9. Aliphatic hydrocarbons and aliphatic halogenated hydrocarbons

Question 1

What are the subcategories of Aliphatic hydrocarbons?

Answer 1

1. Saturated
2. Unsaturated
3. Halogenated
4. Alcohols
5. Aldehydes

Question 2

Carbohydrate pathophysiology in general

Answer 2

Pulmonary – aspiration Pneumonitis Hemorrhagic alveolitis Nervous system certain hydrocarbons are highly lipophilic – narcotic effect white matter degeneration atrophy peripheral neuropathy sensory impairment… Cardiovascular myocardium becomes sensitized to the effects of catecholamines!!! Gastrointestinal burning sensation because they are irritating to the GI mucosa Hepatic chlorinated hydrocarbons, in particular carbon tetrachloride - free radical formation - lipid peroxidation Renal Chronic exposure to toluene distal renal tubular acidosis Hematologic Prolonged exposure (especially benzene) can lead to an increased risk of aplastic anemia, multiple myeloma, and acute myelogenous leukemia

Question 3

Carbohydrate treatment:

Answer 3

Prehospital care: Decontamination - clothes or skin - activated charcoal does not absorb hydrocarbons GI decontamination has no role in prehospital care Patients should be kept calm to prevent arrhythmia as a result of myocardial sensitization ABCD If ventricular fibrillation occurs, and the thought is that the arrhythmia is because of myocardial sensitization, catecholamines, including epinephrine, should be avoided. In this setting, lidocaine or beta-blockers (Propranolol, Esmolol) can be used!!! The hydrocarbons with significant systemic toxicity for which the benefits of gastric decontamination may outweigh the real risks of inducing aspiration follow the mnemonic CHAMP: Camphor (toxicity is seizures) Halogenated hydrocarbons (toxicity is arrhythmias and hepatotoxicity) Aromatic hydrocarbons (toxicity is CNS toxicity, myelosuppression, and malignancy) Metals (heavy metals) Pesticides (cholinergic symptoms, seizures)

Question 4

Saturated Aliphatic compounds:

Answer 4

Benzine, petroleum  number of carbons -  narcotic and toxic effect Inahalation Acute toxicity: conjunctivitis, irritation of upper respir. and GIT Narcotic effect Chronic toxicity: Lung injury, signs of alcochol intoxication

Question 5

Unsaturated Aliphatic compounds - olephines

Answer 5

 number of carbons -  narcotic and toxic effect  C atoms acts as convulsants and hepatotoxics Propyne (methylacetylene) – lung oedema

Question 6

Halogenated Aliphatic Hydrocarbons

Answer 6

industrial solvents, degreasing agents, and cleaning agents extreme lipid solubility, more toxic than the non-halogenated Monohalogen methane: methyl- bromide, methyl- chloride, methyl-iodide Carbon tetrachloride (CCl4), Teflon Carcinogens MOA: Chronic workplace exposure significant neurotoxicity with impaired memory and peripheral neuropathy. Hepatotoxicity Nephrotoxicity can occur in humans exposed to carbon tetrachloride, chloroform, and trichloroethylene. All halohydrocarbon solvents can cause cardiac arrhythmias in humans, particularly in situations involving sympathetic excitation and norepinephrine release. TREATMENT: There is no specific treatment for acute intoxication resulting from exposure to halogenated hydrocarbons. Management depends on the organ system involved

Question 7

Aliphatic compounds -Alcohols - Methanol

Answer 7

Methanol (wood alcohol), a constituent of windshield cleaners 30-100ml to death Intoxication causes visual dysfunction, gastrointestinal distress, shortness of breath, loss of consciousness, and coma. metabolized to formaldehyde and formic acid, which causes severe acidosis, retinal damage, and blindness. The formation of formaldehyde is reduced by prompt intravenous administration of fomepizole, an inhibitor of alcohol dehydrogenase Ethanol - competitively inhibits alcohol dehydrogenase

Question 8

Alcohols - Ethylene Glycol

Answer 8

Industrial exposure to ethylene glycol (by inhalation or skin absorption) or self-administration (eg, by drinking antifreeze products) leads to severe acidosis and renal damage from the metabolism of ethylene glycol to oxalic acid. Prompt treatment with intravenous fomepizole or ethanol may slow or prevent formation of this toxic metabolite

