CDC Telebriefing Transcript

CDC Releases Most Extensive Assessment to Date of Americans' Exposure to Environmental Chemicals

January 31, 2003

AT&T OPERATOR: At this time all participants are in a listen-only mode. Later, we will have a question-and-answer session and I'll give you instructions at that time. Should you require assistance while you're on this call, simply press zero and then star, and an operator will come on to your line to assist you. As a reminder, this conference is being recorded for a digitized replay.

If you wish the replay information, please stay on the line at the conclusion of the call and I will give it to you.

I would now like to turn the conference over to our host, Ms. Bernadette Burden of CDC Office of Communications. Please go ahead.

CDC MODERATOR: Thank you, Ken. Good morning everyone, and welcome to CDC's telebriefing. This morning, we will be releasing information to you on the Second National Report on Human Exposure to Environmental Chemicals.

First, I'd like to begin by letting you know that you will be able to access the full report, in its entirety, online, at our Web site. Let me give you that Web address now. That is www.cdc.gov/exposurereport. Again, that's www.cdc.gov/exposurereport. 

This morning, our speakers that will guide you through the exposure report, we have Dr. David Fleming, the deputy director for Science for the Centers For Disease Control and Prevention.

Joining Dr. Fleming will be Dr. Richard Jackson, the director of CDC's National Center for Environmental Health, and Dr. Jim Pirkle, the deputy director for Science at CDC's environmental health laboratory.

They will provide a brief overview of the report, describing its public health uses, and discuss selected findings from the report. After their remarks, we will have a question-and-answer session in order for you to be able to learn more about the report and discuss some of its findings.

So now I'd like to turn things over to Dr. Fleming.

DR. FLEMING: Thanks, Bernadette. Good morning.

Thank you for joining us today to hear about this Second National Report on Human Exposure to Environmental Chemicals. We're pretty excited

This report is, by far, the most extensive assessment ever made of the exposure of the U.S. population to environmental chemicals. CDC's committed to protecting people's health and safety but whether it be investigating a cancer cluster, assessing a toxic spill, evaluating lead in our children or protecting people from environmental tobacco smoke, a common imperative is ensuring that exposure to chemicals in our environment are not at levels that affect our health.

This task is scientifically challenging. It requires an understanding of how much exposure Americans have to environmental chemicals as well as the health risk associated with different levels of exposure. Let me emphasize that first point.

In order to make sound public health decisions that help us correctly identify and prevent health problems, we must have reliable information about exposure to environmental chemicals. That's the purpose of the National Exposure Report, and as you're about to hear, this second report is a quantum leap forward in providing objective, scientific information about what's getting into people's bodies and how much is getting in.

Bernadette.

CDC MODERATOR: Thank you, Dr. Fleming.

Our next two presenters will discuss the specific public health uses of the report and selected findings for some of the chemicals.

These findings will include expanded data on lead exposure in children, data on exposure to organophosphate pesticides, new data on the exposure of Americans to environmental tobacco smoke, data on exposure to dioxin and dioxin-like chemicals, new findings on exposure to phthalate and new data on exposure to DDT.

Dr. Jackson will now discuss the public health uses of the report.

DR. JACKSON: Thank you, Bernadette, and good morning everyone. As Dr. Fleming just indicated, better information about people's exposure means better decisions to protect public health, and the report's a giant step forward in exposure information and a milestone for environmental public health.

Now some details. The chemicals that were measured in the blood and urine of the people who participated in CDC's national health and nutrition examination survey--we call this NHANES--it was conducted by CDC's National Center for Health Statistics, and it's a series of surveys designed to collect data on the health and nutritional status of the U.S. population.

Our report includes data obtained through physical exams and laboratory examinations of persons, and this was done for the years 1999 and the year 2000. Our environmental health laboratory made the blood and urine measurements that we're reporting today and for each of the chemicals we're reporting on, we have measurements from about 2000 to 2500 people; at least that many. The report builds on the, the report that we put out two years ago, the last report had information on 27 environmental chemicals. This report is four times larger than the first report and covers 116 chemicals, 89 of which have never been measured in the U.S. population.

It also gives us better and new exposure information for population groups that are defined by age, sex, race, or ethnicity. I must stress that just because a chemicals can be measured in blood or urine doesn't mean that it causes illness of disease, and research separate from this report must be done to determine which exposure levels are safe and which are not.

For most of the chemicals in the report, well-established guidelines are not available. This is an area of ongoing research and CDC's participating in this research effort along with federal and academic scientists. In fact at this very minute, we have about 50 studies underway in just our toxicology branch with various partners around the country.

I'm not going to list all 116 chemicals that are in the report. You can find the list at the beginning of the report on our Web site. I will give you twelve categories of the chemicals that we looked at.

Metals is one category and that includes lead, mercury, thallium, uranium, and cadmium. It includes a marker of exposure to tobacco or tobacco smoke, and that's cotinine. Will include pesticides in the group organophosphates. It will include agents called phthalates. It will include pesticides that are organochlorines. It will include the group dioxins, furans and coplanar PCBs, and also, separately, noncoplanar PCBs.

Polycyclic aromatic hydrocarbons or PAHs are in there. We have a couple of herbicides in the report as well. It reports on them. We have insecticides in the carbamate group and we also have pest repellents and disinfectants, and, finally, plant estrogens which are called phytoestrogens.

I'll be describing four specific public health uses of the report.

First, it identifies chemicals that are actually getting into Americans and how much of each chemical is getting in, and you have to know what the exposure levels are in order to make good health-related decisions. I spent more than 25 years in environmental public health, both in state public health departments and at CDC, and I know that this kind of information makes a huge difference for public health workers on the frontline, who are trying to figure out environmental health problems every single day.

Secondly, the report tells us whether efforts to reduce exposure to specific chemicals are really working.

If efforts to reduce an exposure are effective, we should see the levels declining, over time, and it gives us direct information on whether that is actually so, and if so, how much.

Third, for chemicals where we have known toxicity levels, the report tells us how many Americans have elevated levels.

For example, CDC defines elevated lead levels, elevated levels of lead in children at 10 micrograms per deciliter. It's important to compare our results with that standard as we go forward.

Finally, the report provides reference ranges for blood and urine concentrations of chemicals, so we can recognize unusual exposures.

