Chemical compounds could play a role in causing
unborn boys to have fertility problems in later life.
Edinburgh University researchers claimed a crucial window
between eight and 12 weeks of pregnancy determined future
They believe that exposure to chemicals found in products
such as cosmetics during this period may affect later sperm
But they stressed there was not yet conclusive proof this
was the case.
The research team was led by Professor Richard Sharpe of
the Medical Research Council's Human Reproductive Sciences
Unit, based in Edinburgh.
During tests on rats, they blocked the action of androgens,
which include male sex hormones such as testosterone, for
a short period in the womb.
The experiments confirmed that if the hormones are blocked,
the animals suffered fertility problems.
Some of the chemicals which can block the hormones are widely
used in items such as cosmetics, household fabrics and plastics.
Prof Sharpe said the chemicals may also increase the risk
of baby boys developing other reproductive conditions in later
life, including testicular cancer.
He added that if women planning on becoming pregnant were
anxious about such issues they could avoid putting any cosmetic
products on their skin which could then be absorbed into their
He stated "There are lots of compounds in perfumes that
we know in higher concentrations have the potential to have
biological effects, so it is just being ultra safe to say
that by avoiding using them your baby isn't at risk.
"If you are planning to become pregnant you should change
your lifestyle. Those lifestyle things don't necessarily mean
that you are going to cause terrible harm to your baby, but
by avoiding them you are going to have a positive effect.
"We would recommend you avoid exposure to chemicals that
are present in cosmetics, anything that you put on your body
that might then get through your body into your developing
"It is not because we have evidence that these chemicals
categorically cause harm to babies, it is only based on experimental
studies on animals that suggest it is a possibility."
However, Prof Sharpe said women were exposed to many of the
chemicals he was concerned about through many other routes,
as they are widespread in the air and in the fabrics of their
He is due to unveil his findings next week at the Simpson
Symposium in Edinburgh, a gathering of fertility experts organised
by Edinburgh University.
A spokeswoman for the Department for Business, Enterprise
and Regulatory Reform said all cosmetics undergo testing and
current legislation ensures public safety.
She added: "All cosmetic products including perfume undergo
a rigorous safety assessment by manufacturers.
Whether these safety assessments are rigorous enough to protect
public health is a matter of debate.