- Mangifera L.
The 40 species were originally natives of south-eastern Asia and Indomalaysia, but many are now cultivated or have become naturalised in tropical regions throughout the world because of their importance as sources of food and timber.
Inconsistency in the use of trade names is particularly confusing in this genus. The term asam is commonly applied to these timbers; the coloured heartwood present in some species is referred to as figured asam. Unfortunately, the term asam is applied also to timbers derived from members of the family Burseraceae, notably species of Canarium L., Dacryodes Vahl, Santiria Blume, Scutinanthe Thwaites, and Triomma Hook.f.
The identity of material from some Mangifera species is in doubt, as the genus awaits botanical revision (Burgess 1966). The following are grown commercially for timber: Mangifera caesia Jack, Mangifera foetida Lour., Mangifera indica L., Mangifera macrocarpa Blume, Mangifera odorata Griffith, Mangifera pajang Kosterm., and Mangifera quadrifida Jack.
- Mangifera caesia Jack
- (syn. Mangifera verticillata C.B.Rob.)
- Binjai, Malaysian Mango
This species is grown for its timber and to some extent for its fruit, although the foetid odour of the fruit reduces its palatability (Corner 1952).
Eating the fruit may cause dermatitis localised to the angles of the mouth (Simmons & Bolin 1921), or stomatitis, being caused by contamination of the fruit with plant sap. The fruit pulp is innocuous (Fasal 1945).
The sap of the fully grown tree is irritant and has been used for criminal purposes. Raindrops contaminated by bruised foliage may irritate the skin. The smoke from burning foliage or wood is unpleasantly acrid (Burkill 1935) and may cause dermatitis in those exposed to it (Simmons & Bolin 1921, Landor 1943).
- Mangifera indica L.
- Indian Mango, Pauh, Mempelam, Mangga
The mango is extensively cultivated throughout the tropics, and there are a large number of varieties to be found, differing in the quality of their fruit and timber. Varieties do not reliably reproduce their qualities in their seedlings and are therefore propagated vegetatively, often being grafted onto Mangifera foetida rootstock.
The fruit is widely consumed in the tropics, some being exported to temperate regions. Chutneys are made from unripe mangoes; very young leaves and flowers may also be eaten. The leaves are sometimes fed to cattle in times of scarcity.
The timber, sold under the trade name of amba, is used locally for boat building and furniture, but is not exported (Hausen 1973). Another trade name for the timber is aruba, and there are a number of local names in current use: machang (Malaya and Sarawak), sepam (Malaya), mango or mangga (India and Pakistan), xoai (Vietnam), and membatjang (Indonesia).
Allen (1943) noted that the growing plant itself and many of the commercial products derived from it are potential causes of dermatitis; and that handling the green fruits or breaking the branches may result in dermatitis, as may contact with windblown pollen. Morton (1969, 1971) cautioned that the tree is a major cause of widespread respiratory difficulty when in bloom. However, according to Lakhanpal & Nair (1958), mango pollen is not anemophilous.
Contact with the wood or its sawdust may cause dermatitis (Simmons & Bolin 1921). Dermatitis of irregular distribution may occur in children climbing the trees.
The most commonly observed clinical syndrome of mango dermatitis follows peeling and eating the fruit. The face, especially around the mouth, is most severely involved (Nasution et al. 1973), but the irritant may be carried by the fingers to the neck. Some dermatitis of the hands is not unusual (Kirby-Smith 1938). The linear vesicles of poison ivy (Toxicodendron Mill. species) dermatitis are not a feature. Allergenic material is found in stems, leaves, and pericarp (peel), but not in the fruit juice which may be drunk with impunity by sensitised persons (Behl et al. 1966). Zakon (1939) obtained a positive patch test reaction to the peel in one case of facial dermatitis. Goldberg (1954) reported two cases of facial dermatitis that followed peeling and eating mangoes, but patch tests were not carried out. In other cases (Brown & Brown 1941) patch tests were positive to an oil extracted from the peel, but not to the pulp of the fruit. The fruit may be eaten safely by sensitised persons provided all contact with the peel or the stem can be avoided (Keil et al. 1946). During harvesting of the fruit, stem sap may contaminate the peel which then shows bleached, varnished, or blackened patches. This dried sap may cause dermatitis localised to the angles of the mouth (Simmons & Bolin 1921), or stomatitis (Fasal 1945).
