Rising exposure to chemicals that disrupt and mimic hormones may present a significant threat to human health, especially that of children in the womb, and to wildlife populations, a new global study of the effect of man-made substances in the environment has concluded.
The study was produced for the World Health Organisation (WHO) and the United Nations Environment Programme (UNEP) by a team of 25 international scientific experts, including Professor Susan Jobling of Brunel’s Institute for the Environment who was also a main editor of the report.
Summarising ten years of work since the last major report on this subject in 2002, the WHO/UNEP study says that the sharp, global rise in many hormonal diseases and disorders over the past half century cannot be solely due to genetic causes. Environmental factors must be involved.
Rapid rise in disease
“Instances of infertility and subfertility, hormone-related cancers of the breast, prostate, testis and thyroid as well as childhood neurodevelopmental disorders have increased too fast and too steeply to be natural phenomena,” said Professor Jobling. “These increases coincide with accelerated industrialisation, involving the release of large numbers of chemicals into the environment. Many of these chemicals are actual or potential endocrine disruptors – substances that can interfere with hormonal functions.”
Of the 143,000 industrial chemicals now in use around the world, around 800 have been shown to be endocrine disruptors. Little is known about the health impact of the rest, but they are nevertheless present in almost everything around us, including furniture, food, cosmetics, clothing, even water and air.
Mixtures may be harmful
“Experimental studies show that exposures to chemicals that are individually safe may be harmful when they are present in a mixture with others,” said Professor Jobling. “What this means is that the cocktails of literally hundreds of endocrine disrupting substances that we are exposed to every day may be key contributors to the rising rates of hormonal diseases and disorders in human populations, as well as to the declining biodiversity of animal species.”
“A key outcome of the research is that irreversible adverse effects of endocrine disruptors are more likely to occur when exposures take place during the very earliest stages of life, in children in the womb. Their organs are still developing, and hormones are critical for normal development during this time.”
Endocrine disruption at this stage may cause health problems both at birth and also many years later in life. Consequently, pregnant women are advised to do what they can to reduce their exposure to endocrine disrupting chemicals.
Better testing needed
The WHO/UNEP study also urges investment in better testing for endocrine disrupting chemicals and more study of their effects, so that governments can make informed decisions about which substances to allow and which to ban outright.
“In the past it has taken anything from 10 to 100 years to get potentially harmful chemicals banned from industry,” said Professor Jobling. “The huge increase in the complexity of our chemical environment over the past ten years means that it may take even longer to decide what is harmful and what is not using current approaches to risk assessment.”
“These approaches must change and our work at the Institute for the Environment is playing a key role in encouraging that change through our collaborations with regulatory bodies and the European Commission.”
“Any sensible approach to the future prevention of hormonal diseases and disorders in humans will require us to know much more about exposures and potential effects of the chemicals that surround us, and to use this knowledge to avoid harm from endocrine disrupting chemicals through our own behaviour and choices. Where exposures are unavoidable, then these substances must be removed from the market or, in the case of newly registered chemicals, caught before they enter commerce.”
Download a full copy of the report
Professor Jobling will be discussing the report and its recommendations on the BBC TV programme “Bang Goes the Theory” on BBC 1 at 7.30pm on Monday 4 March.