These reference ranges describe the typical exposure of people in America to each chemical and doctors need to compare these results from an individual to the reference range to determine whether a person has an unusual level or a level similar to the rest of the U.S. population.

As a pediatrician, I know firsthand, the value of having information that tells me whether my patient has an unusual amount of exposure that merits further attention and the report gives us a unique opportunity to look at this valuable information for a broad range of chemicals.

I'm going to now ask Dr. Jim Pirkle, the head scientist in our laboratory to add additional information on findings in the report.

DR. PIRKLE: Thank you, Dr. Jackson.

Overall, for specific chemicals, we have a mixed picture, some encouraging findings and some of concern. For lead, some encouraging data.

In previous work by CDC examining lead levels during the period 1991 through 1994, we estimated that 4.4 percent of children aged one to five years had blood lead levels above the 10 microgram per deciliter level that Dr. Jackson referred to.

The second report presents data for 1999 and 2000, and shows that this estimate has declined to 2.2 percent, with a 95 percent confidence interval of 1.0 to 4.3 percent. The geometric mean blood lead level for these children also decreased from 2.7 to 2.2 micrograms per deciliter over the same time period. These results indicate that lead exposure among children in the general population is declining. Although this finding is encouraging, we must note that exposure of children to lead from homes containing lead-based paint and lead-contaminated dust remains a serious public health problem.

CDC and other federal partners will continue important lead poisoning prevention programs targeting interventions to eliminate this entirely preventable disease among exposed children throughout the nation.

Next, let's take a look at chlorpyrifos. Chlorpyrifos is an organophosphate pesticide that has been used heavily in the United States. Retail sales of chlorpyrifos for residential use were stopped in December 2001.

The second report presents urinary levels for the major metabolite of chlorpyrifos for the years '99 and 2000. Thus, we have baseline data on the exposure of the U.S. population to this pesticide while it was still in residential use.

Our data also show that levels of chlorpyrifos in children are about twice as high as those in adults. In future reports that CDC will put out every two years, CDC will compare chlorpyrifos levels with these baseline levels to assess the effectiveness of the recent restriction on chlorpyrifos in reducing exposure of the population to this pesticide.

If the restriction has been effective, we would expect to see in outgoing years the levels of this pesticide drop.

The report contains information about serum levels of cotinine in the nonsmoking U.S. population. Cotinine is a major metabolite or breakdown product of nicotine. Levels of serum cotinine track the amount of exposure a person has to tobacco smoke and other tobacco products. For a person who does not use tobacco products, a nonsmoker, cotinine tracks exposure to environmental tobacco smoke.

In the first report that we released in March of 2001, we noted that for nonsmokers, cotinine levels have declined substantially in the U.S. population as a whole since the early 1990's.

The second report has new expanded data that enable us to examine trends in cotinine levels broken down by age, sex, and race ethnicity groups. The report shows that since the early 1990's, cotinine levels in nonsmokers have decreased by 58 percent in children, 55 percent in adolescents, and 75 percent in adults.

These declines support the effectiveness of public health efforts through the '90s to reduce exposure to environmental tobacco smoke. These efforts were targeted primarily at reducing exposure among adults.

Of some concern, the report also shows that in 1999 and 2000, children had cotinine levels that were more than twice as high as levels in adults.

Also, non-Hispanic blacks had levels that were twice as high as levels among non-Hispanic whites and Mexican Americans. Environmental tobacco smoke exposure remains a serious public health concern and efforts are warranted to reduce exposure, especially among children and non-Hispanic blacks.

The report presents serum levels of dioxins, furans and coplanar PCBs, polychlorinated biphenyls. In terms of their toxicity, furans and coplanar PCBs are dioxin-like compounds. All of these chemicals persist in the environment and in the human body for years.

Most people who were tested for these compounds had levels of dioxins, furans and coplanar PCBS that were below the detection limits of our analytical method. These findings are encouraging and consistent with other data, indicating exposure to these chemicals has been declining in the past two decades.

In the future, CDC plans to lower the limits of detection of our analytical methods by using more serum and new measurement technology. With lowered limits of detection, we expect to be able to measure the levels of each of these chemicals in the population and track them well, over time.

Next, results on phthalates. Phthalates are chemicals found in many consumer products including vinyl flooring adhesives, detergents, lubricants, food packaging, soap, shampoo, hairspray, nail polish, and all kinds of flexible or soft plastics.

Animal testing has shown reproductive toxicity for some phthalates. The second report presents levels of seven separate metabolites or breakdown products of phthalates. One metabolite, monoethyl phthalate, tracks exposure to dimethyl phthalate, commonly used in personal care products such as soap, shampoo and cosmetics.

The second report documents that levels of monoethyl phthalate were lower among children than among adolescents or adults. Another metabolite, mono 2 ethylhexel [ph] phthalate, tracks exposure to Dy 2 [ph] ethylhexel phthalate, which is commonly found in flexible or soft plastic products. Levels of mono 2 ethylhexel phthalate showed a different trend and were higher among children than among adolescents or adults.

No generally recognized guidelines that indicate threshold values for adverse effects are yet available for levels of these phthalate metabolites.

Production and use of different kinds of phthalates is changing. In future releases of the report we'll be able to determine whether or not these changes in production and use results in changes in exposure to any of these chemicals in the overall population or in a subgroup of the population.

The last finding I'll present is for the insecticide DDT. DDT was widely used in the United States until EPA banned its use in 1973. However, DDT is still being produced and used in limited quantities in other countries.

Both DDT and DDE--that's e as in elephant--a major metabolite, persist in people and persist in the environment.

The second report presents data showing serum levels of DDE that are three times higher in Mexican Americans than in either non-Hispanic whites or non-Hispanic blacks. Additionally, DDE levels were clearly measurable in people aged 12 to 19 years, even though people in this age group were born after DDT was banned in the United States.

The national toxicology program has classified DDT as reasonably anticipated to be a human carcinogen. As yet, no generally recognized guidelines that indicate threshold values for other adverse effects are available.

On the encouraging side, compared with levels found in several small studies of DDT exposure in selected groups in the United States before 1990, the DDT and DDE levels in the report are clearly lower.

