THE CHALLENGE

A good place to start in understanding the challenge facing the country is to get a sense of just how many chemicals are produced and used in society. To offer some historical context, Goldman quoted Paracelsus, the 16th-century Swiss-German physician, botanist, and alchemist who is credited with founding the science of toxicology. Listing the chemicals present in commerce nearly 500 years ago, Paracelsus wrote:

What, then, shall we say about the receipts of Alchemy, and about the diversity of its vessels and instruments? These are furnaces, glasses, jars, waters, oils, limes, sulphurs, salts, salt-petres, alums, vitriols, chrysocollae, copper-greens, atraments, auri-pigments, fel vitri, ceruse, red earth, thucia, wax, lutum sapientiae, pounded glass, verdigris, soot, crocus of Mars, soap, crystal, arsenic, antimony, minium, elixir, lazarium, gold-leaf, salt-nitre, sal ammoniac, calamine stone, magnesia, bolus armenus, and many other things. Moreover, concerning preparations, putrefactions, digestions, probations, solutions, cementings, filtrations, reverberations, calcinations, graduations, rectifications, amalgamations, purgations, etc., with these alchemical books are crammed. Then, again, concerning herbs, roots, seeds, woods, stones, animals worms, bone dust, snail shells, other shells, and pitch. (Paracelsus, 1531)

“It was a fairly short list of chemicals,” Goldman noted. “They lived in a world where most human needs, material needs, were met by the natural world through wood, metals, and other resources that were extracted from the natural environment. Today, we live in a very different world, where nearly everything in this room is in some way derived from industrial chemicals.”

The volume of chemicals in commerce increased a great deal during the 20th century, she noted. In just the 25 years between 1970 and 1995, the volume of synthetic organic chemicals produced tripled, from about 50 million tons to approximately 150 million tons (see Figure 2-1) (Goldman, 2002). And today it is much more, she noted.

FIGURE 2-1

Volume of chemicals in commerce: U.S. synthetic organic chemical production, 1966–1994. SOURCE: Adapted from Goldman, 2002. Copyright © 2002, Environmental Law Institute^®, Washington, DC. Reprinted with permission.

Richard Denison, Senior Scientist at the Environmental Defense Fund, also spoke about the increase in chemical use. “Clearly, there has been a strong upward trend in just the sheer volume of chemicals being produced,” he said. According to one estimate, global sale of chemicals has increased by a factor of about 25 since 1970, from $171 billion to $4.1 trillion (UNEP, 2013). Over the next few decades, he added, the rate of increase in the volume of chemicals used worldwide is expected to continue, or even accelerate (UNEP, 2013), and it will dramatically outpace the increase in population (see Figure 2-2) (Wilson et al., 2008).

FIGURE 2-2

Projected growth in worldwide chemical production and global population through 2050. SOURCE: Wilson and Schwarzman, 2009. Reprinted with permission.

The other thing that has changed, Denison said, is the diversity of use of chemicals, especially in consumer products and building materials, with manufactured substances replacing natural materials. One estimate is that chemicals are used in 96 percent of manufactured materials and products (ACC, 2014).

THE PUBLIC HEALTH APPROACH TO INDUSTRIAL CHEMICAL ASSESSMENTS

Given the presence of so many chemicals that humans may be exposed to, a natural question is how best to ensure human health in the face of these chemicals. William E. Halperin, Chair of the Department of Preventive Medicine at the New Jersey Medical School, described how the field of public health approaches industrial chemicals and industrial chemical assessment.

There is actually no single “public health approach,” Halperin said. Instead, public health resembles the proverbial elephant examined by a group of blind men—it can seem to be a rope (the tail), a wall (the side), a pillar (the leg), a tree branch (the trunk), a fan (the ear), and so on, depending on exactly which part is being examined. So, Halperin said, he would illustrate the public health approach to chemicals by describing five different paradigms that could be used in dealing with such chemicals: the industrial hygiene approach, prevention, surveillance, embeddedness, and dose response.

The first paradigm—the traditional public health approach—is one of anticipation, recognition, evaluation, intervention, and effectiveness. “This is what is taught in industrial hygiene,” Halperin said. Anticipation is easy to understand, he said: If you combine a micro-car, a teenage driver, and high speed on a highway, you have to anticipate the problem that you are going to run into.