A reaction of a different type occurs more rarely. Contact with the peel may cause urticarial whealing (Behl et al. 1966) and asthma (Kahn 1942). Urticaria alone or with shock has been reported after eating mangoes (Lindenbaum 1962, Lindenbaum 1963, Rubin et al. 1965, Dang & Bell 1967).
Dermatitis from the mango occurs wherever this tree is grown. During its fruiting season in Hawaii, it is the predominant cause of dermatitis from plants (Arnold 1972). Mango dermatitis has been reported from the Philippines (Gibson & Concepción 1914, Concepción 1914), from Argentina (Silva 1945), the Dutch West Indies (Tillema 1936), Florida (Blank 1957), as well as from the East Indies and Japan (Asai 1939).
Patch tests carried out using the leaves of the mango crushed in a small quantity of normal saline elicited a positive reaction in 1 of 10 contact dermatitis patients tested in New Delhi, India (Singh et al. 1978).
Mango appears to be a less powerful primary sensitiser than poison ivy (Toxicodendron species). North Americans already sensitised to poison ivy are more likely to develop mango dermatitis than are the inhabitants of mango-growing regions (Blank 1957). Previous clinical or subclinical sensitivity to other anacardiaceous species will also influence the incidence of mango dermatitis. It seems probable that varieties of mango differ in their allergenic potential (Blohm 1962). The evidence for racial as distinct from environmental influences on the incidence of dermatitis is not conclusive.
Although the chemical nature of the allergenic material in mangoes has not been studied, cross-sensitivity has been demonstrated to poison ivy in man (Keil et al. 1946) and to 3-pentadecylcatechol in guinea pigs (Wechsler 1960).
- Mangifera kemanga Blume
Senear (1933), Burkill (1935), and Schwartz et al. (1957) noted that the resin from this species is injurious to the skin of wood cutters.
- Mangifera lagenifera Griffith
The vapour from freshly bruised tissues, the smoke from a bonfire of the leaves, or raindrops from the crown of the tree may affect the skin (Corner 1952).
- Mangifera odorata Griffith
- Kwini, Kwining
Although the fruit is inferior to that of M. indica, this tree is extensively cultivated for its fruit in Malaya because it is more easily grown there.
The sap of the bark is irritant (Burkill 1935) but it is chiefly the sap of the unripe fruit that causes skin reactions (Corner 1952). The fruit, depending on variety, may have a strong turpentine-like smell. Known as sapian mango in Guam, the plant is also reported by Souder (1963) and Ridley (1922) to cause dermatitis.
Hou (1978) believes that Mangifera odorata is of hybrid origin: Mangifera foetida × Mangifera indica. It is very variable and apparently includes many forms of a hybrid swarm.
- Mauria biringo Tul.
This species is said by the natives to be poisonous. The plant can cause dermatitis (Triana 1872).
- Mauria heterophylla Kunth
According to an herbarium note found by von Reis Altschul (1973), this species produces skin eruptions in some persons.
- Mauria puberula Tul.
Cross-sensitivity in humans was observed between this plant, Toxicodendron Mill. species, and Lithraea caustica Hook. & Arn. Experiments in guinea pigs showed that an extract of the tree bark has sensitising properties and that cross-sensitivity to 3-n-pentadecylcatechol occurs (Hurtado et al. 1982, Hurtado 1968).
- Melanochyla Hook.f.
The 12 species are natives of western Malaysia. Together with species from other genera (see Gluta and Parishia), they are often called rengas trees.
- Melanochyla auriculata Hook.f.
- Swamp Rengas, Kerbau Jalang
This uncommon tree is not usually cut because of its irritant sap (Corner 1952, Burgess 1966) which is known to cause dermatitis (Senear 1933, Schwartz et al. 1957).
- Melanochyla beccariana Oliver
- Melanochyla elmeri Merr.
These two species are reported to cause skin reactions (Corner 1952)?.
- Metopium P.Browne
The three species are natives of the West Indies, Florida, and Mexico. The genus was at one time classified in the family Spondiaceae (or Spondiadaceae).
Holiday-makers from British Columbia visiting the Caribbean have developed dermatitis after their return home from contact with Metopium species during their holiday (Mitchell JC 1979 — unpublished observation).
