MAP Technical Reports Series No. 106 UNEP

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Sacchetti, 1983). A Gymnodinium spp. bloom also occurred in the gulf of Olbia (Sardinia) during
the fall 1985. This case of eutrophication may be due to the discharge of untreated sewage into
the gulf. The alga did not produce exotoxins (Sechi et al., 1987).
It is fundamentally important to carry out deeper taxonomic studies for obtaining
evaluation not only of a biological, biochemical, physiological and ecological kind for each
individual species of genus Gymnodinium, but also to consider possible properties that might
prove toxic for man.
7.3.6 Cyanophyta toxins causative agents of respiratory irritation and contact dermatitis
Cyanophyta in the freshwater are the main organisms responsible for eutrophication
effects and for producing toxins (Viviani, 1981; Carmichael and Mahmood, 1984). Esotoxins are
also produced by planktonic bloom forming genera of marine cyanobacteria belonging to the
Oscillatoriaceae family, which poses potential public health problems for the respiratory tract
(Trichodesmium erytraeum) (Sato et al., 1963-64) or cutaneous (Lyngbya majuscula)
symptoms of poisoning (Grauer, 1959). As far as Trichodesmius erytraeum respiratory
symptoms are concerned, these are related to the presence of sea water aerosol containing
fragments of this cyanophita during blooms in coastal waters of Brazil (Sato et al., 1963-64) and
in the Thailand Gulf (Hungspreugs et al., 1989). The filamentous cyanophita L. majuscula that
grows abundantly in many areas of the sub-tropical and tropical Pacific basin and also in
Caribbean, is the causative agent of a severe contact dermatitis that affects swimmers and
bathers at the beaches (Grauer, 1959; Moore, 1984).
7.3.6.1 Chemical structures
The active principle of the blue-green alga L. majuscula have been isolated and
identified as two phenolic bis-lactones, aplysiatoxin and debromoaplysiatoxin (Kato and Scheuer,
1975), and an indole alkaloid, lyngbyatoxin A (Cardellina et al., 1979) (Fig. 27). All of these three
substances have been showed to be potent irritants, producing erythema, blisters and necrosis
when applied to the skin (Solomon and Stoughton, 1978; Cardellina et al., 1979).
7.3.6.2 Human intoxication
A total of 86 cases were reported to the Hawaii State Department of Health. The most
recent major outbreak of this severe contact dermatitis that affects swimmers and bathers at
beaches on the windward side of Oahu occurred in August 1980, at Kailua, Kalama, and Pilapu
beaches. The severe contact dermatitis was described as similar to a burn and generally
involved the genital and perianal areas. The initial symptoms, which appeared after a few hours,
were erythema and a burning sensation, followed by blister formation and deep desquamation
which lasted for several days (Moore, 1984).
7.3.6.3 Toxicology
The mechanism of action at cutaneous and respiratory organs level can be explained
on the basis of knowledges about tumor-promoting properties, in that lyngbyatoxin A,
debromoaplysiatoxin, and aplysiatoxin induce irritation in mouse skin to the same degree as TPA
(Fujiki et al., 1981). Carcinogenesis involves at least two stages, namely initiation and promotion.
The tumor initiation stage is caused by agents that produce damage in DNA. The most well
known promoter is 12-o-tetradecanoylphorbol-13-acetate (TPA), a deterpenoid ester from Croton
oil (Fig. 27). Unlike carcinogens which act directly on the cellular DNA, tumor promoters exert
their effects by binding to receptors.