Sometimes it is not possible to anticipate an issue; in those cases one must recognize it when it appears. Halperin mentioned the case of Ramazzini, who was quoted in about 1710 saying something to the effect of, “I have never visited a nunnery that has escaped the scourges of breast cancer. There must be a connection between the breast and the uterus which escapes the detection of the prossectors [i.e., dissectors].” Ramazzini, who is considered the father of occupational medicine, invented occupational epidemiology in that observation that delayed childbirth put a woman at greater risk of certain adverse effects. Although it was not possible at the time to explain Ramazzini's observation, still it was a classic example of recognition.

Evaluation is somewhat different from recognition. To illustrate, Halperin pointed out that there have been many toxicological studies showing that TCDD (2,3,7,8-tetrachlorodibenzodioxin) is associated with adverse effects. That was recognition. “The evaluation came in the 1980s with NIOSH [the National Institute for Occupational Safety and Health] doing a cohort mortality study of about 6,000 workers highly exposed to dioxin in various occupational situations,” which made it possible to then identify the adverse effects associated with TCDD exposure.

Intervention is a product of education, engineering, and regulation, he said, and effectiveness refers to the process of observing whether the steps taken during the intervention were actually effective. “This is the industrial hygiene approach. It is a good broad approach that helps us work on issues of recognition and of hazards.”

To illustrate the other paradigms he would be talking about, Halperin began with an anecdote concerning ortho-toluidine, an organic compound used in the production of dyes. Aniline-based dyes such as benzidine have long been known to be carcinogenic. In the 1970s, Halperin said, bioassays suggested that toluidine was actually much more carcinogenic than aniline and that toluidine was associated with bladder cancer in animals. Furthermore, there were a few studies in the 1970s that demonstrated that aniline was not associated with bladder cancer, but that mixed exposures of the aniline-based dyes were.

There were two different groups exposed to toluidine. The first consisted of workers exposed to the chemical in the workplace; the National Occupational Survey in the early 1980s estimated that about 30,000 workers received this occupational exposure. The second group consists of those people exposed to the toluidine found in cigarette smoke, which amounted to tens of millions of people whose exposure was at a much lower level than the workers. Given these occupational and environmental exposures to something that was a known carcinogen in animal studies, there was a reasonable expectation that there would be a resulting health effect.

“That brings us to 1988 when Steve Markowitz, who was an occupational physician working with the Oil, Chemical, and Atomic Workers Union, visited a plant in upstate New York to give a general talk on occupational health,” Halperin said. “Workers approached him and asked, Is it meaningful that seven of our cohort have bladder cancer?” The result was that NIOSH was brought in to perform a hazard evaluation. “I was there,” Halperin said. “I was on the walk-through.” The NIOSH team found signs warning of a suspected carcinogen. “There were literally signs saying there was a suspected carcinogen and that there may well be a problem associated with this plant.” The team found out that the suspected carcinogen was toluidine.

After performing an incidence study, the team found that people who had been exposed for 10 years had a risk of developing bladder cancer that was 30 times greater than the general population. There really was a problem.

The effect of all of this work was that ortho-toluidine is now accepted as carcinogenic. And this, Halperin said, is in reality the way that public health has traditionally approached chemicals. The approach is reactive. “We react to observations by astute observers, whether it is Ramazzini or a group of workers at a chemical plant in northern New York State, that there is a problem. We react rather than systematically investigate.”

With that example as a touchstone, Halperin described the four other paradigms. The second is the preventive medicine approach, which can be thought of as consisting of primary, secondary, and tertiary prevention. Primary prevention refers to action taken before there is an exposure, he explained. “It is premarket testing so that something doesn't ever get to the workplace. It is substitution or elimination. It is environmental controls. It is personal protective devices. It is all of those kinds of things.”

Secondary prevention refers solely to routine periodic screening with the goal of detecting a disease early while it is easier to treat. And tertiary prevention refers to the range of medical care and health care used to respond to a disease once it appears, from drug treatments and surgery to rehabilitation and accommodation. Tertiary prevention has grown immensely in importance over the past 10 years, Halperin said, largely because of the observations of the Institute of Medicine about the number of people who die because of lack of medical care (IOM, 2002, 2003).

In the example of ortho-toluidine, primary prevention would include such things as premarket testing, substitution or elimination, environmental monitoring, environmental controls, and biologic monitoring. “All of this falls in the area, if you will, of toxicologists talking to industrial hygienists,” he said. An example of secondary prevention related to toluidine would be screening cytoscopy, and tertiary prevention could include surgery, compensation, and accommodation.