In conclusion, I want to echo what Dr. Jackson has to say earlier. Better exposure information means better decisions to protect health. Because of time, we have presented only selected results. The second report is extensive, containing more than a 185 tables of exposure information for many other chemicals, from mercury to uranium to PPHs, to organochlorine pesticides, to phytoestrogens, to carbamate insecticides.

This major expansion in exposure information will help physicians and scientists better identify and prevent health problems from exposure.

Again, you can access our Web site which posts the entire report at www.cdc.gov/exposurereport, one word. No space in between exposure and report. exposurereport--one word. The entire report can be readily downloaded as a PDF file and it is indexed by chemical for easy reference.

Thank you for your time and attention. Now we'll move on to your questions. Ms. Burden will explain the process.

CDC MODERATOR: Again, I'd like to thank, first of all, Dr. Fleming for this remarks, as well as Dr. Jackson and Dr. Pirkle. We will now begin with the question-and-answer session. The moderator will assist you with asking your questions.

AT&T OPERATOR: Ladies and gentlemen, if you wish to ask a question please press one on your touchtone phone. If you're using a speaker-phone, please, do pick up your handset before you ask your question.

Our first question is coming from the line of Andrew Revkin [ph] at the New York Times. Please go ahead.

QUESTION: Thanks. You might want to grab a pencil. I'm going to make a couple of quick, detailed, small questions. One is on the stuff about the difference between kids' exposure, kids' levels and those in adults.

For secondhand smoke and for chlorpyrifos, do you, as public health professionals, can you give a sense of, hypothetical on where that might be coming from. I assume kids play on grass, and kids aren't in the workplace. They're at home. They're in places where secondhand smoke is not banned. So is that presumably where those things are coming from? I have a quick follow-up.

DR. JACKSON: This is Dick Jackson. I'll speak to chlorpyrifos. I'll ask Dr. Pirkle to speak to the cotinine.

Chlorpyrifos, particularly until the year 2000, was very widely used. It was used in various foods that were being produced. Grains. It was also being used in many home uses to control roaches and other pests in the home.

Particularly because of A, children eat, breathe and drink two to three times as much as adults do, it's not surprising that children's exposures will be higher from dietary and respiratory sources.

Children also have, at least very young children have two to three times the surface area that an adult does. Just the amount of skin per pound of body weight. So if they are on a floor that has been treated with chemicals, you would expect that they would be absorbing more than someone sitting on a couch and far less exposed.

I think the critical thing here is EPA has taken action to reduce population exposure to this chemical and also to diazinon. We do have background data now for '99-2000. It will be important to see if those regulatory actions are actually going to make a difference in kids' exposures and population exposures.

Dr. Pirkle?

DR. PIRKLE: Yes, in terms of environmental tobacco smoke, throughout the 1990's, the actions that we took from public health largely were targeted at adults, so that we largely targeted workplace kinds of exposures and exposure that would occur, actually, where adults would tend to gather more.

Now, overall, again, we saw a decline for all age groups, it was just bigger for adults and it left kids with twice the levels of adults.

What we are looking at now is one of the benefits of the report and that is to say we have now a group that we need to specially target and think about new things to do, and we're going to be doing that very thing to try to lower their exposure to ETS.

QUESTION: Okay, and the follow is related to DDE in Mexican Americans. There, too--by the way, was the test the subject group there, the test group, were they all people who were born in the States and who are of Mexican American descent, or are they people who were born in Mexico and now live here? In other words, what would account for the triple exposure level there?

DR. PIRKLE: Okay. We have several things. We did not--it's not excluded, it covers people that were both born in Mexico and now living in the States, and people that were born in the United States. Some of the things that we want to look at in regard to this is the possibility of exposure outside the United States and, in addition, the possibility of occupational exposure and its contribution.

So that is something we'll definitely be looking at in the future.

QUESTION: Thanks.

CDC MODERATOR: All right. We'll take our next question, please.

AT&T OPERATOR: Our next question is coming from the line of Dan Fagan [ph] at Newsday. Please go ahead.

QUESTION: Hi. Thanks. I have a question similar to Andy's, except that it concerns the phthalates. Dr. Jackson or Dr. Pirkle, or whoever can handle this, is there some possible mechanistic theory, why the mono 2 metabolite would show up higher among children while the other one didn't, or is it somehow related to the use of the products?

What's the working hypothesis on that?

DR. PIRKLE: This is Dr. Pirkle answering the question. The mono 2 phthalate, mono 2, actually metabolite, is higher in children--excuse me--is lower in children and then gets to a higher level as we move to adolescents and adults, and we haven't researched this to say, with confidence, what is causing that trend, but certainly something that is high on our list is the use of personal care products that increase as a person ages. So children six to eleven years old we think are using less personal care products than adolescents who are 12 to 19, and again, it's only slightly higher amongst adults after that.

So high on our list is to look at that kind of exposure to see if it accounts for this increase in levels but we haven't entirely ruled out other sources and that's something that we'll continue to investigate.

QUESTION: Is the other metabolite the one that is used in children's products? There's been some attention to teething rings and other plasticizers and toys.

DR. PIRKLE: Yes, that would be correct. This is Dr. Pirkle again. That's correct. The other product, if you kind of think of soft bendable plastics, then that's where the other product is used, and, again, that product was found to be higher in children and then stepped down to lower levels in adolescents and slightly lower levels in adults.

QUESTION: Thank you.

CDC MODERATOR: We'll move on to our next question, please.

AT&T OPERATOR: The next question comes from the San Jose Mercury News. We go to the line of Glenda Tree [ph].

QUESTION: Hi. I have a couple of questions. As to phthalates, what is known about the health effects of these? I understand there have been some attempts to discontinue their use in things like hospital tubing, and I have a follow-up.

CDC MODERATOR: Glenda, may we ask you to repeat that, please. You're not coming in clear.

QUESTION: Okay, let's see if I can--hang on a second. We'll do this. Can you hear me?

CDC MODERATOR: Much better, thank you.

QUESTION: I just had a question about the possible health effects of Phthalates. I understand there have been some attempts to discontinue their use or limit their use in hospital products, and I do have a follow-up.

DR. JACKSON: It's of interest that you're from the San Jose Mercury. We are not reporting on mercury in this report, but we hope to in the next. We did report on mercury in this report, but we'll speciate it in the next one. This is Dr. Dick Jackson.

