Pesticides

Question 1

What are the main classes of pesticides?

Answer 1

1. Organophosphates – Affect nervous system by inhibiting acetylcholinesterase.
2. Organochlorines – Persistent in environment; disrupt neuronal ion channels.
3. Carbamates – Similar to organophosphates but less persistent.
4. Pyrethroids – Synthetic analogs of natural pyrethrins; affect sodium channels.
5. Neonicotinoids – Act on nicotinic acetylcholine receptors (more in insects).
6. Glyphosate – Herbicide; disrupts plant enzyme EPSP synthase.
7. Paraquat – Herbicide; generates oxidative stress.
8. Fungicides – Often include strobilurins, azoles, and dithiocarbamates.

Question 2

How do organophosphates affect the nervous system?

Answer 2

They inhibit acetylcholinesterase, leading to accumulation of acetylcholine, causing prolonged nerve signaling. Chronic low-level exposure may contribute to Parkinson’s Disease (PD) and cognitive decline.

Question 3

Which pesticide is most strongly linked to Parkinson’s Disease?

Answer 3

Paraquat, a herbicide, is one of the most strongly linked. It causes oxidative stress and dopaminergic neuron death in animal models, resembling PD pathology.

Question 4

What have studies shown about organochlorines and neurodegeneration?

Answer 4

Some organochlorines (e.g. DDT, dieldrin) have been linked to increased PD risk. They persist in fat tissue and have long biological half-lives. Post-mortem studies show higher levels in PD brains.

Question 5

Which pesticides are banned in the EU but still used in the US?

Answer 5

• Paraquat – Banned in EU; still used in parts of the US.
• Chlorpyrifos (organophosphate) – Banned in EU since 2020; banned in US for food crops only (2022).
• Atrazine (herbicide) – Banned in EU; widely used in US.

Question 6

What is glyphosate, and is it neurotoxic?

Answer 6

Glyphosate is a broad-spectrum herbicide (e.g. Roundup). It targets plant EPSP synthase. It’s not acutely neurotoxic but may have indirect effects on the gut microbiome and inflammation, potentially contributing to ND in vulnerable populations.

Question 7

What are neonicotinoids, and how might they affect the brain?

Answer 7

They are insecticides that act on nicotinic acetylcholine receptors. Primarily insect-targeted, but chronic exposure may affect mammalian neurodevelopment, especially in utero or early life.

Question 8

Are fungicides linked to neurodegeneration?

Answer 8

Some fungicides (e.g. maneb, a dithiocarbamate) have been implicated. Animal studies show that maneb + paraquat exposure causes synergistic dopaminergic toxicity, modeling Parkinsonian damage.

Question 9

What regions have strict pesticide bans and regulations?

Answer 9

• European Union – Generally strict, precautionary principle-based. Many pesticides banned (e.g. paraquat, atrazine, chlorpyrifos).
• United States – More permissive; bans often slow and contested.
• Brazil/India – High usage; regulatory frameworks evolving.

Question 10

What are key studies linking pesticide exposure to neurodegenerative disease?

Answer 10

• Farming and Movement Evaluation (FAME) study – Found links between pesticide exposure and PD in US farmers.
• Rotenone and paraquat animal models – Replicate Parkinson’s-like symptoms.
• Twin studies (e.g. Tanner et al., 2011) – Show increased PD risk with pesticide exposure, independent of genetics.