Exposure to DDT alters sperm, putting children at risk

A new study suggests that environmental toxins, specifically DDT, can affect the sperm of fathers, potentially leading to reproductive and health issues in their offspring. This extensive research, spanning a decade, was conducted by experts from McGill University, the University of Pretoria, Université Laval, Aarhus University, and the University of Copenhagen.  

The research was focused on the sperm epigenome alterations in men from the South African Vhavenda and Greenlandic Inuit populations, highlighting the impact of DDT exposure

Modifications in the sperm epigenome

Published in the journal Environmental Health Perspectives, the research established a connection between prolonged DDT exposure and modifications in the sperm epigenome. 

These modifications, particularly in genes crucial for fertility, embryonic development, neurodevelopment, and hormone regulation, are associated with increased incidences of birth defects and disorders, including neurodevelopmental and metabolic issues.

“We identified regions of the sperm epigenome that are associated with the serum levels of DDE (chemicals that form when DDT breaks down) and this association follows a dose-response trend. I think that’s quite striking, in that the more DDE you’re exposed to, the higher the chromatin, or DNA methylation defects are in the sperm,” said lead author Ariane Lismer, an expert in embryogenesis and epigenetic inheritance at McGill.

Study significance 

The study’s significance is further emphasized by Sarah Kimmins, who led the research at McGill and is now employed at the University of Montréal. 

“This is a critical new step for the field because while there are many studies of animals demonstrating toxin effects on the sperm epigenome, studies in humans have not comprehensively demonstrated this.”

Contentious issue

The continued use of DDT in some regions to combat malaria is a contentious issue. Despite its global ban to safeguard human and environmental health, exceptions like those granted to the South African government highlight the complex balance between disease control and environmental health. 

Tiaan de Jager, PhD, commented on the dilemma, emphasizing the necessity of house spraying in malaria-endemic areas while also acknowledging the need for alternative disease control methods.

The study also draws attention to the broader implications of climate change, which exacerbates the spread of DDT through the so-called “grasshopper effect,” illustrating how this toxin can travel and persist in colder regions, particularly the Arctic food chain.

Paternal role in child health

Furthermore, the experts advocate for a more inclusive approach to child health and development, stressing the importance of considering the paternal role. For instance, co-author Janice Bailey,  the Scientific Director at Fonds de Recherche du Québec en Nature et Technologies (FRQNT), highlighted the overlooked impact of fathers’ environmental exposures. 

“We tend to think all fathers have to do is fertilize. But in fact, we forget that half of that genome and epigenome comes from the fathers, and half of it comes from the mothers. What that epigenome does in embryo development is critical for normal development.”

Study implications 

While the research primarily focuses on DDT, it suggests that exposure to everyday endocrine disruptors found in cosmetics and personal care products could similarly influence sperm and future generations. 

This study underscores the need for a broader understanding and approach to managing environmental toxin exposure and its implications for human health and development.

More about DDT

Dichloro-diphenyl-trichloroethane (DDT) is a synthetic chemical compound famous for its insecticidal properties. Discovered to have pesticidal qualities in 1939 by Swiss chemist Paul Hermann Müller, who was later awarded the Nobel Prize in Physiology or Medicine for his discovery, 

World War II

DDT was widely used during World War II to control malaria and typhus among civilians and troops. Following the war, its use expanded significantly in agriculture and for vector control.

Serious impacts

DDT is highly effective at killing a wide range of insects, which contributed to its widespread adoption. However, its environmental and health impacts soon became a matter of concern. In the environment, 

DDT is very persistent, taking years or even decades to break down. It accumulates in the fat tissue of animals, leading to bioaccumulation up the food chain and affecting birds, fish, and mammals.

Dangers

One of the most significant impacts of DDT is on birds, as it causes thinning of eggshells, leading to reduced bird populations. This was famously documented by Rachel Carson in her 1962 book “Silent Spring,” which is credited with launching the environmental movement.

Carson’s work highlighted the dangers of indiscriminate DDT use, eventually leading to a ban on its agricultural use in many countries during the 1970s.

Continued use

Despite its environmental impact, DDT is still used in some parts of the world for controlling mosquitoes that transmit diseases like malaria, under strict regulations. The World Health Organization (WHO) supports its use in vector control because of its effectiveness and low cost, but emphasizes the need for safe and judicious application to minimize negative impacts on health and the environment.

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