Phthalates, various categories of the phthalates are of some concern. Some of them are estrogenic or anti-androgenic, and certain of the other categories have been identified as possible human carcinogens.

That said, no one has been able to do the research that we correlate the levels we are looking at right now in the overall population with the dose levels that have been found to have effects in test animals. This is, of course, a very important first step because once you know what is actually in people, you can begin to do further study in this area.

Jim, do you want to correct or add anything to that?

DR. PIRKLE: I just want to add to that. What Dick said is exactly right. The kind of information that we have in the Exposure Report is the kind of thing that lets us do the right studies to answer what levels are dangerous and what levels are safe.

When we figure out what kind of levels are in people in the United States, we can design those studies, and look at the right chemicals, and try to, we will have a much better opportunity to make determinations on whether the levels that are in people are of little health consequence or something to be of health concern, but right now that's not something that's well-established.

QUESTION: And the other question I had was about Mexican Americans. Was there any effort to--I wondered what percentage of people that you tested were farm workers and if there was any effort to single out farm workers to see if their exposure levels to different things are higher.

DR. JACKSON: Glenda, this is Dick Jackson.

The report really is a snapshot of the whole U.S. population with about 5,000 people a year. There is some oversampling to try and get a better view of what's going on in women of reproductive age, but to go to smaller groups, for example, farm workers, would require special studies, and I do not believe there was oversampling in that population.

This kind of study, though, would be the kind of thing that a researcher would use if he or she then wanted to do a special study of farm worker populations because it would give you reference levels for the U.S. population. So you would use this to then build for other studies.

QUESTION: If I could just follow up briefly, I understand that the population of Mexican Americans used in this study was mostly from East Los Angeles. Can you say anything about that?

DR. JACKSON: This is Dick Jackson.

The way that NHANES was done, and we are not from the National Center for Health Statistics, but I believe there are 20-plus different stands[?] around the country that are looked at each year, and it is done in order to reflect the overall U.S. population, but we would not be able to look at that in particular.

Do you want to add to that, Jim?

DR. JACKSON: The Mexican Americans were actually obtained across multiple sites, not just in Los Angeles, but it is a national representation that we're looking at. So the design here is to be nationally representative of Mexican Americans in the United States.

QUESTION: Thanks.

CDC MODERATOR: We'll now move on to our next question.

AT&T OPERATOR: And our next question is coming from Marla Cohen at the Los Angeles Times. Please go ahead.

QUESTION: Good morning. Can you talk a bit about what you find with the non-coplanar PCBs. Were they found in most of the population and at what levels?

DR. PIRKLE: This is Dr. Pirkle. The non-coplanar PCBs were similar to the findings with dioxins, furans and the coplanars, and that is that their levels were generally lower than what our methods could detect, and so that was also encouraging.

Now, having said that, that's a general comment, and for specific PCBs, especially those with more chlorine atoms around the ring, we have definite levels that we have in the report that can be used. Again, this kind of information gives us that reference range that we need for what the typical exposure is in Americans, and I think that people that are looking at the tables on the dioxins, the furans, the non-coplanar and the coplanar PCBs still will find very useful information because we have detection limits.

So when we say we're not able to see it, we're able to say with confidence, but the levels were less than four or five parts per trillion. So we are able to give you a good bit of assurance that the levels are lower than a certain number. We just didn't quite have the ability to nail the number down, but that will change in the future, and by the next report you will see definite numbers on all of these different dioxins, furans, and PCBs.

DR. JACKSON: Ms. Cohen, this is Dick Jackson.

One use of this is that, as you well know, there are hot spots in the U.S. where one would be more concerned about PCB exposures--around the Hudson River, for example, or in the Los Angeles bite--in terms of DDT, DDE breakdown products. And so this is the kind of data one would need then, when someone was doing a special study in those locales, to figure out what is the distribution in the rest of the country.

DR. PIRKLE: I really want to make sure that what Dick said about detecting unusual exposure gets emphasis, and that is that when people have a particular situation, they really want to know has this population been exposed in an unusual manner, and they need to have an understanding of what is the typical exposure in the U.S. in order to make that decision, so that if you were doing studies on PCBs about a river, and you were concerned that people had unusual exposure because of PCBs in a river, you could actually sample some people and then compare it to the data that we have in this report.

You might find that all of their levels are similar to what's in the rest of the population, so their exposure is no different-- that's extremely helpful--and you might find their levels are 100 or 1,000 times higher. That's also extremely helpful because it lets you identify the problem and the study that needs to be done in the follow-up.

This was Dr. Pirkle.

QUESTION: I have a follow-up question, if I may.

Why do you think that PCBs seems to be disappearing from the American public, but DDT is remaining?

DR. PIRKLE: This is Dr. Pirkle.

DDT is fading. PCBs are also fading. Now, they are both going down. Studies that were done, small studies, not nationally representative studies, but small studies that were done before the 1990s show levels of PCBs that are definitely higher than the levels we're seeing now.

So, actually, there's actually encouraging news, in terms of the decline, for both of those; DDT and DDE, those are going down; PCBs are going down; dioxins, furans are also going down.

DR. JACKSON: This is Dick Jackson.

The point though is that durable chemicals that stay in the environment for a long time, we are going to continue to find them for a long time.

The second point being that regulatory controls have worked. We are seeing declines in chemicals where we have put regulation in place, whether it's lead, PCBs or DDT. But things do not happen quickly when you have this widespread level of exposure.

CDC MODERATOR: Next question, please.

AT&T OPERATOR: The next question comes from the line of Eric Piana [ph] at the Washington Post. Please go ahead.

QUESTION: Hi, there.

Could you go back and generalize more on the potential health threat of these levels of chemicals in humans; you know, what can you say with certainty, and what can you say generally about government regulation of these chemicals and how well the public is being educated on their dangers?

DR. FLEMING: This is Dr. Fleming.

The question that you're raising obviously is a critically important one. I think it's important also, though, to realize the kind of information that this report can provide and the kind it cannot.

The purpose of this report is to evaluate the levels of exposure in humans. By having that information, we can then integrate that with other information and make better decisions. However, in and of itself, the information in this report won't allow us to make the regulatory decisions that you're talking about.

