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 journal Human Reproduction today.
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.
Findings
According to the authors, blood samples were taken at the time of the women’s first antenatal visit so that concentrations of the perfluorinated chemicals PFOS and PFOA could be measured.
The researchers said they also interviewed the women at around the 12th week of pregnancy to find out whether the pregnancy was planned or not and how long it took them to become pregnant.
Infertility was defined as a time to pregnancy of longer than 12 months or infertility treatment to establish the current pregnancy, and the results were adjusted for potential confounding factors such as age, lifestyle and socio-economic status, continued the report.The levels of PFOS in the women’s plasma ranged from 6.4 nanograms per millilitre (ng/ml) to 106.7 ng/ml and from less than 1 ng/ml to 41.5 ng/ml for PFOA, the researchers found.
The team divided the women’s levels of PFOS/PFOA into four quartiles, and found that, compared with women with the lowest levels of exposure, the likelihood of infertility increased by 70-134 per cent for women in the higher three quartiles of PFOS exposure and by 60-154 per cent for those in the higher three quartiles of PFOA exposure.
Hormone interference
The researchers said that the biological mechanisms by which exposure to PFOS and PFOA might reduce fertility are unknown, but PFCs may interfere with hormones that are involved in reproduction.
“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,” said Dr Chunyuan Fei, from UCLA, one of the study’s authors.
Professor Jørn Olsen, Chair of Department of Epidemiology at UCLA, and the principle investigator of the study, said that the team is waiting for further studies to replicate its findings in order to discover whether PFCs should be added to the list of risk factors for infertility.
EFSA opinion
The European Food Safety Authority’s (EFSA) CONTAM Panel adopted an opinion on PFOS, PFOA and their salts in February last year, after looking at several different sources of exposure to the two substances.
With regard to PFOS, the Panel established a Tolerable Daily Intake (TDI) of 150ng/kg per body weight (bw) per day. The Panel noted that the highest exposed people within the general population might slightly exceed this TDI, but considered it unlikely that adverse effects of PFOS were occurring in the general population.
For PFOA, the Panel established a TDI of 1.5µg/kg bw per day, which it said was well above the indicative average and high level human exposure (2 and 6 ng/kg bw respectively). While the Panel considered it unlikely that adverse effects of PFOA were occurring in the general population, it did note uncertainties in regards to developmental effects.
And the Panel also recommended that further investigations should be carried out in a number of areas related to PFOS and PFOA.