant than those with lower levels.

The findings were published in the January 2009 journal Human Reproduction.

PFCs are found in grease-resistant packaging such as microwave popcorn bags and pizza boxes; they are also used in manufacturing processes, for instance for industrial surfactants and emulsifiers. PFCs are commonly used in non-stick cookware, and eating off non-stick cookware inevitably results in the consumption of these chemicals.

The U.S. study found that women with higher levels of two types of PFCs in their blood took longer to conceive than women with lower levels.

Previous research had suggested that high levels of the chemicals, which persist in the environment for decades, may harm unborn babies.

The researchers say the biological mechanisms by which exposure to PFCs might reduce fertility are unknown, but they may interfere with hormones involved in reproduction.

Dr Chunyuan Fei, one of the study's authors said:

"Our data showed that higher proportions of women reported irregular menstrual periods in the upper three quartiles of PFOA and PFOS compared with the lowest, and so this could indicate a possible pathway,"

The study concluded:

"These findings suggest that PFOA and PFOS exposure at plasma levels seen in the general population may reduce fecundity; such exposure levels are common in developed countries."

Fei C et al Maternal levels of perfluorinated chemicals and subfecundity Human Reproduction, Vol.1, No.1 pp. 16, 2009