Women exposed to cleaning products at work are more likely to give birth to kids with asthma - even if the exposure was long before conceiving

• Kids whose mothers were exposed to cleaning products at work were more likely to develop asthma than other kids, a study found.
• That was true even for mothers exposed to the products up to 2 years before giving birth.

A mother's exposure to cleaning products at work could hurt the health of her future child - even if the exposure comes before that child is ever conceived.

That's the conclusion of a study published last week, which showed that children whose mothers were exposed to cleaning products at work before or around the time they got pregnant were more likely to develop asthma than the children of moms with minimal exposure to these products.

Scientists have long understood that frequent exposure to chemicals in cleaning products can lead some people to develop asthma or make asthma symptoms worse. But the new research shows how that health risk can be passed from mother to child.

The study relied on data from two generations: around 3,300 people born between 1962 and 1998, and their mothers, who were born between 1945 and 1973. Each mom had a job that put her at a high or medium level of exposure to cleaning products for at least six months. That included work as professional cleaners for offices, hotels, or homes, as well as positions as housekeepers, restaurant workers, embalmers, or hair dressers.

Within that group of mothers, 150 were exposed to cleaning products at least two years before their kids were born, but not during or after pregnancy. Their children were more likely to develop asthma before age 10 than any other kids included in the study. Children whose moms were exposed during pregnancy, up to a year after giving birth, or 3 to 15 months before they conceived were also more likely to develop asthma before age 10.

The study "adds a new dimension to the growing concern about health effects of cleaning agents," the researchers wrote. The products we use now may pose harm to future generations, they said.

Chemicals in detergents and disinfectants are linked to asthma symptoms

The study looked at mothers across Northern Europe, Spain, and Australia who'd been exposed to indoor cleaning products - mostly detergents and disinfectants. The results showed that their kids' asthma risk was consistent regardless of whether the mothers smoked or had asthma before having children.

But the study didn't look more specifically at particular cleaning products, or the chemicals found in those products. A 2015 study, however, found that bleach, glass cleaner, detergents, and air fresheners all worsened asthma symptoms for professional cleaners.

Many of those products contain ammonia, a potent chemical that breaks down grease and mildew. Several studies have suggested that frequent exposure to ammonia may cause asthma symptoms.

Cleaning products can also release volatile organic compounds, a group of colorless (and often odorless) fumes. Scientists have found that indoor exposure to these chemicals may be associated with asthma, but more research is needed to assess the risk they might pose.

Exposure to cleaning chemicals could alter a mother's reproductive cells

The researchers weren't able to determine exactly why children in the study developed asthma.

One theory is that cleaning chemicals cross the placenta during pregnancy, so transfer from mother to unborn child. The chemicals might then alter the development of a child's airways inside the womb, leading to asthma symptoms in early childhood.

But that theory doesn't explain why children were most likely to develop asthma when their mothers had been exposed to cleaning products well before pregnancy.

So the researchers offered another hypothesis: Exposure to cleaning chemicals might alter a mother's germ cells - the cells responsible for passing genes to the next generation. In that case, even if a mother isn't exposed to cleaning chemicals during pregnancy, her child could still inherit a set of genetic instructions that hinders their breathing once they're born.

Prior research has also found that the compounds a mother - or even grandmother - is exposed to can influence a child's asthma risk.

Last year, a study found that children had a higher risk of asthma if their mothers had been exposed to air pollution when they were kids. Amd a 2018 study found that children under age 6 had an increased risk of asthma if their grandmothers had smoked during early pregnancy - regardless of whether their mothers had also smoked.