17 April 1997 Edition
Challenging the hormones
Robert Allen warns of the dangers of chemicals found in everyday use in your kitchen and bathroom
In animals, including humans, the body regulates itself by sending hormones through the blood stream.
Hormones are natural chemicals, present in very low concentrations (measured in parts per trillion), that carry messages to turn on and off many essential bodily processes.
In recent years a large number of studies have shown that vertebrates (animals with a backbone) can mistake some common industrial chemicals for hormones, thus disrupting normal chemical messages.
As a result of hormone disruption, many bodily functions can be turned on or off at the wrong time, resulting in birth defects, cancers, deformed sex organs, sterility, reduced mental capacity, immune system damage and other serious health problems.
Recently the US Environmental Protection Agency (EPA) issued a major new report about hormone-disrupting chemicals and came to the remarkable conclusion that no action is needed to protect public health or the environment from the dangers of such chemicals. Instead, the report said, more study is needed.
To prepare the report, the EPA reviewed 300 scientific studies of hormone disruption. Dr Robert Huggett, EPA's assistant administrator for research, told the New York Times that these 300 studies ``demonstrate that exposure to certain endocrine [hormone] disrupting chemicals can lead to disturbing health effects in animals, including cancer, sterility, and developmental problems.''
With 300 studies indicating serious problems, wouldn't it be reasonable to limit further exposure to these chemicals?
No. Instead, industry and state deem it acceptable to focus on further study.
Yet the assertion that certain chemicals are capable of mimicking sex hormones appears to have been accepted by a large body of the scientific community as the evidence continues to mount up. Man-made chemicals such as organochlorine pesticides (DDT, for example, which was used in large quantities until the 1960s when it was banned or restricted in the western world) head the list of environmental estrogens.
The Danish Environmental Protection Agency, focusing on the work of several scientists studying this problem, identified 27 classes of pesticide in common use as environmental estrogens. Chemicals used in detergents, emulsifiers, wetting agents and dispersing agents in household products and in agricultural and industrial products such as herbicides and paints are responsible for xenoestrogenic behaviour; as are those used as spermicides in contraceptive foams, jellies and creams and in most commerically available plastics, including polyvinyl chloride (PVC) . Chemicals found in food wrapping, tin cans and even some face creams and dental fillings have also come under the microscope. This source of exposure to estrogenic chemicals via food was discovered when Spanish scientists found that bisphenol-A from the inner lining of food cans leaches into many vegetables.
Theo Colborn of the World Wide Fund has theorized that the number of chemicals that can harm reproduction add up to hundreds, if not thousands.
Toxicologists, she has argued, will have to change the way they study the effects of chemicals on human health. It is no longer safe to assume that the dose makes the poison, she said, adding that scientists already know that the body shuts down when it receives an overload of hormone-disrupting chemicals. Thus synthetic chemicals which disrupt the endocrine system are at their most dangerous at low levels.
Around the time that Colborn was promoting her book, Our Stolen Future, Science Magazine, which represents the highly conservative scientific community in the US, published a study which showed that some combinations of hormone-disrupting chemicals are much more powerful than any of the individual chemicals by themselves. Combinations of two or three common pesticides, at low levels that might be found in the environment, are up to 1600 times as powerful as any of the individual pesticides by themselves.
The study showed that one chemical, chlordane, which has no ability to disrupt hormones by itself, nevertheless greatly magnifies the ability of other chemicals to disrupt hormones.
Despite what is now known about hormone-disrupting chemicals, state agencies like the US EPA believe it is not enough even to question their use in society. David LaRoche, the secretary of the Internatonal Joint Commission, has it right: ``The responsibility should not be on the people exposed to chemicals to prove they have been hurt. The responsibility should be on industry to prove that chemicals cause no harm.''
In animals, including humans, the body regulates itself by sending hormones through the blood stream.
Hormones are natural chemicals, present in very low concentrations (measured in parts per trillion), that carry messages to turn on and off many essential bodily processes.
In recent years a large number of studies have shown that vertebrates (animals with a backbone) can mistake some common industrial chemicals for hormones, thus disrupting normal chemical messages.
As a result of hormone disruption, many bodily functions can be turned on or off at the wrong time, resulting in birth defects, cancers, deformed sex organs, sterility, reduced mental capacity, immune system damage and other serious health problems.
Recently the US Environmental Protection Agency (EPA) issued a major new report about hormone-disrupting chemicals and came to the remarkable conclusion that no action is needed to protect public health or the environment from the dangers of such chemicals. Instead, the report said, more study is needed.
To prepare the report, the EPA reviewed 300 scientific studies of hormone disruption. Dr Robert Huggett, EPA's assistant administrator for research, told the New York Times that these 300 studies ``demonstrate that exposure to certain endocrine [hormone] disrupting chemicals can lead to disturbing health effects in animals, including cancer, sterility, and developmental problems.''
With 300 studies indicating serious problems, wouldn't it be reasonable to limit further exposure to these chemicals?
No. Instead, industry and state deem it acceptable to focus on further study.
Yet the assertion that certain chemicals are capable of mimicking sex hormones appears to have been accepted by a large body of the scientific community as the evidence continues to mount up. Man-made chemicals such as organochlorine pesticides (DDT, for example, which was used in large quantities until the 1960s when it was banned or restricted in the western world) head the list of environmental estrogens.
The Danish Environmental Protection Agency, focusing on the work of several scientists studying this problem, identified 27 classes of pesticide in common use as environmental estrogens. Chemicals used in detergents, emulsifiers, wetting agents and dispersing agents in household products and in agricultural and industrial products such as herbicides and paints are responsible for xenoestrogenic behaviour; as are those used as spermicides in contraceptive foams, jellies and creams and in most commerically available plastics, including polyvinyl chloride (PVC) . Chemicals found in food wrapping, tin cans and even some face creams and dental fillings have also come under the microscope. This source of exposure to estrogenic chemicals via food was discovered when Spanish scientists found that bisphenol-A from the inner lining of food cans leaches into many vegetables.
Theo Colborn of the World Wide Fund has theorized that the number of chemicals that can harm reproduction add up to hundreds, if not thousands.
Toxicologists, she has argued, will have to change the way they study the effects of chemicals on human health. It is no longer safe to assume that the dose makes the poison, she said, adding that scientists already know that the body shuts down when it receives an overload of hormone-disrupting chemicals. Thus synthetic chemicals which disrupt the endocrine system are at their most dangerous at low levels.
Around the time that Colborn was promoting her book, Our Stolen Future, Science Magazine, which represents the highly conservative scientific community in the US, published a study which showed that some combinations of hormone-disrupting chemicals are much more powerful than any of the individual chemicals by themselves. Combinations of two or three common pesticides, at low levels that might be found in the environment, are up to 1600 times as powerful as any of the individual pesticides by themselves.
The study showed that one chemical, chlordane, which has no ability to disrupt hormones by itself, nevertheless greatly magnifies the ability of other chemicals to disrupt hormones.
Despite what is now known about hormone-disrupting chemicals, state agencies like the US EPA believe it is not enough even to question their use in society. David LaRoche, the secretary of the Internatonal Joint Commission, has it right: ``The responsibility should not be on the people exposed to chemicals to prove they have been hurt. The responsibility should be on industry to prove that chemicals cause no harm.''