Food Dyes
A Rainbow of Risks

SUMMARY OF STUDIES ON FOOD DYES
Food dyeAllergic reactions

Carcinogenic
contaminants

Tests for cancer*

Other**

Mouse

Rat

No in utero studies.
One abstract (study
not published)reported kidney
tumors.

No tumors in the
only good study.

Blue 2

Both studies were
too brief and did
not include in utero
exposure.

Dosage was likely
too low; possible
brain and bladdertumors.

Citrus Red 2(used only on
peels of someoranges at 2 ppm)

Bladder and othertumorsBladder tumors

Green 3The only study did
not include in utero
exposure.

Possible bladderand other tumors

Orange B(no longer used;in 1978 FDA proposed, but never
finalized, a ban)

The only two studies
did not include inutero exposure.

Toxic

Red 3
(FDA has banned
it from cosmetics,
externally applieddrugs, and lakes)

The only study did
not include in utero
exposure.

Thyroid tumors

Yes

Blue 1

Red 40Yes

p-Cresidine

Possible reticuloendothelial tumors of
the immune system

No tumors in the
only good study

Yellow 5

Yes

Benzidine,
4-amino-biphenyl

Only mouse study
was too brief, used
too few mice, andbegan with 6-weekold mice.

No tumors in the
only good study

Yellow 6

Yes

Benzidine,
4-amino-biphenyl

Neither study
included in utero
exposure.

Possible adrenal
and testiculartumors.

Test tube study
found inhibitionof nerve-celldevelopment.

6 of 11 studies
showed genotoxicity.
Hyperactivity inchildren.

*T ests should be done on both sexes of two rodent species, use sufficient numbers of animals, include in utero exposure, lastat least two years after birth, and use maximally tolerated dosages. Ideally, tests would be conducted by independent labs,
but most tests on dyes were conducted by industry.
** I n addition, numerous studies have found that mixtures of dyes cause hyperactivity and other behavioral impairments inchildren.

The colors on the front cover and the chapter headings are approximations. The exact color ofdyes depends on concentration, pH, nature of the food, and other factors. Back cover photo(by Michael Jacobson, CSPI) of cupcakes with natural colorings made by D.D. Williamson Co.

Food Dyes
A Rainbow of Risks

Sarah Kobylewski, Ph.D. Candidate
Molecular Toxicology Program
University of California, Los Angeles
andMichael F. Jacobson, Ph.D.
Executive Director
Center for Science in the Public Interest

FOOD DYES

A Rainbow of Risks

Acknowledgments
We are grateful to Kamal M. Abdo, Ph.D., retiree of the National Toxicology Programat the National Institute of Environmental Health Sciences for his thoughtful reviewof this report. We also thank Shula Edelkind, research and information director of
the Feingold Association of the United States; Michael J. Prival, Ph.D.; and Dale B.
Hattis, Ph.D., of Clark University for highlighting and clarifying the issue of carcinogenic contaminants in dyes. Judith Kidwell of the U.S. Food and Drug Administration
kindly provided information about acceptable intakes of dyes, Aspan Dahmubed provided useful edits, and Masaru Shinyashiki of UCLA interpreted a Japanese-language
article. However, it is the authors alone who are responsible for the contents of thisreport and any errors in facts or judgments.
The Center for Science in the Public Interest thanks the Freed Foundation, Park
Foundation, and Wacker Foundation for their generous financial support for thisproject.
Report designed by Debra Brink.

Copyright © 2010 by Center for Science in the Public Interest
First Printing June 2010
Printing: 5 4 3 2 1
The Center for Science in the Public Interest (CSPI), founded in 1971, is a non-profit
health-advocacy organization that conducts education, research, and advocacy programs in nutrition and food safety. CSPI is supported by its 850,000 members in the
United States and Canada and by foundation grants.
Center for Science in the Public Interest
1875 Connecticut Avenue, NW, Suite 300 • Washington, DC 20009
Suite 2701, CTTC Building • 1125 Colonel By Drive
Ottawa, Ontario K1S 5R1
Tel: 202-332-9110 • Fax: 202-265-4954
Email: cspi@cspinet.org • www.cspinet.org

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Contents
Abbreviations.............................................................. iv
Summary.......................................................................v
Overview.......................................................................1
FD&C Blue No. 1............................................................9
FD&C Blue No. 2..........................................................13
Citrus Red No. 2..........................................................19
FD&C Green No. 3......................................................21
Orange B.....................................................................24
FD&C Red No. 3..........................................................25
FD&C Red No. 40........................................................29
FD&C Yellow No. 5.......................................................33
FD&C Yellow No. 6.......................................................38
Appendix – Genotoxicity Studies..............................43
Endnotes ....................................................................50

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Abbreviations
ADI: Acceptable Daily Intake
CCMA: Certified Color Manufacturers Association
CSPI: Center for Science in the Public Interest
FDA: U.S. Food and Drug Administration
FD&C: Foods, drugs, and cosmetics
GI: Gastrointestinal
HRG: Health Research Group (of Public Citizen)
IARC: International Agency for Research on Cancer
mg/kg bw/day: milligrams per kilogram of body weight per day
MTD: maximum tolerated dosage
NOAEL: No observable adverse effects level
NOEL: No observable effects level
NTP: National Toxicology Program
ppm: parts per million
RE: reticuloendothelialµg: microgramµM: micromolar

v

FOOD DYES

A Rainbow of Risks

Summary
Food dyes, synthesized originally from coal tar and now petroleum, have long been
controversial. Many dyes have been banned because of their adverse effects on laboratory animals. This report finds that many of the nine currently approved dyes raise
health concerns.
Blue 1 was not found to be toxic in key rat and mouse studies, but an unpublishedstudy suggested the possibility that Blue 1 caused kidney tumors in mice, and a
preliminary in vitro study raised questions about possible effects on nerve cells. Blue
1 may not cause cancer, but confirmatory studies should be conducted. The dye cancause hypersensitivity reactions.
Blue 2 cannot be considered safe given the statistically significant incidence of tumors, particularly brain gliomas, in male rats. It should not be used in foods.
Citrus Red 2, which is permitted only for coloring the skins of oranges not used forprocessing, is toxic to rodents at modest levels and caused tumors of the urinary bladder and possibly other organs. The dye poses minimal human risk, because it is onlyused at minuscule levels and only on orange peels, but it still has no place in the foodsupply.
Green 3 caused significant increases in bladder and testes tumors in male rats.
Though the Food and Drug Administration (FDA) considers it safe, this little-used dye
must remain suspect until further testing is conducted.
Orange B is approved for use only in sausage casings, but has not been used formany years. Limited industry testing did not reveal any problems.
Red 3 was recognized in 1990 by the FDA as a thyroid carcinogen in animals andis banned in cosmetics and externally applied drugs. All uses of Red 3 lakes (combinations of dyes and salts that are insoluble and used in low-moisture foods) are alsobanned. However, the FDA still permits Red 3 in ingested drugs and foods, with
about 200,000 pounds of the dye being used annually. The FDA needs to revoke thatapproval.
Red 40, the most-widely used dye, may accelerate the appearance of immune-system
tumors in mice. The dye causes hypersensitivity (allergy-like) reactions in a small
number of consumers and might trigger hyperactivity in children. Considering thesafety questions and its non-essentiality, Red 40 should be excluded from foods unlessand until new tests clearly demonstrate its safety.
Yellow 5 was not carcinogenic in rats, but was not adequately tested in mice. It may
be contaminated with several cancer-causing chemicals. In addition, Yellow 5 causes

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FOOD DYES

A Rainbow of Risks
sometimes-severe hypersensitivity reactions in a small number of people and might
trigger hyperactivity and other behavioral effects in children. Posing some risks, whileserving no nutritional or safety purpose, Yellow 5 should not be allowed in foods.
Yellow 6 caused adrenal tumors in animals, though that is disputed by industry andthe FDA. It may be contaminated with cancer-causing chemicals and occasionallycauses severe hypersensitivity reactions. Yellow 6 adds an unnecessary risk to the foodsupply.
Almost all the toxicological studies on dyes were commissioned, conducted, andanalyzed by the chemical industry and academic consultants. Ideally, dyes (and otherregulated chemicals) would be tested by independent researchers. Furthermore, virtually all the studies tested individual dyes, whereas many foods and diets contain mixtures of dyes (and other ingredients) that might lead to additive or synergistic effects.
In addition to considerations of organ damage, cancer, birth defects, and allergic
reactions, mixtures of dyes (and Yellow 5 tested alone) cause hyperactivity and otherbehavioral problems in some children. Because of that concern, the British government advised companies to stop using most food dyes by the end of 2009, and theEuropean Union is requiring a warning notice on most dye-containing foods after July20, 2010. The issue of food dyes and behavior has been discussed in a separate CSPI
report and petition calling on the FDA to ban most dyes.
Because of those toxicological considerations, including carcinogenicity, hypersensitivity reactions, and behavioral effects, food dyes cannot be considered safe.The FDA
should ban food dyes, which serve no purpose other than a cosmetic effect, thoughquirks in the law make it difficult to do so (the law should be amended to make it
no more difficult to ban food colorings than other food additives). In the meantime,companies voluntarily should replace dyes with safer, natural colorings.

1

FOOD DYES

A Rainbow of Risks

Overview
It is said that we “eat with our eyes as much as with our mouths,” and that’s certainly
the case when we walk down the aisles of a supermarket. Fresh produce beckons
us with its vivid colors and organic shapes,
brightly colored packages and images seek
Table 1. Food Dye Certification
to draw our eyes to those brands instead ofby the FDA in Fiscal Year 2009
competitors, and countless products—from
Food DyePounds of Total Dye Certified Percentage
Jell-O to Froot Loops—are colored with(includes lakes)of Totalbright synthetic dyes that turn unattractive
Blue 1
711,659
4.7
21 CFR 74.101
mixtures of basic ingredients and food addiBlue 2
tives into alluring novelties.1
550,883

3.7

Citrus Red 2
21 CFR 74.302

1,764

0.0

Green 321 CFR 74.203

15,8170.1

Orange B
21 CFR 74.250

0

0.0

Red 3
21 CFR 74.303

216,235

1.4

Red 4021 CFR 74.340

6,205,374

41.3

Yellow 5
21 CFR 74.705

3,756,551

25.0

Yellow 6
21 CFR 74.706

3,558,351

23.7

TOTAL

15, 016,634

100

21 CFR 74.102

Dyes are complex organic chemicals thatwere originally derived from coal tar, but
now from petroleum. Companies like using
them because they are cheaper, more stable,
and brighter than most natural colorings.
However, consumers’ growing preference fornatural foods is leading some companies toeither not add colorings or to switch to safe
natural colorings, such as beta-carotene (aprecursor to vitamin A), paprika, beet juice,and turmeric (see back cover). That trend
is stronger in Europe than the United States,
but some U.S. companies recognize that an“All Natural” label can attract customers andmay be moving in that direction.

Unlike other food additives, dyes are not permitted to be used unless the U.S. Foodand Drug Administration (FDA) has tested and certified that each batch meets thelegal specifications. One benefit of the certification process is that it provides information about the amounts of dyes sent into commerce each year for use in foods,
drugs, and cosmetics (see Table 1). Just three dyes—Red 40, Yellow 5, and Yellow
6—account for 90 percent of all dyes used. The FDA’s data show a dramatic five-foldincrease in consumption of dyes since 1955 (see Figure 1). That increase is a good
indication of how Americans increasingly have come to rely on processed foods, suchas soft drinks, breakfast cereals, candies, snack foods, baked goods, frozen desserts,
and even pickles and salad dressings, that are colored with dyes.

1. For a list of all approved synthetic and natural colorings, see FDA (2007).

2

FOOD DYES

A Rainbow of Risks

Carcinogenicity
Long-term animal feeding studies are done to determine whether long-term exposure
to dyes causes cancer or other effects. However, most of the studies reviewed in thisreport suffer from several significant limitations. First, most of the studies were commissioned or conducted by dye manufacturers, so biases could influence the design,
conduct, or interpretation of the studies. Ideally, the tests would have been conducted
and interpreted by independent scientists. Second, most of the studies lasted nolonger than two years—and some were much
shorter. Also, many studies did not include
an in utero phase. Chronic bioassays would be
more sensitive if they lasted from conception
through 30 months or the natural lives of therodents (as long as 3 years) (Huff, Jacobson etal. 2008).

70

mg/capita/day

60
50
40
30
20
10
0

1955

1975

1998

2009

Figure 1. Food dyes marketed per capita per day (mg).
Based on FDA data of certification of straight dyes and lakes (adjusted by the authors
for percentage of pure dyes) and current U.S. population.

Another consideration of unknown importanceis that virtually all the studies evaluated thesafety of individual dyes. Many foods, though,contain mixtures of dyes, such as the Blue 1,
Blue 2, Red 40, Yellow 5, and Yellow 6 inKellogg’s Hot Fudge Sundae Pop Tarts. Dyes
conceivably could have synergistic (or, indeed,antagonistic) effects with one another or withother food additives or ingredients.

It is worth noting that dyes are not pure chemicals, but may contain upwards of
10 percent impurities that are in the chemicals from which dyes are made or develop
in the manufacturing process. For instance, Yellow 5, the second-most widely used
dye, may contain up to 13 percent of a witch’s brew of organic and inorganic chemicals (FDAg).2
Certain of those contaminants, such as 4-aminobiphenyl, 4-aminoazobenzene, andbenzidine, are carcinogens, but are supposed to be present at safely negligible levels inthe dyes (FDA 1985). Any carcinogenic effects of those low-level contaminants would
not be detected in animal studies of the dyes.
2. Constituents permitted in Yellow 5: 4,4’-[4,5-Dihydro-5-oxo-4-[(4-sulfophenyl)hydrazono]-1H-pyrazol-1,3-diyl]bis[benzenesulfonic acid], trisodium salt, not more than 1 percent; 4-[(4’,5-Disulfo[1,1’-biphenyl]-2-yl)hydrazono]4,5-dihydro-5-oxo-1-(4-sulfophenyl)-1H-pyrazole-3-carboxylic acid, tetrasodium salt, not more than 1 percent;Ethyl or methyl 4,5-dihydro-5-oxo-1-(4-sulfophenyl)-4-[(4-sulfophenyl)hydrazono]-1H-pyrazole-3-carboxylate,disodium salt, not more than 1 percent; Sum of 4,5-dihydro-5-oxo-1-phenyl-4-[(4-sulfophenyl)azo]-1H-pyrazole3-carboxylic acid, disodium salt, and 4,5-dihydro-5-oxo-4-(phenylazo)-1-(4-sulfophenyl)-1H-pyrazole-3-carboxylicacid, disodium salt, not more than 0.5 percent;4-Aminobenzenesulfonic acid, sodium salt, not more than 0.2 percent;
4,5-Dihydro-5-oxo-1-(4-sulfophenyl)-1H-pyrazole-3-carboxylic acid, disodium salt, not more than 0.2 percent; Ethylor methyl 4,5-dihydro-5-oxo-1-(4-sulfophenyl)-1H-pyrazole-3-carboxylate, sodium salt, not more than 0.1 percent;4,4’-(1-Triazene-1,3-diyl)bis[benzenesulfonic acid], disodium salt, not more than 0.05 percent; 4-Aminoazobenzene,
not more than 75 parts per billion; 4-Aminobiphenyl, not more than 5 parts per billion; Aniline, not more than 100
parts per billion; Azobenzene, not more than 40 parts per billion; Benzidine, not more than 1 part per billion; 1,3-Diphenyltriazene, not more than 40 parts per billion; Lead (as Pb), not more than 10 parts per million; Arsenic (as As),
not more than 3 parts per million; Mercury (as Hg), not more than 1 part per million.

