Herbal Dietary Supplements: Examples of Deceptive or Questionable Marketing Practices and Potentially Dangerous Advice
Published: 2010-05-26T00:00:00

Fast Facts:

Highlights:
section_title: Why GAO Did This Study
paragraphs: Recent studies have shown that use of herbal dietary supplements--chamomile, echinacea, garlic, ginkgo biloba, and ginseng--by the elderly within the United States has increased substantially. Sellers, such as retail stores, Web sites, and distributors, often claim these supplements help improve memory, circulation, and other bodily functions. GAO was asked to determine (1) whether sellers of herbal dietary supplements are using deceptive or questionable marketing practices and (2) whether selected herbal dietary supplements are contaminated with harmful substances. To conduct this investigation, GAO investigated a nonrepresentative selection of 22 storefront and mail-order retailers of herbal dietary supplements. Posing as elderly consumers, GAO investigators asked sales staff (by phone and in person) at each retailer a series of questions regarding herbal dietary supplements. GAO also reviewed written marketing language used on approximately 30 retail Web sites. Claims were evaluated against recognized scientific research published by the National Institutes of Health (NIH) and the Food and Drug Administration (FDA). GAO also had an accredited lab test 40 unique popular single-ingredient herbal dietary supplements for the presence of lead, arsenic, mercury, cadmium, organichlorine pesticides, and organophosphorous pesticides.
section_title: What GAO Found
paragraphs: Certain dietary supplements commonly used by the elderly were deceptively or questionably marketed. FDA statutes and regulations do not permit sellers to make claims that their products can treat, prevent, or cure specific diseases. However, in several cases, written sales materials for products sold through online retailers claimed that herbal dietary supplements could treat, prevent, or cure conditions such as diabetes, cancer, or cardiovascular disease. When GAO shared these claims with FDA and the Federal Trade Commission (FTC), both agreed that the claims were improper and likely in violation of statutes and regulations. In addition, while posing as elderly customers, GAO investigators were often told by sales staff that a given supplement would prevent or cure conditions such as high cholesterol or Alzheimer's disease. To hear clips of undercover calls, see http://www.gao.gov/products/GAO-10-662T . Perhaps more dangerously, GAO investigators were given potentially harmful medical advice. For example, a seller stated it was not a problem to take ginkgo biloba with aspirin to improve memory; however, FDA warns that combining aspirin and ginkgo biloba can increase a person's risk of bleeding. In another case, a seller stated that an herbal dietary supplement could be taken instead of a medication prescribed by a doctor. GAO referred these sellers to FDA and FTC for appropriate action. GAO also found trace amounts of at least one potentially hazardous contaminant in 37 of the 40 herbal dietary supplement products tested, though none in amounts considered to pose an acute toxicity hazard. All 37 supplements tested positive for trace amounts of lead; of those, 32 also contained mercury, 28 cadmium, 21 arsenic, and 18 residues from at least one pesticide. The levels of heavy metals found do not exceed any FDA or Environmental Protection Agency (EPA) regulations governing dietary supplements or their raw ingredients, and FDA and EPA officials did not express concern regarding any immediate negative health consequences from consuming these 40 supplements. While the manufacturers GAO spoke with were concerned about finding any contaminants in their supplements, they noted that the levels identified were too low to raise any issues internal product testing.

section_title: Letter
paragraphs: Thank you for the opportunity to discuss findings from our investigation  into the manufacture and marketing of selected herbal dietary  supplements commonly used by the elderly. The Dietary Supplement  Health and Education Act of 1994 (DSHEA) defines dietary supplements as  products that, among other things, are intended for ingestion to  supplement the diet, labeled as dietary supplements, and not represented  as conventional foods or as a sole items of a meal or diet. Recent studies  have shown that use of herbal dietary supplements, such as chamomile,  echinacea, garlic, ginkgo biloba, and ginseng, by the elderly in the United  States has increased substantially.
In 2000, we reported that consumers did not consistently receive clear,  scientifically supported information concerning products’ health benefits  so they could make informed dietary choices. Further, we have reported  that consumers faced health risks because federal laws and agencies’  efforts did not effectively and consistently ensure that dietary supplements  were safe. Most recently, we expressed concern that weaknesses in the  regulatory system may increase the likelihood of unsafe products reaching  the market, and a lack of consumer knowledge increases the potential  health risks associated with uninformed consumption. At your request,  we determined (1) whether sellers of herbal dietary supplements are using  deceptive or questionable marketing practices to encourage the use of  these products and (2) whether selected herbal dietary supplements are  contaminated with harmful substances.
