Carbamates insecticides are the lesser evils of organophosphates. Exposure leads to similar but less severe adverse effects. But, do not be fooled: always wear full body protective gear when using them.
First introduced in 1956, carbamates have progressively replaced organophosphates as insecticides – used in agriculture and humans. They were favoured over the latter due to their low toxicity profile following exposure. However, lack of awareness within low-income countries about the toxins and their proper use renders them disastrous toxins that can easily cause unnecessary morbidity and mortality after accidental, chronic, or suicidal exposure. Most of the people who attempt or commit suicide in the remote villages of sub-Saharan Africa drink such poison.
Carbamates are chemical compounds. They are esters of N-methyl or N, N- dimethyl carbamic acid with either a phenol or oxime backbone. They include propoxur, benomyl, carbofuran, pirimicarb, aldicarb, carbosulfan, methomyl, carbaryl, et cetera.
Unlike organophosphates, carbamates are less lipid soluble – they poorly penetrate the central nervous system. Nonetheless, clinicians have found them within brain tissue at prolonged exposure or ingestion of large quantities of the toxin.
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When ingested, carbamates have a short half-life, so the body clears them within one or two days. It’s imperative to note that carbamate poisoning is entirely reversible. It is so due to the absence of ageing that occurs with organophosphates.
Carbamates affect the nervous system that deals with automation – the autonomic nervous system. Once exposure to them occurs, you may experience any or all of the following clinical features depending on the organs or systems affected.
| Tissue Target | Clinical effect |
|---|---|
| Gastrointestinal system | Vomiting, diarrhea, cramping |
| Genitourinary system | Urination |
| Lungs | Bronchorrhea, bronchospasm |
| Heart | Bradycardia (Heart rate below 60 bpm) |
| Eyes | Miosis, lacrimation |
| Salivary glands | Salivation |
| Sweat glands | Diaphoresis |
| Adrenal glands | Increased secretion of epinephrine and norepinephrine causing increased heart rate (tachycardia) |
| Brain | Agitation, seizures, coma |
| Skeletal muscle | Weakness, fasciculations, paralysis |
The good news is that exposure to carbamates is rarely fatal except over poisoning. Treatment involves supportive care and atropine administration. Atropine reverses the effects of the toxins. Clinicians rarely give the antidote, pralidoxime, as ageing doesn’t occur, unlike organophosphate poisoning.
That said, do not use insecticides without full-body protection. Studies have reported acute pancreatitis upon exposure: however, chronic low-dose exposure may cause chronic pancreatitis and diabetes mellitus.
