Occupational Exposure of Forest Workers to the Urticating Setae of the Pine Processionary Moth Thaumetopoea pityocampa

The larvae of the pine processionary moth are a threat to public health because they produce detachable setae that are about 200 µm long and 6 µm wide, reaching a total number of up to 1 million per mature individual. The setae are intended to be released to protect the larvae from predators but become a public health issue when in contact with humans and warm-blooded animals. Symptoms associated with the setae are typically urticaria and local swelling erythema, although edema of the skin, conjunctivitis or respiratory mucosa may occur. Occupational exposure concerns mainly forest workers but also farmers and gardeners. In the present study, we quantify the exposure to the setae of forest workers in a district of Northern Italy. The pine processionary moth represents a real case of occupational exposure as the urticating setae produced by the larvae caused symptoms in most forest workers directly in contact with the infested trees. In addition, the urticating setae were detected on the body of the chainsaw operators and in the surroundings of the felled trees during the operations. The non-exposed workers of the same agency did not report symptoms, with only one exception, likely linked to a non-occupational exposure. As the risk is not immediately perceived by the workers because direct contact with the larvae is unlikely, a campaign of information to workers and the general population living nearby infested forestry areas about the risk associated with airborne exposure is recommended. This becomes especially important in the areas of recent expansion of the insect, where people are inexperienced.