Question 9

Aliphatic aldehydes

Answer 9

Formaldehyde Major symptoms may include eye, nose, and throat irritation; headaches; and/or skin rashes If formaldehyde is swallowed it causes burns to the esophagus and stomach – see acids - protein precipitation Th: water, milk, no specific antidote Acetaldehyde Local irritative, central narcotic effect Metaldehyde used to control slugs and snails metaldehyde undergoes partial hydrolysis in the stomach to produce acetaldehyde Symptoms: GI – local irritation, hemorrhagic gastritis; CNS –muscle rigidity, convulsion, respiratory depression Th: gastric lavage, charcoal, cathartics, sympthomatic

Question 10

Methane (CH4)

Answer 10

Methane is a flammable natural gas, often used as a fuel. Methane has been the cause of many deadly mining disasters. Methane gas can penetrate the interiors of buildings near landfills and expose occupational workers to significant levels of methane. It is an asphyxiant, when oxygen is reduced to below 16% by displacement in the blood causing a poisonous effect in the body. Usually we can tolerate a reduction between 21% and 16% but below this level ill effects start to occur.

Question 11

Propane, Butane

Answer 11

 Propane is a by-product of natural gas processing and petroleum refining, commonly used as fuel.

 Butane is highly flammable and a easily liquefied gas.

 Toxic doses of these compounds are rapidly absorbed in the lungs into the bloodstream and distributed to the organs. Both can cause a narcotic effect and can induce seizures because they are highly lipophilic and can therefore penetrate the CNS. In children these effects will be immediately fatal.

 Propane and Butane are also asphyxiants, and abused as an inhalant it can cause hypoxia, pneumonia, cardiac failure or cardiac arrest. This is known as the Sudden sniffer’s death syndrome.

Answer 12

Petroleum Benzine: (hydrocarbon-based solvent mixture):

 The acute signs of toxicity include conjunctivitis, irritation of the upper respiratory and GI Tract, as well as the narcotic effect (euphoria, loss of consciousness) eventually leading to coma. The acute danger is the asphyxia (choking).

 Eventually under chronic exposure lung problems and injury will develop, polyneuropathy including: psychotic reactions, depression, delirium, similar symptoms to alcohol intoxication develop.

Question 13

Saturated aliphatic

Answer 13

Treatment options:

 There is no antidote.

 Sympathomatic agents should be used to treat the symptoms.

 Respiratory support (endotracheal intubation, oxygen supply, bronchodilators (E.g: salbutamol) should be given).

 Gastric lavage

 The degree of treatment depends on the symptoms and organs involved.

Question 14

Unsaturated Aliphatic Hydrocarbons (Olefines/Alkenes and Alkynes) I.

Answer 14

One double bond  stronger narcotics

 More double bonds  even stronger narcotic effects

 More than 4 carbons  causes convulsions and hepatotoxicity

Answer 15

Propyne (methylacetylene):

 Used in gas welding and found in rocket fuel.

 It is absorbed into the body via inhalation of the combustion

of fuel.

 Also found in cigarettes: (A study showed that the exhalation of this compound was noted higher in smokers than non smokers).

 In severe cases, it can progress to lung edema which may have a delayed onset (about 24 to 72 hours) after the exposure.

Treatment:

 There is no antidote

 Treatment of symptoms and lung edema.

 Bronchospasm: Inhalational sympathomatic agents (inhaled beta2-adrenergic antagonist).

 Dermal exposure needs medical attention  frostbite wash with water and do not remove clothes

 Eyes exposure: rinse with water for several minutes.

Answer 16

They are a derivative in which the hydrogen atom in the open chain hydrocarbon is replaced by an halogen element (fluoro, chloro, bromo or iodo derivative)

 Found in: industrial solvents, degreasing agents and cleaning agents.

 It is extremely lipid soluble, more toxic than the non- halogenated compounds. (narcosis, CNS toxicity).

 All halogenated hydrocarbon solvents can cause cardiac arrhythmias, particularly in situations involving sympathetic excitation and norepinephrine release.

 They also cause hepatotoxicity.

 NOTE: Intoxication Phase 1 (Narcosis), Latency period of 1-2 days, Phase 2 (Toxic Hepatitis and Nephrosis).

Monohalogen Methane: very toxic, mainly CNS toxicity

 Bromomethane (Methyl-bromide): Colorless, odorless, nonflammable gas. It was used extensively as a pesticide until being phased out recently. It is manufactured for agriculture and industrial use.

