Certain chemical burns require a little extra thought than just irrigation and good wound care – which may even be contraindicated. An article in The Journal of Emergency Medicine addresses these, and some of the points are summarised below, with some additional information from Toxbase:
Hot tar (bitumen)

• Immerse contaminated area in cool water until the bitumen has hardened and cooled.
• Adherent material may be left in place to avoid causing further injury by removal attempts, and will spontaneously detach after a few days.
• If a finger or limb is completely surrounded, split the bitumen to prevent a tourniquet effect.
• To remove bitumen, apply a lipid or polysorbate based agent and a clean non-adherent dressing. Suitable products include melted butter, sunflower oil, liquid paraffin, and petroleum or polysorbate based antibiotic ointments. Solvents such as alcohol, acetone, kerosene, ether or gasoline are not suitable.
• Change the dressing frequently, and reapply the product as necessary, until the bitumen is completely removed. This may take up to 72 hours.
• Treat as a thermal burn.

Elemental sodium

• – utilised in the manufacturing of methamphetamine.
• will spontaneously ignite above 115°C
• Contact with water releases sodium hydroxide and hydrogen gas. It is the heat released in the reaction with the water in air that then ignites locally produced hydrogen gas.
• Burns involving the metallic forms of sodium, potassium, and lithium (alkali metals) produce both thermal and chemical injury to the tissue. The thermal tissue damage is due to the extreme exothermic reaction that metallic sodium undergoes when exposed to water.
• At times, water, when mixed with either elemental sodium or potassium, undergoes an explosive reaction.
• Avoid water irrigation; if metal is still present in the tissues, the added water could ignite it.
• All clothing should first be removed from the victim. If retained metal exists, the affected area should be covered in mineral oil. Removal of embedded sodium should then be undertaken with forceps.
• Mineral oil is a practical, and potentially safer, alternative to isopropyl alcohol for the storage of elemental sodium.

Chromic acid

• – a corrosive, oxidizing acid. After skin has been exposed to chromium, burns covering as little as 10% of body surface area (BSA) have proven fatal.
• Burns involving as little as 1% of total BSA have resulted in acute renal failure.
• Wash thoroughly with copious amounts of water and treat as a thermal burn.
• Application of 10% ascorbic acid solution at least three times per day may improve the rate of healing
• Prompt excision of burned, contaminated areas is recommended to prevent absorption of the chemical.

White phosphorus

• – will ignite spontaneously in 30°C air temperature; typically stored in water.
• burns of > 10% can have associated mortality.
• Three stages of systemic toxicity exist: (1) gastrointestinal symptoms (nausea, vomiting and “smoking stool”). Symptoms of headache, seizures, and coma, as well as the potential for cardiovascular collapse, may occur in the initial phase. Decreasing serum calcium concentrations; (2) symptom-free period; (3) (4 to 8 days post-exposure) neurological toxicity, bleeding diathesis, hepatic failure, renal failure, and shock.
• Continuous coverage with water will protect both the patient and staff from ignition and fumes that result from white phosphorus’s contact with air.
• Brushing particulate not incorporated in wounds can accomplish a significant amount of decontamination. This brushing should be followed by continuous irrigation until all particles are removed. Those debriding and decontaminating an exposed patient should have a safe method of disposing of particles: a container of cold water would suffice.
• A way to identify phosphorous particles for removal is the use of a Wood’s lamp, which will cause the white phosphorous to fluoresce.
• Excision may be necessary to remove the chemical if deeply entrenched in fascia.

Phenol

• – a corrosive aromatic hydrocarbon that can be absorbed at toxic levels through all routes of absorption
• causes extensive denaturisation of tissue proteins, producing an eschar with shallow ulcers
• Rescue personnel should use butyl rubber gloves and aprons, and conduct decontamination in a well-ventilated area.
• wipe exposed areas immediately with low-molecular-weight polytheylene glycol (PEG 300 or 400)
• however Toxbase states: “The use of solvents (such as glycerol, polyethylene glycol and isopropanol) has been suggested. One (animal) study (Hunter et al, 1992) indicated that isopropanol was more effective than water, but there is no evidence in humans that solvents are more effective than washing with copious amounts of water.”
• if the burn covers a large skin area, high pressure shower irrigation before PEG application is preferable
• Any water applied must be applied in high pressure, as small amounts might dilute the phenol present on the skin and thus expand not only the involved area but also the amount of phenol absorbed.

Hydrofluoric acid

• HF is highly corrosive and causes damage by two mechanisms. It produces a corrosive burn from the high concentration of hydrogen ions. It also penetrates tissues due to the lipophilic nature of fluoride, and causes liquefactive necrosis.
• Tissue penetration leads to systemic reactions with effects on the cardiac, respiratory, nervous, and gastrointestinal systems. The fluoride ion precipitates calcium, leading to hypocalcemia, and may interfere with enzyme systems by binding magnesium and manganese, as well as important nerve conduction functions that depend on calcium.
• Copious irrigation of HF-burned skin with water should begin immediately. Most HF burns will respond well to this.
• Pain that persists after irrigation is a marker that the fluoride ion needs detoxification. This can be accomplished through superficial topical treatment, infiltrative treatment, or intra-arterial treatment.
• The preferred topical agent is calcium gluconate gel.

Special considerations in hazardous materials burns.
J Emerg Med. 2010 Nov;39(5):544-53