3

FOOD DYES

A Rainbow of Risks
The FDA has established legal limits for cancer-causing contaminants in dyes. Thoselimits are intended to ensure that a dye will not pose a lifetime risk of greater than one
cancer in one million people. FDA chemists test each batch of dye to confirm thatthose tolerances are not exceeded. Unfortunately, the FDA’s process is riddled withproblems. For one thing, those tolerances were based on 1990 dye usage, but percapita usage has increased by about 50 percent since then. Second, the FDA did notconsider the increased risk that dyes pose to children, who are both more sensitive
to carcinogens and consume more dyes per unit of body weight than adults (Hattis, Goble et al. 2005). Third, and most importantly, FDA and Canadian government
scientists showed that levels of bound benzidine, a carcinogenic contaminant in atleast Yellow 5 and Yellow 6 dyes, far exceeded levels of free dyes (Peiperl, Prival et al.
1995; Lancaster and Lawrence 1999). (Bound carcinogens have also been found in
Allura Red AC, the un-certified form of Red 40 (Lancaster and Lawrence 1991).) Indeed, the Canadians found several bound carcinogens in soft drinks and hard candies(Lancaster and Lawrence 1992). Bound benzidine is largely converted to the freeform in the large intestine. Large amounts of other carcinogenic contaminants mightalso be present in the bound form. However, the FDA generally only measures “free”
contaminants and, hence, is blind to those (except possibly aniline) bound up in othermolecules (FDA February 26, 2010). Fourth, the FDA should consider the cumulative risk of all dyes, rather than of each dye independently. Indeed, the Food, Drug,and Cosmetic Act requires the FDA to consider “the cumulative effect, if any, of such
additive...taking into account the same or any chemically or pharmacologically related
substance...”3 If the FDA considered thosefour factors in evaluating risks, the risks posed
Table 2. Numbers of positive and negativeby the two yellow dyes—which comprise 49
genotoxicity studies of FD&C food dyes.
percent of all dyes used—let alone all dyes
taken together, would exceed the one-in-aFD&C Color
Total Number of
Positive in
Negative
Positive Studies
vivo Studies*
Studies(generic name)million standard.

Genotoxicity
A chemical’s ability to cause mutations or
damage chromosomes in bacterial or eukaryotic cells (ones with a nucleus) is an indicationthat the chemical might cause cancer in humans. While one or two positive genotoxicity
studies might not ring alarm bells, a chemical
like Yellow 5, which showed positive findingsin 6 out of 11 genotoxicity studies deserves
special attention and study—perhaps new andlarger chronic feeding studies. On the other
hand, only 1 of 11 genotoxicity studies on
3. 21 USC 379e((b)(5)(A)(ii).

Blue No. 1207(Brilliant Blue)
Blue No. 2
1
0
10(Indigo Carmine)
Green No. 3
3
06(Fast Green)
Red No. 3418(Erythrosine)
Red No. 40
337(Allura Red)
Yellow No. 562
5(Tartrazine)
Yellow No. 62
1
6(Sunset Yellow)* The numbers of “Positive in vivo studies” are included in “Positive
Studies.”4

FOOD DYES

A Rainbow of Risks
Blue 2 was positive. The discussions below of each dye summarize the results of genotoxicity tests. Table 2 lists the number of negative and positive results for genotoxicity
studies on the seven main dyes covered in this report. Further details are provided inTables A1–A7 of the Appendix.
One significant limitation of this report is that the authors were restricted to reviewing mostly published studies. Unpublished toxicology studies in the files of the FDA
or companies were not always obtainable and might shed further light on the safety ofthe dyes.

Neurotoxicity
This report focuses on traditional toxicology, which considers organ damage, cancer, birth defects, and the like. We do not explore
If you believe your children are sensineurobehavioral toxicity. But we would be remiss if we did not note
tive to food dyes, please file a reportthat in the early 1970s, San Francisco allergist Benjamin Feingold obat www.cspinet.org/fooddyes.
served that food dyes and certain other synthetic and natural components of food could cause hyperactivity and other impaired behaviors
A list of more than a thousand foodsin child and adult patients. His recommendation that parents try
made with dyes is also at that Web
putting their hyperactive children on an “elimination” diet genersite.
ated huge publicity and spurred dozens of scientific studies over theyears.4 A 2004 meta-analysis of many of the studies concluded that
there, indeed, was a cause-and-effect relationship between food dyes
and hyperactivity. The authors stated that dyes “promote hyperactivity in hyperactive
children, as measured on behavioral rating scales” and that “society should engage in a
broader discussion about whether the aesthetic and commercial rationale for the use of[artificial food colorings] is justified” (Schab and Trinh 2004).

Note to Parents

Two recent studies sponsored by the British government on cross-sections of British
children found that mixtures of four dyes (and a food preservative, sodium benzoate)
impaired the behavior of even non-hyperactive children (Bateman, Warner et al. 2004;
McCann, Barrett et al. 2007). As a result, the British government told the food andrestaurant industries to eliminate the dyes tested by the end of 2009, and the European Parliament passed a law that will require a warning notice on all foods that containone or more of the dyes tested after July 20, 2010. The notice states that the dyed
food “may have an adverse effect on activity and attention in children” (Parliament
accessed February 20, 2010).
Distressingly, some products made by McDonald’s, Mars, Kraft, PepsiCo, and othermajor U.S. multinational companies contain dyes in the United States, but naturalor no colorings in the United Kingdom. In June 2008, the Center for Science in the
4. See http://cspinet.org/fooddyes/index.html for more detailed information about food dyes and hyperactivity, especially “Diet, ADHD & Behavior: a quarter-century review – 2009 Update.” Jacobson MF, Schardt D. (Washington:
Center for Science in the Public Interest). http://www.cspinet.org/new/pdf/dyesreschbk.pdf; accessed Feb. 20, 2010.
Also, see CSPI’s 2008 petition to the FDA.

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A Rainbow of Risks
Public Interest (CSPI) petitioned the FDA to ban all the widely used food dyes becauseof their impact on children’s behavior.5 Ideally, food dyes and all other food additives would be screened in animals and in vitro systems for potential behavioral effects
before they are allowed into the food supply.

Food Dyes and the Law
A 1914 editorial in The Journal of Industrial and Engineering Chemistry stated that“America can have a coal-tar dye industry if she pays the price” (Hesse 1914). Unfortunately, America did develop a coal-tar dye industry, and we may well be paying akind of price that the journal editors did not have in mind. Down through the years,
more food dyes have been found to be risky than any other category of food additive.6
Prior to 1960, dyes had to be absolutely “harmless,” regardless of dose—a virtual
impossibility. Congress wanted to loosen the law, which, if applied strictly, could havebanned every single coloring. But in passing and implementing the 1960 Color Additives Amendment, Congress and the FDA apparently had special concerns about thesafety of food dyes, though enforcement of the law has not reflected those concerns.
James T. O’Reilly, an adjunct professor at the University of Cincinnati College of Law,observed that “Congress felt that ...colors deserved greater regulation because of theirlesser net benefit to society than such items as food preservatives and common spices.”
For instance,•

Congress required that each batch of food dyes, but not other colorings (suchas from carrots or grape skins), be tested and certified to contain only acceptable levels of contaminants, such as lead and benzidine. Food additives, suchas preservatives or flavorings, are not subject to such testing.

•Congress did not permit companies to declare that any dyes are “generally
recognized as safe” (GRAS), and thereby not further regulated by the FDA. In
contrast, companies are permitted to declare flavorings, emulsifiers, and othersuch ingredients to be GRAS.

•

The FDA’s definition of safety for color additives states that “safe means that
there is convincing evidence that establishes with reasonable certainty that noharm will result from the intended use of the color additive” (FDAa). [emphasis added] The term “convincing evidence” is not in the definition of safety
for non-color additives.

5. See http://cspinet.org/new/pdf/petition-food-dyes.pdf.
6. Banned dyes include: Green 1: liver cancer; Orange 1 and Orange 2: organ damage; Orange B (ban never finalized): contained low levels of a cancer-causing contaminant (it was used only in sausage casings, but is no longer
used in the United States); Red 1: liver cancer; Red 2: possible carcinogen; Red 4: high levels damaged adrenal
cortex of dog; Red 32: damages internal organs and may be a weak carcinogen (since 1956 it continues to be used as
Citrus Red 2 [see discussion in this report] only to color oranges at 2 parts per million [ppm]); Sudan 1: toxic andcarcinogenic; Violet 1: cancer (used to stamp USDA’s inspection mark on beef carcasses); Yellow 1 and Yellow 2: highdosages caused intestinal lesions; Yellow 3: high dosages caused heart damage; Yellow 4: high dosages caused heartdamage. Note, though, that in some cases companies didn’t bother to re-test chemicals that might have been harmful only at high dosages and not at the lower dosages consumed in foods. http://cspinet.org/reports/chemcuisine.
htm.

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Some Members of Congress have emphasized that the safety standard for artificial colorings should be particularly high because the colorings don’t offer any health benefit
to offset even small risks. Representative Ted Weiss (D-NY) said, “It doesn’t make any
difference how much or how little (of a carcinogenic additive) a particular substancecontains, especially when you’ve got a color additive that has no nutrient value andno therapeutic value” (Weiss July 6, 1985). Representative King said, “The colors
which go into our foods and cosmetics are in no way essential to the public interest or
the national security…Consumers will easily get along without (carcinogenic colors)”(D.C. Cir. 1987). [Note: It is unclear which Rep. King was quoted in the case: Rep.
Cecil King, D-CA, or Rep. David King, D-Utah.]Consumer activists have long sought to persuade the FDA to ban dyes. In the early
1970s, CSPI urged the government to ban Violet No. 1, which, ironically, was thecolor used in the U.S. Department of Agriculture’s meat inspection stamp, because
it appeared to cause cancer in animal studies (the dye was banned in 1973). Subsequently, in the 1970s and 1980s, Public Citizen’s Health Research Group was the mostaggressive critic of dyes, petitioning and suing the FDA to ban dyes (Burros February
13, 1985). Some of those actions were based on the 1960 law—the Delaney amendment7—that bans the use of colorings that cause cancer in animals or humans. Also,
as noted above, in 2008 CSPI urged the FDA to ban colors because of their effects onchildren’s behavior.
Even if color additives were all deemed to be safe, many uses of colorings, bothsynthetic and natural, still could be considered illegal under the Food, Drug, andCosmetic Act. Sections 402(b)(3) and (b)(4) of that law stipulate that “A food shallbe deemed to be adulterated…(3) if damage or inferiority has been concealed in any
manner; or (4) if any substance has been added thereto or mixed or packed therewith
so as to…make it appear better or of greater value than it is.” And section 403 of thesame law says that a food is misbranded “if its labeling is false or misleading in any
particular.”
Clearly, food colorings are added to fruit drinks, frozen desserts, gelatin desserts, salad
dressings, child-oriented breakfast cereals and snack foods, and countless other products solely to conceal the absence of fruits, vegetables, or other ingredients and makethe food “appear better or of greater value than it is.” Defenders of colorings would
say that consumers could simply plow through the list of ingredients on the back of
the package to detect the presence of colorings, but it simply isn’t fair to require consumers to do that plowing. Currently, the use of artificial flavorings must be declaredconspicuously as part of the product names on the front labels. If nothing else, the
FDA should require the same of artificially colored foods. A national Internet-basedpoll commissioned by CSPI and conducted by Opinion Research Corporation in January 2010 found that 74 percent of respondents favored such labeling.
7. 21 USC 379e(b)(5)(B)7FOOD DYES

A Rainbow of Risks
As this report discusses, studies of the nine dyes currently approved by the FDA
suggest, if not prove, that most of the dyes cause health problems, including cancer,
hypersensitivity, or neurotoxicity (including hyperactivity). And that’s the case eventhough most of the research was commissioned, conducted, and interpreted by thechemical industry itself and its testing labs and academic consultants. The health concerns indicate that most dyes fail the FDA’s safety requirement “that there is convincing evidence…that no harm will result from the intended use of the color additive.”
Fortunately, numerous natural colorings could be used in place of dyes: beet juice,beta-caramel, carotene, carrot juice, chlorophyll, elderberry juice, grape juice/skin,paprika extract, purple corn, purple sweet potato, red cabbage, and turmeric.

Getting Dyes Out of Foods
CSPI has urged several major multinational companies that do not use dyes in Europe
to do the same in the United States. Unfortunately, most of those companies said thatthey don’t use dyes in Europe because government has urged them not to—but thatthey would continue to use dyes in the United States until they were ordered not to or
consumers demanded such foods. (Starbucks and the maker of NECCO Wafers haveeliminated dyes, and Frito-Lay said that it would be phasing out dyes in the coming
years (Jacobson and Small 2009).)
Consumers should not have to wait decades, if not forever, for companies to voluntarily remove questionable dyes from their products. The FDA, which is charged
with protecting the public from unsafe food ingredients, should ban most or all of thedyes. However, it is worth noting that the Food, Drug, and Cosmetic Act makes it
even harder for the FDA to revoke previous approvals of food colors than other foodadditives.8 As one legal analyst stated,Thanks to the foresight and effective lobbying of the cosmetics industry in the 1960s, the proponent of a color additive petition is in an excellent position if the FDA decides to remove [a coloring’s] permanent
listing. The burdens of proof in a complex process fall on the FDA,
and the time required to pass through the procedural maze acts as adisincentive to FDA undertaking any delisting action (O’Reilly 2007).
Ideally, the law would be changed to provide greater consumer protection from unsafe
dyes. We turn now to detailed assessments of the toxicology research done on thenine dyes currently permitted for use in some or all foods in the United States. Basedon those assessments, the authors’ conclusion is that the time has come to eliminate

8. To challenge a proposed ban on a food or color additive, companies can request that the FDA hold a formal public
hearing and, if the FDA subsequently still wants to ban the substance, companies can go to court. The process forcolor additives, though, includes another hurdle, because, if a dye is alleged to cause cancer, companies can requestthat FDA create an outside advisory committee to opine on the matter. Compare 21 USC 379e(b)(5)(C) and 21 USC
371(e)(2) and (f)(2) for colorings with 21 USC 348 409(f) and (h) and 21 CFR 171.130 for other additives.

8

FOOD DYES

A Rainbow of Risks
dyes from our food supply and return to the use of natural colorings (or foods that
don’t require colorings to be marketable), the direction in which Europe—and someAmerican companies—are moving.