The series of actions in preventive medicine can be thought of in terms of a cascade (see Figure 2-3). “This is how we operate in the industrial setting to reduce adverse effects,” Halperin said. “We try our best at these [primary] levels up here. Often times we only find out that there is a problem down here [in the tertiary levels] when there is clinical care made available to seven workers who have bladder cancer.”

FIGURE 2-3

Cascade of prevention: Hierarchy of controls. SOURCE: Halperin, 2013.

The third paradigm, surveillance, was fathered by Alex Langmuir at the Centers for Disease Control in the 1950s, although historically it goes back to the 18th and 19th centuries, Halperin said. It is “the systematic, ongoing collection of relevant health-related data—disease, injury, hazard, intervention, etc.—and their constant evaluation and dissemination to all who need to know for the purpose of prevention.”

A crucial related concept is the idea of a “sentinel health event.” This is a paradigm that was developed at NIOSH in the 1980s, he said. A sentinel health event is “an unnecessary disease or injury, disability, or untimely death which is known to be preventable and whose occurrence serves as a warning signal that preventive or medical care may need to be improved.” A closely related hazard, such as a high rate of lead exposure or a low rate of immunization, may also serve in place of a disease or an injury.

Surveillance serves, in essence, as a feedback mechanism in the cascade of prevention (see Figure 2-4). It is not done to reduce exposure or to ameliorate symptoms directly. Instead, it serves to provide information concerning what is going on and thus to inform various preventive steps, Halperin explained. “Okay, there are seven cases of bladder cancer—what does that mean when we go back to the design of the operation? What does it mean to how we ought to take care of environmental monitoring? Should we be protecting workers better from the exposure?”

FIGURE 2-4

Cascade of prevention with feedback from surveillance added. SOURCE: Halperin, 2013.

The fourth paradigm, “embeddedness,” refers to the fact that all of the various actions taken to detect and respond to health issues take place in a larger context. “It is all imbedded in an economics, social, political, regulatory, and ethical matrix,” Halperin said. “We all have to work in this matrix.”

The fifth paradigm is responding to risk through preventive medicine, which Halperin said could be traced to a book by Geoffrey Rose, The Strategy of Preventive Medicine (Rose, 1992). Rose calls for reducing risk throughout an entire population rather than focusing on the small percentage of people within a population who are most affected by a particular risk. Halperin illustrated the idea with a pair of diagrams that could refer to a large number of situations (see Figure 2-5).

FIGURE 2-5

Responding to risk: (a) traditional approach and (b) preventive medicine. SOURCE: Adapted from Halperin, 2013.

The graphs could represent a number of things, he explained. They could represent the distribution of systolic blood pressure in the population, for example, or the population exposure to toluidine. In each case there is a group (represented by the hatched region to the far right in Figure 2-5a) that is most at risk and that gets most of the attention in the traditional clinical approaches. “We set a bright line, and we call everybody to the right of it a hypertensive. We see them every two months, and these other people [to the left of the line] we reassure and tell them to go home. The same is true if you think about toluidine.”

What Rose proposed was not only to take care of the people at the highest exposure, but to shift the population to the left, as illustrated in Figure 2-5b. The idea is to reduce exposure for everybody, which will have a greater effect than simply working with those people at the highest level of exposure.

This approach has been shown to work with hypertension, Halperin said. Although those people with the highest blood pressures are most at risk of heart attacks, there is an increased risk of heart attack in those with somewhat elevated blood pressures, and because those with moderate levels of hypertension make up a much larger percentage of the population, they account for a large percentage of the overall population risk for heart attack. Those with blood pressures over, say, 180 actually account for a relatively small percentage of the total population effect, Halperin said. Something similar is true for chemical risks, such as with toluidine. In this case there were some 30,000 workers with very high occupational exposure, but there were tens of millions of people with a much lower—but still hazardous—exposure due to smoking. By reducing exposure for everyone—shifting the curve to the left—the preventive strategy seeks to have a greater overall reduction in population risk than would be achieved by focusing on those most at risk.

NATIONAL CONVERSATION ON PUBLIC HEALTH AND CHEMICAL EXPOSURES

In June 2009 the Centers for Disease Control and Prevention (CDC) along with the Agency for Toxic Substances and Disease Registry (ATSDR) launched the National Conversation on Public Health and Chemical Exposures. The project, which was designed to gather input from a diverse collection of public and private interests, had as its goal the development of ways to ensure that chemicals are used and managed in ways that are safe and healthy for all people. Nsedu Obot Witherspoon, Executive Director of the Children's Environmental Health Network, served as co-chair of the project's leadership council, and she described the National Conversation effort and the Action Agenda it produced to the workshop audience.

