Dioxin: a toxin for our times

The only surprising thing about the great dioxin scare now surrounding the foot-and-mouth funeral pyres is that it has been so slow to take off.

Though it is doubtful whether more than a handful of people have ever died from dioxin poisoning, it has been a favourite among environmental scaremongers for more than 30 years.

Dioxins – a group of more than 200 chemicals – have been recognised over the past century as by-products of the synthesis of chlorinated organic compounds in various manufacturing processes. They are also produced naturally by forest fires and volcanoes – and by the incineration of industrial and agricultural wastes, such as animal carcasses.

Though environmental pollution with dioxins has been blamed for causing a wide range of diseases, a recent survey concluded that ‘the search for adverse health effects from dioxin has found no unequivocal epidemiological evidence to link dioxin to human cancers, suppression of immune function, or reproductivity, even among workers exposed to somewhat higher concentrations of dioxin’ (1).

Because of their involvement in a number of incidents and controversies over the past 50 years, dioxins have been subjected to the most intensive studies.

• Industrial exposure

As a result of a number of accidents and explosions in the1940s, 50s and 60s, workers involved in the production of chemicals and herbicides were exposed to high levels of dioxins. One death resulted from an explosion in Germany in 1953 and another four deaths may have been caused by dioxins in the Netherlands in 1963. The main symptom attributed to dioxin toxicity was a skin eruption of yellow spots and blackheads, known as chloracne.

Acute intoxication also produced nausea, stomach upsets and muscle pains, fatigue, irritability, insomnia and other nervous disorders. By the late 1960s it became clear that a few members of the dioxin group were highly toxic, particularly if fed in high doses to mice, in which they induced tumours and birth defects. These experiments led one dioxin to acquire the menacing soubriquet of ‘the most toxic man-made chemical known’.

• Agent Orange, Vietnam

In the course of the 1960s the US armed forces sprayed vast quantities of herbicides over the countryside of Vietnam in an attempt to destroy crops and deprive enemy guerrillas of the cover of foliage. They used a range of trichlorophenol herbicides, including one – Agent Orange – which was contaminated with a particularly toxic dioxin. It appears that they were sanguine about using these chemicals because they had been widely used in the USA and abroad over the previous decade, without adverse consequences for human health.

In the context of growing opposition to the Vietnam War in the late 1960s, radical critics of the US government used experimental evidence of dioxin toxicity to demand an end to defoliant spraying (which ceased in 1971). In the course of the 1970s and 80s, Vietnam veterans pursued claims that exposure to dioxins had resulted in diverse illnesses, most seriously malignancies and birth defects in children.

However, extensive laboratory, clinical and epidemiological studies failed to confirm that dioxins had caused these problems. In 1986 Judge Jack Weinstein dismissed outstanding claims on the grounds that ‘all reliable studies of the effect of Agent Orange on members of the class so far published provide no support for plaintiffs’ claims of causation’ (2). He insisted that the data supplied by the claimants rested ‘on surmise and inapposite extrapolations from animal studies and industrial accidents’.

• Seveso, Italy, 1976

In July 1976 an explosion at a chemical plant in Seveso in northern Italy released a toxic cloud containing dioxins, which covered an area of about a square mile and affected a population of more than 30,000. Though Seveso became a cause célèbre for the environmentalist campaign against organochlorine compounds, a recent review of the literature concluded that ‘chloracne (nearly 200 cases with a definite exposure dependence) was the only effect established with certainty’ (3).

Reports of a higher rate of death from heart and chest diseases, a rise in cases of diabetes and an increased rate of certain uncommon cancers were noted, but the authors considered that the ‘results cannot be viewed as conclusive’.

(Though dioxins have never been proved to cause cancer in humans, on 23 April 2001 the BBC website referred to ‘cancer-causing dioxins’ and claimed that dioxins are ‘known to increase the likelihood of cancer’ (4). It also reported claims that dioxins lower sperm counts, cause behavioural problems and increase the incidence of diabetes – complications which have been associated with high-dose occupational exposure, but never confirmed as a result of environmental pollution.)

• Times Beach, Missouri, 1983

In 1983 the small town of Times Beach in the US state of Missouri became the focus of a major scare after the town’s streets were sprayed with oil contaminated with dioxin-laced wastes from a nearby chemical factory (5). Though studies revealed that local dioxin levels were well below the danger threshold and discovered ‘no serious adverse health consequences that [could] be linked to dioxin’, the scare led to the evacuation of the town and the permanent relocation of more than 2000 residents.

Some years later the official responsible for recommending the evacuation admitted that it had been ‘unnecessary’ and an ‘overreaction’. Briefly a national example of the dangers of toxic waste, Times Beach subsequently became a potent symbol of the menace of ‘exaggerated risk models’.

• Holsworthy, Devon, 2001

The UK government estimates that fires during the first six weeks of the foot-and-mouth crisis have released 63g of dioxins into the atmosphere. By comparison, forest fires in Canada every year release 60kg of dioxins into the atmosphere – 1000 times the quantity released by the foot-and-mouth pyres, and more than 10 times the quantity resulting from the Seveso explosion. The health risks to the citizens of the West Country from the burning of sheep and cattle are likely to be less than those arising from the annual burning of incense and other substances at Glastonbury.

As Aaron Wildavsky comments, the tendency to overreact to dioxins loses sight of a simple truth – ‘dioxin itself does serious human damage only at high doses’:

‘The hundreds of millions of dollars spent on scrubbing air, soil and water free of only recently perceptible particles of dioxin could be better utilised. When we add the hundreds of millions of dollars spent on researching insignificant dioxin health effects and the hundreds of millions in costs to companies (and consumers) trying to avoid producing the particles that have these insignificant effects, public health has been harmed. We must not forget the hundreds of millions of dollars paid to people who were not injured, nor the hundreds of millions spent regulating inconsequential exposures. Why expend so many resources in the name of public health with so little to show for it?’

Dr Michael Fitzpatrick is the author of MMR and Autism, Routledge, 2004 (buy this book from Amazon (UK) or Amazon (USA)); and The Tyranny of Health: Doctors and the Regulation of Lifestyle, Routledge, 2000 (buy this book from Amazon UK or Amazon USA). He is also a contributor to Alternative Medicine: Should We Swallow It? Hodder Murray, 2002 (buy this book from Amazon (UK) or Amazon (USA)).

Read on:

Epidemiology uncovered

Foot-and-mouth issue
This account owes much to two critical surveys:
‘The Risks of Dioxin to Human Health’, by Hans E Muller, in What Risk?, by Roger Bate (ed), Butterworth-Heinemann 1997
But Is It True? A Citizen’s Guide to Environmental Health and Safety Issues, by Aaron Wildavsky, Harvard 1995
(1) ‘The Risks of Dioxin to Human Health’, by Hans E Muller, in What Risk?, by Roger Bate (ed), Butterworth-Heinemann 1997, p214
(2) Quoted in But Is It True? A Citizen’s Guide to Envronmental Health and Safety Issues, by Aaron Wildavsky, Harvard 1995, p102
(3) ‘The Seveso Studies on Early- and Long-Term Effects of Dioxin Exposure: A Review’, by Pier Bertazzi et al, in Environmental Health Perspectives, Vol 106, Supplement 2, April 1998
(4) BBC News Online, 23 April
(5) But Is It True? A Citizen’s Guide to Environmental Health and Safety Issues, by Aaron Wildavsky, Harvard 1995, p106-123