To determine whether sellers of herbal dietary supplements are using  deceptive or questionable marketing practices to encourage the use of these  products, we investigated a nonrepresentative selection of 22 storefront and  mail-order retailers. We identified these retailers by searching online using  search terms likely to be used by actual consumers and by observing  newspaper advertisements. Posing as elderly potential consumers, we asked  sales staff at each retailer a series of questions regarding the potential health  benefits of herbal dietary supplements as well as potential interactions with  other common over-the-counter and prescription drugs. We also reviewed  written marketing language used on approximately 30 retail Web sites. We  evaluated the accuracy of product marketing claims against health benefit  evaluations published through the National Institutes of Health (NIH) and  Food and Drug Administration (FDA). While our work focused on herbal  dietary supplements, we also evaluated claims made regarding nonherbal  supplement products recommended to us during undercover storefront  visits and telephone calls.
To determine whether selected herbal dietary supplements are  contaminated with harmful substances, we purchased 40 unique single- ingredient herbal supplement products from 40 different manufacturers  and submitted them to an accredited laboratory for analysis. We selected  the types of herbs to purchase based on recent surveys about the  supplements usage of the elderly. These surveys identified the most  commonly used herbs among the elderly as chamomile, echinacea, garlic,  ginkgo biloba, ginseng, peppermint, saw palmetto, and St. John’s wort. We  purchased these 40 unique products from a combination of retail chain  storefronts and online or mail-order retailers; these retailers were selected  independently from those selected for evaluation of marketing practices.  For each online retailer, we selected brands based primarily on relative  popularity according to the site’s list of top sellers. One unopened,  manufacturer-sealed bottle of each of these 40 products was submitted to  an accredited laboratory where they were screened for the presence of  common hazardous contaminants: lead, arsenic, mercury, cadmium, and  residues from organichlorine and organophosphorous pesticides. These  contaminants were selected based on prevalence and the likelihood of  negative health consequences as a result of consumption. We did not  independently validate the results received with another lab, or through  any other mechanism. The likely negative health consequences from  consumption of these contaminants were determined based on a review of  relevant health standards and discussions with FDA and Environmental  Protection Agency (EPA) experts. For a complete discussion of our scope  and methodology, see appendix I. See appendix II for the complete list of  contaminants we reviewed.
Our investigative work, conducted from September 2009 through March  2010, was performed in accordance with standards prescribed by the  Council of the Inspectors General on Integrity and Efficiency.
subsections: section_title: Background
paragraphs: Herbal dietary supplements are traditionally used to alleviate certain  medical conditions, such as anxiety, digestive problems, and depression,  and to improve general quality of life. However, for many traditional uses,  there is not clear scientific evidence to show that they prevent or treat  underlying diseases or conditions. Further, some herbal dietary  supplements may interact in a potentially harmful manner with some  prescription drugs. For example, according to NIH, St. John’s wort can  negatively affect the efficacy of antidepressants, HIV treatments, cancer  drugs, and anticoagulants, though this is not always noted on product  labels. The possibility of adverse drug interactions is one of the reasons  that FDA recommends that consumers check with their health  practitioners before beginning any supplement regimen. The elderly are  particularly at risk from these interactions since recent studies have found  that approximately 85 percent of the elderly take at least one prescription  drug over the course of a year and 58 percent take three or more. Many  herbal supplements have not been exhaustively tested for hazardous  interactions with prescription drugs, other supplements, or foods.
Under DSHEA, dietary supplements are broadly presumed safe, and FDA  does not have the authority to require them to be approved for safety and  efficacy before they enter the market, as it does for drugs. However, a  dietary supplement manufacturer or distributor of a supplement with a  “new dietary ingredient”—an ingredient that was not marketed in the  United States before October 15, 1994—may be required to notify FDA at  least 75 days before marketing the product, depending on the history of  use of the ingredient. Also, all domestic and foreign companies that  manufacture, package, label, or hold dietary supplements must follow  FDA’s current good manufacturing practice regulations, which outline  procedures for ensuring the quality of supplements intended for sale.
