Hello Cjam,
As with many things of this nature, one can find information
?proving? dangers, as well as evidence ?proving? safety of a given
product. I indeed found supporting evidence on both sides of the
fence. Please note that I used information and data from reliable
sources, and I do not include any scientific data from skin cream
manufacturers, sites that sell lightening creams, or clinics that
offer skin lightening services, except one(whose information I have
corroborated). This type of data, while occasionally correct, can be
skewed.
Warnings and contraindications posted on products for human use
certainly err on the side of caution. One can find information
claiming that aspirin, milk, coffee and other seemingly innocuous
items are harmful as well, and used incorrectly, they could be
(Remember the McDonald?s hot coffee litigation?)! In my humble
opinion, I think the proper use of prescription strength hydroquinone,
under a doctor?s supervision, and after skin testing on a small area,
is safe. Your doctor knows your medical history and can recommend if
you should attempt to use hydroquinone, as well as the strength and
frequency that is best for you. Following the physician?s guidelines
should preclude ochronosis, which is very rare.
Factors affecting chemical toxicity to humans
?? Rate of entry and route of exposure - how fast the toxic dose is
delivered and by what means.
? Age - can effect the capacity to repair damaged tissue.
? Previous exposure - can lead to tolerance, increased sensitivity,
or make no difference.
? State of health, medications, physical condition, and life style -
can affect the toxic response. Pre-existing disease can result in
increased sensitivity.
? Environmental factors - temperature and pressure, for example, can
affect exposure.
? Host factors - genetic predisposition and the sex of the exposed individual.?
http://www.weizmann.ac.il/safety/chappi.html
?A basic understanding of the pigmentation pathway is helpful prior
to a discussion of various skin-lightening agents and their known
mechanisms of action. The type and amount of melanin synthesized by
the melanocyte and its distribution pattern in the epidermis
determines the actual color of the skin. Melanin forms through a
series of oxidative reactions involving the amino acid tyrosine and
the enzyme tyrosinase.
The first step is the most critical because the remainder of the
reaction sequence can proceed spontaneously at physiological pH. Here,
tyrosinase converts tyrosine to dihydroxyphenylalanine (DOPA) and then
to dopaquinone. Subsequently, dopaquinone is converted to dopachrome
through auto-oxidation, and finally to dihydroxyindole or
dihydroxyindole-2-carboxylic acid (DHICA) to form eumelanin
(black-brown pigment). The latter reaction occurs in the presence of
dopachrome tautomerase and DHICA oxidase. In the presence of cysteine
or glutathione, dopaquinone is converted to cysteinyl DOPA or
glutathione DOPA. Subsequently, pheomelanin, a yellow-red pigment, is
formed.?
http://www.emedicine.com/derm/topic528.htm
You ask ??that clinics know if patients are overusing it?? Doctors
and clinics will know if patients are overusing the product, because
any cream stronger than 2% requires a prescription. The FDA is calling
for a ban on OTC (over the counter) bleaching creams, and if this
takes effect, only the prescription strength hydroquinone will be
available. Directions for usage, both OTC and prescription strengths
clearly state that hydroquinone is to be used for only 4-6 months.
Exogenous Ochronosis
?Despite the remarkable overall safety of HQ, bear in mind the
potential adverse effects. Contact dermatitis occurs in a small number
of patients and responds promptly to topical steroids. An uncommon,
yet important, adverse effect of HQ is exogenous ochronosis. This
disorder is characterized by progressive sooty darkening of the skin
area exposed to HQ. Histologically, degeneration of collagen and
elastic fibers occurs. This degeneration is followed by the appearance
of characteristic ochronotic deposits consisting of crescent-shaped,
ochre-colored fibers in the dermis.
Exogenous ochronosis has generally been observed in black patients
who have used high concentrations of HQ for many years. However, cases
occurring after the use of 2% HQ have also been reported. An exogenous
ochronosis due to HQ has been reported from South Africa. For this
reason, the general recommendation is that HQ should be discontinued
if no improvement occurs within 4-6 months. HQ-induced ochronosis is
often difficult to treat, but it may respond to topical steroids and
chemical peeling.?
http://www.emedicine.com/derm/topic528.htm
?However, the drug?s link to a disfiguring condition called
ochronosis has been widely documented since 1975 in black women and
men in South Africa, Britain and the U.S.
