effects of phthalates on human health

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A recent study has reported that exposure to phthalates affects fine motor skills in girls.

Phthalates are a class of chemicals that are commonly found in plastic containers and personal care products.  There are two families of phthalates, known as DEHP and non-DEHP, and there are many chemicals from each family used in the products we buy every day. These chemicals help make plastics soft, flexible and clear, such as in food packaging and children’s toys.  They are used as solvents for aromatic solutions, such as in perfumes, and air fresheners.  You can also find them in certain types of pill coatings, glues, paints, personal grooming products, and electronics.

While phthalates are commonly used chemicals, the effects of phthalates on human health are just starting to become clear to us.  Phthalates are known to disrupt the endocrine system that controls our hormones.  There is also some early evidence that they may affect male fertility and increase risks of obesity, diabetes, and cancer. But the place where phthalates may cause the most harm is in the unborn child.  Phthalates can cross the placenta, where the mother and baby’s blood exchange life-giving gases and nutrients.  This means that they enter a baby’s bloodstream and may affect the development of the baby.

Some evidence has shown that phthalates cause some cognitive (thinking) and behavioural problems, as well as problems with motor functions (the ability to move, keep your balance, and so on).

In a recent study, researchers look at different types of phthalates, as well as combinations of phthalates, in the urine of pregnant mothers and measured the motor function of their tween children.

The researchers measured the urine levels of phthalates in the third trimester (last three months) of over 200 pregnant mothers.  They then waited until the women’s children were eleven years old and measured the motor functions of the girls and boys.  Using a special test, they were able to measure both their gross motor skills (the overall ability to move, run, balance, and throw) and their fine motor skills (such as pinching, handwriting, handling small objects).

What they found was that three phthalates from the DEHP family (MBP, MBZP, and MIBP), as well as the phthalates from the non-DEHP family, seemed to affect the eleven-year-old girls’ ability to use fine motor skills in a way that did not affect the eleven-year-old boys.  This was despite accounting for many factors that could also have changed the results, such as smoking or drinking during pregnancy, marital status, the mother’s mental health, the child’s age and weight (measured in BMI), ethnic background, and home environment.

The researchers think that the reason for the disruption in fine motor skills may be due to the phthalates’ ability to affect the thyroid gland, which produces hormones that are important for brain development.  The development of the cerebellum, which is a part of the brain that is very important in balance and movement, is affected by these thyroid hormones.  If the cerebellum is affected and does not develop properly, it could reduce a person’s motor functions.

It was noted by the researchers that girls develop their motor skills at a younger age than boys, and that could explain why they were affected while the boys showed no change in their motor skills.  It is not known how the motor skills of the boys might be affected a few years later, since the study did not go beyond the age of eleven.

There are, however, some things that should be taken into consideration when interpreting the results of the study. For example, the mothers were from lower socio-economic neighbourhoods in the New York City area.  The researchers explained that there is a known association between lower socio-economic status and lower motor skills as well as an increase in phthalate exposure.  This means that in a general population, there may be less of an observed effect on the girls’ motor skills with similar phthalate exposure.  Also, pregnant mothers in the general population may have lower phthalate exposures than the mothers who were studied in this research.

This study adds to the growing body of evidence showing the effects of phthalates on human health.  Such information helps us better understand the unwanted side-effects of these chemicals in our everyday environment.

Written by Nancy Lemieux

References:

Daniel, S. et al (2020). Perinatal phthalates exposure decreases fine-motor functions in 11-year-old girls: Results from weighted Quantile sum regression. Retrieved 12 January 2020, from https://www.sciencedirect.com/science/article/pii/S0160412019325115?via%3Dihub

Plasticizers may contribute to motor control problems in girls. (2020). Retrieved 12 January 2020, from https://www.eurekalert.org/pub_releases/2020-01/cums-pmc010620.php (2020). Retrieved 12 January 2020, from https://en.wikipedia.org/wiki/Phthalate

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