The purpose of this report, again, is to provide information, information that's going to be useful to everybody, most of all the public, but as you're pointing out, policymakers, as well as scientists.

CDC MODERATOR: Next question, please.

AT&T OPERATOR: The next question comes from the line of Tom Watkins at CNN. Please go ahead.

QUESTION: How much did the study cost, and what do you have budgeted for the next iteration of it, and did industry sources have any input into its design or the future one?

DR. PIRKLE: This is Dr. Pirkle.

The study cost about $6.5 million, and do we have it budgeted to continue. The report will come out every two years, and right now we plan to continue it into the indefinite future. We will be adding additional chemicals to the report, and we have solicited general input, in terms of what chemicals should be measured, and we have put that out in the Federal Register. We can provide more details on that to you, but it is detailed on our website.

We have talked with industry, we have talked with environmental groups, we have talked with other Federal agencies about what things we should be measuring and how these things would be helpful to them. So we've had broad input actually from all of those sources.

QUESTION: You say it's budgeted to continue at that same rate?

DR. PIRKLE: That's correct.

QUESTION: Thank you.

CDC MODERATOR: Next question, please.

AT&T OPERATOR: The next question is coming from Randy Loftus at the Dallas Morning News.

QUESTION: Hi. Good morning.

I have a couple of questions; one about the DDT and the metabolites and one about geographical breakdowns.

The levels that were found among the Mexican-American community on the DDE, how do those compare to any known or posited health-effect threshold, and if you could describe what the potential health effects of DDE might be.

DR. JACKSON: This is Dick Jackson. Let me lead off and then ask Jim Pirkle to follow up.

There have been a number of studies looking at DDT and DDE exposures, particularly among Mexican farm workers. Of interest in those studies women that had high levels, relatively high levels, had shorter periods of lactation. They were actually able to nurse much less long, and there were other health endpoints that were discovered in that study.

Mexico banned DDT several years ago, although we believe that some minor uses still continue under the control programs. To be able to figure out the hazards at the levels that we're looking at now would take much larger studies and much more extensive research. The good news is that levels are going down.

Jim, do you want to comment further on that?

DR. PIRKLE: This is Dr. Pirkle.

That's got most of it. Basically, the encouraging news, again, about the DDT and DDE is it's going down. So even though Mexican Americans have higher levels, they have got lower levels than we were seeing in the general population in certain studies in the 1980s.

DR. JACKSON: In the U.S.

DR. PIRKLE: In the United States. So we want to pay attention that here is a population group that has got higher levels than others, but we want to keep it in the broader picture to note that the overall trend for DDT and DDE is very encouraging.

QUESTION: All right. Good. Thank you.

And the follow-up is about geographical breakdowns. I was talking earlier this week to a long-time dioxin researcher who said that he had inquired about the availability of any kind of geographical subsets within this data so that people could get a jump-start on localized investigations. Is there anything like that available in this set or is that anticipated in the future?

DR. PIRKLE: I think this is very important to understand the design of NHANES is for a nationally representative sample, and that's actually very difficult to do, and the National Center for Health Statistics at CDC has worked very hard to pull that off. It is not possible to pull out state-by-state or region-by-region data from that national design. It's just not in the design.

Now, having said that, the kind of information we get from the national design will help us do studies in selected populations in specific regions. So that is not something that's being omitted, it's just not being reported today.

CDC MODERATOR: Thank you. Next question, please.

AT&T OPERATOR: The next question comes from the line of Nicola Jones at the San Francisco--oh, excuse me, we go to Jane Kay at the San Francisco Chronicle. Please go ahead.

QUESTION: Did you say that there's some information on mercury in this report and that we can expect more specific information in the next report? Could you talk about that.

DR. PIRKLE: Yes, this is Dr. Pirkle.

Yes, in this report, we have got levels of mercury in blood and levels of mercury in urine in this report. We have especially focused on children, one to five years old, and also women of child-bearing age; that would be 16 to 49 years old. We have very detailed information on their exposure in the U.S. population.

What Dr. Jackson was referring to is that in the future, our laboratory is very close to finishing development on a method that will give us better breakdowns of the kinds of mercury. You might have noticed in the news people are concerned about different kinds of mercury from fish and from water, and in the body these are different forms. We refer to this as species or speciated mercury. So we can measure then the methyl mercury, the ethyl mercury, the phenyl mercury, and the other kinds of mercury, and each one of those tracks back to specific kinds of sources. So we'll be able to say this is mercury from fish, this is mercury that comes from water, this is mercury that comes from other sources.

This is very valuable information, and it's the kind of thing that we really hope to get into the report within the next couple of years.

QUESTION: Thank you.

DR. JACKSON: This is Dick Jackson. I want to add a critical piece of information, if I may.

NHANES, the purpose of the National Health and Nutrition Examination Survey, it's the only survey where actual physical examinations are done on a sample of the U.S. population, actual urine and blood specimens are taken.

The purpose of the survey is much broader than simply the toxicity data that we're talking about. It gives us important information about nutrition levels, about serum folate levels, things that are very important, the cholesterol levels--very important to the health of the American people.

It's an immense data set, only one part of which is the toxicity data that we're talking about. The data set on the toxicity data that we are talking about will be available through NHANES to the researcher--the gentleman from Texas that asked about a researcher that wanted more information. Researchers will be able to mine this data set in much more depth than we ever would be able to come March or so.

And so our goal is to really put this out to the scientific world so they can continue to make maximum good use of this.

CDC MODERATOR: Next question, please.

AT&T OPERATOR: The next question comes from Nicola Jones at News Scientist. Go ahead.

QUESTION: Thanks. I just wanted to ask very simply which results did you find most surprising and if you could recommend a study to address one of the particular levels to determine why they are like that, and then what would that study be?

DR. JACKSON: I'm laughing because all of this goes on over time and one ends up not being surprised because it's a little bit at a time.

Jim, do you have a comment?

DR. PIRKLE: Yes. I think I want to make sure that this is clear; that we have got 116 chemicals that we looked at, and there are reams of new information here, and the emphasis I think would be on the amount of new information that's here.

