Women whose male partners had higher levels of plasticizers in their bodies took longer to become pregnant than women whose partners had lower levels of these chemicals, , according to a National Institutes of Health study.
The peer-reviewed study points to phthalates, which are found in plastics, shampoos and food and dozens of other consumer products, as slowing the couples' ability to achieve pregnancy. It also looked at levels of BPA, another plastic additive found in containers and in the lining of food cans, researchers did not find the same strong association between delayed pregnancy and BPA.
For the study, scientists measured the levels of BPA and 14 phthalate compounds in couples trying to conceive. While it found a correlation between high levels of certain phthalates and longer conception times, it did not parse how the delays occurred. Researchers could not say, for example, whether the higher phthalate levels lowered sperm counts or motility.
Pregnancy took the most time to achieve in couples in which the males had high concentrations of three specific phthalates: Monomethyl phthalate, mono-butyl phthalate, and monobenzyl phthalate.*
"Our study shows that exposure to certain phthalates can reduce the chance of conception for otherwise healthy couples," said first author, Germaine M. Buck Louis, Ph.D., Director of the Division of Intramural Population Health Research at NIH's Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD).
"Many people have been exposed to these compounds, so it's important to continue to investigate whether they have any health effects," Louis said.
The study, published online this week in the journal Fertility and Sterility, also included researchers from the Texas A&M School of Public Health in College Station, the New York state Department of Health, and the University at Albany of the State University of New York.
The men and women tested came from Texas and Michigan and were part of the Longitudinal Investigation of Fertility and the Environment (LIFE) study looking at the relationship between fertility and exposure to environmental chemicals and lifestyle. Previous analyses from the LIFE study found that high levels of PCBs as well as of lead and cadmium also were linked to pregnancy delay, the NIH reported.
Phthalates are commonly found in synthetic fragrances in shampoo and body products, vinyl flooring, adhesives, detergents, lubricating oils, solvents, automotive plastics, garden hoses, medical tubing, some toys and PVC plastic sheeting, according to the Centers for Disease Control, which maintains fact sheets on chemicals of concern.
Phthalate exposure is widespread, with most American adults showing some level in urine tests and women showing higher levels for phthalates used in soaps, shampoos and cosmetics, according to the CDC.
Previous studies have shown that phthalates act as endocrine disruptors and may interfere with the development of fetuses and young children, particularly the sexual organs of boys. Research also has shown that some phthalates are carcinogenic and may affect girls later in life by raising their risk of breast cancer.
BPA, though not a culprit in this study of conception times, also has been identified as an endocrine disruptor that contributes to health issues in developing children.
See “HOW TO AVOID PHTHALATES AND BPA” for more information.
*According to the CDC, monomethyl pthalate is excreted in the urine of people exposed to dimethyl phthalate, which is used in manufacturing rocket propellant and consumer products such as insect repellents and plastics. Mono-n-butyl phthalate , excreted in the urine of people exposed to the dibutyl phthalates, is used as additives to personal care products such as nail products and cosmetics, and in printing inks, pharmaceutical coatings, and insecticides. Mono-n-benzyl phthalate , excreted in the urine of people exposed to benzylbutyl phthalate, is used in products such as adhesives, vinyl tile, sealants, car care products, and some personal care products. People exposed to benzylbutyl phthalate also excrete small amounts of mono-n-butyl phthalate in their urine.