Phthalates, a class of chemicals used to make plastics more flexible and durable, may impact health across multiple generations.
New research suggests phthalate exposure in one generation can lead to adverse effects in subsequent generations through changes in gene regulation.
This raises concerns that the public health impacts of phthalates may be more extensive than previously thought.
Key Facts:
- Phthalates are used in many consumer products and can leach out, leading to widespread exposure.
- Phthalates may act as endocrine disruptors and have been linked to reproductive issues, obesity, asthma, and other health problems.
- Animal studies show phthalates can affect future generations through “epigenetic inheritance”, changes in gene regulation transmitted through the germline.
- Early embryo development appears especially sensitive to epigenetic effects of phthalates. Effects are seen many generations later.
- Human studies show links between phthalate exposure, epigenetic changes in sperm, placenta, and other tissues, and health issues in children.
- More research on multigenerational impacts in humans is critically needed. Public health policies should apply the precautionary principle to potentially toxic exposures.
Source: Front Genet. 2020
Widespread Human Exposure to Phthalates
Phthalates are a group of chemicals used as plasticizers in polyvinyl chloride (PVC) plastics and many other consumer products.
They make plastics more flexible and durable. Phthalates can leach out of plastics and other products over time.
As a result, phthalate exposure is widespread. Phthalates are found in food, dust, air, and a variety of personal care products.
Exposure starts prenatally, as phthalates can cross the placenta.
Major phthalate exposure sources include medical tubing and blood storage bags, children’s toys, food packaging, lotions, soaps, shampoo, and indoor air and dust.
People are exposed through ingestion, inhalation, and absorption through the skin.
Once in the body, phthalates are quickly metabolized and excreted in urine and feces.
However, chronic exposure is common.
By measuring phthalate metabolites in urine, studies have shown widespread exposure in the general population starting from childhood.
Potential Health Effects of Phthalates in Humans
In lab studies, exposure to some phthalates, especially at high doses, has been found to disrupt the endocrine system and male reproductive development.
Human studies also link phthalates to potential reproductive issues in both males and females.
In addition, phthalate exposure has been associated with obesity, asthma, neurodevelopmental issues, behavioral problems, and cancer, though findings are mixed.
Children with chronic illnesses and premature infants may be especially vulnerable due to exposures from medical devices.
Most studies have focused on health effects in the exposed individual.
However, there are increasing concerns that phthalate exposure may also negatively affect the health of future generations.
Phthalates & Epigenetics: Multigenerational Impact via Inheritance
Researchers now know that some environmental exposures can affect not just the exposed individual but also their descendants, through a phenomenon known as epigenetic inheritance.
The epigenome regulates gene expression and is influenced by environmental factors.
Changes to the epigenome can be passed down through the germline to future generations without changes to the underlying DNA sequence.
Animal studies show that in utero phthalate exposure can lead to reproductive effects in subsequent generations through epigenetic changes in sperm and eggs.
For example, reduced sperm counts and testicular disease have been found up to three generations after the initial exposure.
Few human studies have directly investigated multigenerational effects.
However, some have found links between phthalate exposure, epigenetic changes in sperm and placental tissue, and reproductive effects in offspring, suggesting epigenetic inheritance may be occurring.
Critical Windows of Susceptibility to Phthalates
The developmental period appears especially sensitive to epigenetic effects.
Exposure during embryonic development can imprint changes that lead to disease later in life.
Studies in embryonic stem cells show phthalates can impact gene expression patterns and change how the cells differentiate.
This suggests phthalates may disrupt early embryonic development in humans as well.
The preconception period and pregnancy are also critical windows where phthalate exposure could epigenetically alter the developing fetus with impacts generations later.
More research is critically needed on effects across the lifespan.
Human Studies Link Phthalate Exposure With Epigenetic Changes
Though most data on multigenerational epigenetic effects come from animals, emerging evidence in humans supports concerns over phthalate exposure.
Multiple studies have associated phthalate exposure in pregnant women with epigenetic changes in umbilical cord blood and placenta.
Exposure has also been linked to reproductive effects in their babies.
The placenta may be especially vulnerable.
In men, phthalate metabolites in urine have been associated with epigenetic changes in sperm genes related to growth and development.
Some changes correlated with lower embryo quality.
While findings are preliminary, they suggest phthalate exposure could impact gene regulation and health across generations through the germline.
More studies in humans are urgently needed.
Public Health Implications and Precautionary Principles
The possibility that phthalate exposure could affect descendants even generations later raises serious public health concerns.
If true, the population health impacts and costs would be substantial.
While more evidence is still needed, researchers argue precautionary measures are wise.
Women planning pregnancy may consider avoiding phthalate exposures. Medical device manufacturers can strive for phthalate-free alternatives.
Though phthalates are still widely used, some have been banned in children’s products.
Broader restrictions may merit consideration to protect health now and decades into the future.
The effects of environmental chemicals across generations remain poorly understood.
But early evidence on phthalates suggests a need for greater caution to avoid unintended consequences for our descendants.
References
- Study: Phthalate exposure and long-term epigenomic consequences: a review
- Authors: Sudipta Dutta et al. (2020)