When we're looking at levels of lead or dioxin or things like this, we have some general ideas of what these levels might be, but we have got a tremendous amount of new information here. To focus on just one or two, we can do that, and we gave you some selected findings. I wouldn't call it so much surprising as important new information. That's the way that I would characterize it.

We work in the field all of the time, and so we know what are exposure levels are in people who work and people who are exposed at local sites because of different situations. So I think that I would better characterize it as we have a tremendous amount of new information that's going to guide us in the future.

This is information that people are going to take months to digest. The book is 260 pages long. Some people are going to focus on one table, and that's all, because that's got information they're interested in. This should be a reference document used by medical toxicologists for years to come.

DR. JACKSON: This is Dick Jackson.

I'd like to point a practical use, for example. The last report had the distribution of tungsten, the metal tungsten levels in the U.S. population. CDC was asked to investigate a cancer cluster of children with cancer in Fallon, Nevada. Amongst the results of that cluster investigation--we talk about it later--elevated levels in that population of the metal tungsten were found.

A practical outcome was, as a result, we made contact with sister agencies, including the National Toxicology Program. They are in the process of putting tungsten through an intensive evaluation for possible cancer-causing potential. We will be briefing the sister agencies. We've briefed them already, but we'll be providing the in-depth data to FDA, EPA and the sister agencies shortly, and they're going to make a lot of practical use out of this as well.

CDC MODERATOR: Next question, please.

AT&T OPERATOR: The next question comes from the Minneapolis Star Tribune. We go to the line of Tom Nearman. Please go ahead.

QUESTION: Thank you. A fairly general question.

Of the 116 chemicals in the study, how many do not have any known toxicity levels and have the results of the study caused you to think that there is a more urgent need to establish levels for any particular chemicals that you could name?

CDC MODERATOR: Dr. Pirkle?

DR. PIRKLE: Yes, this is Dr. Pirkle.

I can't give you the exact number. Again, we're talking here, in terms of toxicity levels, many of these things, most of these things certainly have been evaluated in animal testing. Since we have chosen chemicals to start with that we want to make sure that we get measurements on, by and large, it's fair to say that the vast majority have clearly got animal toxicity data associated with them, but I can't give you the exact number that's yea or nay.

Help me with that second part of the question again.

QUESTION: Have the results caused you to think that there's a more urgent need to have more research in this area, to have established levels for some of these chemicals that you don't have them for already or are there any that you could name that you think there's a bit more urgent need to have that kind of background information about?

DR. PIRKLE: The way that I would look at that is to say that the value here is that we've been able to identify those things that are measurable in people and at what levels. So it does help us to prioritize research.

Just exactly like Dr. Jackson mentioned before, that when we have looked at things on tungsten and other things like this, we are able to go to other agencies and say, you know, we're finding measurable levels here. Certainly, over time, as we continue this report, we'll be able to document whatever chemical is going up in people in the United States, and we certainly will want to use that information to make sure that we are augmenting our research studies to make sure that these levels of the chemical are safe.

So it helps us on a lot of fronts, in terms of prioritizing research studies and making sure we're spending dollars efficiently. If it's something that's in Americans and is increasing in Americans, we want to be confident that it's not at levels that pose a health danger.

DR. JACKSON: You know, Jim--this is Dick Jackson--we want to point out the distinction between environmental levels and human body burden levels because there are many standards that are set for water, for air, for food and the rest. There are very, very few standards where one is actually setting it on the basis of human exposure levels of lead, a couple of others.

DR. PIRKLE: That's correct. This is Dr. Pirkle. The important thing to bear in mind is that we made these measurements in human blood and urine, so these are levels of the chemicals that actually got into people.

There are lots of other measurements that you'll hear about, that might be in air or water or soil or food. You can't directly relate those measurements to the measurements in people. 10 micrograms per liter in water doesn't mean it's going to be 10 micrograms per liter in blood.

So we wanted to make the measurements in people, those are the most health-relevant measurements, and give us the best information on what a person's total exposure is.

CDC MODERATOR: Thank you. Next question, please.

AT&T OPERATOR: The next question comes from the Chicago Tribune. We go to the line of Jeremey Menieur [?]. Please go ahead.

QUESTION: Yes; thanks a lot. My question is organophosphates, were there other sorts of organophosphates that you measured that are worth commenting on, including some that might still be available in the U.S.?

DR. PIRKLE: Yes. We did several things with organophosphates. This is Dr. Pirkle.

I would really encourage you just to download the file and take a look at the section on organophosphates. I'll give you a brief summary of it here, though.

We measured six organophosphate metabolites that actually track exposure to 28 different organophosphate pesticides that are in use, and these are still in use ,and we have measured those and gotten the levels in people.

It turns out, for those pesticides, one interesting finding is that they were higher in children, just like the finding for chlorpyrifos.

So it seems to be more of a consistent finding across the organophosphate pesticides, that children have higher levels, and in addition to that, we have measurements that track specific pesticides. So we want to take a broad look at an array of organophosphate exposure and how that's changing, and we want to look at specific heavily-used organophosphates like chlorpyrifos and diazinon, and we have specific chemicals that track their use.

Coming in the future, we're going to be adding six more metabolites that track six more specific organophosphate pesticides.

So this is really a tremendous database, and as EPA makes moves, or as we get more information that's needed on exposure to these things, we're going to have it from this survey, to say what is getting into people's bodies and how that's changing.

CDC MODERATOR: Next question, please.

QUESTION: I'm sorry. If--

CDC MODERATOR: Pardon? You have a follow-up?

QUESTION: Yeah. Just one little thing. I know you answered this for a couple of other chemicals. For the organophosphates, did you say there was a reason why this might be higher in children?

DR. JACKSON: I really--I think--this is Dick Jackson. As a pediatrician, we've been long concerned that because children's metabolism is different, the literally eat, drink and breathe three times as much as an adult does on a weight basis, and certain behaviors, hand-to-mouth activities, and the larger skin surface to body size, means that they really absorb more from their environment than do adults.

CDC MODERATOR: The next question, please.

AT&T MODERATOR: The next question comes from Kathy Faculman [ph] at USA Today. Please go ahead.

QUESTION: The 116 chemicals that you looked for, how many did you find in the whole group? and also did you get an average number per person?

DR. : Okay, an average number per person. Can you tell me what you mean by that.