- Metopium brownei Urb.
- (syns Terebinthus brownei Jacq., Bursera gummifera L.)
The timber, known as black poison wood, is used locally for general purposes (Hausen 1973). The sap can cause painful irritation of the skin (Pardo-Castello 1923, Standley 1927, Baumer 1955).
- Metopium toxiferum Krug & Urb.
- (syns Rhus metopium L., Amyris toxifera L.)
- Poison Wood, Black Poison Wood, Poison Bark, Burn Wood, Coral Sumac, Mountain Manchineel, Chechém, Guao de Costa
The tree is widely distributed in Florida (Morton 1971) and in the Caribbean region (Kingsbury 1964).
Both the sap of the plant and its fruit are irritant (Weber 1937, Simons 1953, Usher 1974). According to Morton (1958), contact with any part of the tree, and especially with the clear, sticky sap which turns black on exposure to the air, can produce any degree of dermatitis from a mild rash to large blisters which spread from one part of the body to another. The smoke from the burning wood is as dangerous as the sap (Dahlgren & Standley 1944). The sap of Rhus metopium L. in Jamaica is pale yellow but changes to a deep brown colour on the skin. Lifting and carrying the branches on the shoulders caused vesicular dermatitis of the hands, neck, and shoulders (Grabham 1899). When used in wreaths and bouquets, the plant can cause dermatitis; it may also do so if overhanging branches brush against clothes hanging on a line (Morton 1971). An outbreak of dermatitis occurred among Air Force personnel clearing undergrowth in the Bahamas, and in residents incautiously gathering trees for Christmas (Jackson 1946). In a subsequent clinical investigation involving 20 volunteers, the juice from under the bark, when applied to the skin, produced local vesiculation and erythema. Twelve subjects reacted only locally; one subject developed a generalised spreading rash; six were unaffected. Jackson himself experienced itching a few minutes after application of the bark juice. This developed into a small papule by the next day and superficial ulceration after four days with resolution starting after seven days. The berry juice tested on himself seemed to be more virulent, causing a widespread erythematous vesicular eruption that lasted for several weeks. Lunin (1969) observed patients with dermatitis from Metopium toxiferum in Russia. Brown et al. (1973) also reported contact dermatitis from this species.
The stem yields a resin (doctor's gum, hog gum) which has been used as a violent purgative; the wood has been used to adulterate Quassia amara L. (Usher 1974).
Metopium toxiferum has been reported to contain a mixture of 3-n-pentadec(en)yl and 3-n-heptadec(en)ylcatechols (Gross et al. 1975).
- Oncocarpus vitiensis A.Gray
- (syns Semecarpus atra Vieill., Semecarpus vitiensis Engl.)
- Itchwood Tree
Hitch (1944), referring to Semecarpus atra, and King (1966), referring to Semecarpus vitiensis, state that the irritant milky juice may cause dermatitis. However, Halim et al. (1980) could not detect the presence of urushiols in a chloroform extract of the heartwood of this species.
- Parishia Hook.f.
Twelve species are found in Burma and western Malaysia. The timber from some species, which may be known as rengas (see also Gluta, Melanochyla, and Semecarpus), has been used for fine furniture and ornamental work. It can cause dermatitis (Senear 1933).
- Pentaspadon Hook.f.
The five species occur in Malaysia and the Solomon Islands. According to Corner (1952), the sap of Pentaspadon species in general is not dermatitic and indeed the oil from some species is used in Malaya for treating skin diseases.
- Pentaspadon motleyi Hook.f.
An incompletely characterised 2-carboxy-3-heptadecadienylphenol named pelandjauic acid has been reported from this species (Backer & Haack 1941b).
- Pentaspadon officinalis Holmes
- White Pelong Tree, Pelong, Pelanjau
The oil from the wood consists largely of 2-carboxy-3-heptadecadienylphenol, and is very similar to the oil from P. motleyi (Lamberton 1959b).
According to Burkill (1935), the oleoresin is black and greatly irritant to the skin.
- Pseudosmodingium perniciosum Engl.
This species can produce dermatitis (Von Humboldt et al. 1825). The plant was listed as irritant by Pammel (1911). According to an herbarium note found by von Reis Altschul (1973), the sap and wood are acrid causing skin eruptions.