subsections: section_title: Marketing Claims
paragraphs: Under DSHEA, a firm, not FDA, is responsible for determining that any  representation or claims made about the dietary supplements it  manufactures or distributes are substantiated by adequate evidence to  show that they are not false or misleading. Except in the case of a new  dietary ingredient, where premarket review for safety data and other  information is required by law, a firm does not have to provide FDA with  the evidence it relies on to substantiate effectiveness before or after it  markets its products. For the most part, FDA relies on postmarket  surveillance efforts—such as monitoring adverse event reports it receives  from companies, health care practitioners, and individuals; reviewing  consumer complaints; and conducting facility inspections—to identify  potential safety concerns related to dietary supplements. Once a safety  concern is identified, FDA must demonstrate that the dietary supplement  presents a significant or unreasonable risk, or is otherwise adulterated,  before it can be removed from the market.
A product sold as a dietary supplement cannot suggest on its label or in  labeling that it treats, prevents, or cures a specific disease or condition  without specific approval from FDA. Under FDA regulations, a  manufacturer may submit a health claim petition in order to use a claim on  its product labeling that characterizes a relationship between the product  and risk of a disease, and FDA may authorize it provided the claims meet  certain criteria and are authorized by FDA regulations (e.g., diets high in  calcium may reduce the risk of osteoporosis). However, manufacturers  may make “qualified health claims” when there is emerging evidence for a  relationship between a dietary supplement and reduced risk of a disease  or condition, subject to FDA’s enforcement discretion. The claim must  include specific qualifying language to indicate that the supporting  evidence is limited.
Dietary supplement labeling may include other claims describing how a  dietary ingredient is intended to affect the normal structure or function of  the body (e.g. fiber maintains bowel regularity). The manufacturer is  responsible for ensuring the accuracy and truthfulness of such claims, but  must submit a claim to FDA for review no later than 30 days after  marketing it. Because FDA does not confirm the claim—a lack of  objection allows the manufacturer to use it—the following disclaimer  must be included: “This statement has not been evaluated by the FDA. This  product is not intended to diagnose, treat, cure, or prevent any disease.”  The manufacturer does not need to provide FDA with documentation, and  FDA does not test to determine if the claim is true.
In addition, these claims generally may not state that a product is intended  to diagnose, mitigate, treat, cure, or prevent a disease or the adverse  effects associated with a therapy for a disease, either by naming or  describing a specific disease. A claim also cannot suggest an effect on an  abnormal condition associated with a natural state or process, such as  aging. Context is a consideration; a product’s name and labeling cannot  imply such an effect by use of pictures or scientific or lay terminology.  Finally, a product cannot claim to be a substitute for a product that is a  therapy for a disease, or claim to augment a therapy or drug. To make any  of these claims, a manufacturer must submit and receive authorization of a  health claim petition.
The Federal Trade Commission (FTC) regulates advertising for dietary  supplements and other products sold to consumers. FTC receives  thousands of consumer complaints each year related to dietary  supplements and herbal remedies. FTC has, in the past, taken action  against supplement sellers and manufacturers whose advertising was  deemed to pose harm to the general public. FDA works with FTC in this  area, but FTC’s work is directed by different laws.
section_title: Harmful Substance Contamination
paragraphs: Consuming high levels of the contaminants for which we tested the 40  products can lead to severe health consequences, such as increased risk of  cancer, as noted in table 1. The negative health effects described are,  unless otherwise noted, for the acute toxicity in the human body.  However, the exact effects of these contaminants on an individual are  based on an individual’s specific characteristics. For instance, since lead  can build up in the human body, the effect of consuming a potentially  dangerous level of lead by a 55-year-old man depends on the amount of  lead that man has consumed during his lifetime, among other factors.
FDA has not issued any regulations addressing safe or unsafe levels of  contaminants in dietary supplements, but both FDA and EPA have set  certain advisory levels for contaminants in other foods. The human body’s  absorption of many contaminants is governed by intake method, so  advisory levels for other foods (e.g., drinking water) cannot be strictly  applied to dietary supplements. In addition, EPA sets limits on how much  pesticide residue can remain on food and feed products. These pesticide  residue limits are known as tolerances and are enforced by FDA. If no  residue tolerance has been set for a particular pesticide, any product  containing that pesticide residue is considered adulterated and its sale is  prohibited by law. See table 2 for a summary of the regulations issued by  FDA or EPA regarding some of the contaminants we tested for.