QUESTION: An average number of the total chemicals looked for.

DR. : Yes. We're not reporting the data in that manner, like we do not take a single individual--we're not reporting, saying there were X percent detects of the 116, or 80 of the 116 were detected, and the reason that we're not doing that is in the discussion in the report, we provide, what we've tried to do, to be very careful about interpreting each individual chemical, and it is very important to understand that the health risk and toxicology of each chemical is different and you can't make broad sweeping statements based on percentages or numbers.

You actually need to look at each chemical and see what's there, and that's actually how you determine the health risk, and if you look at the report, you'll see a section for each chemical that explains general background understanding of what it is and what its toxicity has been, and then you'll also see our best understanding of interpreting the levels.

So the short answer is we haven't reported stuff out that way but we would encourage you to look at the report because we have a lot of detail so that an interested person can find that kind of information for each individual chemical.

CDC MODERATOR: Is there a follow-up?

QUESTION: Yes. Of the 116 that you looked for, how many did you find in the whole group?

DR. : In the whole group? Well, we found all of them. If you're trying to say--I mean we were able to measure at least some of the 116 in at least one person. So that's the only way I can answer that question. If you're wanting to say, you know, did we--when we were explaining the dioxins and furans, the majority of dioxins and furans we were not able to measure in most people, but we still found some in all the people that we measured.

CDC MODERATOR: Thank you. Next question, please.

AT&T MODERATOR: The next question comes from the line of John Lowerman [ph] at Bloomberg News. Please go ahead.

QUESTION: Hi; thanks for taking the question. I understand what you're saying about lead levels, that they seem to be falling in, particularly in children, yet you're still concerned.

Is there anything else that particularly concerns you or that you think should be addressed in terms of exposure to chemicals other than lead?

DR. PIRKLE: Okay. This is Dr. Pirkle. It's a little bit of a vague question. All the things that we--

QUESTION: I just want to know what concerns you. Is there anything that you think something should be done about right away?

DR. PIRKLE: Okay. I think that what we would say is that all the chemicals that we're measuring in the report are important to us. These are things we want to look at and continually make assessments as to whether, you know, these things are at dangerous levels or things that we need to take action on.

We mentioned in the examples that we looked at, that there were--you know, in lead we want to keep working for children. The environmental tobacco smoke. We definitely want to keep working to reducing levels of that.

If you look through a number of other chemicals, there are levels that we're going to watch, we're going to pay close attention to how those levels change, so, you know, there's some level of concern in man places. But if you're asking is there some urgent alarm or something like that among other chemicals, then what I would say is that we haven't got an urgent alarm that's sounding.

DR. FLEMING: This is Dr. Fleming. I think that the important point here, really, is to look at this as a work in progress. We are getting new information, information that we've never had before, and when we and others look at that information, questions that can be answered by additional research will come up, and that's wonderful because that's our intent here, is to advance the scientific knowledge that we have regarding all of these chemicals so that better decisions can be made about ways to protect people from environmental hazards.

CDC MODERATOR: Thank you. Next question, please.

AT&T MODERATOR: The next question is coming from the line of Stan Harder [ph] at Science news Magazine. Please go ahead.

QUESTION: Hello. I have two questions. The first is on cotinine and the dioxin-like compounds. What baseline data were you using, when you referred to data from the '80s and the early '90s, and how comparable are they to the representative sample that you've got of the U.S. population in this case?

DR. PIRKLE: This is Dr. Pirkle. For cotinine, we actually measured cotinine in the same survey from 1988 to 1994, and so when we talk about population, and so when we talk about population levels of cotinine, it's very directly comparable, and this is a survey that was done in the past, that was another version of the NHANE survey, and so that's very directly comparable and a very good national estimate in both surveys.

When we talk about dioxin, this is the first time that dioxin and dioxin-like compounds have been measured in a sample that represents the U.S. population. This has never been done before. we've not had this data. There have, however, been selected studies across the United States that had control groups and other things in the studies and we have participated in those, and from looking at those studies in aggregate, we see much higher levels of dioxin in the 1980's than we do on the measurements that we're seeing now.

So we don't have a national sample from back then but we do have a series of smaller studies which had much higher levels.

QUESTION: Okay; thank you. My second question is I know that this is not fundamentally a look at the health impact of these compounds but many of the toxicity studies that you alluded to have looked at these compounds as individual actors, and I wonder what sort of interactions or possible health effects from interactions of multiple compounds seem to pop to the forefront based on the data that you've gathered in the study?

DR. JACKSON: This is Dick Jackson. We are working closely with the national toxicology program, the National Institute on Environmental Health Sciences.

They're the ones that actually do the in-depth toxicology and really assess the toxicology impacts along with ATSDR does it as well.

CDC's role really is to look at the practical levels in the U.S. population, to get out there, put hands on people and figure out what's out there, and then report back to the agencies that actually do the toxicology risk assessment. We view our role as more of a field investigation role, if you will.

DR. PIRKLE: Let me ask some to that. This is Dr. Pirkle. Like for some specific things that we mentioned, like the phthalates and the organophosphate pesticides, we are able to add together some of the analytes that we have to look at how they might additively affect an endpoint. For instance, when we look at the organophosphate pesticides, there are pesticides that break down to methyl, predominantly methyl metabolites, and pesticides that, as a group, break down not predominantly ethyl metabolites, and we can sum the ones in those two groups and they seem to affect the body in different ways, and that gives us information as kind of to the sum of the exposure for a group.

So we do have that for several groups of compounds that we have, where we're not talking just on an individual chemical, but we're able to talk about concentrations of chemicals that act through common pathways in the body.

But what you're talking about is a very scientifically challenging area and it's something that our data hopefully will make a big difference in because we'll be able to look at what the aggregate exposure of people is, not just a few metals, not just a few organophosphate pesticides, but people who are exposed to different groups of compounds at the same time.

CDC MODERATOR: Next question, please.

AT&T MODERATOR: The next question is coming from the line of John Nielsen at National Public Radio. Please go ahead.

QUESTION: Hi. I'm wondering if you can give a couple of specific examples of questions that it is impossible to answer on the basis of these two studies, just so that you can make the point and--I mean, I know there are many questions; but relevant questions. So that you can make that point instead of me.