B

B

9

FOOD DYES

A Rainbow of Risks

FD&C Blue
No. 11FD&C
Blue
Introduction
SO3Na
FD&C Blue No. 1 (Fig. 2), or Brilliant Blue,9 is a water-solC2H5
uble coloring used in many baked goods, beverages, desNCH2
sert powders, candies, cereals, drugs, and other products.
C
Blue 1 received FDA approval for general use in foods andN+CH2
ingested drugs in 1969. In 1982, the FDA permanently
SO3Na
C2H5
approved the color for use in externally applied drugs andSO3Na
general use in cosmetics excluding the area of the eye. The
FDA suggests a maximum Acceptable Daily Intake (ADI)
Figure 2. FD&C Blue No. 1; Brilliant Bluefor Blue 1 of 12 mg/kg bw/day (FDA 1982a). For a 30kilogram (66-pound) child, that would equate to 360 mg/
day. Current average dye production is equivalent to about 3 mg/person/day (basedon the entire population, not just children). Chemically, Blue 1 is almost identical toGreen 3, except for a hydroxyl group.

Metabolism
In a study of rats, Blue 1 was largely excreted unchanged in the feces (96%) within 36
hours after a 200-mg oral administration. None of the dye was excreted in the urine.
In the same study, only 0.7% and 2.8% of a 200-mg oral dose was excreted in the bileof two bile-duct cannulated dogs indicating some intestinal absorption. Investigators calculated that the quantity of absorption of the color from the gastrointestinal(GI) tract was about 10 mg out of a 200-mg dose (Hess and Fitzhugh 1955). Brown
et al. reported similar results after administering a single 0.27‑mg dose of 14C-labeledBlue 1 to female Sprague-Dawley rats. Bile duct-ligated rats excreted the dye in theirurine and feces at concentrations of 2.02 and 97.28%, respectively. Given the lower
percentage of dye being excreted in the bile, the large amount eliminated throughthe feces indicates that the dye is poorly absorbed by the GI tract. In this particularstudy, total intestinal absorption was estimated to be about 2.05% and 0.27% of thetotal dose in bile duct-ligated and intact rats, respectively. Analysis of the biliary andurinary excretion showed that 95% of the recovered radioactivity was from unchanged
Blue 1 while 5% was an unidentified metabolite or degradation product (Brown, Dorsky et al. 1980). These results indicate that in rats Blue 1 is not susceptible to breakdown by intestinal microbiota, but up to 5% is absorbed via the GI tract.

9. The color of each section heading is printed in the color of the dye being discussed; the actual color in a fooddepends on the dye’s concentration and the colors imparted by other dyes and ingredients.

10

FOOD DYES

A Rainbow of Risks

Genotoxicity
Table A1 in the Appendix summarizes the genotoxicity studies performed on Blue 1.
Based on those assays, the dye is not genotoxic in terms of DNA damage, base pairmutations, base substitutions, or frameshift mutations. However, Blue 1 caused chromosomal aberrations in two studies (Ishidate, Senoo et al. 1974; Hayashi, Matsui et al.
2000).

Chronic Toxicity/Carcinogenicity
Hansen et al. performed chronic toxicity studies using Blue 1 on rats and dogs. The
rat study lasted 2 years and used 24 Osborne-Mendel rats/sex/group at doses of 0, 0.5,
1, 2, and 5% of the diet. There were no reported compound-related effects in anygroup on mortality, hematology, or organ weights (heart, liver, spleen, testis, kidney).
There was also no reported significant growth inhibition or gross lesions. The small
numbers of rats in each group renders this study quite insensitive and of marginalvalue (Hansen, Fitzhugh et al. 1964).
In Hansen et al.’s dog study, 12 beagles, aged 6-7 months, were fed the dye at dosesof 0 (1 male, 1 female), 1 (2 males, 2 females), or 2% (4 males, 2 females) in the dietfor up to one year. Investigators reported no clinical signs attributable to the color,though one dog in the highest-dose group died of intercurrent viral infections, andone dog in the 1% group was sacrificed due to its poor condition before the end of
the study. Blue 1 caused no gross or microscopic lesions. The NOELs (No Observed
Effect Level) for rats and dogs were 5% and 2%, respectively (Hansen, Fitzhugh et al.
1964). According to FDA guidelines, the dog study was inadequate because a oneyear study in dogs should have equal numbers of males and females and the control
group should have at least 4 animals per sex (FDA 2000). And, of course, a dog study
lasting just one year cannot detect effects that occur only after years of exposure.
Rowland et al. performed a chronic toxicity/carcinogenicity study on Blue 1 in 48
males/group and 50 females/group of ASH/CS1 mice. The mice were administered 0,0.015, 0.15, or 1.5% Blue 1 in their diets for only 80 weeks. Seven out of the surviving 30 male mice in the 0.15% group had kidney tumors compared to only 1 kidney
tumor in the 44 surviving controls. The increase in kidney tumor rates was statistically significant (p<0.05). However, no dose-response relationship was said to be found,diminishing, but not eliminating, concern about carcinogenicity (data on the 1.5%
group were not provided). This study, which was conducted by the British Industrial
Biological Research Association, a now-defunct industry-sponsored organization, wasreviewed by the International Agency for Research on Cancer (IARC) and publishedin abstract form in an IARC monograph, but for unknown reasons the full study wasnever published.10
10. Pers. Comm. Rowland IR. June 26, 2009. Rowland did not know why the study was never published.

11

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The highest-quality carcinogenicity/toxicity studies were performed by Borzelleca et al.
for the Certified Color Manufacturers Association (CCMA). The 2-year studies used
Charles River CD rats and CD-1 mice. The rat study included an in utero phase with60 rats/sex/group. The rats were fed 0 (two control groups), 0.1, 1, and 2% Blue 1 in
the chow for about two months prior to mating. Investigators reported no compoundrelated effects on fertility, gestation, parturition, lactation, pup survival through weaning, and number of live and stillborn pups. F1 generation rats were randomly selected,
and 70 rats/sex/group were used in the lifetime feeding study (same dosage groups,
including two controls). The maximum exposure times for males and females were
116 and 111 weeks from birth, respectively. F1 females in the 2% group had a significant decrease in terminal mean body weight (15%) and decreased survival compared
to controls. No other compound-related effects were noted. The NOAEL (No Observable Adverse Effect Level) for males was 1,072 mg/kg bw/day (2% group) and 631 mg/
kg bw/day for females (1% group) (Borzelleca, Depukat et al. 1990a).
The mouse study did not include an in utero phase and used 60 mice/sex/group. Mice
were administered 0 (two control groups), 0.5, 1.5, and 5% Blue
1 in their food. The maximum exposure time was 104 weeks forboth sexes and the NOAEL was determined to be 5%, or 7,354
and 8,966 mg/kg bw/day for males and females, respectively. No
significant compound-related effects were noted in any of thegroups (Borzelleca, Depukat et al. 1990a).

Neurotoxicity
Lau et al. investigated the individual and potential synergistic
effects of Blue 1 and L‑glutamic acid (a close relative of the foodadditive monosodium glutamate) on neuronal development.
Investigators used NB2a neuroblastoma cells that were induced
to differentiate and grow neurites (projections from a neuron) in
the presence or absence of the two food additives. Neurotoxicity
was measured as an inhibition of neurite outgrowth. Individually, Blue 1 was found to have an IC50 (half-maximal inhibitory
concentration) of 0.0514 µM, while L-glutamic acid was found tohave an IC50 of 48.7 μM. When cells were treated with the two
additives together, rather than just seeing an additive effect, thetwo compounds worked synergistically (Fig. 3). A 50:50 mixtureof L-glutamic acid and Blue 1 produced 46.1% neurite growth
inhibition, which was significantly different from the expectedvalue of 15.8% if the compounds acted additively. On the other
hand, the effect on cell viability from the combination of the two
additives was increased only in an additive fashion (Lau, McLean
et al. 2006). Other food dyes might behave similarly.

Figure 3. Images of Coomassie Bluestained differentiating NB2a cells:(a) in the absence of additives; (b) in thepresence of 0.0001 µM Blue 1 to produce
approximately 20% neurite inhibition; (c)1 μM L-glutamic acid to produce approximately 20% neurite inhibition; (d) a mixtureof Blue 1 and L-glutamic acid each at 50% of
the above concentrations.
Figure used with the permission of Oxford University Press:
Lau, K., W. G. McLean, et al. (2006). “Synergistic interactions
between commonly used food additives in a developmental
neurotoxicity test.” Toxicological Sciences 90(1): 178-187.

12

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Feingold suggested that food dyes and additives are associated with hyperactivity
disorders in children (see page 4 and Feingold 1975). The developmental period ofsynaptogenesis (brain growth-spurt period) occurs in humans from three months before birth to several years after birth (Lau, McLean et al. 2006). Small amounts of Blue
1 are absorbed by the GI tract in rats, but metabolism studies in children have notbeen conducted. Blue 1 might possibly have potent effects, and it might take only asmall absorbed amount to affect a child’s brain development. The blood-brain barrier
is not fully developed until 6 months in humans and even after complete development
some regions of the brain are never protected by the blood-brain barrier (Brightman
and Broadwell 1976; Adinolfi 1985). Further studies need to be done on Blue 1 andon the possible neurotoxicity of other dyes.

Conclusions
The most thorough studies of Blue 1, which were sponsored by industry, did not findevidence of carcinogenicity in rats or mice. On the other hand, other studies raisequestions about possible harm. A review by the IARC of a study (published only in
abstract form) states that male mice had a statistically significant increased incidenceof kidney tumors in the mid-dose group. Also, in an in vitro test, Blue 1 inhibited neurite growth and acted synergistically with L-glutamic acid, suggesting the potential forneurotoxicity. That is particularly worrisome for fetuses and babies under the age ofsix months whose blood-brain barrier is not fully developed. Further research needs
to be conducted before this dye can be considered safe.

FOOD DYES

A Rainbow of Risks

FD&C
Blue
No. 22
FD&C
Blue
Introduction
FD&C Blue No. 2 (Fig. 4) is the approved form of Indigo
Carmine. In 1983, the FDA permanently listed Blue 2 for use
in foods and ingested drugs (FDA 1983). It is widely used tocolor beverages, candies, pet foods, and many other foods anddrugs. Blue 2 has an ADI of 2.5 mg/kg bw/day (FDAb). That
ADI is equivalent to 75 mg for a 30-kg child. The FDA certifies
an amount of Blue 2 that is equivalent to about 2 mg/person/
day.

NaO3S

O

N
H

H
N
SO3Na

O

Figure 4. FD&C Blue 2; Indigo Carmine

Metabolism

5 - Sulfo
Anthranilic Acid
SO3Na

O

Metabolism studies in rats demonstrated that the majority of the dye and/or its
metabolites (including 5-sulfoanthranilic acid, its final breakdown product, Fig. 5)
are excreted in the feces, with smaller amounts being found in the urine (Lethco andWebb 1966; Jones, Ryan, et al., 1964). In one bile-ductcannulated rat given a 20-mg dose of Blue 2, only 0.004%
FD&C Blue No.2of the dye was excreted in the bile—125 times as much
Indigo Carmine
was found in the urine. The authors concluded that the
SO3Na
majority of the small amount of dye that is absorbed intact
5 - Sulfo
Isatin SO3Na
is excreted through the urine and not the bile, and the
dye excreted in the feces is mostly from unabsorbed dye
NH2(Lethco and Webb 1966). Those studies show that 5-sulNH
C O
foanthranilic acid is absorbed more readily by the GI tract
C
NH
than is the intact dye (Lethco and Webb 1966).
O
O

B

13

Genotoxicity

NH2

C O
OH

SO3Na

Details of the genotoxicity studies performed on Blue 2 are
Figure 5. N atural breakdown products of
FD&C
Blue 2
provided in Table A2 in the Appendix. All of the 11 tests
were negative except for a chromosomal aberration assay(Ishidate, Senoo et al. 1974). It would be appropriate for
an independent lab to repeat that study, as well as perform an in vivo chromosomal
aberration test.

Chronic Toxicity/Carcinogenicity
Between 1984 and 1986, Borzelleca et al. performed a series of toxicology studies using Blue 2. One was a high-quality chronic toxicity/carcinogenicity study in rats. The
study included an in utero phase in which 5 groups of 60 male and 60 female Charles

14

FOOD DYES

A Rainbow of Risks
River CD albino rats were fed 0 (two different control groups), 0.5, 1, or 2% Blue 2
starting at least 2 months prior to mating. F1 offspring in each dosage group were randomly selected, and 70 rats/sex/group were continued on the same dosages for 29 and30 months in males and females, respectively. Administration of the dye did not affectthe number of pregnant females per group or pup viability at birth. However, there
was possible evidence of carcinogenicity:•

Treated male rats showed a dose-related increase in the incidence of transitional cell neoplasms (an abnormal mass of tissue that may be benign (notcancer) or malignant (cancer)) of the urinary bladder, but the numbers ofaffected animals were small and the apparent increase was not statisticallysignificant when compared to combined controls (0.8, 1.6, 2.9, and 4.5% of
the animals had bladder neoplasms in the control, low-, mid-, and high-dosegroups, respectively; the trend likely was significant).

•

Male rats in the 2% group had statistically significant increases in malignant
mammary-gland tumors and brain gliomas. However, the investigators concluded that the increased mammary-gland tumors were not related to Blue 2.
They also concluded that the gliomas were not consistent with several criteria
they said were required to classify a compound as a carcinogen. For instance,neither a dose-effect relationship nor a concurrent decrease in survival time
was seen. They also reported that the incidence of gliomas in treated animals
was consistent with historical controls. All too often companies (or the FDA)
will resort to comparisons with historical controls when the test group has
more tumors than the controls in the current study. Based on this study, theinvestigators estimated that the NOAEL for Blue 2 was 2.0%, or 1,282 mg/kg
bw/day and 1,592 mg/kg bw/day for males and females, respectively (Borzelleca, Hogan et al. 1985a).