The condition is marked by the darkening and thickening of the skin,
as well as the appearance of tiny dome-shaped bumps and grayish-brown
spots, the FDA said. Studies report the signs have appeared in users
even after short-term use of the creams. Since 1983, South Africa has
limited the concentration of hydroquinone in skin-lightening products
to 2 percent to combat ochronosis.
Under the proposed FDA rule, all skin-bleaching products ?
prescription and over-the-counter ? would be considered new drugs.
Manufacturers would have to seek FDA approval to sell them, and only
then with a doctor?s note.?
http://www.cantonrep.com/topFive.php?vote=2&Headline=FDA+says+products+that+lighten+skin+pose+dangers&ID=304996&Category=23
Light Therapy
?Exposure to sunlight or ultraviolet light will cause
repigmentation of bleached areas which may be prevented by the use of
various broad spectrum sunscreen agents.?
?There are no sunscreening agents in Hydroquinone USP 4% Cream, since
minimal sunlight exposure may reverse the bleaching effect of this
preparation, it is recommended for use only at night or on areas of
the body covered by protective clothing. During daytime and after
clearing, broad spectrum sunscreen preparations or protective clothing
should be used to prevent the bleached areas from repigmentation.
For the daytime bleaching of unwanted pigmented areas, the use of Hydroquinone
USP 4% Cream with Sunscreens should be considered.?
http://www.parpharm.com/pdf/product/hydroquinone_po.pdf#search=%224%25%20hydroquinone%20safety%22
Seems like hydroquinone is not indicated for light therapy!
Safety of hydroquinone
?The safety of hydroquinone is based upon proper use of the
medication. Hydroquinone cream or gel is for external use only. A thin
layer is applied usually twice daily, in the morning and before
bedtime, or as directed by a physician. Application of the product
should be limited to an area equal to that of the face and neck or
hands and arms. It should not be used near the eyes.
These products should also not be used on irritated, damaged or
sunburned skin. When the affected area has faded to the desired
degree, hydroquinone should be applied only as often as needed to
maintain that desired effect. The effect usually lasts for 2-6 months
after stopping use of the hydroquinone. Safety has not been
established in children younger than 12 years of age. People with
sulfite allergy should read the label carefully as some of these
products such as Esoterica® contain sodium bisulfite or sodium
metabisulfite.
If no bleaching or lightening effect is noted after 2 months of use
(or 3 months if using the 2 % cream), stop treatment with the
hydroquinone.
The most commonly reported side effect is mild skin irritation, such
as burning or stinging. Rarely, a blue-black darkening of the skin may
occur. Should this happen, the product should be discontinued, and a
physician contacted.?
http://www.netwellness.org/question.cfm/32934.htm
A. ?CAUTION: Hydroquinone is a skin bleaching agent which may produce
unwanted cosmetic effects if not used as directed. The physician
should be familiar with the contents of this insert before prescribing
or dispensing this medication.
B. Test for skin sensitivity before using Glyquin?XM? by applying a
small amount to an unbroken patch of skin and check in 24 hours. Minor
redness is not a contraindication, but where there is itching or
vesicle formation or excessive inflammatory response further treatment
is not advised. Close patient supervision is recommended. Contact with
the eyes should be avoided. If no bleaching or lightening effect is
noted after 2 months of treatment use, Glyquin?XM? should be
discontinued. Glyquin?XM? is formulated for use as a skin bleaching
agent and should not be used for the prevention of sunburn.
C. Sunscreen use is an essential aspect of hydroquinone therapy
because even minimal sunlight sustains melanocytic activity. The
sunscreens in Glyquin?XM? provide the necessary sun protection during
skin bleaching therapy. After clearing and during maintenance therapy,
sun exposure should be avoided on bleached skin by application of a
sunscreen agent or protective clothing to prevent repigmentation.
D. Keep this and all medication out of the reach of children. In case
of accidental ingestion, call a physician or a poison control center
immediately.
http://www.drugs.com/pdr/hydroquinone.html
?WARNING: Contains sodium metabisulfite, a sulfite that may cause
serious allergic type reactions (e.g. hives, itching, wheezing,
anaphylaxis, severe asthma attack) in certain susceptible persons.
