Recently we described that citizens are not protected against neurotoxic effects of pesticides. Many active substances, especially insecticides but also fungicides and herbicides, affect the human brain. Authorities like the European Food Safety Authority admit that the long term effects are not sufficiently examined. Medical specialists warn of a Parkinsons epidemic. But there is a perhaps even more devastating effect on the most vulnerable: the unborn and young children. Prof. P. Nicolopoulou Stamati MD. PhD from the University of Athens described the effects of pesticides on young children’s brain in a recent webinar. Here is our transcription of her text.
Synthetic pesticides are toxic to biological systems by design. They are created with the intention to kill a living organism. Humans share a lot in common with so-called “pests” when it comes to routes the toxins are affecting the mechanisms of nerve signal transmission, and other mechanisms, so it should not be a surprise that pesticides intended to kill insects affect human organisms too.
Pesticides act in different ways:
- by disrupting signaling mechanisms in the central nervous system
- by inhibiting neurological function
- by acting as Endocrine Disruptors
Evidence from animal studies and adult occupational poisonings has demonstrated that these insecticides act via similar neurotoxic mechanisms in mammals following high-dose exposure. Less is known about the mechanisms of neurotoxicity at low-level exposures that are relevant to the general population.
Low-level pesticide exposures are an important concern in pregnant women and young children. Fetal and infant brains are rapidly developing, leaving them highly vulnerable to potentially long-lasting effects of pesticide exposure, such as disruption of brain architecture or circuitry.
Adding to concerns for fetal exposure, pesticides are able to cross the placenta and fetuses tend to have lower levels of detoxifying enzymes. Both aspects are thought to increase fetal susceptibility.
Low-level pesticide exposures during pregnancy or childhood have been found to be associated with neurodevelopmental deficits such as:
- lower IQ
- disorders such as autism
- attention deficit-hyperactivity disorder
- pervasive developmental disorder
An old story many times said …… Children are at high risk of exposure to pesticides that are used in and in the vicinity of schools, homes, and day-care centers for agricultural use and control of roaches, rats, and other vermin.
Children are highly vulnerable to pesticides. Because of their play close to the ground, their hand-to-mouth behavior, and their unique dietary patterns, children absorb more pesticides from their environment than adults.
The long persistence of semivolatile pesticides such as chlorpyrifos on rugs, furniture, stuffed toys, and other absorbent surfaces within closed apartments further enhances urban children's exposures.
Compounding these risks of heavy exposures are:
- Children's decreased ability to detoxify and excrete pesticides and the rapid growth, development, and differentiation of their vital organ systems.
- These developmental immaturities create early windows of great vulnerability.
- Recent experimental data suggest that chlorpyrifos may be a developmental neurotoxicant and that exposure in utero may cause biochemical and functional aberrations in fetal neurons as well as deficits in the number of neurons.
- Certain pyrethroids exert hormonal activity that may alter early neurologic and reproductive development.
- Methods currently used for assessment of the toxicity of pesticides are insensitive and cannot accurately predict effects to children exposed in utero or in early postnatal life.
Protection of children, and particularly of inner-city children, against the developmental hazards of pesticides requires
- a comprehensive strategy that monitors patterns of pesticide use on a continuing basis
- assesses children's actual exposures to pesticides
- uses state-of-the-art developmental toxicity testing
- establish societal targets for reduction of pesticide use
Fetus and child brain is more vulnerable to neurotoxic effects than adults In addition, exposure to pesticides during pregnancy could adversely affect fetal development because pesticides can cross the placental barrier and have even been found in amniotic fluid that protects the growing fetus.
In recent years, concern has arisen worldwide about the potential adverse effects that could result from early-life exposure to pesticides. Asthma, bronchitis, and persistent cough in children have been linked to gestational exposure to pesticides. The respiratory effects of gestational exposure to pesticides are controversial.
Why is the developing brain particularly susceptible to neurotoxicity?
The blood-brain barrier restricts the passage of substances from blood to brain. In its absence, toxic agents can freely enter the developing brain. This blood-brain barrier is not yet well developed at birth. It is widely believed that in embryos and newborns, this barrier is immature or “leaky,” rendering the developing brain more vulnerable to drugs or toxins entering the fetal circulation from the mother.
In summary, the developing brain is extremely vulnerable to toxic insults because a large number of processes occur during an extended period of time.
Between conception and age three, a child's brain undergoes an impressive amount of change. At birth, it already has about all of the neurons it will ever have. It doubles in size in the first year, and by age three it has reached 80 percent of its adult volume.
Thanks to recent advances in technology we have a clearer understanding of early brain development. Neuroscientists can now identify patterns in brain activity that appear to be associated with some types of negative early experiences.
Genetic and environmental factors work together to shape early brain development. Although the first stages of brain development are strongly affected by genetic factors, genes do not design the brain completely. Instead, when and where genes are used is fine-tuned according to the input they receive from the environment – this happens even during pregnancy when maternal nutrition and stress can influence the early phases of brain architecture. These gene-environment relations allow for each child to adapt to their surroundings more readily and more quickly than they could if genes alone determined the brain’s wiring.
There are two major ways that genes and environment work together to sculpt the brain. One is through inheriting certain forms of genes that can have very different interactions with the environment. The second is through environmental influences that can alter the read-out of genes without changes to the genes themselves. This second process is becoming better understood thanks to recent research in a relatively new scientific field called epigenetics.
Epigenetics: New understanding of interaction between genes and environment
The field of epigenetics has changed our understanding of how the environment interacts with our genes and how genes interact with the environment. Epigenetics (meaning ‘above’ genetics) is the study of enduring changes in gene activity that do not change the DNA code itself, but through chemical changes, do influence how the code is used. Many environmental factors and experiences result in chemical ‘marks’ on certain parts of genes, and these epigenetic changes can influence the activity, or ‘expression’, of the gene.
You can think of the epigenetic processes as the software that directs the functioning of a gene’s DNA hardware. Because the development of all cells, tissues, and organs is affected by when and how specific genes are expressed, epigenetic processes can be a powerful influence on health and well-being.
The harm that can be done to the youngest and most vulnerable commits us to safeguard them from harmful effects of substances we apply in our environment and for our food production. However, this is currently not the case. Recently PAN Europe described that EU citizens are not protected against the neurotoxic effect of pesticides.
For more information on the medical aspects you can //communications [at] pan-europe.info">contact PAN Europe.