The FDA’s Cancer Assessment Committee concluded that the occurrence of urinary
bladder transitional cell neoplasms, though apparently dose-related, was not related totreatment with Blue 2 because (a) historical evidence suggests that this form of cancer
is not rare in Charles River CD albino rats, (b) the number of neoplasms in the highdose group was small, and (c) the number of tumors in the high-dose group was not
significantly higher than in the control groups.
Regarding the malignant tumors of the mammary gland in the high-dose males, when
the Committee combined malignant and benign tumors, there was no longer a statistically significant difference between the controls and high-dose male rats. The Committee concluded that Blue 2 did not cause any significant treatment-related effects inrats (FDA 1983).
Although there was a significantly higher incidence of brain gliomas in the high-dosemale rats, the FDA’s Cancer Assessment Committee was still reluctant to conclude that

15

FOOD DYES

A Rainbow of Risks
Blue 2 was the cause because (a) of a lack of gliosis (scarring of the central nervous
system) in the high-dose animals, (b) the first two observed gliomas of the brain
occurred in controls animals, and (c) data were lacking on the historical incidenceof brain gliomas in Charles River albino rats that survive for 30 months. The FDA
concluded that “except for brains of male rats for which the data are equivocal, there isno evidence for carcinogenicity in rats or mice of either sex for all organs examined.”Upon reevaluation of the brain microslides and comparison to controls from a simultaneous study on Green No. 3, the new statistics produced p-values that were just above
0.05 (one test, the Breslow time-adjusted analysis, produced a p-value of 0.053). It ishighly questionable to switch a comparison to a different control group after a study iscompleted. Still, the FDA stated, “…although statistical methods provide insight into
the likelihood of being right or wrong in making specific conclusions, they do not provide for certainty as to whether an increase or decrease in tumor incidence is related
to treatment.” The Board of Scientific Advisors of the National Toxicology Program
concluded that Blue 2 is safe for consumption, citing (a) a lack of evidence for a doserelated trend, (b) lack of non-neoplastic cellular changes in addition to frank neoplasia(new and abnormal development of cells that may be benign or malignant), (c) no
reduction in latency period, (d) no varying progression of brain tumors, (e) inability ofBlue 2 to cross the blood-brain-barrier, (f) negative mutagenicity assays, and (g) lack ofevidence in structure-activity analysis (FDA 1983).
Borzelleca et al. consulted three outside sources on the carcinogenicity issues inrats. Robert Squire, a prominent industry consultant at the Johns Hopkins University School of Medicine, found a lack of persuasive evidence for compound-related
carcinogenicity/toxicity in the glioma and urinary bladder samples (Jacobson 1981).
However, Aleksandar Knezevich and Geoffrey Hogan, former vice president of pathology and former vice president of toxicology, respectively, at Bio/dynamics (an industry
consulting firm), concluded that the glioma findings “cannot be dismissed as accidental.” On the other hand, those men agreed with the FDA committee that the rates ofurinary neoplasms in treated male rats were not clearly different from the controls andwere probably not of concern (Knezevich and Hogan 1982).
After Blue 2 was approved for permanent listing in 1983, the Public Citizen HealthResearch Group (HRG) filed an objection on the grounds that the increase in brain
tumors in rats fed Blue 2 was statistically significant. The group argued that the decision to list Blue 2 permanently violated both the Delaney Clause (which bars cancercausing food and color additives) and the general safety clause since the dye had notbeen proven safe (FDA 1988).
In a statement to the HRG in 1982, Dr. William Lijinsky, a cancer specialist at the National Cancer Institute’s Frederick Cancer Research Center, wrote,...the incidence of these (brain) tumors in the high dose group versus thecontrols is highly significant…In my own laboratory this would be considered16

FOOD DYES

A Rainbow of Risks
prima facie evidence of carcinogenicity of a treatment. This is especially sobecause this tumor is so rare, and my conclusion is that Blue 2 is a carcinogen,and should be regulated accordingly.
Regarding his own evaluation of the histopathology of brain/spinal cord sections in
microslides, Dr. Benjamin A. Jackson, of the FDA’s Division of Pathology in the Colorand Cosmetics Evaluation Branch, wrote, “…the possibility cannot be outrightly
excluded that the compound (Blue 2) itself, its metabolite(s) or a secondary effectinduced by the high dose of the color may have acted to increase the number of brain
tumors seen in this study.”
An administrative law judge found that a lack of certain biological factors, such as
gliosis, invasiveness of tumors, a clear dose-response relationship, and an increased
latency, outweighed the statistically significant incidence of brain gliomas in the rats.
Reviewing the matter, the FDA commissioner concluded that the evidence produced
at the hearing supported the notion that Blue 2 was not an animal carcinogen and thatthe permanent listing of Blue 2 was appropriate (FDA 1987).
HRG challenged the FDA’s decision, contending that the rats may not have been
exposed to the maximum tolerated dosage (MTD). According to the FDA, the highest
dosage used in a study “should be sufficiently high to induce toxic responses in test
animals, and should not cause fatalities high enough to prevent meaningful evaluationof the data from the study.” Chronic-study doses “…should be based on results fromsubchronic studies and other related test substance information.” (FDA 2000) HRG
questioned whether the MTD was used in the chronic toxicity rat study because (a) no
subchronic study was conducted to establish the MTD (the FDA found it acceptable torely on the results of a previous 1966 study by Hansen), (b) adult rats in the study did
not show alterations typical of animals given the MTD according to the FDA Redbook(FDA’s guide for the testing of additives), (c) 5% was used as the MTD for the chronicmouse study discussed on page 17 (as opposed to 2% in the rat study), and (d) the
Hansen study used a high dose of 5%, which led to an increase in the overall numberof tumors compared to other groups. HRG argued that allowing a 2% MTD was contradictory to the FDA’s own guidelines (Meyer, Schultz et al. 1987). Notwithstanding
those arguments, the court ruled in favor of the FDA (FDAc).
In another study, 30 Charles River CD-1 mice/sex/group were fed 0.2, 0.4, 0.8, or
1.6% Blue 2 for 84 weeks. Controls consisted of 60 males and 60 females. The overall death rates in treated mice did not differ significantly from that in the controls. The
most common neoplasms seen in both the control and treated mice were generalized
lymphoblastomas and pulmonary adenomas. The incidence of lymphoblastomas was
not associated with the feeding of Blue 2. There was a significant increase in the incidence of pulmonary adenomas in the lowest-dose treatment group in males compared
to controls. That increase was not seen in females or in higher-dosage groups and,
therefore, was not considered by the authors to pose a risk to humans. In this study

17FOOD DYES

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the NOAEL was determined to be 0.4% of the diet or approximately 600 mg/kg/day.
With a safety factor of 100, that translates into an intake of about 360 mg/day for a
60 kg person (Hooson, Gaunt et al. 1975). This study cannot be considered definitivedue, in part, to its brevity—Charles River CD-1 mice often live to well over 2 years(Huff, Jacobson et al. 2008)—and because the mice were not exposed in utero.
Borzelleca et al. also conducted a carcinogenicity/toxicity study of Blue 2 in mice. That
study did not include an in utero phase. Blue 2 was fed to 60 Charles River CD-1
mice/sex in 0 (two control groups), 0.5, 1.5, and 5% groups. The study lasted 22
months for males and 23 months for females—longer than the Hooson study discussed above, but still shy of 2 years, let alone the lifetime of the mice. Investigatorsconcluded that Blue 2 did not cause any significant effects on behavior, morbidity,
mortality, hematology, or physical observation and considered the NOAEL to be 5%,or 8,259 and 9,456 mg/kg bw/day in male and female CD-1 mice, respectively (Borzelleca and Hogan 1985b).

Reproductive Toxicity and Teratogenicity
Borzelleca et al. conducted a 3-generation reproductive study of Blue 2 in Charles
River CD rats. Groups of 10 males and 20 females were fed the dye at levels of 0, 2.5,
25, 75, or 250 mg/kg bw/day. Retinoic acid, a known teratogen in rats, was used asa positive control. Treated parents and pups were normal in terms of general appearance and behavior. The compound was not teratogenic and did not affect fertility,
length of gestation, viability, or lactation indices. The compound did not cause anatomical abnormalities in the uteri or ovaries of females given caesarian sections. There
were also no compound-related effects on organ weights and gross and microscopic
pathological lesions (Borzelleca, Goldenthal et al. 1986).
Borzelleca et al. tested the potential teratogenicity of Blue 2 in Charles River CD ratsand Dutch Belted rabbits. Twenty pregnant rats/group received 0.5% methacol (avehicle control), 7.5 mg/kg/day retinoic acid (a positive control), or 25, 75, or 250 mg/
kg/day Blue 2. Ten pregnant rabbits/group followed the same regimen as the rats, except that 150 mg/kg/day thalidomide was used as a positive control in place of retinoic
acid. Investigators reported no compound-related adverse effects on maternal appearance, behavior, body weight, or mortality. There were also no adverse effects on fetal
body weight, viability, or abnormalities. The NOAEL for Blue 2, on the basis of thisstudy, was determined to be 250 mg/kg/day in rats and rabbits (Borzelleca, Goldenthal
et al. 1987a).

Conclusions
The majority of intact Blue 2 is not absorbed by rats. However, the dye is readily broken down in the GI tract, and the final breakdown product, 5‑sulfoanthranilic acid, isabsorbed and excreted mostly in the urine. However, there are no metabolism studies
in humans.

18

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Blue 2 did not affect reproduction or cause birth defects in rats or rabbits. Twochronic toxicity/carcinogenicity studies in mice did not find any problems, but they
were flawed because they did not include an in utero phase and were shorter than two
years. More worrisome was a chronic toxicity/carcinogenicity study in rats that foundthat males in the 2% group had statistically significant increases in brain gliomas andmalignant mammary gland tumors. The male rats also had dose-related increased
incidences of transitional cell neoplasms of the urinary bladder, but the numbers ofaffected animals were small and the differences from the combined controls were notstatistically significant. The FDA found reasons to excuse that evidence of carcinogenesis and neoplasia and approved the continued use of the dye.
Given the statistically significant occurrence of tumors, particularly brain gliomas, inmale rats, Blue 2 cannot be considered safe for human consumption. Since Blue 2 is a
non-nutritive food additive that does not provide any health benefit and there is hardly “convincing evidence” of safety, it should not be permitted for human consumption.

19

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Citrus Red No. 2
CitrusRed 2
Introduction
Citrus Red No. 2 (Fig. 6) is an azo dye approved to color the skins of Florida
oranges not used for processing. Amounts are permitted up to 2 ppm in thewhole fruit (FDA 1963). Only about 1,500 pounds of this dye are certified
annually, but that’s enough to color about two billion oranges.

Metabolism

CH3

OH

O
N

N

O
CH3

Figure 6. Citrus Red No. 2

Radomski et al. administered a single oral dose of Citrus Red 2 to rats, dogs,
and rabbits. Rats given a single oral dose of 2-20 mg excreted 5-7% of intact
dye in their feces over 48 hours. Similar to water-soluble azo dyes, this waterinsoluble dye is broken down in the GI tract by intestinal bacteria. One breakdown
product is 1-amino-2-naphthol, which has been shown to cause bladder cancer inmice (Bonser, Bradshaw et al. 1956). At single doses higher than 5 mg, the dye accumulated in the fat of rats. Small amounts of 1-amino-2-naphthyl sulfate were found in
the urine of rats, demonstrating that the 1-amino-2-naphthyl metabolite is absorbed,
sulfonated, and then excreted (Radomski 1961).

Chronic Toxicity/Carcinogenicity
In one study, 50 mice/sex/group were fed Citrus Red 2 at levels of 0, 0.01, 0.03, 0.1,
0.3, 1, or 3% of their diet. The study lasted up to 80 weeks, an inadequate duration.
The study was discontinued in the 0.3, 1, and 3% groups due to increased morbidity and mortality. Mice in the 0.1% group also experienced increased mortality, andfemales showed degeneration of the liver (Sharratt, Frazer et al. 1966).
The same researchers conducted a study with 50 mice/sex injected subcutaneously with 10% Citrus Red 2 for 35 weeks, followed by injections every 3 weeks for
15 weeks. The control group received only vehicle injections. Female mice showed
an increase in total malignant tumors, which appeared earlier than tumors in thecontrol group. The most common malignant tumors were adenocarcinomas of thelung and lymphosarcomas. There were no injection-site tumors (Sharratt, Frazer et al.
1966).
Hazleton Laboratories conducted a chronic feeding study in rats. The toxicological
data were evaluated by the director of FDA’s Division of Pharmacology, A. J. Lehman,
who concluded that the synthetic dye is a toxic substance. In this study, 40 rats/sex/
group were fed Citrus Red 2 at doses of 0, 0.05, 0.1, 0.5, 1, 3, and 5%. Rats in thetwo highest dosage groups were sacrificed after 31 weeks because of severe toxicity.
The remainder of the rats remained in the study for 104 weeks. Rats in the 0.5 and20

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A Rainbow of Risks
1% groups experienced differences from controls in gross appearance, growth, organ
weights, and gross and microscopic pathology. At the 0.1% levels, rats showed differences in organ weights, incidence of edema-like swelling, a possible trend toward
an increased incidence of fatty metamorphosis (fat droplets in the cytoplasm of cells),
and a significant difference in weight gain in females. Researchers did not report anincrease in the occurrence of tumors. The NOEL was judged to be 0.05% (500 ppm)
(Fitzhugh 1959).
Dacre administered Citrus Red 2 for 24 months to 20 mice and 20 albino rats per
dosage group. The dye was given at dosages of 0, 0.05, and 0.25% beginning immediately after weaning, without in utero exposure. This study found hyperplasia (anincreased number of cells, but not necessarily leading to a tumor) and a thickening of
the urinary bladder wall in both treatment groups in rats and mice. Of greater concern, 2 out of 20 mice that were examined developed benign papillomas and one male
mouse developed a malignant papilloma in the urinary bladder, and 4 out 28 rats thatwere examined developed benign papillomas. About the same number of pathologicalchanges were seen in the low- and high-dosage groups in both species and sexes. No
problems were seen in control animals (Dacre 1965).
An internal FDA memo expressed concern about the carcinoma seen in Dacre’s mousestudy, because benign tumors and hyperplasia also were seen in the mice (Davis
1970). FDA veterinarian Kent J. Davis wrote, “…this becomes a level of meaningful
significance to cancer research workers.” He added,
Citrus Red 2 then becomes an intolerable human health hazard if
only from the amounts consumed from fingers after peeling oranges
treated with this dye. (Some additional dye may be ingested withpeel or orange.) The continued certification and use of this color may
also be a violation …of the Federal Food, Drug, and Cosmetic Act asamended which prohibits use of any carcinogenic color additive foruses which may result in ingestion of part of such additive.

Conclusions
Citrus Red No. 2 is toxic to rats and mice at modest levels and, according to an FDA
scientist and the IARC, is a bladder carcinogen (IARC 1975). The FAO/WHO Expert
Committee on Food Additives stated bluntly: “This color should not be used as a foodadditive” (FAO/WHO 1969).

B

B

21

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A Rainbow of Risks

FD&C
Green
No. 3 3
FD&C
Green
Introduction
FD&C Green No. 3 (Fig. 7), or Fast Green FCF, is a synthetic
dye approved for use in food, drugs, personal care products,
and cosmetics except for in the area of the eye. It is one of theleast-used dyes, but may be found in candies, beverages, dessert
powders, ice cream, sorbet, and other foods, as well as ingested
drugs, lipsticks, and externally applied cosmetics (FDA 1982a).
The ADI for Green 3 is 2.5 mg/kg bw/day, or 75 mg/day for a
30-kg child (FDAd). Current production is equivalent to only
0.1 mg/person/day.

C2H5

SO3Na

NCH2
HO

C
SO3Na

N+CH2
C2H5

Figure 7. F D&C Green No. 3,
Fast Green FCF

Metabolism
Hess and Fitzhugh studied the metabolism of Green 3 in rats and dogs. Three female
and 3 male Osborne-Mendel rats were orally administered a single 200-mg dose ofGreen 3. An average of 94% of the dye was excreted intact in the feces. No recovery
from the urine was reported. Male and female bile duct-cannulated dogs were orally
administered a single 200-mg dose of Green 3. None of the color was found in theurine and about 2% of the dye was recovered in the bile of two of three dogs. Hessand Fitzhugh calculated the absorption of the dye from the GI tract of rats and dogs to
be about 5% (Hess and Fitzhugh 1955).

Genotoxicity
Table 2 lists the number of negative and positive results for genotoxicity studies performed on Green 3, with Table A3 in the Appendix providing more details. The dye
was not mutagenic in most assays except the S. Typhimurium strain TA100 Ames Assay at 10 mg/plate. That assay tests for base-pair mutations, and Green 3 only yielded
positive results when tested as a mixture of several batches of dye of varying purity(Ishidate, Sofuni et al. 1984). Green 3 was also positive for mutagenicity in a Fischer
rat embryo cell transformation assay (Price, Suk et al. 1978). That particular assay
tests for malignant cell transformation, an indicator of carcinogenic potential. Green 3
was positive at 1 μg/ml but, surprisingly, produced negative results at higher concentrations. In summary, those tests do not raise significant concerns.