CONTRAINDICATIONS
Prior history of sensitivity or allergic reaction to this product or
any of its ingredients. The safety of topical hydroquinone use during
pregnancy or in children (12 years and under) has not been
established.
WARNING
A. CAUTION: Hydroquinone is a skin bleaching agent which may produce unwanted
cosmetic effects if not used as directed. The physician should be
familiar with the contents of this insert before prescribing or
dispensing this medication.?
Warnings on this site also for use in pregnancy and pediatric use.
http://www.parpharm.com/pdf/product/hydroquinone_po.pdf#search=%224%25%20hydroquinone%20safety%22
?Dermal applications of hydroquinone at concentrations in different
bases of less than 3% caused negligible effects in male volunteers
from different human races. However, there are case reports suggesting
that skin lightening creams containing 2% hydroquinone have produced
leukoderma, as well as ochronosis. Hydroquinone (1% aqueous solution
or 5% cream) has caused irritation (erythema or staining). Allergic
contact dermatitis due to hydroquinone has been diagnosed.?
?At room temperature and in the presence of moisture, hydroquinone
oxidizes to quinone, which causes much worse eye irritation than
hydroquinone itself; there is a consequent risk of conjunctivitis and
corneal erosion. Lung oedema symptoms usually develop several hours
after severe inhalation exposure and are aggravated by physical
exertion; rest and hospitalization are essential. As first aid,
administration of corticosteroid spray should be considered.
In cases of dermatitis due to hydroquinone, removal from exposure will
quickly clear up the symptoms.?
http://www.inchem.org/documents/hsg/hsg/hsg101.htm#SectionNumber:2.5
?Probable carcinogen. Toxic. Severe skin irritant. Harmful by
inhalation and ingestion. May cause sensitization. Eye and respiratory
irritant.?
http://allergies.about.com/library/chem/blmsds-hydroquinone.htm
?The Food and Drug Administration proposed a ban Tuesday on
over-the-counter sales of skin-lightening products, saying possible
health risks cannot justify their being sold without a prescription.
The creams typically contain a drug called hydroquinone, a possible
carcinogen also linked to a skin-disfiguring condition, the FDA said.
While the actual risk of the drug is unknown, the agency said the
products should be restricted to prescription use under medical
supervision.?
http://www.cantonrep.com/topFive.php?vote=2&Headline=FDA+says+products+that+lighten+skin+pose+dangers&ID=304996&Category=23
?Generally speaking, skin-bleachers contain hydroquinone which is a
drug that could be a carcinogen -- something often linked to a
condition that disfigures the skin. Also, animal tests show
hydroquinone may be linked with some cancers.
The FDA would reclassify skin-bleachers as a new drug and each new
cream would have to be approved. There are some 130 skin-bleaching
products on the US market that contain hydroquinone.?
http://www.shortnews.com/shownews.cfm?id=56678&CFID=7027595&CFTOKEN=59344020
?? Hydroquinone was discovered in 1880 and has been used by ILFORD in
photographic chemical products for over 100 years. It is also used
throughout the photographic industry.
? It is the main photographic developing agent for most black and
white and ILFORD colour processes.
? Other uses include:
in the cosmetics industry in skin-lightening creams.
as an antioxidant in the manufacture of rubber.
as a polymerisation inhibitor in the chemical industry
? Hydroquinone occurs naturally in:
wheat products (e.g. bread and cereals)
fruits (e.g.pears and blueberries/bilberries) and vegetables (e.g.
broccoli and asparagus)
coffee and tea
some beers
red wine
a number of insects
? Only 2 human hazards have been identified;
Skin irritation, with possible risk of sensitisation
Eye discoloration, with possible impaired vision in cases of extreme
exposure (high levels of hydroquinone dust over several years).
? Absorption through human skin is slow, so liquids pose a low risk,
especially since wearing protective gloves prevents skin contact.?
http://www.ilford.com/html/us_english/sds/PhotoHealth/photohe4.html
Leukemia
Hydroquinone is a metabolite of benzene, which is a known
carcinogen(cancer causing agent). This means that when benzene is
broken down, it produces hydroquinone.
