- Sclerocarya caffra Sonder
The plant was listed as irritant by Pammel (1911).
- Semecarpus L.f.
Some 50 species are native to Indo-Malaysia, Micronesia, and the Solomon Islands. The young fruit of most, perhaps all, species yields an irritant resin which can be used as a marking ink. Some of the species are rare and not well studied (Corner 1952). von Reis Altschul (1973) found herbarium notes on two unidentified Semecarpus species, one from Sumatra and one from Borneo, noting that the juice produced itching and burning of the skin.
- Semecarpus anacardium L.f.
- (syns Semecarpus latifolia Pers., Anacardium latifolium Lam., Anacardium officinarum Gaertn., Anacardium orientale auct.)
- Indian Marking Nut Tree, Bhilawa
This East Indian tree is used locally as a source of timber (Hausen 1973). The fruit of the tree is a nut which contains an edible kernel. The pedicel, which swells under the nut to form a false fruit, is also edible when ripe. The pericarp of the nut yields a black tarry oil known as bhilawan oil which, when mixed with lime-water or alum, has been used in India and Malaya as a marking ink. The ink is insoluble in water but soluble in alcohol (Burkill 1935).
Preparations of the nut were used in ancient medicine and still find a place in indigenous medicine. Trade in the bhilawa nut is very ancient, for this fruit was the "golden acorn" of Galen (A.D. 130 - c.200) and Avicenna (d. 1037). It was estimated in 1946 that the crop consisted of about 50,000 tons of nuts containing some 20% bhilawan oil (King 1957).
Marking nuts enter into the composition of some caustic paints for application to warts and piles. The powerful irritant properties of the juice of the pericarp have frequently been made use of by malingerers in producing ophthalmia and skin lesions, and also in procuring abortions (Nadkarni 1976).
Dermatitis occurs in those preparing the oil, or in those applying it to clothing in their capacity as launderymen (called dhobis in India), or in those wearing the marked clothing. The term dhobi itch has been confusingly applied to both marking ink dermatitis and to tinea cruris (a ringworm infection of the groin). Dermatitis may also be caused by contact with the timber (Hausen 1973).
There are two principal patterns of dermatitis (Behl et al. 1966). Those who use nut preparations medicinally may develop dermatitis of the hands and face. If the nuts are ground with a pestle in a mortar held between the knees, the legs and feet may also be affected. The second clinical pattern involves those who wear the marked clothing. Fifty two American soldiers serving in India were affected - about 14% of those exposed (Fitz-Hugh et al. 1943, Livingood et al. 1943). Indians appear to be less susceptible than Americans, but the difference is probably environmental and could be related to the previous exposure of the latter to poison ivy (Toxicodendron Mill. sp.) or of the former to the relatively weaker sensitising potential of the mango (Mangifera indica L.) (Blank 1957). Since the dhobi is accustomed to mark the inside of the shirt collar, brassière, belt, vest, or underpants, the site of the localised dermatitis tends to be the back of the neck or lower back in men, or the mid or lower back in women. As the resin is not destroyed by boiling, the mark may continue to provoke dermatitis for the life of the garment (Fasal 1945). To prevent recurrence, the mark must therefore be cut out or covered with adhesive plaster.
Extensive dermatitis occurred in a girl who accidentally contaminated her skin while marking her brother's clothing with pure bhilawa juice (Behl et al. 1966). Contamination of mail by a bottle of bhilawan oil contained in the sack caused dermatitis in 16 of 50 workers sorting mail (Goldsmith 1943). A laboratory worker cutting sections of the fruit developed severe dermatitis (Fox 1921).
The black corrosive liquid obtained from the pericarp of the nut is also known as bhilawa nut shell liquid, and is analogous in many respects with cashew nut shell liquid (CNSL) from Anacardium occidentale L. It has been shown by Chattopadhyaya & Khare (1969) to contain anacardic acid (probably a mixture of 2-carboxy-3-alkylphenols), but the finer structural details have not been elucidated. The major constituent of the oil is bhilawanol, a mixture of 3-n-pentadec(en)ylcatechols (Rao et al. 1973, Gedam et al. 1974). Also reported are two incompletely identified phenols, perhaps analogous to the cardanol of CNSL, being decarboxylated anacardic acids. One was named semecarpol, and appears to be an undecenylphenol (Pillay & Siddiqui 1931); the other, named anacardol, appears to be a dodecenylphenol (Naidu 1925). There is evidence in the literature that the relative proportions of bhilawanol and anacardic acid vary with the source of the plant material.
As well as having vesicant and allergenic properties, the bhilawanols have cytotoxic activity as demonstrated by their effect on 9KB nasal pharyngeal carcinoma cells in culture (Hembree et al. 1978). Anacardic acid has been shown to have anthelmintic activity (against an unidentified species of earthworm) which compared favourably with the activity of piperazine (Chattopadhyaya & Khare 1969).
Cross-sensitivity to bhilawanol, ether extracts of marking nut tree leaves and branches, and to an ether extract of the bhilawan nut has been observed in persons with a previous history of poison ivy (Toxicodendron Mill. sp.) dermatitis (Howell 1959).
- Semecarpus australiensis Engl.