Chronic Toxicity/Carcinogenicity
In 1977, the FDA required that additional chronic toxicity studies be conducted before Green 3 could become a permanently listed food coloring (FDA 1977). To fulfill
that requirement, the CCMA sponsored chronic feeding studies in mice and rats.

SO3Na

22

FOOD DYES

A Rainbow of Risks
In the first study, Green 3 was administered to 60 Charles River albino rats/sex/groupat dosage levels of 0 (two control groups), 1.25, 2.5, and 5% for at least 2 months
prior to mating. After reproduction, 2, 3, or 4 pups/sex/litter/group were randomly
selected for the long-term study. The same dosage levels used in the in utero phasewere administered to 70 rats/sex/group for approximately 30 months. No significant
effects were noted during the in utero phase except that pup mortality was increased in
the mid- and high-dose groups of the F1 generation. In the F1 generation, a significant
decrease in survivorship was seen in all treated groups of males and females, but there
was no dose-response trend, making that decreased survivorship difficult to interpret.
Urinalysis, hematologic parameters, physical observations, and ophthalmology did notindicate any adverse effects of Green 3 (Bio/dynamics 1982a).
Histopathological examination revealed that the high-dose group of male rats had
increased incidences of urinary bladder transitional cell/urothelial neoplasms, testes
Leydig’s cell tumors (usually rare and benign in humans), and liver neoplastic nodules. Statistical analysis found that the increased incidences were significant for theurinary bladder transitional cell/urothelial neoplasms (p=0.04, BioDynamics analysis)
and testes Leydig’s cell tumors (p=0.04; FDA analysis), when compared to combined
controls (Bio/dynamics 1982a). Mark Nicolich, a statistician working at the company
that conducted the study, stated, “Therefore, there is statistical evidence that the highdose of the test material increases the occurrence of certain types of tumors in rats”(Bio/Dynamics 1981). Nevertheless, FDA scientists concluded that the tumors in
the testes were not compound-related because (a) they are common in aged rats, and(b) the numbers of tumors in the low-dose and high-dose groups were comparable(though it is possible that the maximum rate of tumors occurred in the low-dosegroup). Regarding the urinary bladder neoplasms, the original report submitted by
the petitioners stated that the high-dose male rats had a significantly increased incidence of those benign tumors. However, in the final submission, the petitioners
submitted an addendum claiming, without any specific justification, lack of statistical significance. The FDA pathologists concluded that neither the incidence nor theseverity of the transitional cell hyperplasia of the urinary bladder was treatment related(FDA 1982b).
In the CCMA-sponsored 24-month chronic toxicity/carcinogenicity study on Charles
River CD-1 mice, 60 mice/sex/group were fed 0 (two control groups), 0.5, 1.5, or 5%
Green 3 in their diet. The mice were not exposed to Green 3 in utero. No gross or
microscopic neoplastic and non-neoplastic observations related to administration of
the color were observed. Statistical analysis concluded that Green 3 did not have any
negative effect on time-to-tumor, survivorship, or tumor incidence in mice (Bio/dynamics 1982b).

23

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Conclusions
Green 3 did not increase tumor rates in CD-1 mice, though the only study did notinclude in utero exposure. Green 3 caused significant increases in bladder transitional
cell/urothelial neoplasms and testes Leydig’s tumors in high-dose male rats. Despitea last-minute assertion by the testing laboratory that the bladder neoplasms were nolonger statistically significant and the FDA’s dismissal (based on qualitative considerations, not statistical analysis) of the significance of the testes tumors, Green 3 mustremain suspect until further testing demonstrates that it is safe.

24

FOOD DYESB

A Rainbow of Risks

B

Orange B

Orange B
Introduction

O

O

N

N

N

NaSO3

N

O

SO3Na

Orange B is an azo dye that is approved by the FDA
for use only in frankfurter and sausage casings up to
150 ppm in the finished food (FDA 2008). Batchesof Orange B have not been certified for use in the past
decade or longer.

Metabolism

Figure 8. Orange B

Orange B is poorly absorbed in rats. The color is reduced in the gut to form naphthionic acid. That metabolite appears in both the feces
and the urine, indicating that some of the metabolite is absorbed (CCIC 1965).

Chronic Toxicity/Carcinogenicity
Orange B was fed to 50 Sprague-Dawley rats/sex/group at doses of 0, 0.5, 1, 2 or 5%
for 2 years (an in utero phase was not conducted). By the end of the second year, allof the rats in the 2% and most in the remaining groups (including the control groups)
were dead. Male and female rats in the two highest-dose groups showed lymphoid
atrophy of the spleen and bile-duct proliferation. All examined animals in the highestdose group experienced moderate chronic nephritis, but increased tumor rates were
not reported. Investigators gave Orange B a NOAEL of 0.5% for rats (CCIC 1965).
Orange B was fed to 50 C3H mice/sex/group and 50 C57BR/cd mice/sex/group at doses
of 0, 1, or 5% dietary supplement for their lifespans (an in utero phase was not conducted). There was no effect on tumor development or lifespan. The growth rate of
the C3H mouse was depressed in the 5% groups. Investigators assigned a NOEL of
1% to mice (CCIC 1965).
Groups of 3 beagles/sex/group were fed 0, 1, 2, or 5% Orange B as a dietary supplement in a chronic study. One dog/group was sacrificed at the end of 1 and 2 years,
and the remaining dogs stayed in the study until the end of 7 years. The investigators
assigned a NOEL of 1% to dogs (CCIC 1965), but the study used too few dogs for too
short a time to provide meaningful information.

Conclusion
In 1978 the FDA proposed banning Orange B (Fed Reg. October 3, 1978), but,because companies stopped using it, the FDA never bothered to finalize the ban; itshould do so now.

B

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A Rainbow of Risks

FD&C Red No. 3

FD&C Red 3

Introduction
FD&C Red No. 3 (Fig. 9), or Erythrosine B, has been used
as a food dye since its approval by the U.S. Department ofAgriculture in 1907. It is a water-soluble dye with about
a 58% iodine content (Lin and Brusick 1986). It is usedin maraschino cherries, sausage casings, oral drugs, baked
goods, and candies. The ADI for Red 3 is 2.5 mg/kg bw/day
or 75 mg/day for a 30-kg child (FDAe). Annual productionof Red 3 is equivalent to only about 1 mg/person/day.

Metabolism

NaO

I

I

O

O

I

I
C
O

Figure 9. F D&C Red No. 3;
Erythrosine B

Osborne-Mendel rats were administered 0.5-500 mg/kg
bw Red 3 by stomach tube. Qualitative analysis demonstrated that the dye excreted
in the urine or bile was unchanged (Webb, Fonda et al. 1962). In another study, 14
male rats were given one dose (0.5 mg/kg bw) of Red 3. Approximately, 55-72%
was excreted unchanged in the feces within 3 days. In two bile-duct cannulated rats,
0.44 and 1.67% of the dye was excreted in the bile, indicating that a small amount isabsorbed. No color was recovered in the urine. Investigators concluded that “Red 3
is metabolized to some extent in the tissue” (Daniel 1962). Rats administered Red 3
twice weekly for 3 months at doses (according to an industry petition) of 5, 10, 15,
and 50 mg/200-250 gm bw had elevated serum levels of protein-bound and total
iodine (Bowie, Wallace et al. 1966). Butterworth et al. also showed that rats administered Red 3 at 0-2% dietary doses over 13 weeks had a dose-related increase in serum
levels of protein-bound and total iodine (Butterworth, Gaunt et al. 1976).
In a human study, subjects were orally administered 16 mg of Red 3 for 10 days (morethan 15 times typical consumption). Subjects had about twice as much protein-boundiodine in their serum compared to levels prior to administration. Levels peakedaround days 15-20 and did not return to normal until about 3 months after the beginning of the study (Anderson, Keiding et al. 1964).

In Vitro Effects on Neurotransmitters
Red 3 was applied to isolated frog neuromuscular synapses to test its effect onneurotransmitter release using electrophysiological techniques. Concentrations of
10 μM and greater caused an irreversible, dose-dependent increase in acetylcholine
release. Investigators concluded that Red 3 may alter the function of more complex
systems, but any conclusions regarding its effects on mammalian behavior would bepremature given the in vitro nature of the study (Augustine and Levitan 1980).

ONa

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Genotoxicity
Table 2 lists the numbers of negative and positive results in in vitro and in vivo genotoxicity studies using Red 3. Although the majority of the tests were negative, several
studies demonstrated the genotoxic potential of the dye (Ishidate, Sofuni et al. 1984;
Matula and Downie 1984; Sasaki, Kawaguchi et al. 2002). Of particular concern isthat the positive results were in studies using mammalian cells or an in vivo method(comet assay), while most of the negative results came from prokaryotic systems.
Some of the key genotoxicity studies are summarized in Table A4 in the Appendix.

Chronic Toxicity/Carcinogenicity
Almost 40 years ago, Hansen et al. performed long-term toxicity studies on Red 3 onrats and dogs, but the numbers of animals in the study did not meet current FDA
recommendations (FDA 2000). The rat study used 12 Osborne-Mendel weanling rats/
sex/group that were fed diets with 0, 0.5, 1, 2, or 5% Red 3 for 2 years. No significant
adverse effects were observed. In the same study, 18 rats were given weekly subcutaneous injections of Red 3 at an initial dose of 12 mg/rat (1 ml of a 2% dose that was
reduced to 1.5%, then 0.75% over the 2-year period due to ulcerations in the animals)for 2 years. Other than injection site ulcerations, no significant adverse effects wereobserved (Hansen, Zwickey et al. 1973a). The dog study used only 3 dogs/sex/group.
Chronic toxicity studies focusing on the effects of Red 3 on hematology, thyroxine,
and protein-bound iodide in Osborne-Mendel rats did not find any adverse effects. 25
rats/sex/group were fed 0 (the only group with 50 rats/sex), 0.5, 1, 2, or 4% Red 3 for
86 weeks or intubated twice weekly with 0, 100, 235, 750, or 1,500 mg/kg Red 3 for
85 weeks. The study did not include an in utero phase. At the end of the treatment
periods, the rats were fed the control diet until the studies reached the 2-year mark.
The studies found no adverse effects in gross or microscopic pathology and no changes in thyroxine-iodide levels. The levels of protein-bound iodide increased, and it wasdetermined that this was due to increased dye levels in the serum (Hansen, Davis et al.
1973b).
Borzelleca et al. performed a CCMA-sponsored chronic toxicity/carcinogenicity study
in Charles River CD-1 mice. The maximum duration of exposure of the mice to 0
(two control groups), 0.3, 1, or 3% Red 3 was 24 months (no in utero exposure). All
groups consisted of 60 males and 60 females. Investigators reported no statisticallysignificant compound-related effects on behavior, morbidity, mortality, hematology or
general physical observations. There was a statistically significant increase in the incidence of lymphocytic lymphoma in male mice in the 0.3% low-dose group. However,that effect was not considered compound-related because there was no dose-response
relationship, and the incidence of lymphomas in the high-dose group was similar tothat in the controls. The NOAELs were deemed to be 3% (4,759 mg/kg/day) in males
and 1% (1,834 mg/kg/day) in females (Borzelleca, Capen et al. 1987b).

27

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Borzelleca et al. also performed two CCMA-sponsored chronic toxicity/carcinogenicity studies in Charles River CD rats. Unlike the mouse study (above), these studies
included an in utero phase. In the F0 generation of both studies, 60 rats/sex/groupwere fed 0 (two control groups), 0.1, 0.5, or 1% (original study) and 0 or 4% (highdose study) Red 3. Random offspring were selected for the F1 generation and 70 rats/
sex/group were given the same dietary levels as the F0 generation. The maximum
exposure was 30 months. Investigators reported no compound-related effects on
fertility, gestation, parturition, lactation, pup survival through weaning, or numbers oflive and stillborn pups. Animals from the chronic feeding phase experienced several
effects. The most notable were statistically significant increases in the incidences ofthyroid follicular cell adenomas in male rats in the 4% treatment group (15 adenomas
in the 4% group compared to 1 in the control groups) and non-significant increases inthese tumors in female rats in the 0.5, 1, and 4% treatment groups. High-dose (4%)
male rats also showed a statistically significant increase in non-neoplastic proliferativechanges of the thyroid. The changes included follicular cell hypertrophy and hyperplasia and follicular cystic hyperplasia. Also, 94% of male rats in the 4% treatmentgroup showed proliferative changes of thyroid follicular cells. Based on the results ofthe two studies, investigators asserted that Red 3 had NOAELs of 0.5 and 1% in maleand female rats, respectively (Borzelleca, Capen et al. 1987b).

Reproductive Toxicity
Borzelleca and Hallagan conducted a 3-generation study on Red 3 in Sprague-Dawley
rats. In each generation 25 rats/sex/group received 0, 0.25, 1, or 4% of the color in
their chow. The only significant finding was a statistically significant reduction inbody weights of parents and pups in all generations at the 4% dietary level. That
could have been due to the large consumption of a non-nutritive compound. There
were no compound-related adverse effects on reproductive indices and no gross anomalies. Investigators concluded that the NOAEL for rats was 0.25%, or approximately
149 and 255 mg/kg bw/day for males and females, respectively. That NOAEL wasbased on the reduced body weight in the 4% group and reduced body-weight gain
during gestation in females in the 1 and 4% groups (Borzelleca and Hallagan 1990b).

Conclusions
Red 3 is genotoxic in in vivo and in vitro assays and is an animal carcinogen. The Red 3
petitioners attempted to prove that the color acts as a secondary carcinogen, a chemical that exerts its carcinogenicity via an indirect pathway, and, therefore, exempt fromthe Delaney Clause. However, the FDA concluded that Red 3 was not proven to be asecondary carcinogen in the industry-sponsored studies and found that “FD&C Red 3
is an animal carcinogen when administered in the diet.” In 1990, the FDA terminatedthe provisional listing of Red 3 for use in cosmetics and externally applied drugs; alluses of Red 3 lakes were also banned (FDA 1990).