DR. : Okay, questions that are impossible to answer based on these two studies. First of all, this is one study, so I'm not sure what the other study is.

QUESTION: The other one was the two years ago.

DR. : Okay. Oh, I'm sorry. The first report and the second. Things that are impossible to answer. I think I would go back to what Dr. Fleming had to say earlier and that is that the information that we're putting forward is exposure information, so we do not have new health effects information coming out from this report.

So it would not be possible to say that we have a new understanding of health effects from exposure to chemicals. That would be the biggest thing I'd want to be clear to people.

The second thing, though, that I would want to be clear to them is that this kind of information is what moves the science forward to answer those health effect questions, and by finding out what are in people and what levels are typical in the population, we're moving a lot of studies forward that will give us that information much faster.

CDC MODERATOR: I need to for a moment ask how many questions we have remaining.

AT&T MODERATOR: Actually, we have about ten or twelve that are in queue.

CDC MODERATOR: Okay. we are going to take two more questions. I would encourage everyone, that if you would like to pursue this further, again, please visit our Web site and look at the report in its entirety.

In addition, we will be scheduling interviews after the telebriefing concludes, so if you have need for further information please contact the CDC Media Relations Office at [404] 639-3286. May we take our next question, please.

AT&T MODERATOR: The next question comes from Suzanne Ballhan [ph] at Oakland Tribune.

QUESTION: Hi. Environmental groups state that the sheer volume of chemicals that these reports show that are getting into humans underscore a need for more extensive studies on the health effects of these chemicals before they're approved for release into the environment or for use in consumer products.

That these kind of precautions are used, certainly, for drugs. What are your thoughts on that?

DR. JACKSON: Suzanne, this is Dick Jackson. Clearly, a fair number of chemicals have been put into common commerce that were not adequately tested, particularly as pesticides were grandfathered in in the early '70s and '80s.

The scrutiny of, for example, new pesticides is much higher than it was in the past, particularly after the Food Quality Protection Act, and others, including putting protections in for children.

It's pretty clear that if you've got population exposure at a high level, it's important to begin to have the toxicology data when large numbers of people are being exposed.

DR. PIRKLE: This is Dr. Pirkle. I'd just like to add one thing to that, and that is to say that, you know, CDC is not a regulatory agency and one of the things that we're doing is passing this information on to EPA, FDA, and others who are concerned about setting the rules and setting the right amount of scientific review about things that are to be used, and we have talked with them about this and they are actually very positive about the benefit that this information will be on that process.

But that process covers a variety of factors and they are really the ones that make the ultimate consideration on that.

CDC MODERATOR: Is there a follow-up?

QUESTION: No, there isn't. Thank you.

CDC MODERATOR: Okay. This will be our final question. Again I would encourage you--I know there are a lot of other very good questions out there. We will attempt to answer everything.

If you have need for an interview, please call the Media Relations Office, [404] 639-3286. Ken, may we have our last question, please.

AT&T MODERATOR: Absolutely. Our next question is from Dan Denoon [ph] from WebMD.

QUESTION: Good morning. With 116 chemicals tested, isn't there something that raised eyebrows, that made you say, wow, this is something that we find alarming? I know that the main value of these studies is clearly the reference values that are sorely needed for future study and I understand that's the main value of this work, but as scientists and as citizens, aren't there some of these levels that you go wow, these are pretty amazing?

DR. : We resisted answering that question earlier, but, you know, one-third of all of our cancers are from tobacco. It's one of the big killers in America and the fact that more than half of our kids still have environmental tobacco smoke exposure when environmental tobacco smoke is known to be associated with sudden infant death syndrome, with ear infections, respiratory infections and the rest.

You know, if we had to pick something to really go after, that wold be one that I would really argue is an extraordinarily high priority and something people can actually do something about.

DR. FLEMING: This is Dr. Fleming; just to follow up. I think that what--the real surprising part of this is that we were able to do it. This is new information. This is not information that had been available before, so we really didn't have major preconceptions about what it is that we were going to find.

We, like you, are now going to have to sit down and look at this, and collectively decide what the best next steps for scientists and researchers are.

We do know, however, that the bottom line is that this report, the information that is in this report can and will be used to identify potential problems in the future.

DR. PIRKLE: This is Dr. Pirkle. I would just add to that that it is a lot of information. I know we've said that ten times, but when you pick up the report and flip through it and see all the tables of information, it is an enormous amount of information, and from a public health point of view, it's going to be a giant step forward for us in exposure information and make big differences in our ability to identify and prevent disease.

CDC MODERATOR: All right. We'd like to thank you very much this morning for participating. That's all the time we have for questions.

Now, again, as I stated previously, we did not have time to get to all questions, but if you do need further follow-up, please contact the CDC Office of Media Relations, [404] 639-3286.

In addition, if you joined us late and you'd like to listen to the telebriefing in its entirety, you'll be able to do so this afternoon at 3:30 p.m. Eastern time.

You will need to dial 1-800-475-6701. The access code is 670561. Let me repeat that. Again, to listen to the telebriefing in its entirety, that will take place this afternoon at 3:30 p.m. Eastern time. You'll need to dial 1-800-475-6701. The access code is 670561.

Again, the entire report will be available on our Web site at www.cdc.gov/exposurereport. That's all one word. In addition, a transcript from this morning's telebriefing will be available this afternoon between 3:00 and 4:00 p.m. Eastern time. I'm now being told that the transcript is available--

DR. : The Web site.

CDC MODERATOR: The Web site. Pardon me. I don't want to confuse anyone. The Web site is up and active, so you can go immediately to that and begin downloading that information.

Again, if you have further need for information, we will have our experts available.

Again, call [404] 639-3286. Again, thank you for participating. I will turn it now back over to our moderate, Ken.

AT&T MODERATOR: Ladies and gentlemen, that does conclude our conference for today. Thank you for your participation and for using AT&T Executive Teleconference. You may now disconnect.

Listen to the telebriefing

Media Home Page | Accessibility | Privacy Policy | Contact Us

CDC Home | Search | Health Topics A-Z

This page last updated January 31, 2003
URL: http://www.cdc.gov/media/transcripts/t030131.htm

United States Department of Health and Human Services
Centers for Disease Control and Prevention
Office of Communication
Division of Media Relations