Inhaling harmful nanoparticulates - that are less than 100 nanometers wide and found in sunscreens to pharmaceuticals to sports equipment - during pregnancy can escape lungs and enter the placenta and lead to low birth weight in babies, finds a study.

The study, reported in the medical journal Placenta, showed that inhaled nanoparticles - human-made specks that can't be seen in conventional microscopes, found in thousands of common products - can cross the natural, protective barrier that normally protects fetuses.

The resulting inflammation may affect bodily systems, such as blood flow in the uterus, that could inhibit growth of the foetus.

Rutgers University scientists studying factors that produce low-birth-weight babies revealed that they were able to track the movement of nanoparticles made of metal titanium dioxide through the bodies of pregnant rats.

After the nanoparticles were inhaled into the lungs of the rodents, some of them escaped this initial barrier.

From there, the particles flowed through the placentas, which generally filter out foreign substances to protect the foetus.

"The particles are small and really hard to find," said Phoebe Stapleton, Assistant Professor at Rutgers.

"But, using some specialised techniques, we found evidence that the particles can migrate from the lung to the placenta and possibly the fetal tissues after maternal exposure throughout pregnancy. The placenta does not act as a barrier to these particles. Nor do the lungs,"Stapleton added.

Most nanoparticles are engineered, with few produced naturally. They are highly valued because they can enhance the effectiveness of drugs and produce sturdy-though-lightweight products.

Despite their usefulness, nanoscale materials are poorly understood, with "very little known about the potential effects on human health and the environment," according to the National Institute of Environmental Health Sciences.

During the experiment, scientists were surprised to also detect titanium dioxide in the "control" group of rats that hadn't been given nanoparticles to inhale.

It turns out the food given to the animals contained titanium dioxide. As a result, the researchers were able to observe the path the metal took through a rat's body.

"Now that we know that the nanoparticles migrate a" from the mother's lungs to the placenta and foetal tissues - we can work on answering other questions," Stapleton said. (AS/IANS)