28

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Notwithstanding its 1990 finding that Red 3 is an animal carcinogen, the agency still
permits Red 3 in ingested drugs and foods, though in 1990 it was reported to havesaid it would “take steps” to ban those uses, too (McLaughlin April 22, 1990). About
200,000 pounds of the dye are used annually. Red 3 is allowed for those uses because
petitioners had submitted CCMA-sponsored studies after the 1960 provisional listings
that showed no safety concern, and in 1969 the FDA permanently approved the dyefor use in ingested drugs and foods (Blumenthal 1990). In 1984, FDA’s Acting Commissioner, Mark Novitch, said that Red 3 was “of greatest public health concern…Theagency should not knowingly allow continued exposure (at high levels in the case of
FD&C Red No. 3) of the public to a provisionally listed color additive that has clearly
been shown to induce cancer while questions of mechanism are explored” (Burros
February 13, 1985). However, around the same time, Secretary of Agriculture John R.
Block was pressing his counterpart at the Department of Health and Human Services
not to ban the dye (Food Chemical News May 28, 1984). He wrote, “Some segmentsof the agricultural community are quite dependent on Red Dye #3 in the processing
and marketing of certain commodities, especially canned fruits. I have assured theaffected industry that their concerns would be made known to you, as well as my own
concern...” And in 1989, Congress, at the behest of growers and packers, temporarily
prohibited the FDA from banning the dye (Washington Post July 19, 1989). Twentysix years later, the FDA still has not acted.
The harm that Red 3, an acknowledged animal carcinogen, is likely causing far outweighs the minor nuisance entailed in banning the dye. It is worth noting that Red 3
has been seen as invaluable by some makers of maraschino cherries, but other brands
are dyed with Red 40 or (shockingly) no added coloring, and some brands (Del Monte,
Giant) of canned fruit cocktail contain cherries colored with natural colorings (unfortunately, the natural colorings used, carmine or cochineal extract, can cause severe
allergic reactions). The food industry and public would survive a ban quite easily.
Another means of protecting the public would be through California’s law that requires warning notices on products that contain chemicals that the state’s Office ofEnvironmental Health Hazard Assessment (OEHHA) has determined pose a certain
degree of cancer risk.‘ In 1999, the California Environmental Protection Agency concluded that while one rat study was positive for tumors and others were not, “There isa HIGH level of concern over the extent of exposure to C.I. acid red 51 [Red 3], since it isused as a dye in food, drugs and cosmetics and is likely to be consumed by the general
population.” [emphasis in original] The risk posed by Red 3 might exceed OEHHA’s“safe” level (which is less strict than the FDA’s level), and California could require
products that contain Red 3 to bear a cancer warning notice—though most companies
likely would switch to a safer coloring. However, California considered Red 3 a lower
concern than other carcinogens and has not taken any action (California OEHHA).

B

B

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FD&C Red 40

FD&C Red 40

Introduction
Red 40 is the FDA-approved version of Allura Red, which was first
produced by Allied Chemical Corp. It is approved for use in beverages, bakery goods, dessert powders, candies, cereals, foods, drugs,
and cosmetics and, in terms of pounds consumed, is by far the
most-used dye. Red 40 has an ADI of 7 mg/kg bw/day (FDAf). That
ADI translates into 210 mg for a 30-kg child. Companies produce
the equivalent of about 25 mg of the dye per person per day, withmany children probably averaging several times as much.

HO

OCH3
NaO3S

N

N

H3C

Figure 10. F D&C Red No. 40;
Allura Red

Metabolism
In an unpublished report, rats were fed 5.19% of the dye in their diets (White 1970).
29% of the intact dye was excreted in the feces while only 0.1% was excreted in theurine. The parent dye appears to be broken down by gut flora via azo-reduction into
two metabolites, cresidine-4-sulfonic acid and 1-amino-2-naphthol-6-sulfonic acid. In
another study, rats and dogs were pretreated daily with unlabeled Red 40 followed by
35
S-Red 40 for up to 72 hours. Within 72 hours, 92-95% and 76-92% of the radioactivity was recovered in the feces of dogs and rats, respectively. Radioactivity in theurine accounted for only 5.7-19.8% and 2.7-3.6% of the total dose in dogs and rats,
respectively. There was significant retention of radioactivity in the guts of sacrificed
animals (White 1970).

Genotoxicity
Table 2 lists the numbers of negative and positive results for genotoxicity studies
performed on Red 40. Red 40 was negative in the majority of genotoxicity assays
performed, but positive in the in vivo comet assay in the glandular stomach, lungs, andcolon of mice (Sasaki, Kawaguchi et al. 2002). That indicates that Red 40 can cause
DNA damage in vivo. Details of the genotoxicity assays are provided in Table A5 of the
Appendix.

Hypersensitivity
52 patients suffering from urticaria and angioedema for more than 4 weeks wereplaced on a 3-week elimination diet. Red 40 administered orally in doses of 1 or
10 mg induced a hypersensitivity reaction in 15% of the patients who were generally
symptom-free at the time of provocation (Mikkelsen, Larson et al. 1978).

SO3Na

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Chronic Toxicity/Carcinogenicity
In the 1970s, Hazleton Laboratories conducted chronic toxicity/carcinogenicity feeding studies in rats and mice, both of which included an in utero phase. Using SpragueDawley rats, the F0 generation included 30 rats/sex/group that were administered 0,0.37, 1.39, and 5.19% of Red 40 in their chow one week prior to mating, during mating, gestation, and lactation. The test of F1 rats involved 50 rats/sex/group created bychoosing random surviving offspring. The F0 and F1 generations were exposed to thesame dosage levels. Males and females were exposed for 118 and 121 weeks, respectively. No compound-related effects were reported during the gestation and lactation
periods. With the exception of a statistically significant decrease in body weight in
high-dose females, investigators reported no consistent adverse effects due to Red 40.
They established a NOAEL of 5.19% (2,829 mg/kg/day) for males and 1.39% (901
mg/kg/day) for females (Borzelleca, Olson et al. 1989).
Hazleton Laboratories also performed two chronic toxicity studies in CD-1 mice. In
the first study, 50 mice/sex/group (F0) were administered 0, 0.37, 1.39, or 5.19% Red
40 in their chow one week prior to breeding through the gestation and lactation periods. The F1 generation was randomly selected from surviving pups and the chronic
feeding study used 50 mice/sex/group. The dosages were the same in the F0 and F1
generations. At 42 weeks, a total of 6 reticuloendothelial (RE) tumors occurred in themales and females (0 in controls, 1 each in the low- and mid-dose groups, and 4 in thehigh-dose groups). (The reticuloendothelial system is a part of the immune system.)That led the investigators to sacrifice and examine 36% of the animals, reducing eachgroup to 30 mice/sex/group. The remaining smaller groups of F1 mice were fed Red
40 for a total of 104 weeks. By the end of the study, the investigators concluded that
Red 40 did not cause acceleration of the appearance of RE tumors (Borzelleca, Olsonet al. 1991). However, Dr. M. Adrian Gross, a senior FDA pathologist, concluded that
there was clear evidence to support an acceleration effect of RE tumors because there
was a decreased latency period without a corresponding increase in overall tumor
incidence.
A second mouse study was conducted to address the possibility suggested by the firststudy that Red 40 accelerated the appearance of RE tumors, a sign of carcinogenicity(Fed. Reg. May 22, 1984). Although the second study used the same dosage groups as
the first, the studies differed in several respects. First, the initial study used Ham/ICR(CD-1) mice, while the second used CD-1 outbred mice. Second, the F0 generationin the second study used 70 mice/sex/group, and the F1 generation consisted of 100
mice/sex/ group. Third, the second study did not include a 42-week interim sacrifice.
Fourth, the second study used two control groups instead of one. Finally, the mice inthe second study were exposed to Red 40 for 109 weeks—five weeks longer than thefirst study.
The second study, according to the investigators, did not show an early appearance ofor increase in RE tumors. Only the high-dose males and females experienced a signifi-

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cant increase in relative and absolute thyroid weight. The investigators set a NOAEL
of 5.19% in mice or 7,300 and 8,300 mg/kg/day for males and females, respectively(Borzelleca, Olson et al. 1991).

Limitations of the Mouse Studies
There were a number of problems with the chronic toxicity studies on Red 40. The
first mouse study suggested a reduced latency period for RE tumors without a final
increased incidence. Also, Hazleton Laboratories found small numbers of RE-system
tumors in all treatment groups prior to the 42-week sacrifice, the highest incidence
being in the high-dose group. At the time, the FDA recommended killing 36% of
the mice to gain information about Red 40’s ability to accelerate the occurrence of RE
tumors. The sacrifices were done at week 42 of the 2-year study. However, that left arelatively small number of mice available at the end of the study and reduced the ability to analyze tumor incidence (Lagakos and Mosteller 1981).
Because of the controversial early results in the first mouse chronic-feeding study, in
1976 the FDA created a working group of scientists from the FDA, National Cancer
Institute, and the National Center for Toxicological Research to monitor the rat andmouse studies being performed for Allied Chemical. Midway through the secondmouse study, the working group concluded that the first study did not indicate a riskof carcinogenesis. Following controversy over that conclusion, FDA Commissioner
Donald Kennedy appointed four non-governmental statisticians, including Havard’s
Frederick Mosteller and Stephen Lagakos, to review the statistical methods used toanalyze the mouse studies. Those statisticians were independent and not a part of the
FDA working group.
Two problems found with the mouse studies included caging and litter effects (Lagakos and Mosteller 1981). Mice housed in the upper row of racks experienced a higher
incidence of RE tumors than the mice in lower cages, according to the FDA consultants (Lagakos and Mosteller, 1979). That might have been because cages in both ofthe mouse studies were not rotated. The incidence of RE tumors was significantly
correlated to the row (p=0.0005) and position (p=0.02) of the racks (Lagakos andMosteller 1979). The working group also noted that it was impossible to know if mice
were being housed with siblings (litter effect), which might have had an influence ontumor incidence (Group 1981). Confounders such as potential caging and litter effects strongly decrease the credibility of a study.
A concern regarding the second mouse experiment was the large variation in RE tumor
rates compared to the first experiment, though that might have been because different
mouse strains were used. Another sign that the second study could not produce definitive results is that the difference in RE death rates between the two control groups
was highly statistically significant at the p=0.008 level (Lagakos and Mosteller 1981).

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Regarding the statistical analyses of the two mouse studies, Lagakos and Mosteller
commented that the difference in RE tumor rates between the two studies limited theconclusiveness of the results. They argued that the statistical methods used by the
FDA Working Group were not oriented to detecting an acceleration effect (decreased
latency in tumor induction) (Lagakos and Mosteller 1981). Their analysis concluded
that both studies suggested a decreased latency period for, and increased incidence of,
RE tumors (Lagakos and Mosteller 1979).

Carcinogenic contaminants
As discussed below with regard to Yellow 5 and Yellow 6, Red 40 might containcancer-causing and other contaminants. Health Canada scientists, using a test methodthat could detect bound and free contaminants, identified small amounts of aniline,
p-cresidine, and 1-naphthylamine in the dye (Lancaster and Lawrence 1991). The
p-cresidine is “reasonably anticipated to be a human carcinogen,” according to the
U.S. National Toxicology Program, and “possibly carcinogenic to humans,” according
to the International Agency for Research on Cancer (IARC; NTP). FDA consideredaniline to be weakly carcinogenic to rats (FDA 1985), though other agencies have notdetermined that aniline— and 1-naphthylamine—pose a risk to humans (FDA 1985;
IARC).

Reproductive Toxicity/Teratogenicity
FDA scientists investigated the potential embryotoxicity and teratogenicity of Red 40.
Pregnant female rats were dosed with 0, 7.5, 15, 30, 100, or 200 mg Red 40 /kg bw
daily on days 0-19 of gestation through intubation or 0 or 2 mg Red 40/kg bw daily
through drinking water on days 0-20 of gestation. No negative effects on maternal
reproduction, embryolethality, or fetotoxicity were observed (Collins and Black 1980).

Conclusions
There is evidence, albeit controversial and inconclusive, that Red 40, the most widelyused dye, accelerates the appearance of tumors of the reticuloendothelial system inmice. Also, outside consultants appointed by the FDA raised concerns about an FDAappointed Working Group’s statistical analysis of the data. Considering the lack ofpublished metabolism data, the positive results in comet assays, the disputed mousestudies, causation of hypersensitivity reactions, possible causation of hyperactivity inchildren, and the non-essentiality of the dye, Red 40 should not be used in foods.

33

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FD&C Yellow 5

FD&C Yellow 5
Introduction
FD&C Yellow No. 5 (Fig. 11), also known as Tartrazine, isused in numerous bakery goods, beverages, dessert powders, candies, cereals, gelatin desserts, pet food, and manyother foods, as well as pharmaceuticals, and cosmetics.
After Red 40, it is the most widely used dye. The ADI for
Yellow 5 is 5 mg/kg/day (FDAg), which equates to 150 mg/
day for a 30-kg child. Companies produce the equivalentof 15 mg of the dye per person per day, with many children
consuming at least several times that much.

NaO3S

N

CO2Na

N
O

N

N

SO3Na
Figure 11. FD&C Yellow No. 5; Tartrazine

Metabolism and Metabolic Effects
Sulfanilic acid is a metabolite that results from the reduction of Yellow 5 at the N=N
azo link However, when Yellow 5 labeled at the phenylazo group with 14C was
administered intraperitoneally in rats and rabbits, no radioactive sulfanilic acid wasrecovered in the urine (Jones, Ryan et al. 1964). In the same study, when Yellow 5
was administered orally to rats, rabbits, and humans, sulfanilic acid, but little or no
unchanged dye, was recovered in the urine. These results indicate that the reductionof Yellow 5 occurs via the GI flora. That is why sulfanilic acid is excreted in the urine
when Yellow 5 is administered orally but not intraperitoneally. Ryan et al. confirmedthat Yellow 5 is primarily metabolized in the guts of rats after an oral dose, where thegut microflora perform the majority of the compound’s degradation (Ryan, Welling etal. 1969).
Apart from the metabolism of the dye, a 50-mg dose of Tartrazine led to increased or
accelerated urinary excretion of zinc in hyperactive children. Whether the effect onzinc is a cause of hyperactivity is not known. Amaranth (formerly FD&C Red No. 2)
had no effect (Ward 1996).

Genotoxicity
Yellow 5 caused genotoxic effects in six out of 11 studies (see Table 2 above and Table
A6 in the Appendix). A 1985 report from the U.S. Department of Health and Human
Services criticized two of the genotoxicity studies (Patterson and Butler 1982; Ishidate,
Sofuni et al. 1984) and disagreed with their conclusions that Yellow 5 induces chromosomal aberrations (Flamm, Jackson et al. 1985). The HHS report stated, though,“If chromosome aberrations of the type reported for Tartrazine in cultured cells occurred in vivo, they certainly would represent a serious adverse effect.” In fact, Sasaki
et al. subsequently demonstrated that Yellow 5 does induce DNA damage in vivo in the

34

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A Rainbow of Risks
comet assay (Sasaki, Kawaguchi et al. 2002). At the very least, the numerous positive
genotoxicity results indicate the need for further investigation.