 Chloromethane (Methyl-chloride): colorless, flammable gas with a mildly sweet odor. It was once widely used as a refrigerant but not anymore. The most important use of chloromethane today is as a chemical intermediate in the production of silicone polymers. Inhalation of chloromethane gas produces CNS effects similar to drug intoxication. At high concentrations, paralysis, seizures and coma can result. In case of ingestion, nausea and vomiting may occur. Skin contact, when in the form of a refrigerated liquid may result in frostbite. Contact with the eyes may result in dim vision and widely dilated pupils that react slowly to changes in light. Chronic exposure to chloromethane during pregnancy may cause the fetus lower spinal column, pelvis and leg malformations.

 Iodomethane (Methyl-iodide): is a dense, colorless, volatile liquid, used as a pesticide. High acute toxicity may occur in industrial accidents including metabolic disturbance, renal failure, venous and arterial thrombosis and encephalopathy with seizures and coma, with a characteristic pattern on brain injury. It is also a carcinogenic compound. Symptoms may include eye irritation, nausea,vomiting, dizziness, ataxia, slurred speech and dermatitis.

Answer 17

Tetrachlor-methane, carbon tetrachloride (CCl4):

 Carbon tetrachloride is a colorless liquid with a “sweet” smell.

 It was formerly widely used in fire extinguishers, precursor of

refrigerants, dry cleaning solvents and in lava lamps.

 Exposure to high concentrations of carbon tetrachloride can affect the CNS, degenerate the liver and kidneys.

 Prolonged exposure can lead to coma and death.

 It is one of the most potent hepatotoxins, so much so that it is widely

used in scientific research to evaluate hepatoprotective agents.

 Chronic exposure to carbon tetrachloride can cause liver and kidney damage, as well as result in several parenchymal cancers.

Answer 18

Teflon/Polytetrafluoroethylene (PTFE):

 Teflon is a synthetic fluoropolymer of tetrafluoroethylene.

 It that has numerous applications including: coating of nonstick pans and other cookware, containers and pipework for reactive and corrosive chemicals due to nonreactive properties. Also used as a lubricant in machinery. It is commonly used as a graft material in surgical interventions. It is also frequently employed as coating on catheters; this interferes with the ability of bacteria and other infectious agents to adhere to catheters and cause hospital acquired infections.

 The degradation by-product of teflon can be lethal and can cause flu-like symptoms known as the polymer fume fever.

Answer 19

Dichloromethane (DCM):

 DCM germinal organic compound, colorless, volatile liquid with a moderately sweet aroma.

 DCM is the least toxic of the simple chlorohydrocarbons, but its high volatility makes it an acute inhalational hazard. It can also be absorbed through the skin.

 Symptoms of acute overexposure to dichloromethane via inhalation include difficulty concentrating, dizziness, fatigue, nausea, headaches, numbness, weakness, and irritation of upper respiratory tract and eyes.

 More severe consequences can include suffocation, loss of conciousness, coma and death.

 DCM is also metabolized by the body to carbon monoxide potentially leading to carbon monoxide poisoning.

 Acute exposure by inhalation has resulted in optic neuropathy and hepatitis. Prolonged skin contact can result in skin irritation or chemical burns. DCM crosses the placenta, fetal toxicity in women who are exposed to it during pregnancy can occur.

 In people with pre-existing heart problems, exposure to DCM can cause arrhythmias and/ or heart attacks, sometimes without any other symptoms of overexposure

Answer 20

Trichloromethane (Chloroform):

 Chloroform is a colorless, sweet smelling, dense liquid (Derivative of Teflon). Many kinds of seaweed and fungi produce chloroform.

 Powerful anesthetic, it also used as a recreational drugs as a Euphoriant, anxiolytics and sedative when inhaled or ingested, or in attempt suicide. Chloroform has reputedly been used by criminals to knock out, daze or even murder victims.

 Tendency to cause fatal cardiac arrhythmia, analogous to “ sudden sniffer’s death”. One possible mechanism of action is that it increases movement of potassium ions through certain types of potassium channels in nerve cells.

 Chloroform causes depression of the CNS, Ultimately producing deep coma and respiratory center depression. The mean lethal oral dose for an adult is estimated at about 45g. Following chloroform-induced anesthesia, some patients suffered nausea, vomiting, hyperthermia, jaundice, and coma due to hepatic dysfunction. The hepatotoxicity and nephrotoxicity of chloroform is thought to be due largely to phosgene.