Parabens have been used as preservatives since the 1920s. Chemically,
parabens have a simple structure. They consist of a six-member carbon
ring with a hydroxyl group on one side (-OH) of the ring and a side
chain called an alkyl ester on the opposite side of the ring. The side
chains can be of varying lengths. One of the most widely quoted sources
of information on the use of, exposure to, and safety of parabens was
published in 1984 in a report authored by Elder.1 This report estimated
that parabens were used in over 13,200 different cosmetic products.
Parabens are colorless and odorless. They also have activity against
a wide range of bacteria. They are less active against fungi and, therefore,
are usually combined with other biocides such as formaldehyde releasers,
isothiazolinones, or phenoxyethanol to provide a broader antiseptic
Products Commonly Containing Paraben Preservatives
Foundations, powders, concealers, eye makeup (liners, shadows, mascara),
facial makeup (blushes), bronzes, makeup removers, lipstick, quick-dry
Topical dermatological medications, eye, ear and nose drops, rectal
and vaginal medications, bandages, parenteral products, including
antibiotics, corticosteroids, local anesthetics, radiopharmaceuticals,
antihypertensives, diuretics, insulin, heparin, and chemotherapeutic
Personal Care Products
Moisturizing lotions and creams, dentifrices, sunscreens, cleansers
and other skin care products, antiperspirants and deodorants, soaps,
including liquid hand soap and toothpastes, shampoos and conditioners,
colognes, and perfumes
Food Products (E210-219)
Marinated fish products, salad dressings, mayonnaise, mustard, spiced
sauces, processed vegetables, frozen dairy products, jams and jellies,
soft drinks and fruit juices, baked goods, and candies
Parabens are used industrially in oils, fats, shoe polishes, textiles,
The Dangers of Parabens
demonstrate the health risks of parabens. Some scientists have raised
concerns that further assessment of parabens may be
needed. This is based
on recent evidence from scientific studies indicating that several types
of parabens can bind to the estrogen receptor and can cause estrogen-like
responses when tested in laboratory animals or in a variety of tissue
culture assays.2 Parabens produced a positive uterotrophic response
in vivo and
also damaged the late stages of spermatogenesis, altered proportion
of pups born
alive, and affected body weight of offspring. They reduced the number
of sperm in the epididymis and reduced the sperm motile activity in
Parabens could compete with [3H] 17beta-estradiol for binding to the
estrogen receptor. The proliferation of two estrogen-dependent cell
and ZR-75-1 could be increased by parabens. They also increased
both transfected and endogenous estrogen-regulated genes in MCF-7 cells.
The studies showed parabens were weakly estrogenic.3
The following studies of estrogenic activity/antispermatogenic potential
of parabens indicated a possible relationship between paraben exposure
cancer and/or male reproductive function: Dr. S. Oishi of the Department
of Toxicology, Tokyo Metropolitan Research Laboratory of Public Health,
reported that exposure of postweaning rats and mice to butylparaben or
propylparaben (but not methylparaben or ethylparaben) adversely affected
of testosterone and the function of the male reproductive system.4 British
Dr. Philippa Darbre and colleagues at the University of Reading5 proposed
that parabens may contribute to the increasing incidence of breast cancer.
et al. carried out tests on 20 samples of human breast tissue taken from
patients undergoing surgery at the Edinburgh Breast Unit in Scotland,
UK. The study
by P. Darbre and colleagues was conducted to assess whether any of the
six parabens commonly used in consumer products in Europe could be detected
human breast tumors. The parabens studied were methylparaben, ethylparaben,
propylparaben, isobutylparaben, butylparaben, and benzylparaben.
The Scottish study is the first report of the detection of parabens in
human breast tumors. It enabled identification and measurement of mean
of individual parabens in samples of 20 human breast tumors. Comparison
of individual parabens showed that methylparaben was present at the highest
level (with a mean value of 12.8 +/- 2.2 ng x g [-1] tissue) and represents
the total parabens recovered in the extractions. This investigation did
that five of the six parabens widely used in consumer products could be
detected intact (not changed or metabolized) in human tissues. The study
however, make any attempt to find out the source of the parabens. It is
not known if
the major exposure was due to the parabens from food or via topical application
of a certain type or a variety of personal care products. Since parabens
can be measured intact in the human breast and possess oestrogenic properties,
it has been suggested that they could contribute to an aberrant burden
signalling in the human breast and so play a role in the rising incidence
of breast cancer.
In the sixteenth century, Paracelsus said, "It is the dose that makes
the poison." However, over a lifetime, with daily use of products
containing parabens, we don't actually know what the cumulative dose really
work will need to address the extent to which parabens can accumulate in
hormonally sensitive tissues and also the extent to which their weak oestrogenic
can add to the more general environmental oestrogen problem.
Type IV Delayed-Type Hypersensitivity
Reactions to Topical and Ingested Parabens in Orally Administered Products
Numerous individual reports describing cases of contact dermatitis
as a result of contact with parabens in topical products – such as reactions to facial
cosmetic products and formulations, gel-like toy products, ultrasound gel,
topical creams, etc. – have been published. Occupational cases of paraben
contact dermatitis (among cooks and food handlers with hand dermatitis caused
by paraben-containing foods) have also been reported. Allergic contact dermatitis
has most commonly been described when paraben-containing products are used
on damaged skin. In a phenomenon known as the "paraben paradox" by
Fisher,6 inflamed skin reacts to parabens whereas intact skin does not. This
concept is important, because patch tests may produce false-negative findings
in patients who are truly sensitive to parabens. There are a few reports of
a systemic allergic contact dermatitis presenting as a generalized eczematous
eruption after ingestion of paraben-containing medications or foods.