Chronic Feeding/Carcinogenicity
The earliest chronic feeding study reported that Yellow 5 was not carcinogenic or toxic
in a 2-year study using Osborne-Mendel weanling rats.11 The rats were fed 0, 0.5, 1,
2, and 5% Yellow 5. However, that study used only 12 rats of each sex per dosage
group (Davis, Fitzhugh et al. 1964). The FDA recommends a minimum of 20 rodents/
sex/group for chronic toxicity studies, though many experts consider that far too small
a number (FDA 2000). Also, the rats were not exposed in utero.
Later, Borzelleca and Hallagan also found that Charles River CD rats fed Yellow 5 did
not show carcinogenic or toxic effects. In a well-designed study sponsored by CCMA,
70 rats/sex/group were exposed to 0, 0.1, 1, 2, or 5% Yellow 5 starting in utero for 30
months or until only 10 rats/sex/group survived (Borzelleca and Hallagan 1988a). The
researchers did not find any compound-related effects on fertility, gestation, parturition, lactation, pup survival, or number of still-born pups. Investigators looked at thehematology, clinical chemistry, and urine of 10
Table 3. Mouse survival at termination
rats/sex at six time points. They also performedof a 24‑month study
complete histopathology on 10 rats/sex/group at
Dose Level (%)
Survival*
an interim sacrifice at 12 months, as recommend0 (control 1)
30/50
ed by the FDA (FDA 2000). Complete histopa0 (control 2)
28/60
thology was performed on all sacrificed animals,
0.5
31/60
and gross necropsies were conducted on animals
Males
that died spontaneously. No problems were seen.
1.5
21/60
This group reported a NOAEL of 5% for both
5.0
29/60
male and female rats.
0 (control 1)

20/60

0 (control 2)

24/60

Borzelleca and Hallagan also performed a chronic
toxicity/carcinogenicity study in CD-1 mice (Bor0.5
18/60
Femaleszelleca and Hallagan 1988b). Groups of 60 males
1.5
24/60
and 60 females were fed 0 (two control groups),
5.0
33/60
0.5, 1.5, or 5% Yellow 5 for 104 weeks. The*No. surviving at termination of study/no. at initiation;
protocol for this study was similar to Borzelleca
boldface indicates inadequate numbers of mice surviving.
and Hallagan’s rat study, but there was no mention(Borzelleca and Hallagan 1988b)of an interim necropsy of 10 mice/sex/group, as
recommended by the FDA. Also, the mice were
not exposed in utero, but were 42 days old at the start of the study—a serious drawback, because infant animals are likely to be more susceptible to toxic or carcinogenic
effects than older animals. The investigators claimed that a sufficient number of mice
11. Davis et al. also tested 3 groups of two male and two female beagles for two years at dosages of 0, 1, and 2% Yellow 5, but that small number of dogs and the brevity of the test do not permit conclusions about the long-term effectsof the dye.

35

FOOD DYES

A Rainbow of Risks
survived until the end of the study (24 months), however, half of the groups did notmeet the FDA recommendation that in a carcinogenicity study at least 25 mice/sex/
group should survive until study termination (see boldface numbers in Table 3). In
any case, the investigators did not find any significant compound-related effects. The
NOAEL for this study was 5% for male and female mice (indeed, the lack of any effectat the highest dosage level indicates that a higher dosage should have been used).

Carcinogenic contaminants
Yellow 5 may be contaminated with several carcinogens, including benzidine and4‑aminobiphenyl. The FDA limits free benzidine to 1 part per billion (ppb), thoughanalytical methods can only detect 5 ppb. More importantly, FDA tests in the early
1990s found that some batches of dye contained as much as 83 ppb of free and boundbenzidine, with the latter probably being liberated in the GI tract (Prival, Peiperl et al.
1993). As noted on page 3, the FDA does not test for bound benzidine when it certifies the purity of dyes. The FDA’s 1985 risk assessment (using projections for 1990
consumption levels) calculated a risk for Yellow 5 of 4 cancers in 10 million people,
which is slightly smaller than the “concern” level of 1 in 1 million (FDA 1985). However, that risk assessment failed to consider the (a) greater sensitivity of children tocarcinogens (FQPA), (b) greater consumption of Yellow 5 by children than the general
population, (c) substantial increase in per capita consumption of Yellow 5 since 1990,(d) possibility that some batches of dye contain large amounts of bound benzidine
and other carcinogenic contaminants, and (e) the presence of similar contaminantsin Yellow 6. FDA scientists found that one company eliminated benzidine contamination in 1992, suggesting that other companies could do (or might have done) thesame (Peiperl, Prival et al. 1995). However, with more chemicals being imported
from China, India, and other countries, it is important that dyes routinely be tested forbound contaminants.

Hypersensitivity
The one generally accepted concern about Yellow 5 is its hypersensitivity effects. In
the 1970s, several cases of Tartrazine-sensitivity were reported, most frequently inthe form of urticaria (hives) and asthma (Dipalma 1990). Neuman et al. reported
that 26% of patients with a variety of allergic disorders had a positive allergic reaction
10-15 minutes after ingesting 50 mg of the dye. Those reactions included heat-wave,
general weakness, blurred vision, increased nasopharyngeal secretions, a feeling of
suffocation, palpitations, pruritus (severe itching), angioedema (swelling or welts
below the skin), and urticaria (Neuman, Elian et al. 1978). An association between
aspirin-intolerance and Tartrazine-sensitivity has been demonstrated in several studies. Stenius and Lemola separately administered aspirin and Yellow 5 to 96 patientsand found that about half of the patients with positive reactions to aspirin also had
positive reactions to Yellow 5, and about three-fifths of the positive Yellow 5 cases also

36

FOOD DYES

A Rainbow of Risks
had positive aspirin reactions (Stenius and Lemola 1976). In a double-blind crossoverstudy Settipane et al. found that 0.22 mg of Yellow 5 (much less than is used in mostdyed foods) caused a positive reaction in 8% of patients with chronic urticaria and
20% of patients with aspirin intolerance (Settipane, Chafee et al. 1976).
These examples indicate the range and potential severity of hypersensitivity reactions
to Yellow 5:•

A 42-year-old woman gradually developed chronic nasal blockage, loss ofher senses of taste and smell, and asthma. She was eventually hospitalized—
sometimes for weeks—three times for her asthma, which developed into atight, unproductive cough and severe wheezing. Several years later she developed severe angioedema after taking two aspirin tablets. She also developed
the same attacks from Tylenol and several other drugs, including antibiotics.
She was cleared of all drugs, but her symptoms returned after she received
Premarin, a menopausal drug that contained Yellow 5. The patient was finallydiagnosed with an allergy to Yellow 5 and several other food additives. Hersevere attacks were relieved when she stopped consuming all synthetic dyes,
sodium benzoate, and drugs containing dyes (Chafee and Settipane 1967).

•

A 15-year-old pregnant girl went into anaphylactic shock after she was given
an enema that contained Yellow 5 and Yellow 6. Approximately 5 minutes
after administration of the enema the patient became dizzy, sweaty, and hypotensive; she collapsed and was unconscious. Her blood pressure became
unrecordable and her carotid pulses were “weak.” Her skin became red all
over. After she regained consciousness, she was nauseous, had dull perception, and eventually developed hives, chest tightness, and shortness of breath(Trautlein and Mann 1978). Subsequent tests indicated that she was sensitive
to both Yellow 5 and Yellow 6.

•

A 38-year-old man experienced relapsing angioneurotic (subcutaneous)edema, giant urticaria, and a relapsing vascular purpura (purple spots). Afterprovocation with Yellow 5, the test area became purpuric and there was purpura, swelling of the legs, and angioneurotic edema of the face (Michaelsson,
Pettersson et al. 1974).

•

A 32-year-old woman experienced recurring purpuric lesions on her lower
legs. The lesions sometimes became more intense with ulcerations, pain, andswelling of the legs. She had occasional superficial thrombophlebitis (swellingof a vein caused by a blood clot). She experienced those symptoms 4-8 times
a year, and they lasted about 2-3 weeks. Provocation with Yellow 5 induced
purpura in the treated area (Michaelsson, Pettersson et al. 1974).

37

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It was because of reactions like those that in 1986 the Joint Council of Allergy and
Immunology told the FDA that just listing Yellow 5 on the label was not protective
enough because reactions could be life-threatening. “Since many reactions are sudden
and occur without warning,” the group urged the agency to ban Yellow 5. The joint
council was established by two of the major medical organizations concerned aboutallergies.

Conclusions
Six out of 11 mutagenicity studies indicated potential problems, but Yellow 5 did notappear to be carcinogenic in rats. The chronic feeding study in mice was inadequate
and cannot be used to support the dye’s safety. In addition, Yellow 5 may be contaminated with significant levels of carcinogens. On another front, Tartrazine (the only dye
to be tested on its own, instead of in mixtures) has caused hyperactivity in children(Rowe 1988; Rowe and Rowe 1994). Yellow 5 can cause mild to severe hypersensitivity reactions. Since Yellow 5 poses some risks, has not been adequately tested in mice,and is a cosmetic ingredient that serves no nutritional or safety purpose, it should not
be allowed in the food supply.

38

FOOD DYES

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FD&C Yellow No. 6

FD&C Yellow 6
HO

Introduction

FD&C Yellow No. 6 (Fig. 13), the FDA-approved form of Sunset
Yellow, is a water-soluble sulfonated azo dye that is used to color
bakery goods, cereals, beverages, dessert powders, candies, gelatindesserts, sausage, and numerous other foods, as well as cosmetics
and drugs. Yellow 6 has an ADI of 3.75 mg/kg bw/day, or 112.5
SO3Na
mg for a 30-kg child (FDAg). Current average per capita producFigure 12. FD&C Yellow No. 6; Sunset
tion of Yellow 6 is equivalent to about 14 mg/day, making it the
Yellow FCF
third most widely used dye. Considering that the FDA estimatesthat an average “high user” consumes about five times as muchdye as an average user over their lifetimes, some children may beconsuming amounts above the ADI (FDA 1986).
NaO3S

N

N

Metabolism and Metabolic Effects
Several metabolites were found in the urine of rabbits given a single 0.5 mg/kg oral
dose of Yellow 6. Yellow 6 is reduced at the azo linkage primarily in the gut by
intestinal microflora to produce sulfanilic acid and 1-amino-2-naphthol-6-sulfonicacid, as well as the n-acetylated form of sulfanilic acid, p-acetamidobenzene-sulfonicacid. Intact Yellow 6 in the feces accounted for only about 2% of the dose (Daniel1962). Those findings were confirmed by Honohan et al. who dosed 5 rats with 2.7
mg of 14C-Yellow 6 orally and found only 1-2% of the dose in the form of intact dye inthe feces after 24 hours (Honohan, Enderlin et al. 1977). In another rat study, after asingle oral dose of 100 mg, only 0.8% of intact dye was excreted in the feces, with therest being the metabolites indicated above. Only 3.6% of the intact dye was absorbed
by rats administered 50 mg of Yellow 6 orally (Radomski and Mellinger 1962).
Apart from the metabolism of the dye, a 50-mg dose of Sunset Yellow (like Tartrazine) led to increased or accelerated urinary excretion of zinc in hyperactive children.
Whether the effect on zinc is a cause of hyperactivity is not known (Ward 1996).

Genotoxicity
Although Yellow 6 was negative in six genotoxicity assays, it did induce forward
mutations and chromosome aberrations in two assays (McGregor, Brown et al. 1988;
Hayashi, Matsui et al. 2000). As shown in Table A7 in the Appendix, Yellow 6 did not
induce DNA damage in a comet assay or cause frameshift, base pair, or forward mutations; chromosomal aberrations; or cause mitotic gene conversion.

39

FOOD DYES

A Rainbow of Risks

Chronic Toxicity/Carcinogenicity
The National Toxicology Program (NTP) conducted carcinogenesis studies using
50 animals/sex/group in F344 rats and B6C3F1 mice. Each group was fed a dietcontaining 0, 12,500, or 25,000 ppm Yellow 6 for 103 weeks. The control groups
consisted of 90 rats or 50 mice of each sex. There was no in utero exposure in either
study, a significant weakness. The rat study did not find any statistically significant
color-related neoplastic or non-neoplastic lesions in any of the groups. Low-dose,
but not high-dose, male mice had a significantly higher incidence of hepatocellular
carcinomas and adenomas compared to controls. Partly because of the lack of a dose
response relationship in the mice, the investigators concluded that Yellow 6 was not
carcinogenic (NTP 1981).
In 1982, Bio/dynamics Inc., under contract to CCMA, conducted two multi-generation long-term feeding studies in Charles River Sprague-Dawley rats at doses of 0
(two control groups), 0.75, 1.5, and 3% in the first study and 0 (one control group),
0.75, 1.5, and 5% in the second study. The first study was conducted for 30 and
28.5 months for males and females, respectively, and the second study lasted for 25.6
and 27.8 months for males and females, respectively. In the F1 generation, females inthe 3% group in the first study and males in the 5% group in the second study had
increased mortality. In the second study, interim sacrifice of some rats at 12 months
revealed an increase in the mean absolute and relative kidney weights in females of the
5% group. At terminal sacrifice of both studies, there was an increase in mean absolute and relative kidney weights in females in the 3% groups and 5% groups, as wellas an increase in the mean relative and absolute thyroid weights in males and females
in the 5% groups. Females in the 3% group and both males and females in the 5%groups had statistically significant increased incidences of adrenal medullary adenomas compared to controls. Also, males in the 3% group had an increased incidenceof testicular interstitial cell adenomas compared to pooled controls. Notwithstanding
those findings, the investigators concluded that the studies did not find any evidenceof carcinogenicity (Bio/dynamics 1982c).
After examining the results of the Bio/dynamics study, the FDA concluded that theincreased incidence of the tumors was not related to Yellow 6 because of the (a) lack of
dose-response in the 3% and 5% dosage groups (though that is comparing two different studies), (b) likelihood of false positives, (c) lack of precancerous lesions, (d) similar morphology of adrenal medullary lesions in control and treated animals, (e) lack of
a difference in the latency periods before tumors occurred, (f) fact that the tumors seen
are common spontaneous tumors in older rats, and (g) lack of other studies finding an
association between Yellow 6 and this type of tumor (FDA 1986).
Bio/dynamics, again under contract to CCMA, performed a chronic toxicity/carcinogenicity study in Charles River CD-1 COBS mice, with 60 mice per sex per group.
The study used dosages of 0 (two control groups), 0.5, 1.5, and 5% Yellow 6 in the

40

FOOD DYES

A Rainbow of Risks
animals’ chow. The study was terminated at only 20 months for the males and 23
months for the females (no in utero phase was conducted). Males in the 5% group had
significantly higher mortality compared to controls, but that is not relevant to people,
who consume far lower amounts of the dye. The laboratory concluded that the study
did not indicate any concern about carcinogenicity in mice (Bio/dynamics 1982d).12
In the 1960s, the FDA completed a seven-year feeding study on a small number ofbeagle dogs. Such studies are rarely large or long enough to detect carcinogenicity,and this one was no exception. However, Kent J. Davis, an FDA veterinarian, attributed “tears, eye lid encrustations, pannus [corneal inflammation], and corneal opacity
approaching blindness” to ingestion of Yellow 6 (Davis July 9, 1970). He concluded
that, because of the eye lesions, “it is apparent that immediate decertification of thiscolor is necessary in order to protect the public health at the recommended level ofpresent safety standards.”

Carcinogenic contaminants
Yellow 6 may be contaminated with several carcinogens, including benzidine and4‑aminobiphenyl. The FDA set a limit of 1 part per billion (ppb) of free benzidine,but some batches of dye have contained a hundred or even a thousand times as muchbound benzidine, which is likely liberated in the colon (Peiperl, Prival et al. 1995). As
reported on page 3, the FDA does not test for bound benzidine. The FDA’s 1986 risk
assessment (using estimates for 1990 consumption levels) estimated a risk of 3 cancers
in 10 million people, which is smaller than the official “concern” level of 1 in 1 million(FDA 1986). However, that assessment failed to consider the (a) greater sensitivity ofchildren, (b) greater consumption of Yellow 6 by children than the general population,(c) substantial increase in per capita consumption of Yellow 6 since 1990, (d) possibility that some batches of dye contain bound forms of benzidine and other contaminants (FQPA), and (e) presence of similar contaminants in Yellow 5. FDA scientists
found that in 1992 one company eliminated benzidine contamination of Yellow 5,
suggesting that other companies could do the same for Yellow 6 (Peiperl, Prival et al.
1995). However, a Health Canada study found that Sunset Yellow FCF (Yellow 6 in
the United States) was still contaminated in 1998 (Lancaster and Lawrence 1999).
With more and more chemicals being imported, it is important that dyes routinely betested for bound contaminants.

