Hormonal effects of Tea tree oil

Tea tree oil may cause abnormal breast enlargement in men and prepubertal children.A 2018 study by the National Institute of Environmental Health Sciences found that four of the chemical constituents (eucalyptol, 4-terpineol, dipentene, and α-terpineol) were endocrine disruptors substances, raising concerns about the potential impact of oil on environmental health.

In animals

In dogs and cats, death or transient signs of toxicity (lasting two to three days) such as lethargy, weakness, incoordination, and muscle tremors have been reported after high topical doses.As an oral ingestion toxicity test, the median lethal dose (LD50) in rats was 1.9–2.4 ml/kg.

Composition and properties 

Tea tree oil, as defined by the international standard ISO 4730 (“Oil of Melaleuca, terpinen-4-ol type”), contains terpinen-4-ol, gamma-terpinene and alpha-terpinene, which constitute 70% to 90% of the total oil, while cymene, terpinolene, alpha-terpineol, and alpha-pinene together account for about 15% of petroleum (right table).The oil is described as colorless to pale yellow and has a clean camphor-like odor.Tea tree oil products contain a variety of phytochemicals, of which terpinen-4-ol is the main component.Adverse effects decreased with lower eucalyptol content.

History and extraction

The name tea tree is used for several plants, mostly from Australia and New Zealand, belonging to the myrtle family and related to the myrtle tree.The use of the name probably stems from Captain James Cook's description of one of the shrubs, which he used to make tea instead of tea.The commercial tea tree oil industry originated in the 1920s when Australian chemist Arthur Penfold investigated the commercial potential of various naturally derived oils; he reported that tea tree oil was promising because of its antiseptic properties.Tea tree oil was originally extracted from the Australian Melaleuca alternifolia, which remains the most commercially important species.In the 1970s and 1980s, commercial plantations began to produce tea tree oil in large quantities from alternifolia trees.Many of these plantations are located in New South Wales.Since the 1970s and 1980s, the industry has expanded to include the extracted oils of several other species: Melaleuca armillaris and Melaleuca styphelioides in Tunisia and Egypt; Melaleuca leucadendra in Egypt, Malaysia and Vietnam; Melaleuca acuminata in Tunisia; Melaleuca ericifolia; and Melaleuca quinquenervia in the United States.Similar oils can also be produced from Melaleuca linariifolia and Melaleuca dissitiflora by hydrodistillation.Although the availability and non-proprietary nature of tea tree oil would make it if proven effective especially suitable for treating a disease like scabies,which disproportionately affects the poor, these same properties would reduce corporate Interest in its development and validation.According to Allied Market Research,"The global tea tree oil market size was valued at USD 38.8 million in 2017 and is expected to reach USD 59.5 million by 2025".