It does appear that hydroquinone, in tandem with phenols, can
induce leukemias, but this hypothesis report speculates it is from
sources such as smoking, medications, and diet:
?High background levels of phenol and hydroquinone are present in the
blood and urine of virtually all individuals, but vary widely. Phenol
and hydroquinone have been strongly implicated in producing leukemia
associated with benzene exposure, because they reproduce the
hematotoxicity of benzene, cause DNA and chromosomal damage found in
leukemia, inhibit topoisomerase II, and alter hematopoiesis and clonal
selection. The widely varying background levels of phenol and
hydroquinone in control individuals stem mainly from direct dietary
ingestion, catabolism of tyrosine and other substrates by gut
bacteria, ingestion of arbutin-containing foods, cigarette smoking,
and the use of some over-the-counter medicines.?
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&list_uids=11243376&cmd=Retrieve&indexed=google
?What I am saying here is that diet and genetics are possibly the
two main factors which are responsible for de novo MDS with alcohol,
occupational exposures and smoking also contributing, and these
dietary factors I am going to focus on are high protein and phenolic
content in the diet, high calories and low vitamin intake.? Note: MDS
is myelodysplastic syndrome, of which some leukemias belong.
http://www.webtie.org/SOTS/Meetings/Leukemia/10-30-2000/transcripts/07/transcripts.htm
Leukemia roughly doubled in a female rat study. Note that the
hydroquinone was given to the rats by gavage, that is, fed into the
stomach by a tube, and not on the skin.
?Mononuclear cell leukemia in female rats occurred with a dose-
related trend and the incidences in the dosed groups were greater than
in the vehicle controls (vehicle control, 9/55; low dose, 15/55; high
dose, 22/55; p < 0.05). The historical incidence of leukemia in water
gavage vehicle control female F344/N rats is 25 15 percent
and in untreated controls is 19 7 percent.?
http://www.pharmcast.com/FederalRegistrar/Yr2006/Aug2006/082806/Skin082906.htm
Hydroquinone is not quickly absorbed through human skin into the body.
?HQ would be classified as 'slow' with respect to its absorption
through human stratum corneum.?
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=7482585&dopt=Abstract
?There is a possible relationship between the restricted nutrient
intake of slimming diets and the development of acute leukemia (Visani
G et al 1997). Another theory is that phenol and hydroquinone,
chemicals mainly ingested from meat and protein-rich diets, known to
produce DNA damage, and antibiotics, may cause leukemia (McDonald TA
et al 2001).?
http://www.lef.org/protocols/cancer/leukemia_01.htm
?Benzene (BZ), a Class I carcinogen, causes acute myelogenous
leukemia (AML) upon chronic exposure, possibly via its bone marrow
(BM) metabolite, hydroquinone (HQ). The ability to alter
cytokine-dependent growth/differentiation in hematopoietic
stem/progenitor cells is a property of agents with leukemogenic
potential. BZ and HQ induce granulopoiesis in mice and act on the
HL-60 human promyelocytic leukemia cell line. Here, it is reported
that noncytotoxic concentrations of BZ or HQ can also induce
granulocytic differentiation in the normal murine diploid
interleukin(IL)-3-dependent myeloblastic cell line, 32D cl?
http://jdc.jefferson.edu/dissertations/AAI9703676/
?The general rule of thumb in this situation is to discontinue
hydroquinone-based bleaches after 4-6 months if improvement is not
seen. Let me put it bluntly. Ochronosis is so rare, that after 20
years in dermatology and thousands of prescriptions given out for this
ingredient, I have only seen one patient with it and that was at a
medical conference where another doctor brought that patient to the
meeting to show the derms their ?rare case?.?
?Now the reality ? has any doctor ever seen a case of mutation or
cancer associated with higher potency rx level hydroquinone? I?ve
never seen one, heard about one or read about one, which makes the
lower strength of the ingredient seem all the safer.?
http://www.dermadoctor.com/drmessage.asp
Is Kojic Acid a derivative of Hydroquinone?
No. Hydroquinone?s synonyms are: alpha-hydroquinone, hydroquinol,
quinol, benzoquinol, p-benzenediol, 1,4-benzenediol,
p-dihydroxybenzene, p-hydroxyphenol, p-dioxobenzene,
1,4-dihydroxybenzene, dihydroquinone, pyrogentistic acid, quinnone,
aida, arctuvin, eldoquin, eldopaque, phiaquin, tecquinol, tenox HQ,
tequinol
Molecular formula: C6H6O2 Kojic acid is 5-hydroxy-4-pyran-4-one-2-methyl.