Hypersensitivity
Human hypersensitivity to Yellow 6 was reported as early as 1949 (Baer and Leider1949). Since then, several cases, such as the following, of hypersensitivity to the color
have been reported:
12. In the 1960s, the FDA published a 7-year study in which five female beagles were fed Yellow 6 at 2% in theirdiet. No abnormalities were reported, but a study involving so few animals, and only females, cannot be consideredadequately sensitive FDA (1964).

41

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A Rainbow of Risks•

A 15-year-old pregnant girl experienced anaphylactic shock after receiving anenema that contained Yellow 5 and Yellow 6. The patient was tested via theskin-prick technique for sensitivity to all of the soluble components in the enema. Positive results were observed for both Yellow 5 and Yellow 6 (Trautleinand Mann 1978).

•A 43-year-old physician was hospitalized for stomach cramps four times overa two-year period. Double-blind tests confirmed that the cramps were caused
by a hypersensitivity to Yellow 6 (Gross, Lance et al. 1989).

•

A 53-year-old woman visited the doctor for severe skin lesions. Two days after
receiving treatment she was hospitalized for distaste for food, as well as indigestion, retching, belching, severe abdominal pain, and vomiting. When the
drugs (administered orally) were discontinued, the symptoms subsided, andwhen the drugs were administered again the symptoms reappeared. A challenge test confirmed that Yellow 6 was the causative agent (Jenkins, Michelson
et al. 1982).

A study by Michaelsson and Juhlin involved 52 patients with, and a control group of
33 patients without, recurrent urticaria (hives). All subjects were put on a dye-free dietand were free of antihistamines prior to administration of the possible allergen. The
researchers tested the effects of several food dyes (including Yellow 6) and preservatives, as well as aspirin, sulfanilic acid (a metabolite of Yellow 6), and placebo. A doseof 0.1 mg (initial dose for asthma patients) or 1 mg of Yellow 6 was administered topatients with slight or no urticaria symptoms. If no reaction was observed after the
initial dose, a higher dose of 2, 5, or 10 mg was administered to the latter group ofpatients 1 hour after each previous dose. Symptoms of a hypersensitivity reaction
included urticaria; angioedema of lips, eyes, or face; reddening of the eyes; sweating;increased tear secretion; nasal congestion; sneezing; rhinitis (runny nose); hoarseness;wheezing; and a variety of subjective symptoms. Of the 33 control patients, only two
with a history of rhinitis showed signs of rhinitis when administered Yellow 5 and Yellow 6. Of the 27 patients with recurrent urticaria who were challenged with Yellow 6,
ten developed urticaria and six experienced subjective symptoms; 11 were negative for
symptoms. Eight out of nine patients with positive reactions to Yellow 6 also experienced a positive reaction to aspirin (people sensitive to Yellow 5 also are often sensitive
to aspirin) (Michaelsson and Juhlin 1973).
Michaelsson et al. tested seven patients having allergic vascular purpura (purplish
spots) with oral provocation by 5 mg Yellow 6. One patient had a strongly positive
reaction to the dye. That patient was a 32-year-old woman who suffered for 12 years
from recurring purpuric lesions. After the patient was put on a diet free from dyes andbenzoates (a preservative that has been linked to allergy-like reactions) for six months,
she was essentially free from lesions (Michaelsson, Pettersson et al. 1974).

42

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Conclusions
The NTP study did not detect any problems in chronic feeding studies on rats andmice, though the animals were not exposed in utero. Bio/dynamics concluded that its
studies on rats and mice showed that Yellow 6 was not an animal carcinogen, but rats
in the two highest dosage groups (3%, 5%) experienced higher incidences of adrenal
medullary adenomas. The FDA has given reasons for not considering those tumors
significant, but those reasons are not persuasive. A Bio/dynamics mouse study did not
find evidence of carcinogenicity but it did not include an in utero phase. It is of concern that Yellow 6 may be contaminated with significant levels of recognized carcinogens. Also, while rarely life-threatening, Yellow 6 causes mild to severe hypersensitivity reactions in a small percentage of the population and may cause hyperactivity insome children. Even if it does not cause cancer, Yellow 6 raises other, lesser concerns.
Because it provides no health benefit whatsoever, Yellow 6 should be removed fromthe food supply.

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Appendix – Genotoxicity Studies
Table A1. Summary of genotoxicity studies for Blue No. 1.
Assay

Mutation TypeS9 Activation

Dose

Results

Reference

Comet Assay

DNA damage

NA2,000 mg/kg

Negative(Sasaki,Kawaguchi etal. 2002)

Cytogenetics
Assay in Chinese
Hamster Cells

Chromosomal
Aberrations

No?

Positive(Hayashi,Matsui et al.
2000)

S. Typhimurium
TA1535 andTA100

Base Pair

Yes and No

10 mg/plate

Negative

S. Typhimurium
TA1538, TA98,
and TA1537

Frameshift

Yes and No

10 mg/plate

Negative(Auletta,
Kuzava et al.
1977; Bonin,
Farquharson etal. 1981)

S. Typhimurium
TA1538

Frameshift

Yes and No

10 mg/ml

Negative

E. coli WP2 uvrA

Base
Substitution

Yes and No

10 mg/ml

Negative

S. Typhimurium
TA92, TA1535,
TA100

Base Pair

Yes and No

5 mg/plate

Negative

S. Typhimurium
TA1537, TA94,
TA98

Frameshift

Yes and No

5 mg/plate

Negative

Chromosomal
aberration test,
CHL cells

Chromosomal
aberrations

No

5 mg/ml

Positive(HavelandSmith andCombes 1980)(Ishidate,
Sofuni et al.
1984)

44

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A Rainbow of Risks
Table A2. Summary of genotoxicity studies on Blue No. 2.
Assay

Mutation TypeS9 Activation

Dose

Results

Reference

Comet Assay

DNA damage

NA2,000 mg/kg

Negative(Sasaki,Kawaguchi
et al. 2002)

S. Typhimurium
TA1535 andTA100

Base Pair

Yes and No

10 mg/plate

Negative(Auletta,
Kuzava et al.
1977)

S. Typhimurium
TA1538, TA98,
and TA1537

Frameshift

Yes and No

10 mg/plate

Negative

S. Typhimurium
TA1538

Frameshift

Yes and No

1 mg/ml

Negative

E. coli WP2 uvrA

Base Substitution

Yes and No

10 mg/ml

Negative

S. Typhimurium
TA92, TA1535,
TA100

Base Pair

Yes and No

5 mg/plate

Negative

S. Typhimurium
TA1537, TA94,
TA98

Frameshift

Yes and No

5 mg/plate

Negative

Chromosomal
aberration test,
CHL cells

Chromosomal
aberrations

No

12 mg/ml

Positive

S. Typhimurium
TA1535 andTA100

Base Pair

Yes and No

1 mg/plate

Negative

S. Typhimurium
TA1538, TA98,
and TA1537

Frameshift

Yes and No

1 mg/plate

Negative

rec-Assay

DNA damage

No

NA

Negative(HavelandSmith, Combes
et al. 1979)(Ishidate, Senoo et al. 1974)(Brown, Roehm
et al. 1978)(Kada, Tutikawa et al. 1972)

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A Rainbow of Risks
Table A3. Summary of genotoxicity studies on Green No. 3
Assay

Mutation TypeS9 Activation

Dose

Results

Reference

Comet Assay

DNA damage

NA2,000 mg/kg

Negative(Sasaki, Kawaguchi
et al. 2002)

S. Typhimurium
TA100

Base Pair

Yes

10 mg/plate

Positive (incrude sample)(Ishidate, Sofuni et al.
1984)

S. Typhimurium
TA92, TA1535

Base Pair

Yes and No

10 mg/plate

Negative

S. Typhimurium
TA1537, TA94,
TA98

Frameshift

Yes and No

10 mg/plate

Negative

Chromosomal
aberration test,
CHL cells

Chromosomal
aberrations

No

4 mg/ml

Positive

Diploid yeast
Saccharomyces
Cerevisiea (BZ 34)

Mitotic geneconversion

No

5 mg/ml

Negative(Sankaranarayanan
and Murthy 1979)

Fischer rat embryo
cell transformation

Malignant celltransformation(indicator ofcarcinogenic
potential)No

1 μg/ml

Postive (Negative at 10 and
100 μg/ml)(Price, Suk et al.
1978)

S. Typhimurium
TA1535 andTA100

Base Pair

Yes and No

50 μg/plate

Negative(Brown, Roehm et al.
1978)

S. Typhimurium
TA1538, TA98,
and TA1537

Frameshift

Yes and No

50 μg/plate

Negative

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Table A4. Summary of genotoxicity studies on Red No. 3.
Assay

Mutation TypeS9 Activation

Dose

Results

Reference

Comet Assay

DNA damage

NA

100 mg/kg inglandular stomach and colon;>100 mg/kg in
urinary bladder

S. Typhimurium
TA1535, TA100

Base pair

Yes and No

1-10 mg/plate

Negative

S. Typhimurium
TA1537, TA98,
TA1538

Frameshift

Yes and No

1-10 mg/plate

Negative

Mouse
lymphoma assay(L5178Y/TK+/-)

Gene mutation

No

100-600 μg/ml

Negative

Mouse micronucleus Assay

Chromosomal
breakage/spindle
damageYes

24, 80, 240 mg/kg

Negative

Rec-assay

DNA damageNA100-10,000 μg/ml

Negative

E. coli WP2 uvrA

Base substitution

Yes and No

0.5 mg/ml

Negative(HavelandSmith,
Combes et al.
1979)

In vitro chromosome aberrations in Chinese
Hamster fibroblast cells

Chromosome
aberrations

No

0.6 mg/ml

Positive(Ishidate,
Sofuni et al.
1984)

Yeast strain D7

Mitotic geneconversionNA

0-10 mg/ml

Positive(Matula andDownie 1984)

Yeast strain
XV185-14C

Reverse mutationin eukaryotesNA0-10 mg/ml

Positive

Yeast strain D5

Mitotic
recombinationNA

0-5 mg/ml

Negative

Positive after (Sasaki,
3 hours;
Kawaguchi
negative af- et al. 2002)
ter 24 hours(Lin and
Brusick 1986)

47

FOOD DYES

A Rainbow of Risks
Table A5. Summary of genotoxicity studies on Red No. 40.
Assay

Mutation TypeS9 Activation

Dose

Results

Reference

Comet Assay

DNA damage

NA

10 mg/kg in colon;
100 mg/kg inglandular stomach;
1,000 mg/kg in
lungs

Positive(Sasaki,Kawaguchi
et al. 2002)

Comet Assay

DNA damage

NA2,000 mg/kg to
pregnant mice

Positive incolon

10 mg/kg in malemice

Positive incolon(Sasaki,Kawaguchi
et al. 2002)

E. coli WP2 uvrA

Base substitution

Yes and No

10 mg/ml

Negative(HavelandSmith andCombes 1980)

S. Typhimurium
TA1535 andTA100

Base pair

Yes and No

50-500 μg/plate

Negative(Brown,Roehm et al.
1978)

S. Typhimurium
TA98, andTA1537

Frameshift

Yes and No

50-500 µg/plate

Negative

S. Typhimurium
TA1535 andTA100

Base pair

Yes and No

0.2-400 μg/plate

Negative

S. Typhimurium
TA98, andTA1537

Frameshift

Yes and No

0.2-400 μg/plate

Negative

S. Typhimurium
TA 1535 andTA 1538

Base pair(TA1535) andFrameshift(TA1538)

Yes and No

1, 10, 50, 100 and
250 μg/plate

Negative

Yeast strains D-3
and D-5

Mitotic
recombination

Yes and No

10 mg/ml

Negative(Muzzall andCook 1979)

FDA Genetic
Toxicology
Branch48

FOOD DYES

A Rainbow of Risks
Table A6. Summary of genotoxicity studies on Yellow No. 5.
Assay

Mutation TypeS9 Activation

Dose

Results

Reference

Comet Assay

DNA damage

NA

10 mg/kg>10 mg/kg

Positive (colon)(Sasaki,Kawaguchi et al.
2002)

Positive (glandular stomach)

Cytogenetics
Assay

Chromosomal
aberrations

NA

NA

Positive(Hayashi, Matsui
et al. 2000)

S. Typhimurium
TA94, TA1537,
TA98

Frameshift

Yes and No

5 mg/plate

Negative(Ishidate, Sofuni
et al. 1984)

S. Typhimurium
TA1535, TA100,
TA92

Base pairNo

2.5 mg/ml

Positive

Chromosomal
aberration test,
CHL cells

Chromosomal
aberrations

No

6 mg/ml

Positive

In vitro Muntiacus
muntjac

Chromosomal
aberrationsNo

3 μg/ml

Positive(Patterson andButler 1982)

S. Typhimurium
TA1537, TA1538,
TA98

Frameshift

Yes and No

5 mg/plate

Negative(Chung, Fulk
et al. 1981)

S. Typhimurium
TA1535, TA100

Base Pair

5 mg/plate

Negative

S. Typhimurium
TA100

Base pair

Yes and No

Negative

S. Typhimurium
TA98

Frameshift

Yes and No

Negative

Rec assay

DNA damage

Yes and No

Negative

Chromosomal
aberration test,
CHL cells

Chromosomal
aberrations

Yes and No

Negative(Kawachi, Yahagi
et al. 1980)

49

FOOD DYES

A Rainbow of Risks
Table A7. Summary of genotoxicity studies on Yellow No. 6.
Assay

Mutation TypeS9 Activation

Dose

Results

Reference

Comet Assay

DNA damage

NA2,000 mg/kg

Negative (stomachcolon, liver, kidney, bladder, lung,or brain)(Sasaki,Kawaguchi et al.
2002)

Cytogenetics
Assay

Chromosomal
aberrations----

Positive(Hayashi, Matsui
et al. 2000)

S. Typhimurium
TA98

Frameshift

Yes and No

300 μg/plate

Negative(Rafii, Hall et al.
1997)

S. Typhimurium
TA100

Base Pair

Yes and No

300 µg/plate

Negative

Bone marrow micronucleus assay

Chromosomal
damageNA

2,000 mg/kg

Negative(Westmorelandand Gatehouse
1991)

L5178Y TK+/mouse lymphoma
assay

ForwardmutationYes

1 mg/ml

Positive(McGregor,
Brown et al.
1988)

S. Typhimurium
TA1537, TA1538,
TA98

Frameshift

Yes and No

5 mg/plate;also tested
1 mg/platesulfanilic
acid

Negative(Chung, Fulk
et al. 1981)

S. Typhimurium
TA1535, TA100

Base pair

Yes and No

5 mg/plate;also tested
1 mg/platesulfanilic
acid

Negative

Saccharomyces
cerevisiae BZ 34

Mitotic geneconversion

No

5 mg/ml

Negative(Sankaranarayanan and
Murthy 1979)

E. coli WP2 uvrA

Base substitution

Yes and No

10 mg/ml

Negative(HavelandSmith, Combes
et al. 1979)

50

FOOD DYES

A Rainbow of Risks

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A Rainbow of Risks
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