If we don't act soon, the health effects will persist for generations
Editor's note: This is adapted from a lecture Zoeller gave at the 51st Session of International Seminars on Planetary Emergencies: Science for Peace the World Over, in Erice, Italy, in August. It has been lightly edited.
Chemicals are manufactured for use in almost everything with which humans come into contact including food, plastics, personal care products, clothing and building materials.
In addition, manufactured chemicals contaminate our environment in ways not always anticipated in air, dust, food and water.
Most of these chemicals are derived from crude oil; in fact, petrochemical production is now driving oil demand. This demand for petrochemicals is expected to increase.
It is therefore important to recognize that only a few – and a minuscule percentage – of chemicals with which we come into contact have been tested for human safety.
The cause of chemical exposures to the human population is profit and convenience. If the production and use of chemicals resulting in human exposures were not profitable, they would not be produced and used.
If consumers did not feel that products containing petrochemicals were worth the money, they would not buy them.
A hidden issue is that consumers most often are unaware of the chemicals to which they are being exposed.
Would they think it was worth the money if they knew?
Credit: Edward Cisneros/Unsplash
Every baby born – at least in the developed world – has well more than 100 industrial chemicals in their bloodstream at birth, demonstrating that they are exposed in utero.
In other words, humans are born pre-polluted.
This is a well-known situation among governments, so it is important to ask not only why and how the human population has become exposed to hundreds of chemicals, but also why we allow it to continue.
If a man in a suit were to knock on your door every morning offering a teaspoon of clear liquid to your children, you would certainly decline the offer, even if they said it was "government approved."
So why do we accept it when the exposures are "hidden"?
If chemical exposures are benign, then these questions are not important. However, there is sufficient scientific evidence to conclude that chemical exposures are currently causing harm to the human population, and that their effects profoundly increase health care costs, decrease the quality of life for millions of people, reduce cognitive function and increase the expression of neurobehavioral disorders, and that at least some of these effects can be passed from one generation to the next without further chemical exposure.
These are observations that have been confirmed by many of the world's most credible scientific organizations including the World Health Organization, the United Nations, many medical societies, and international groups of independent health science professionals.
We are, in short, affecting not only individuals and populations, but also human society and its future as we know it.
Why does it continue?
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To begin to understand why we continue to contaminate the human population, it may be useful to break this large question down into more focused questions.
- Why do suppliers of products continue to make products with chemicals for which there is evidence of harm?
- Why do consumers continue to ignore known risks?
- Why do regulators (government agencies charged with public health protection) continue to approve chemicals for which there is evidence of harm?
Within this context, it is germane to emphasize that an important mechanism by which chemical exposures can harm the general population is by interfering with hormones. This is important because hormones control many – if not most – processes of human development and physiology.
In addition, the few chemicals that are evaluated for safety are evaluated by a strategy that is tuned to identify acute toxicity, not endocrine disruption.
We know for certain that a variety of chemicals and chemical classes affect human health by interfering with hormone systems. These include lead, mercury, polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and other flame-retardants, perchlorate, some pesticides, BPA and other estrogenic chemicals.
In general, there are two inter-dependent reasons to explain each of these questions posed above. The first is that governments employ an antiquated discipline that informs us about toxicity and safety. This system is based on the 400 year-old concept that the "dose makes the poison."
The implication of this concept is that everything is toxic at some dose. In this way, arsenic is the same as water – it just takes more water to kill a person than it does arsenic.
This false equivalency supports a regulatory system that calculates the risk of harm to humans exposed to a variety of chemicals from pesticides designed to interact with biological systems to plasticizers, flame-retardants or heavy metals that are used only for their product functionality.
But, what is the harm that risk calculations are designed to prevent? Operationally, those harms, or adverse effects, are defined by the tests employed to evaluate the hazard. Cancer studies identify carcinogens; reproductive studies identify reproductive toxicants; endocrine studies identify endocrine disruptors; immunology studies identify immune toxicants.
These tests are prescribed studies with measurements that have been approved by various committees. However, there is good reason to question both the sensitivity of these measurements to identify hazards, and the degree to which they reflect hazards to the human population.
In addition, hazard identification is only the first step in calculating risks; the potency of the chemical and the exposure of humans to the chemical must then be determined to calculate risk.
A significant issue is that "potency" is a relative measure.
For example, researchers who work for or with industry defined the potency of chemicals that act like the female hormone estrogen by their ability to affect the weight of a rat uterus. This is a standard measure of estrogen activity used by industry and by the government, but there are other, more sensitive measures, such as the ability of estrogen to affect brain development.
