Pyrethrine or Pyrethroid Exposure


H. Müller-Mohnssen
Munich, Germany

Since 1988 it was observed in Germany that there has been a considerable increase in reports of illness with inability to work in crew members of long distance flights. Though the clinical pictures of illness exhibit resemblance for different patients, the symptoms that lead to inability to fly are different as follows:

I). Mucocutaneous alterations: Conjunctivitis, alopecia, disfiguring weeping eczema of uncovered skin which flares up after in-flight spray missions, after entering the aircraft or hotel.

II). Cerebro-organic disorders: decrease of intellectual performance, increasing loss of memory, mixup of words, word finding difficulties, narcoleptic attacks alternating enhanced arousal and agitation. Abrupt nausea is observed followed by black out with collapse from seconds up to minutes (person falls down the stairs or, while car driving, wakes up when the car has come to standstill off the road), sudden attacks of clouding of consciousness with complete loss of orientation for 30 to 60 min (persons being at a familiar place suddenly does not know where they are).

III). Movement disturbances: walking “like on cotton”, problems with correct estimation of distances (walking into door frames or missing stair steps). Clumsy while serving (when pouring the coffee, missing the cup and spattering the passenger).

IV). Suspicion of autoimmune diseases: multiple sclerosis, collagenosis, thrombocytopenia. In 80% of the patients, the fitness to practice another occupation was obtained one year after termination of flying activity.

As a cause of the illness to the flight crew members, the occupational stress was considered arising from:

1.) Enhanced psychophysical strain due to irregular way of life, lack of sleep, jet lag, temperature jump, loss of social contacts;

2). Cosmic radiation;

3). Insecticide exposure in aircraft and hotels.

The diagram demonstrates the latency period, i.e. the time interval from the beginning of the employment on long distance flights till the complaints exceed the threshold of perception (n=65). Ordinate: year, Abscissa: number of person sorted according to start of flying. Each person is represented by two vertically arranged marks; circles: beginning of occupation on long distance aircraft, filled squares: onset of illness. If the unavoidable components of stress (1 and 2) would cause the illness, the latency should be almost constant, i.e., the upper dotted line should run parallel to the lower. The results show, however, that the illness begins independently from the date of employment at a fixed date around 1992. Obviously there is no causal relation of illness with the stress components 1 and 2 but with a component firstly appearing between 1960 and 1992. The time span of 4 years between the introduction of pyrethroids for aircraft disinfection (1988) and outbreak of illness in the air crew members corresponds to the latency of 4,7 (±2,5) years of chronic pyrethrine/pyrethroid intoxication after indoor disinfection.

The symptoms leading to inability to work depend on which of the three clinical phenotypes of pyrethroid-intoxication is expressed in the particular patient. In the majority of air crew members the I-(immunmodulatory-) type was found.

Muller-Mohnssen, H., Hahn, K. (1995): About a method of early recognition of neurotoxic diseases (Exemplified by Pyrethroid intoxication) in German, Gesundheitswesen 57, 214-222.
Muller-Mohnssen, H. (1999): Chronic sequelae and irreversible injuries following acute pyrethroid intoxication. Toxicological letters, 107, 161-175 (further references).