The underlying rationale behind the project, Witherspoon said, was that the landscape regarding chemicals in the environment had changed considerably over the previous few years. There had been a growing recognition that there are many different exposure pathways, for example, as well as a recognition that chemicals can lead to a broad range of health outcomes. Biomonitoring had become feasible, and new approaches to toxicity testing had appeared. There had also been movement in the areas of environmental justice, green chemistry, and social media and communications. Thus, it was important to discuss how to effectively proceed in this changed landscape.

As noted, the vision behind the project was to see that chemicals are used and managed in ways that are safe and healthy for all people. Accomplishing that vision would require a number of things, Witherspoon said. It would require accurate information and improved scientific understanding, better policies and practices, and improved prevention, preparedness, and response. It would demand the elimination of inequities and increased engagement by the public and by health care providers. And it would require the development of networks for collaboration and coordination. “We saw this as an opportunity to leverage the work already being done,” she said. “This was not at all intended to be a new aspect of work to reduce or eliminate chemical exposures, but rather to leverage and increase partnerships and opportunities, especially during these hard economic times.”

A wide variety of partners were involved in the effort. CDC and ATSDR supported the National Conversation initially, and then they worked with a number of organizations to help manage the process. Resolve, which is an independent, nonprofit facilitator, convened and facilitated the National Conversation leadership council and a number of work groups. “To ensure strong engagement and input from environmental and public health stakeholders and the public, CDC partnered with the American Public Health Association, the National Association of County and City Health Officials, the National Association of State and Territorial Health Officials, and the National Environmental Health Association,” Witherspoon said. “Also, Westast's Web dialogue group provided interactive online discussions at key points throughout the project.”

The National Conversation had a leadership council and six work groups—on policies and practices, monitoring, serving communities, scientific understanding, education and communication, and chemical emergencies. Witherspoon explained that, during the 2-year process, thousands of members of the public participated through online and in-person forums. The work groups released detailed reports in October 2010. The 40-member leadership council issued the final Action Agenda in July 2011 (National Conversation on Public Health and Chemical Exposures, 2011).²

There was a major effort to make sure that the National Conversation included a broad set of perspectives. The leadership council and work groups included representatives from 13 federal agencies, with state, local, and tribal government agencies; national nongovernmental organizations; community and environmental justice groups; academia; industry; and affected communities. “Members of the public participated in over 52 community conversations held across the country and two Web-based dialogues,” Witherspoon said. “The leadership council drew heavily from the work group reports and public input in developing the Action Agenda.”

The project's main product was an Action Agenda that was intended to offer clear, achievable recommendations that could help government agencies and other actors and organizations strengthen their efforts to protect the public health from harmful chemical exposures. The Action Agenda was divided into seven chapters, each focused on a single priority topic: prevention, monitoring, science, communities, public engagement, health professionals, and emergencies. Each chapter describes the relevant public health problem, the challenges to resolving that problem, and the opportunities for new directions. It then offers several featured recommendations, along with additional recommendations related to that topic. In total, the Action Agenda offers 19 featured recommendations and 29 additional recommendations. For the remainder of her presentation, Witherspoon focused on the key issues and recommend-ations found in two chapters, Chapter 1 on prevention and Chapter 3 on science.

Chapter 1 is titled “Protecting Public Health by Preventing Harmful Chemical Exposures.” It notes that although public health has traditionally emphasized primary prevention—the elimination or reduction of the causes of health problems—this has not typically been the approach taken in the United States regarding exposure to chemicals, and it concludes that, by not focusing on primary prevention, the country is missing opportunities to protect the public from harmful chemical exposures, said Witherspoon.

To improve the situation, the chapter offers several featured recommendations. She noted that it calls on government agencies to prioritize the reduction of exposure to harmful chemicals. All levels of government are encouraged to provide policy incentives, to invest in research and development, to develop enhanced hazard screening methods, and to disseminate information for personal decision making.

The chapter also calls on Congress to reform TSCA and encourages states to enact similar legislation. And indeed, Witherspoon said, such actions have been taking place at the state level for many years now. California, Maine, Massachusetts, Minnesota, and Washington have all implemented toxics use reduction legislation and initiatives. At the federal level there have been various efforts to reform TSCA, although none has yet come to pass.