section_title: Deceptive or Questionable Marketing Claims May Lead to Harm for Elderly Consumers of Herbal Supplements
paragraphs: Our investigation found examples of deceptive or questionable marketing  and sales practices for dietary supplements popular among the elderly (see  table 3). The most egregious practices included suspect marketing claims  that a dietary supplement prevented or cured extremely serious diseases,  such as cancer and cardiovascular disease. Other dietary supplements  were claimed to mitigate age-related medical conditions, such as  Alzheimer’s disease and diverticular disorder. We also found some claims  that followed FDA’s labeling regulations and guidelines, but could still be  considered deceptive or questionable and provide consumers with  inaccurate information. In addition, while conducting in-person and  telephone conversations with dietary supplements sellers, our  investigators, posing as elderly consumers, were given potentially harmful  medical advice by sales staff, including that they could take supplements  in lieu of prescription medication. In making these claims, sellers put the  health of consumers at risk. A link to selected audio clips from these calls  is available at: http://www.gao.gov/products/GAO-10-662T.
Below are details on several cases in which herbal supplement marketing  practices were deceptive or questionable and sometimes posed health  risks to consumers. All cases of deceptive or questionable marketing and  inappropriate medical advice have been referred to FDA and FTC for  appropriate action.
Case 2: In online materials, this garlic supplement included claims that it  would (1) prevent and cure cardiovascular disease, (2) prevent and cure  tumors and cancer, (3) prevent obesity, and (4) reduce glycemia to prevent  diabetes. According to NIH, all these claims are unproven, and garlic is not  recommended for treating these conditions. In fact, for several of these  conditions, garlic may interact adversely with common FDA-approved  drug treatments. Nowhere in this product’s marketing materials does the  seller suggest that consumers should consult their health care providers  prior to taking its supplement. While NIH recognizes that garlic may have  some anticancer properties, the agency notes that additional clinical trials  are needed to conclude whether these properties are strong enough to  prevent or treat cancer. Further, studies have shown that garlic may alter  the levels of some cancer drugs in the human body, lessening their  effectiveness. For diabetes, there are no studies that confirm that garlic  lowers blood sugar or increases the release of insulin in humans. In fact,  NIH recommends caution when combining garlic with medications that  lower blood sugar, and further suggests that patients taking insulin or oral  drugs for diabetes be monitored closely by qualified health care  professionals.
Case 3: According to its labeling, this ginseng supplement—which costs  $500 for a 90-day supply—cures diseases, effectively prevents diabetes and  cardiovascular disease, and prevents cancer or halts its progression. These  claims are unproven—no studies confirm that ginseng can prevent or cure  any disease. In fact, NIH recommends that breast and uterine cancer  patients avoid ginseng. In addition, ginseng may adversely interact with  cancer drugs. The product labeling claims do not differentiate between  type 1 and type 2 diabetes. According to NIH, ginseng’s effect on patients  with type 1 diabetes is not well studied. While ginseng may lower blood  sugar levels in patients with type 2 diabetes, the long-term effects of such a  treatment program are unclear, and it is not known what doses are safe or  effective. NIH specifically recommends that consumers with type 2  diabetes use proven therapies instead of this supplement.
Case 7: While our investigators posed as consumers purchasing dietary  supplements, sales staff provided them with an informational booklet  regarding an enzyme that claims to “ us against dementia and  Alzheimer’s, exhibiting a truly miraculous capacity to optimize mental  performance and fight off cognitive decline.” In fact, FDA reviewed the  scientific evidence for the active ingredient of this supplement and found  that it was not adequate to make such a claim. Because the agency  considered such a health claim potentially misleading, FDA provided for  the use of a qualified health claim that contains a disclaimer that must  accompany the health claim in all labeling in which these claims appear.  While the booklet we received does state the FDA disclaimer on the first  page, the manufacturer follows it with a rejoinder: “The very cautious  language of these claims, which FDA mandates can only be stated word  for word, is at best a grudging concession to the extensive clinical  research done with . Considering this agency’s legendary  toughness against dietary supplements, FDA’s willingness to go this far  with the  suggests that the FDA must be sure it is safe to take  and also that the FDA is unable to deny  can improve  human brain function.”
