Nerolina Australian Essential Oil (Melaleuca quinquenervia)

Key constituents

1,8-Cineole 55.0–65.0%

a-Pinene 7.0–12.0%

(þ)-Limonene 6.0–12.0%

a-Terpineol 4.0–10.0%

b-Pinene 1.5–4.5%

Viridiflorol 1.0–3.5%

b-Caryophyllene tr–2.0%

b-Myrcene tr–2.0%

Quality  A very high 1,8-cineole content may indicate adulteration with eucalyptus oil. ‘Modified’ eucalyptus oil is commonly used as a substitute for niaouli oil. Kerosene or fatty acids are occasionally used as adulterants.

Safety summary
Hazards  Essential oils high in 1,8-cineole can cause CNS and breathing problems in young children.
Contraindications  Do not apply to or near the face of infants or children.

Regulatory guidelines
The German Commission E Monograph for Nerolina oil recommends a daily oral dose of 300–600 mg, and 50–20% for dermal applications. It also contraindicates internal use in cases of inflammatory diseases of the GI tract and bile ducts, and in severe liver disease.

Organ-specific effects
Adverse skin reactions  No information found. 1,8-Cineole is not a high-risk skin irritant or allergen.
Reproductive toxicity  Nerolina oil was both maternally toxic and fetotoxic when injected ip to pregnant rats
for 18 days at 1,350 mg/kg/day.

Signs of maternal toxicity included  low relative weight, higher mortality, and increased weight of both liver and kidneys.

Signs of fetotoxicity included  low number of surviving fetuses, high rate of fetal resorption, low birth weight and low placental weight. Since the dose used is equivalent to injecting 94.5 g of essential oil into the abdomen of a pregnant woman every day for 18 days, this information has no bearing on the real world use of essential oils. The low reproductive toxicity of eucalyptus oil, a-pinene and (þ)-limonene suggests that niaouli oil cineole CT is not hazardous in pregnancy.

Systemic effects
Acute toxicity  No information found. 1,8-Cineole has been reported to cause serious poisoning in young children when accidentally instilled into the nose.
Carcinogenic/anticarcinogenic potential  No information was found for Nerolina oil (cineole CT). It contains no known carcinogens.

Comments
We are not aware of any research that would support the Commission E contraindications which are presumably based on the 1,8-cineole content, since they are also applied to some eucalyptus oils. Oral 1,8-cineole was not hepatotoxic in rats at doses of up to 800 mg/kg/day for three days, and a single dose of 400 mg/kg significantly protected against  chemically induced hepatotoxicity in mice. At 100 mg/kg/day for 60 days, gavage doses of 1,8-cineole protected rat liver from chemically induced oxidative stress. Pre-treatment with 1,8-cineole by rectal instillation at 200 or 400 mg/kg attenuated TNBS-induced colonic damage in rats, and there are many other papers showing an anti-inflammatory action for 1,8-cineole. Most of the research showing anti-hepatotoxic and anti-inflammatory effects
for 1,8-cineole has been published since the Commission E contraindications for niaouli oil were written. We suggest they now need revision. The only dose used in the fetotoxic study is equivalent to 85 mL being injected into a human adult; over 18 days the total dose would be over 1.5 kg. Nothing useful can be extrapolated from the outcomes of such massive dosing. The German Commission E Monograph for niaouli recommends a daily oral dose of 200–2,000 mg for niaouli oil. However, the higher range may be unsafe, considering the toxicity of eucalyptus oil in humans. This chemotype of M.  quinquenervia is the one normally referred to as ‘niaouli oil’, though the other three (below) are also commercially available.