Therefore, risk calculations of chemicals that act like the female hormone estrogen (e.g., BPA) are often based on its ability to affect the weight of a rat uterus. The lack of sensitivity of traditional measures of potency of chemicals to interfere with hormones is generalizable across endocrine systems.
In addition, if the measurement (e.g., uterine weight) is not plausibly reflective of a risk of disease or disability in the human population, it is difficult to understand why it is employed other than that it is the traditional measure.
Likewise, estimates of exposures are error prone at best. For example, reports of the effect of perchlorate in drinking water on thyroid function in newborn babies used measures of perchlorate exposure in municipal water supplies in Las Vegas, Nevada (contaminated) compared to Reno, Nevada (not contaminated) as a surrogate measure of exposure.
Perchlorate is known to inhibit thyroid function and thyroid hormone is essential for normal brain development. Therefore, calculating the risks associated with perchlorate exposure has important public health implications. However, more recent studies demonstrate that everyone is exposed to perchlorate, independent of municipal water contamination; therefore, risk estimates were flawed based on these early reports using city of residence as a surrogate for exposure to perchlorate.
A second reason that the status quo of human chemical exposures continues is that financial self-interest motivates campaigns to confuse both the public and regulatory agencies with the goal of limiting or avoiding regulations. The strategies employed, well-documented in a number of legal cases, range from outright fraud and corruption to the selective manipulation of information to make a chemical or product appear safe.
These two categories of explanations for the status quo are not mutually exclusive. The "principle" that the "dose makes the poison" lends itself quite readily to manipulation because it creates a false equivalency between chemicals that are causing harm in the human population and those (e.g., water) that are not. Moreover, it relies on potency as a primary metric, when potency is neither relevant to hazard identification nor an absolute metric.
There are two additional issues: One is that regulatory decisions are made by government agencies in secret collaboration with the industries that manufacture the chemical. It is secret because the data provided to regulatory agencies are proprietary.
However, the people from government and industry involved in these negotiations and decisions are not experts in human health and therefore must necessarily make decisions based on traditional ways of interpreting traditional data.
The second is that there seems to be a general acceptance that petrochemical-based products are required for modern life and that environmental regulations negatively impact market competitiveness.
The concept that petrochemical-based products are required for modern life implies necessarily that we cannot manufacture safer products using bio-based feedstocks and green chemistry. This is a particularly unflattering and pessimistic view of human society and it should be summarily rejected.
The concept that environmental regulations negatively impact market competitiveness has been refuted over and over again by a variety of economic studies.
Thus, when governments overtly move to restrict or eliminate environmental regulations, they are acting neither to protect public or environmental health nor to protect the market. Rather, they are acting to protect the market share of industries currently dominating the market.
In other words, the chemical industry and regulatory system has evolved to maintain itself rather than to protect public health.
Implications of inaction
The consequence of this status quo is becoming increasingly clear. Non-communicable disease now results in more deaths per year than communicable diseases, and these chronic diseases profoundly impact quality of life and the global economy.
The human health effects of exposures to only a few endocrine disruptors for which there is sufficient data alone cost the economy hundreds of billions of dollars per year, not to mention impacting quality of life.
In addition, there is a cultural cost to the status quo of chemical regulations.
A large number of chemicals are known to affect brain development and cognitive function. Loss of IQ as well as increasing the incidence of neurobehavioral disorders in generations of children can have profound effects on society. It is germane here that the U.S. Centers for Disease Control and Prevention has recently reported that the incidence of autism in the U.S. is now 1 in 40 children.
Moreover, there is increasing evidence that the health effects of endocrine disrupting chemicals can be passed from one generation to the next.
What will be required for the status quo to change?
We must first admit that this status quo is not sustainable and is responsible for contributing significantly to human health and global economic challenges. That admission will provide the political will to begin to change this status.
It isn't simply a matter of loving our children more than we love money.
Rather it is a matter of clearly evaluating the system we have created and the price we are paying for its maintenance. It may not be uncommon that human enterprises reach a point where more effort goes into maintaining the status quo than adapting to new data to refine and improve the system.
But we can and should do better, both for our future and for our economy.
Reducing chemical exposure should be considered "low hanging fruit."
Dr. R. Thomas Zoeller, Ph.D., is Professor of Biology at the University of Massachusetts, Amherst. His research focuses on the role of thyroid hormone in brain development and the mechanisms by which environmental endocrine disruptors can interfere with thyroid hormone action in the developing brain.