Type I Immediate Hypersensitivity Reactions to Topical and Parenteral
The same paraben compounds that cause delayed-type reactions can also
cause type I immediate reactions such as contact urticaria.7 Several
immediate hypersensitivity reactions (including bronchospasm, pruritus,
and generalized dermatitis) to parenterally administered compounds
containing parabens have been reported.1
Type IV Hypersensitivity Reactions to Parenteral Parabens
Fine and Dingman reported one case of generalized eczematous dermatitis
following suction-assisted lipectomy when a local anesthetic containing
Patch Testing with Paraben Mix
Two or more paraben esters are often found in a single product, so
it is useful to test paraben sensitivity with paraben mix, as there
incidence of cross-reactions between the esters. Paraben mix is a mixture
of five different
paraben esters: methyl-, ethyl-, propyl-, butyl-, and benzyl-parahydroxybenzoic
acids. Paraben-mix sensitivity produces classic allergic contact dermatitis
reactions. Sometimes, the reactions may be seen as a flare or spread
of an existing treated rash. It appears that repeated applications
low concentrations of parabens in medications and cosmetics may lead
Paraben-mix allergy is diagnosed from the clinical history and by performing
special allergy tests, i.e., patch tests. Patch testing with 15% paraben
in petrolatum (three percent each of methyl-, ethyl-, propyl-, butyl-,
and benzyl-parahydroxybenzoic acids) is used. This mix caused ACD in
of patients patch-tested by the North American Contact Dermatitis Group
The "para" group of antigens (para-aminobenzoic acid [PABA] esters,
paraphenylenediamine) are frequent sensitizers and consist of chemicals with
a free amino group in the para position of a benzene ring. A debate exists
about the cross-reactivity of parabens and the "para" group, because
parabens have a hydroxyl group instead of an amino group in the para position.
Although PABA itself does not cross-react with parabens, the esters of PABA
may show cross-reactivity.7
Parabens as Urinary Biomarkers of Exposure in Humans
A team from the Division of Laboratory Sciences, National Center for
Environmental Health, Centers for Disease Control and Prevention, Atlanta,
now provided the field with new biomarkers that could help researchers
document exposures to parabens.10 Until now, the only biomarker used
for human paraben
exposure was p-hydroxybenzoic acid in urine. However, that metabolite
by the hydrolysis of all the various paraben compounds, so it is nonspecific
to individual parabens, which vary widely in estrogenic bioactivity.
Ye et al. measured the presence of free and conjugated parent parabens
in urine to determine their suitability to be biomarkers of human exposures.
the urinary concentrations of methyl, ethyl, n-propyl, butyl (n- and
iso-), and benzyl parabens in 100 human adults with no known industrial
to the compounds. The results appear to support the viability of those
as biomarkers of exposure. Methyl and n-propyl parabens, the parabens
most commonly used in cosmetics and foods, were found at the highest
concentrations in almost all the samples—99% contained the former and 96% the latter.
The authors say this could result from the widespread use of these compounds;
from differences in the absorption, distribution, metabolism, and excretion
of the various parabens; or from a combination of both factors. Other parent
compounds, such as ethyl and butyl paraben, appeared in more than half of the
samples. Regardless of the reason for such high frequencies of detection, the
researchers say their results suggest that urinary parabens and their conjugates
could be valid biomarkers of exposure to these chemicals. The detection and
measurement methodologies used by Ye et al. could help investigators as they
seek to characterize the potential health risks associated with exposure to
the individual paraben compounds.10
1) Elder RL. Final report on the safety assessment of methylparaben,
ethylparaben, propylparaben and butylparaben. Journal of the
American College of Toxicology. 1984;
2) Endocrine Disruption Bibliographies. Available at: http://envirocancer.cornell.edu/Bibliography/cENDOCRINE.cfm.
Accessed August 27, 2007.
3) Ge JH, Chang B. Estrogenic activities of parabens. Wei Sheng
Yan Jiu. 2006 Sep;35(5):650-2.
4) Oishi S. Effects of butyl paraben on the male reproductive system
in mice. Arch Toxicol. 2002;76(7):423-429.
5) Darbre PD, Aljarrah A, Miller WR, Coldham NG, Sauer MJ, Pope GS.
Concentrations of parabens in human breast tumors. Journal of
Applied Toxicology. 2004; 24: 5-13.
6) Fisher AA. The paraben paradoxes. Cutis.
7) Cashman AL, Warshaw EM. Parabens: a review of epidemiology, structure,
allergenicity, and hormonal properties. Dermatitis.
8) Fine PG, Dingman DL. Hypersensitivity dermatitis following suction-assisted
lipectomy: a complication of local anesthetic. Ann Plast Surg.
9) Pratt MD, Belsito DV, DeLeo, et al. North American Contact Dermatitis
Group patch-test results, 2000-2002 study period. Dermatitis.
10) Ye X, Bishop AM, Reidy JA, Needham LL, Calafat AM. Parabens as
urinary biomarkers of exposure in humans. Environmental Health
December 2006; 114 (12):1843-1846.