Ethanol and Alcohols

Introduction & chemistry

• Definition — alcohols are hydroxy (–OH) derivatives of aliphatic hydrocarbons; unqualified, "alcohol" means ethyl alcohol / ethanol (CH₃CH₂OH), a 2-carbon alcohol rapidly distributed into body water and brain.
• Public-health scale — ethanol is the oldest recreational drug and likely causes more morbidity, mortality and cost than all illicit drugs combined; its pharmacological importance is in beverages, alcoholism and intoxication, not as a medicine.
• Alcohol use disorder (AUD) — DSM-5 merges "abuse" and "dependence" into a single AUD on a mild–moderate–severe continuum (≥2 of 11 behaviours/12 months; mild 2–3, moderate 4–5, severe 6–11) across four domains — impaired control, social consequences, risky use, altered physiology (tolerance/withdrawal). Heritability 50–60%.
• Beverages & forms — made by fermentation of sugars (self-limiting at ~15%); Indian licensed spirits standardised to 42.8% v/v (37% w/w), chiefly from molasses. Other forms: absolute alcohol (99% w/w), rectified spirit (90%), proof spirit (57.1% v/v), and methylated/denatured (industrial) spirit = rectified spirit + 5% wood naphtha (methanol), tinted blue to render it undrinkable.
• Standard drink — a US standard drink (12 oz beer / 5 oz wine / 1.5 oz shot) ≈ 14 g ethanol; "proof" = twice the % alcohol. Indian "1 drink" (KDT) = 50 mL spirits ≈ 16 g → peak BEC ~30 mg/dL on an empty stomach.