- Tar Tree, Marking Nut
The black tarry sap causes severe dermatitis (Sulit 1940, Flecker 1945, Francis & Southcott 1967).
- Semecarpus borneensis Merr.
The juice of this plant produces a severe inflammation (Homsey, J.F. - cited by Hou 1978).
- Semecarpus cassuvium Roxb.
The oil has been used by the Amboinese as a varnish. The oily fruit has irritant properties (Burkill 1935).
- Semecarpus cuneiformis Blanco
- (syn. Semecarpus microcarpa Wall.)
This species was described as the most common of the contact poisons of the Philippine Islands; rain dripping off the tree, and the smoke from burning branches produces dermatitis (Burkill 1935). The oil of the pericarp has been used as an escharotic, and the sap produces violent dermatitis (Quisumbing 1951).
- Semecarpus decipiens Merr. & Perry
According to an herbarium note found by von Reis Altschul (1973), "the sap of this tree is very caustic, burning and taking the skin right off". Another note stated that "the bark is macerated and applied to Tinea and eruption of the skin". Both herbarium samples had been collected in the Soloman Islands.
- Semecarpus heterophylla Blume
The resin of this Javanese plant produces severe dermatitis (Burkill 1935). Backer & Haack (1938) isolated renghol, a 3-pentadecenylcatechol, from the vesicant latex of this plant.
- Semecarpus laxiflora Schumann
This species causes dermatitis in Melanesia (Record 1945).
- Semecarpus obscura Thwaites
A methanol extract prepared from the fruits of this Sri Lankan species was found to be rich in 3-alk(en)ylcatechols, including penta-, hepta-, and nonadec(en)yl- homologues. Further structural details were not elucidated because "the vesicatory characteristics of the oil … precluded further study" (Carpenter et al. 1980).
- Semecarpus subpeltata Thwaites
- Semecarpus walkeri Hook.f.
The fruits of these two Sri Lankan species have been found to yield phenolic oils with "vesicatory characteristics" (Carpenter et al. 1980). The nature of the phenolic constituents was not reported.
- Semecarpus travancorica Beddome
- Marking Nut Tree, Bhilawa
The juice can cause dermatitis (Behl et al. 1966). The bark exudate has been found to contain laccol, an incompletely characterised 3-n-heptadecadienylcatechol (Nair et al. 1952b, Puntambekar & Beri 1954).
- Semecarpus venenosa Volkart
This species was reported to cause dermatitis by Iseki (1932).
- Semecarpus vernicifera Hayata & Kawak.
This species provides Formosan lacquer (Hausen 1970). The juice poisons the skin (Kumada 1940).
- Smodingium argutum E.Mey. ex Sonder
- Um-tovane, Tovana
This is the only species of the genus, and is confined to southern Africa. The latex is irritating, contact with the skin resulting in itching, swelling, a rash, and even blistering (Watt & Breyer-Brandwijk 1962). The sap or latex is irritant in high concentrations, but is also a potent sensitiser (Findlay 1963, Whiting 1971, Heyl 1972, Hindson & Oliver 1975).
Urushiols are present in prominent intercellular secretory canals (Ellis 1974). Pruning the plant spatters the sap. It has been alleged that high wind can break the leaves and spray sap droplets on a passer-by who has not even touched the tree. The sap also spreads in a layer on the surface of water, and can produce a sock-like distribution of dermatitis in persons who dangle their feet in contaminated water (Findlay et al. 1974).
The sensitising agent appears to be a mixture of 3-n-heptadec(en)ylcatechols, with traces of pentadecyl- and pentadecenyl- catechols (Eggers 1974, Findlay et al. 1974).
- Spondias L.
There are perhaps 12 species in this genus, being natives of Indo-Malaysia, south-eastern Asia, and tropical America. Four species are extensively cultivated throughout the tropics for their edible fruit known as the hog-plum. All parts of the plants have a foetid, turpentine-like odour when broken or bruised; the smell differs in each species and is characteristic (Corner 1952).
- Spondias mombin L.
- (syn. Spondias purpurea L.)
- Spanish Plum, Mope, Mombin, Jobo
A Nigerian sawyer with mild papular dermatitis showed a strong positive patch test reaction to the sawdust of this species, and weak positive reactions to the sawdust of Pterygota macrocarpa Schumann (fam. Sterculiaceae) and of Terminalia ivorensis A.Chev. (fam. Combretaceae). Control tests were not recorded (Woods & Calnan 1976).
- Spondias pinnata Kurz
- (syn. Spondias mangifera Willd.)
- Indian Hog-Plum, Wild Mango
The tree is cultivated in India for its fleshy fruit which is eaten raw or pickled. The bark of the tree is rubefacient, being used in Indian indigenous medicine for rubbing on the skin over painful joints (Chopra et al. 1958).
- Swintonia Griffith
There are 15 species in south-eastern Asia and western Malaysia. The plants are said to be as poisonous as Melanorrhoea (see Gluta L.) species (Foxworthy 1909), but according to Burgess (1966) the sap is apparently not irritating.
- Swintonia floribunda Griffith
Mucocutaneous reactions from this species in the woodworking industry were reported by Hublet et al. (1972).