This family of 580 species in 15 genera is of palaeotropical distribution, but is found chiefly in Indomalaysia. They are trees which often dominate humid tropical forests.
As well as being valuable timber trees, several species yield a useful wood oil, balsam, or resin when tapped.
Confusion may arise from the use of the term Philippine red mahogany which is applied commercially in the United States to woods belonging to 3 genera - Shorea Roxb., Parashorea Kurz, and Pentacme A.DC. The timbers may be classified according to heartwood colour:
The species within each group may be shipped interchangeably (Kukachka 1970).
Contact allergy and irritancy to the eyes and respiratory tract has been reported in woodworkers from the wood dust of various species.
The wood dust has been reported to cause dermatitis in woodworkers (Wagenführ 1961, Hausen 1973, Orsler 1973).
Gurjun balsam, otherwise known as East Indian copaiba, is a pathological exudate of the wood of this and other species of Dipterocarpus C.F.Gaertn. It is used as a fragrance raw material but has a history of usage in India for the treatment of certain skin diseases including leprosy (Macdonald 1972). It has not been reported to produce dermatitis (Greenberg & Lester 1954). However, when applied to rabbit skin under occlusion for 24 hours it has been found to be moderately irritating. Neither irritancy nor a sensitising ability could be demonstrated on human skin after application of gurjun balsam at a concentration of 12% in petrolatum (Opdyke 1976, p. 789).
Gurjun oil is prepared by steam distillation of the balsam, and is used as a fragrance raw material. Neither irritancy, allergenicity, nor phototoxicity could be demonstrated with the oil on the skin of mice, rabbits, swine, and man (Opdyke 1976, p. 791, Forbes et al. 1977).
The pulverised kernel of the fruit is rubefacient (Perry & Metzger 1980). This and other species yield Borneo or Sumatra camphor which has rubefacient properties (Ridley 1906, Burkill 1935). Camphors are also obtained from Blumea balsamifera DC. (fam. Compositae) and Cinnamomum camphora J.Presl (fam. Lauraceae).
Contact urticaria and rhinoconjunctivitis occurred in a 33 year old female worker in a caravan building plant from exposure to the sawdust of an unnamed Shorea species known as Philippine red mahogany and lauan. An open patch test with moistened sawdust produced wheals (Göransson 1980). In a series of cases showing skin and mucosal reactions to the wood, patch tests with aqueous extracts of the wood were negative (Oleffe et al. 1975).
Contact dermatitis from an unnamed Shorea species known as meranti was reported by Siregar (1975). Leturque et al. (1973) described a case of a lorry driver who was at first thought to have scabies, but was subsequently shown to be contact sensitive to meranti. These reactions may have been caused by 2,6-dimethoxy-1,4-benzoquinone, a known contact allergen which has been reported to be present in an unidentified species of Shorea known as meranti (Hausen 1978a).
Meranti was listed by Hublet et al. (1972) and by Oleffe et al. (1975a) as a cause of dermatitis in the Belgian timber industry.
Meranti, the timber obtained from Shorea maranti, a species native to Malaysia, has been listed as being known or suspected to be a cause of allergic bronchial asthma or rhinitis (Orsler 1973, Hausen 1970, 1981a). Red meranti is sometimes sold as western red cedar, the term used to describe the timber from Thuja plicata Donn ex D.Don (fam. Cupressaceae).