By Dr Vyvyan Howard
Head of Research, Developmental Toxico-Pathology Research Group
The pressures of safe waste disposal are mounting, as illustrated by IF's latest drama-documentary. Toxico-pathologist Dr Vyvyan Howard argues that the threats to human health from toxic emissions mean incinerators are not an acceptable option.
The past 150 years have seen a significant increase in the toxicity of both domestic and industrial wastes.
Dr Howard: We are leaving a toxic legacy for future generations
The waste stream used to consist mainly of natural products, such as paper, wood and fabrics - neutral wastes which seldom caused problems.
But nowadays, many products include high levels of heavy metals and, in addition, synthetic plastics such as PVC, whose disposal has caused enormous health and environmental problems, plus a toxic legacy for future generations.
IF... THE TOXIC TIMEBOMB GOES OFF
Thursday, 31 March, 2005
Studies of the development of foetuses and young children have led to an understanding of the effects of a number of global environmental pollutants which have their maximal impact during development.
Many of these chemicals are persistent and bio-accumulative, building up in our bodies over time.
Mothers pass these chemicals to their babies, both in the womb and in breast milk.
Some disrupt the action of the hormone systems, affecting babies' development in many different ways.
A number of well-documented effects have been shown to be happening at current environmental levels of dioxins and Polychlorinated biphenyls (PCBs), the best studied of the hormone-disrupting chemicals.
The so-called "background" levels of dioxin-like compounds are almost totally caused by human activities, mainly through combustion of organochlorine products, such as PVC.
Levels of dioxins have been reducing in recent years, but infants still receive many times the dose currently deemed "safe".
Indeed, recent evidence indicates that there may be no safe dose.
As the effects on the foetus occur at extremely low levels, always in combination with many other manufactured chemicals, dioxin levels need to be reduced as low as possible.
The foetus is the stage of life which is the most vulnerable to damage from hormone-disrupting chemicals.
These affect the many ways in which hormones regulate development in the womb and early childhood, with effects which can last throughout life.
These effects can range from an increased likelihood of respiratory problems or allergies, to reduced IQ, less efficient kidneys, reproductive problems or a higher probability of contracting cancer.
Effects on the intelligence, immune status and hormonal status of infants have been related quantitatively to the amount of dioxin-like substance in the mother's body.
Furthermore, many effects, including altered brain function and lung function, appear to persist past the age of seven.
Neurobehavioural and immune system deficits have been shown to be correlated with the level of PCBs and dioxins that infants received from their mothers while in the womb.
Effects on brain development include altered play behaviour as well as general mental and psychomotor development. Other papers also document various reproductive problems.
There is general acceptance that male reproductive health is under threat, and dioxin-like substances have also been related to a reduction in the proportion of male to female births.
It is impossible to accurately cost out the health benefits arising from dioxin reduction, as the potential developmental health effects are so diverse, and can occur in synergy with other chemicals.
It is impossible to calculate the cost to society of, for example, a reduction in IQ levels, or the reduction in quality of life due to foetal kidney growth impairment, immune system or reproductive system, developing less than optimally, causing reduced potential, occasional illness throughout life or a higher risk of cancer.
A precautionary approach would be to reduce human exposure to all chemicals which persist and bioaccumulate or are capable of hormonal disruption, down to the absolutely unavoidable level, especially as mixtures of chemicals may have synergistic effects.
Above, I have cited scientific evidence of harm from just one group of persistent chemicals.
However, we are all exposed to a complex mixture of manufactured toxic chemicals and we have no way of testing the effects of such a cocktail.
Many of the components of this mixture come to us via our food as a secondary consequence of waste disposal.
Even the most modern incinerators still emit some dioxins and similar chemicals. These 'end of pipe' waste disposal solutions simply encourage manufacturers to continue with 'business as usual'.
There are two fundamental approaches to handling waste - either reduce the amount and toxicity of inputs to the waste stream; or attempt to deal with wastes once they have been produced.
Substitution of toxic chemicals in products, is the key to reducing health hazards.
For most of the known hormone-disrupting chemicals, there are substitutes which are less obviously problematic.
In summary, my researches have led me to the firm conclusion that there is no place for incineration in municipal waste management.
Policy should instead concentrate on maximal waste minimisation, reuse and recycling, together with substitution of toxic chemicals in products.
Dr Vyvyan Howard is a contributor to BBC Two's If... The Toxic Timebomb Goes Off, to be broadcast on Thursday, 31 March, 2005, at 1900 BST.