Case 8: One of our fictitious consumers visited a supplement specialty  store looking for a product that would help with high blood pressure. The  sales representative recommended a garlic supplement and stated that the  product could be taken in lieu of prescribed blood pressure medication.  According to NIH, while this herb may lower blood pressure by a small  amount, the scientific evidence is unclear. NIH does not recommend this  supplement as a treatment for high blood pressure and warns patients to  use caution while taking this product with other drugs or supplements that  can lower blood pressure. Further, it is not recommended that a consumer  start or stop a course of treatment without consulting with his or her  health care provider. Even if a sales representative is licensed to dispense  medical advice, he or she still does not know the consumer’s patient  history, including other drug programs, allergies, and medical conditions,  making it potentially dangerous for the sales representative to provide  medical advice.
Case 9: At a supplement specialty store, one of our investigators posed as  an elderly consumer who was having difficulty remembering things. A  sales representative recommended one of the store’s ginkgo biloba  supplements. The consumer told the representative that he takes aspirin  everyday and asked if it was safe to take aspirin and ginkgo biloba  together. The sales representative told him that it is completely safe to  take the two together. However, according to FDA, if aspirin is taken with  the recommended product, it can increase the potential for internal  bleeding.
We spoke to FDA and FTC regarding these 10 claims, and they agreed that  the statements made in product labeling for cases 1 through 6 are largely  improper, as the labeling suggests that each product has an effect on a  specific disease. For case 7, FDA stated that while the specific claims  discussed here are allowable, depending on the context in which they  were made, FDA might consider the totality of marketing materials to be  improper. FDA also agreed that the claims made to our undercover  investigators in cases 8 and 10 were questionable or likely constituted  improper disease claims, but that to take action, additional information as  to the prevalence and context of the claims would be necessary. For case  9, FDA noted that, since the statement made by sales staff was safe usage  information, not a claim about the product’s effects, it would not violate  FDA regulations, unless the agency could develop other evidence to show  that the claim was false or misleading or constituted an implied disease  claim. In addition, FDA and NIH both noted that by definition, no dietary  supplement can treat, prevent, or cure any disease.
section_title: Trace Contaminants Found in Selected Herbal Dietary Supplements, but None Pose an Acute Toxicity Hazard to Humans
paragraphs: We found trace amounts of at least one potentially hazardous contaminant  in 37 of the 40 herbal dietary supplement products we tested, though none  of the contaminants were found in amounts considered to pose an acute  toxicity hazard to humans. Specifically, all 37 supplements tested  positive for trace amounts of lead. Thirty-two also contained mercury, 28  contained cadmium, 21 contained arsenic, and 18 contained residues from  at least one pesticide. See appendixes III and IV for the complete results  of these tests.
The levels of contaminants found do not exceed any FDA or EPA  regulations governing dietary supplements or their raw ingredients, and  FDA and EPA officials did not express concern regarding any immediate  negative health consequences from consuming these 40 supplements.  However, because EPA has not set pesticide tolerance limits for the main  ingredients of the herbal dietary supplements we tested, the pesticide  contaminants exceed FDA advisory levels. FDA agreed that 16 of the 40  supplements we tested would be considered in violation of U.S. pesticide  tolerances if FDA, using prescribed testing procedures, confirmed our  results. We note that 4 of the residues detected are from pesticides that  currently have no registered use in the United States. According to FDA,  scientific research has not been done on the long-term health effects from  consumption of such low levels of many of these specific contaminants, as  current technology cannot detect these trace contaminants when they are  diluted in human bloodstreams. We have referred these products to FDA  for its review.
After reviewing test results with EPA and FDA officials, we also spoke  with several of the manufacturers of supplements that had trace amounts  of contaminants. The manufacturers we spoke with stated that they  ensure that their products are tested for contamination, and that these  tests have shown that their products do not contain contaminants in  excess of regulatory standards. Manufacturers also stated that they  comply with all FDA regulations and follow good manufacturing practices  as defined by the agency. While the manufacturers we spoke with were  concerned about finding any contaminants in their supplements, they  noted that the levels identified were too low to raise any issues during  their own internal product testing processes.
