Pesticides and Skin Diseases in Man - Pesticides: Evaluation of Environmental Pollution - page 534

Skin symptoms may be accompanied by signs of systemic toxicity. Acnegenic properties
of chlorine compounds become most apparent under regular exposure; therefore, workers
of pesticide factories and pesticide sprayers are at a highest risk. Chloracne was found in
over 80% of the workers involved in the production of pentachlorophenol (Cheng et al. 1993;
Jirasek et al. 1976). A case of severe therapy-resistant chloracne, coexisting with palmoplan-
tar keratoderma and scleroderma, was reported in a man with a lifelong exposure to chlo-
rinated pesticides (Poskitt et al. 1994). Next to the declared content, the assessment of the
acnegenic potential of a pesticide must take into account traces of raw materials, intermedi-
ate compounds, and decay products that are not specified on the label. For example, heating
of chlorophenols in the process of pesticide production leads to the formation of unwanted
chlorodioxins with strong acnegenic properties that may contaminate the final product
(Delvaux et al. 1975). TCDD (2,3,4,8-tetrachlorodibenzo-p-dioxin) is a strong acnegenic
substance, contaminating, as an impurity, the herbicide 2,4,5-trichlorophenol (Hogan and
Tanglertsampan 1992). Acnegenic activity of chloraniline pesticides propanil, 3,4-dichloro-
aniline, and methazole was attributed to their contaminants 3,4,3′,4′-tetrachloroazobenzene
and 3,4,3′,4′-tetrachloroazoxybenzene (Kimbrough 1980). The clinical picture of chloracne
includes straw-colored cysts, comedones, pustules, and abscesses located on the predilection
sites, that is, the cheeks, the ears, the postauricular regions, the genitalia, the chest, and the
back (Li 1986). Chloracne should be differentiated from elastosis with comedones, which is
not uncommon among outdoor workers (Hogan and Tanglertsampan 1992).
16.5.10 Porphyria Cutanea Tarda
Porphyria cutanea tarda (PCT) is the most common form of porphyria, characterized by
cutaneous photosensitivity that causes scarring bullae, hyperpigmentation, excessive hair
growth on the face, sometimes also skin thickening, and hair loss. Porphyrinogens influ-
ence heme synthesis and porphyrin metabolism, which, under heavy exposure, may lead
to clinical symptoms accompanied by elevated porphyrins in the urine (Sciarra et al. 2010).
An outbreak of PCT from 1955 to 1959 in Turkey (“Turkish porphyria”) was caused by eat-
ing wheat seeds that were preserved with hexachlorobenzene (HCB) (Peters et al. 1987).
16.5.11 Pigmentation Disorders
This group includes skin disorders with an abnormal (diminished or excessive) production
of the natural skin dye melanin by melanocytes. Pigmentation disorders (melasma, vitiligo,
and leukoderma) were found in 25% of the Ecuadorean pesticide applicators, as compared
with 10% of unexposed controls (Cole et al. 1997). The putative mechanisms of diminished
melanin production could be either a direct cytotoxic effect on the melanocytes (apoptosis)
or pesticide-induced damage to the sympathetic nerves that control the melanocytes via
chemical synapses, resulting in functional disturbances of melanin production. Furthermore,
hyperpigmentation is a frequent outcome of phototoxic reactions. Postinflammatory hypopig-
mentation that persisted for over 2 years was reported in a pesticide sprayer, whose patches
of depigmented skin emerged at the sites of the previous contact dermatitis to 4-chloro-2-
butynyl N-(3-chlorophenyl) carbamate (Brancaccio and Chamales 1977).
16.5.12 Nail Disorders
Permanent nail dystrophy was described in persons exposed to herbicides and insecticides
( Table 16.1 ). Pesticide-related nail dystrophy may start as a deformity with the breakdown