Flumethrin. Article: Physiological causes of OP [Organophosphate] poisoning? PEX Newsletter, No. 3, June 1999.

FLUORIDE ACTION NETWORK PESTICIDE PROJECT

Flumethrine. Article: Physiological causes of OP [Organophosphate poisoning]?

• As published in PEX Newsletter No.3, June 1999

from: http://www.pan-uk.org/pex/pexartilces/op~physi.htm

Physiological causes of OP poisoning?

OP campaigner Helen Fullerton believes that sensitisation is the characteristic marker of the OP poisoning syndrome. Her paper Sensitisation: clue to the pathology pathway of chronic organophosphate poisoning is available from the Pesticides Trust. In it she describes how the inhalation of OPs is a neglected hazard, and concludes that the potentiation effects of pyrethroid toxicity by OPs are highly dangerous. People are still victims of a persistent lack of medical knowledge about OP effects, and some of their cases are summarised below.

Ill-effects of gallanthamine on OP-sensitised
Case 1 Chronic Fatigue Syndrome patients are sometimes treated with gallanthamine to relieve muscular pains, stiffness, and certain neurobehavioural symptoms. But a farmer's son with a history of exposure to OPs was recruited to a trial of the drug. His depression increased and he committed suicide (Radio 4, Farming Today, 9 January 1998).

Ill-effects of suxamethonium on OP-sensitised
Case 2 A sheep-farmer who had dipped for years with no symptoms of dippers' flu, and who retired a fit and active man in 1994, developed joint and back pain after a hip operation. He became permanently drowsy, sometimes confused. He suffered myoclonus, loss of grip, and sudden temperature rises lasting one or two days, usually accompanied by a rash. His first convulsive fit was in September 1995. He was very ill when the dog was flea-sprayed. When his family and his GP learnt that the anaesthetic adjuvant suxamethonium potentiates OP poisoning everything fell into place. Despite the fact that the interaction between suxamethonium and acetyl cholinesterase inhibitors is well-known to anaesthetists, noone had thought to ask if he was a sheep-farmer with a history of OP exposure.

Potentiation of pyrethroid toxicity by OPs

Case 3 In Professor Behan's trial investigating the effect of pyridostigmine on farmers and workers chronically ill from exposures to OPs, the researchers did not realise that the dip to which patient 2 had been exposed to for at least three years was sheep Cypor 'spot on', a cypermethrin pyrethroid. His symptoms matched those of the OP-exposed and were in the top rank of severity: fatigue 4+, myalgia 4+, attacks of sweating 4+, depression 3+. Since he had had the illness for five years, it can be assumed he switched from OPs to cypermethrin. Hence either his chronic OP toxicity had lost none of its severity, or the cypermethrin toxicity was potentiated by the previous two and unrecorded earlier years of OP exposure.

Case 4 A fit farmer became ill after dipping with the pyrethroid flumethrine. He had extensive urticaria, abdominal pain, vomiting, malaise and generalised muscle ache that developed into acute, though temporary polyarthralgia. He had never before been exposed to pyrethroids and previously had only used OPs, to which he may have become sub-clinically sensitised, potentiating the pyrethroid toxicity.

Case 5 A 58 year-old man was referred to a psychiatrist after an 18 month history of Chronic Fatigue Syndrome and depression. He reported that his symptoms developed one August after he had been using a pour-on insecticide containing 1 per cent of the pyrethroid deltamethrin. He said he was a 'changed man, anxious and irritable'. Four years after this initial referral he was no longer lethargic but still anxious, irritable and indecisive, 'not the bright, joking, social person I used to be'.

Case 6 Cone and Sult (1992) described a group of casino workers exposed to a mixture of carbamate and pyrethrin insecticides who subsequently devloped chronic multi-system symptoms cognitive difficultires, and sensitivity to the odour of pesticides, perfumes, gasoline, newsprint and cleaning agents.

Case 7 A sheep farmer who has suffered chronic OP poisoning since 1987 has paralysis in the flexor muscles of his left foot, and in all his intercostal muscles, so he can only breathe from his diaphragm. OPs have made him asthmatic and he cannot go near OP-dipped sheep without gasping. He has not dipped with OPs since he deduced the cause of his illness in 1991. From 1994 to 1996 a contractor dipped his sheep with Bayticol, a long-acting flumethrin pyrethroid. In contrast to OPs which the farmer can sense for up to a month, the pyrethroid does not stay more than 48 hours on the wool, so that after dipping, he can work with his sheep. In 1997, he dipped them himself, using Crovect, a cis-cypermethrin dip. He wore a respiratory mask, but it still gave him a severe headache and made him sweat. He did not use the dip for 8 months, but in September 1998 he cleaned out the Crovect. The next day he was dizzy, uncoordinated, and unable to keep to his feet. He had pains in his forearms and hands, prickling in the skin of his right thigh followed by loss of feeling. No doubt his careful note-taking would be classed by some as hypochondria and dismissed as a symptom of anxiety, instead of being valued as more evidence of OP sensitisation potentiating a pyrethroid poisoning that would not otherwise have occurred.

Case 8 A nurse whose workplace was sprayed weekly for cockroaches, at night, when windows and doors were kept closed for safety, developed symtoms of poisoning in 1988. She experienced lachrymation, headaches, dizziness, ataxia, muscle pains, asthmatic wheezing and airway obstruction, temporary numbness and paralysis and 'personality changes'. But her request for information about what was sprayed was met with blank refusal. The hospital eventually disclosed it (at the requirement of Guy's Hospital National Poisons Unit) after a sit-in with media support. Pyrethroids had been alternated with OPs coroxon and primiphosmethyl. Although Guys declined to treat the nurse, she eventually gained funding for treatment at the Breakspear hospital.

[As published in PEX Newsletter No.3, June 1999]