Mr. Chairman, this concludes my statement. I would be pleased to answer  any questions that you or other members of the committee may have at  this time.
section_title: Contacts and Acknowledgments
paragraphs: For further information about this testimony, please contact Gregory D.  Kutz at (202) 512-6722 or kutzg@gao.gov. Contact points for our Offices of  Congressional Relations and Public Affairs may be found on the last page  of this testimony. Individuals who made major contributions to this  testimony were Jonathan Meyer and Andrew O’Connell, Assistant  Directors; John Ahern; Dennis Fauber; Robert Graves; Cristian Ion;  Elizabeth Isom; Leslie Kirsch; Barbara Lewis; Flavio Martinez; James  Murphy; Ramon Rodriguez; Tim Walker; and John Wilbur.
section_title: Appendix I: Scope and Methodology
paragraphs: To determine whether sellers of herbal dietary supplements are using  deceptive or questionable marketing practices to encourage the use of  these products, we investigated a nonrepresentative selection of 22  storefront and mail-order retailers selling herbal dietary supplements. We  identified these retailers by searching online using search terms likely to  be used by actual consumers and by observing newspaper advertisements.  Posing as elderly customers, we asked sales staff at each company a series  of questions regarding the potential health benefits of herbal dietary  supplements as well as potential interactions with other common over-the- counter and prescription drugs. While our work focused on herbal dietary  supplements, we also evaluated claims made regarding nonherbal  supplement products during undercover storefront visits and telephone  calls. We also reviewed written marketing language used on approximately  30 retail Web sites. We evaluated the accuracy of product marketing  claims against health benefit evaluations published through the National  Institutes of Health and Food and Drug Administration (FDA).
To determine whether selected herbal dietary supplements were  contaminated with harmful substances, we purchased 40 unique single- ingredient herbal supplement products from 40 different manufacturers  and submitted them to an accredited laboratory for analysis. We selected  the types of herbs to purchase based on recent surveys about the  supplements usage of the elderly, defined for this report as individuals  over the age of 65. These surveys identified the most commonly used  herbs among the elderly as chamomile, echinacea, garlic, ginkgo biloba,  ginseng, peppermint, saw palmetto, and St. John’s wort.
We purchased these 40 unique products from a combination of retail chain  storefronts and online or mail-order retailers. For each online retailer, we  selected products based primarily on relative popularity according to the  site’s list of top sellers. At each retail chain storefront, because of limited  selection, we selected only items that would be expected to be sold at all  chain locations. All 40 products were submitted to an accredited  laboratory where they were screened for the presence of lead, arsenic,  mercury, cadmium, and residues from organichlorine and  organophosphorous pesticides. These contaminants were selected based  on prevalence and the likelihood of negative health consequences due to  consumption. The recommended daily intake levels of these contaminants  and the likely negative health consequences because of consumption were  determined based on a review of relevant health standards and  discussions with FDA and Environmental Protection Agency experts.
For each herbal dietary supplement product, we submitted one unopened,  manufacturer-sealed bottle to the laboratory for analysis. To identify levels  of arsenic, cadmium, lead, and mercury, products were analyzed using  inductively coupled plasma mass spectrometry according to method AOAC  993.14. Detection limits for these contaminants were .075  milligrams/kilogram, .010 milligrams/kilogram, .005 milligrams/kilogram,  and .050 nanograms/gram, respectively. To identify levels of pesticide  residues, products were analyzed using a variety of residue-specific  methods, including those methods published in the FDA Pesticide  Analytical Manual. We did not independently validate the results received  with another lab or through any other mechanism. See appendix II for a  complete list of analytes and their related detection levels.
section_title: Appendix II: Full List of Analytes and Detection Limits
paragraphs: Detection limit (ppm)
Detection limit (ppm)
Dacthal (DCPA)
Diazinon (O Analog)
Endosulfan I (alpha-endosulfan)
Detection limit (ppm)
Detection limit (ppm)
Endosulfan II (beta-Endosulfan)
Malathion OA (Malaoxon)
Detection limit (ppm)
Detection limit (ppm)
Quintozene (PCNB)
S 421 (Octachlordipropylether)
Detection limit (ppm)
Detection limit (ppm)
Parts per million is a measure equivalent to milligrams per kilogram or milligrams per liter.
section_title: Appendix III: Contaminants Found in Selected Herbal Dietary Supplements (in Parts per Million)
section_title: Appendix IV: Pesticide Residues Identified in Selected Herbal Dietary Supplements (in Parts per Million)
paragraphs: Chlorpyrifos (Dursban)
St. John’s wort  gamma-HCH (Lindane)
Chlorpyrifos (Dursban)
Hexachlorobenzene (HCB)
Dacthal (DCPA)
This is a work of the U.S. government and is not subject to copyright protection in the  United States. The published product may be reproduced and distributed in its entirety  without further permission from GAO. However, because this work may contain  copyrighted images or other material, permission from the copyright holder may be  necessary if you wish to reproduce this material separately.