Another featured recommendation in the chapter is to make improved protection of children's health a priority. Witherspoon noted that government agencies are asked to require explicit consideration of children's unique vulnerabilities, susceptibilities, exposures, and developmental stages as well as of the places where children, live, learn, and play.

Chapter 1 also has several additional recommendations, explained Witherspoon. They call for increasing the emphasis on public health principles and precaution; developing standard scientific criteria and protocols for applying a precautionary approach to chemicals; strengthening protections of workers' health; ensuring that industrial and federal facilities comply with environmental health regulations, laws, and policies; and developing an overarching paradigm for assessing risk.

Chapter 3, which is titled “Achieving a More Complete Scientific Understanding of Chemicals and Their Health Effects,” concerns the importance of knowledge and understanding concerning chemical toxicity, modes of action, sources of exposures, and potential adverse health effects. The United States has undertaken significant research efforts, Witherspoon said, yet we lack critical information on the health effects of chemicals, including low-dose, multiple, and cumulative exposures; on individual susceptibility and intolerance including, but not limited to the interplay between genes and environment; on community vulnerability and disproportionate effects from past exposures; and on the effectiveness of interventions to protect public health.

The featured recommendations in Chapter 3 are aimed at enhancing scientific methods, tools, and knowledge. They encourage the expanded use, further development, and validation of modern molecular biology techniques, computational systems biology, and other novel approaches, said Witherspoon. Government agencies are encouraged to identify the data needed to fill gaps in the scientific understanding of health risks of chemicals and also to prioritize chemicals of concern for further assessment of exposures and safer alternatives.

The enhancements that the EPA made to its Integrated Risk Information System (IRIS) in summer 2013 are just one example of recent actions consistent with Chapter 3's recommendations, Witherspoon said. “The recent IRIS enhancements are intended to improve the scientific foundation of assessments, increase transparency in the program and the process, and allow the agency to produce more IRIS assessments each year. Standard protocols and tools to characterize human exposures across the life cycle of chemical products and across human life stages are also prioritized.”

Chapter 3 has five additional recommendations as well, explained Witherspoon. They address coordinating and improving accessibility of databases, understanding individual susceptibility to chemical exposures, defining gene–environment interactions related to chemical and environmental exposures and social and lifestyle factors, identifying the health impacts of indoor air quality during fetal and child development, and evaluating ATSDR's scientific methods.

In the 2.5 years between the release of the report and the workshop, there were a number of examples of agencies acting in ways that were consistent with the report's recommendations, Witherspoon said. For example, the National Center for Environmental Health at CDC convened a workshop to examine ATSDR's scientific approaches, which reflected Recommendation 3.8. And in the chapter on communities, it was recommended that the ATSDR be more focused on community concerns. “Since then,” Witherspoon said, “they have been creating geographic branches to ensure that all work is happening in a particular area and is more coordinated and also moving staff from their ATSDR headquarters to more of the local community levels and hiring more staff in the regions.”

In June 2012, she said, the National Conversation Network was formed with the intention of encouraging further progress toward implementing the report's recommendations and identifying opportunities for collaboration. Furthermore, the Environment Section of the American Public Health Association has a work group specifically organized around the Action Agenda. In particular, she added, there seems to be a great deal of interest right now in including environmental considerations into undergraduate, graduate, and health professional curriculum development and training. In addition, the call for TSCA reform is “resonating very loud and clear.”

In conclusion, Witherspoon said that the National Conversation's Action Agenda offers an effective roadmap for leveraging current partnerships and dealing with the lack of resources available. “This is a great time for us to take a step back to take an assessment of some aspects and initiatives that haven't been so effective and think about rerouting ourselves,” she said. “This is a roadmap that I encourage all of us to spend some time reviewing and acting on.”

REFERENCES

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• Goldman LR. Chapter 17: Toxic chemicals and pesticides. Dernbach JC, editor. Washington, DC: Environmental Law Institute; 2002. (Stumbling toward sustainability).
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Footnotes

1

Toxic Substances Control Act of 1976, Public Law 94-469, 94th Congress.

2

Further information about the National Conversation on Public Health and Chemical Exposures and the final report, Addressing Public Health and Chemical Exposures: An Action Agenda, are available at http://www​.nationalconversation.us (accessed March 31, 2014).