Kojic acid (5-hydroxy-4-pyran-4-one-2-methyl) is a metabolite of a
fungus, and inhibits the synthesis of melanin, the skin pigment.
?Kojic acid is also consumed widely in the Japanese diet, with the
belief that it is of benefit to health. Indeed, it has been shown to
significantly enhance neutrophil phagocytosis and lymphocyte
proliferation stimulated by phytohemagglutinin. Melanocytes treated
with kojic acid become nondendritic, with a decreased melanin content.
Additionally, it scavenges reactive oxygen species released
excessively from cells or generated in tissue or blood.
Kojic acid is used in concentrations ranging from 1-4%. Although
effective as a skin-lightening gel, it has been reported to have high
sensitizing potential and may cause irritant contact dermatitis.?
Because of copyright restrictions, I can post no more. Please read
this site for further information.
http://www.emedicine.com/derm/topic528.htm
Because Kojic acid can inhibits caseinase activity, then inhibits
skin melanin formation, kojic acid and it's derivatives widely used in
high-quality skin lightening cosmetics, bath preparation and mouth or
teeth care products. Cosmetics containing kojic acid can treat
freckle,acne, pigmentation and macula effectively without any toxic
and bad results, At present, kojic acid's use level added in cosmetics
is to O.2-1.0 percent.
(2) Medicine material:
Kojic acid and it's derivatives are used as an important material in
antibiotic - cephamycin, anodyne, and antiphlogistic production.
(3) Food additive:
Kojic acid and it's derivatives work as antiseptic,antioxidant,
preservative and color stablizer in meat processing, also act as
useful materials of food aromatizer - maltol and ethylmaltol.
(4) Preservative and color stablizer of cut-flower:
Kojic acid and it's derivatives are added to cut-flower to keep flower
colorful and fresh.
(5) Film despecking agent and iron ananysis reagent.
(6) Non-toxic to person and livestock, pollution-free pesticide
ininsecticide production
http://www.peakchem.com/PRODUCTS/kojic.htm
?You can lighten the skin with various bleaching agents, the most
utilized was hydroquinone in a 4% formulation (need a prescription) or
over the counter in a 2% formulation. Much higher percentages can be
utilized for more permanent results and there is speculation that this
is what Michael Jackson used but I have no confirmed information about
his treatments. Kojic acid is another chemical that may help lighten
the skin.?
http://www.locateadoc.com/questions.cfm?SearchKey=hydroquinone
Additional Information
This site has a useful chart comparing 50 skin lightening products
for safety. Notice on the last page that popular products like
Porcelana and Ambi, that have only 2% hydroquinone are rated as toxic,
with quite a list of possible side effects.
http://www.ewg.org/reports/skindeep2/search.php?category=Skin+Fading%2FLightener
Troubles in Asian and African Countries
http://skingeek.com/node/55
?Results
? Two of 17 skin bleaching products contained high concentrations of
hydroquinone, between 3.7% and 5.6%. The use of hydroquinone is also
banned in the EU. One product did not mention hydroquinone on the
ingredients list. According to the declaration the active bleaching
ingredients were kojic acid, which is only banned in Switzerland, and
bearberry leaf extract (Arctostaphylos uva ursi). Bearberry leaf
extract contains the hydroquinone glucoside p-Arbutin. As the product
would be legal for trade in Europe if its ingredients were those
actually indicated, this is either a gross deception or an error in
production. The product was marketed under a French label but produced
in the Ivory Coast, where the use of hydroquinone as a skin bleaching
agent may still be permitted.
? Kojic acid was found in two products at levels of 0.07% and 0.27%.
It was declared as an ingredient in both
products.? http://www.kantonslabor-bs.ch/files/75/Bleichmittel2006%20(3)1%20en.pdf#search=%22hydroquinone%20%2B%20absorption%20rate%20%2B%20skin%22
This previous answer may be interesting to you:
http://answers.google.com/answers/threadview?id=737014
I hope this answer has adequately answered all of your questions.
Please request an Answer Clarification, and allow me to respond,
before your rate. I will be glad to assist you further, before you
rate.
Sincerely, Crabcakes
PS - This is my 1,000th answer on Google Answers!
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