| MadSci Network: Neuroscience |
Question: is the cooling sensation of mint related to the hot sensation of
chili?
Sorry it took me a while to get back on this one. It was a busy month.
This is really an interesting question. We see a lot of advertisements on
TV about how cool some mint favored gums or breath fresheners are implied
to be so cool as to freeze the people.
The mint flavor one is commonly refereeing to is a wintergreen mint. There
are a number of chemicals associated with the mint flavor. One in
particularly is methyl salicylate and methanol.
The methyl salicylate is even know to give off sparks of light when you
bites down on a candy containing it. For more info on that topic see -
http:
//www.madsci.org/posts/archives/dec99/945895598.Ch.r.html
Now for the cool feeling one gets from such a chemical. I did not know
anyone examined this topic until I found a reference on this www site
http://members.aol.com/doder
1/mint1.htm
Which stated ˇ°Anatomy. Menthol (a crystalline alcohol obtained from
peppermint oil) tricks heat-sensing organs (thermoreceptors) of the tongue
and skin into sending messages to the brain that the sensation tastes and
feels "cool" (Feldman 1991:192).ˇ±
I tried to track down the reference to Feldman 1991 but I could not find
any related scientific article, but I did find another one below. It
basically states that methyl salicylate can alter cutaneous nociceptors.
These are a type of pain receptor. So, I am still at a loss in how the
cooling effect come about.
Somatosens Mot Res 1989;6(3):253-74
Methyl salicylate as a cutaneous stimulus: a psychophysical analysis.
Green BG, Flammer LJ.
Monell Chemical Senses Center, Philadelphia, Pennsylvania 19104.
"Two experiments were performed to examine the perceptual effects of
methyl salicylate on hairy skin in humans. In the first experiment, the
sensitivity to methyl salicylate (prepared in an ethanol and water vehicle
and applied via filter paper) was measured in a paradigm that required
subjects to report both the perceived intensity and the perceptual quality
of the sensations they experienced. The results indicated that methyl
salicylate could be reliably detected at concentrations between 3 and 12%.
Peak perceived intensities increased with increasing concentration, and
the dominant sensation quality reported was "burning". The second
experiment, which measured the effect of methyl salicylate on the
perception of temperature change, revealed that the compound enhances the
perception of warming but does not affect the perception of cooling. For
most subjects, methyl salicylate produced a hyperalgesia to heating.
Overall, the data suggest that methyl salicylate probably produces its
sensory effects via stimulation and/or sensitization of a population of
cutaneous nociceptors."
The hot sensation of Chili also effects cutaneous nociceptors. In fact the
active compound in chili is capsaicin. There are many reports on its
effects. It is known to activate cutaneous nociceptors. In fact, over year
of use of capsaicin the C- pain fibers in mammals are killed so the hot
taste is not even sensed. In short to answer this part of the question,
capsaicin gives a hot feeling or a burning sensation by activating the
pain sensory neurons.
It appears that both of the compounds wintergreen and capsaicin do have
some relation with cutaneous nociceptors. How wintergreen produces the
cooling effect I do not know. If your interested in what the compounds do
that you put in your mouth one should check out the chemical data sheets
for such compounds and their toxic effects. Below I copied the data sheet
for methyl salicylate.
All the best,
Robin Cooper
http://www.jtbaker.com/msds/m7
257.htm
METHYL SALICYLATE
MSDS Number: M7257 --- Effective Date: 07/13/00
1. Product Identification
Synonyms: O-Hydroxybenzoic acid, methyl ester; synthetic wintergreen oil;
Betula oil; salicylic acid, methyl ester
CAS No.: 119-36-8
Molecular Weight: 152.15
Chemical Formula: 2-HOC6H4COOCH3
Product Codes:
J.T. Baker: 2700
Mallinckrodt: 2064
2. Composition/Information on Ingredients
Ingredient CAS No Percent
Hazardous
--------------------------------------- ------------ ------- ------
---
Benzoic Acid, 2-hydroxy-, Methyl Ester 119-36-8 98 - 100%
Yes
3. Hazards Identification
Emergency Overview
--------------------------
WARNING! HARMFUL IF SWALLOWED, INHALED OR ABSORBED THROUGH SKIN. CAUSES
IRRITATION TO SKIN, EYES AND RESPIRATORY TRACT. AFFECTS THE KIDNEYS AND
CENTRAL NERVOUS SYSTEM.
J.T. Baker SAF-T-DATA(tm) Ratings (Provided here for your convenience)
---------------------------------------------------------------------------
--------------------------------
Health Rating: 1 - Slight
Flammability Rating: 1 - Slight
Reactivity Rating: 0 - None
Contact Rating: 1 - Slight
Lab Protective Equip: GOGGLES; LAB COAT
Storage Color Code: Orange (General Storage)
---------------------------------------------------------------------------
--------------------------------
Potential Health Effects
----------------------------------
Inhalation:
Inhalation can cause severe irritation of mucous membranes and upper
respiratory tract. Symptoms may include burning sensation, coughing,
wheezing, laryngitis, shortness of breath, headache, nausea and vomiting.
High concentrations may cause lung damage.
Ingestion:
Ingestion of sizable amounts can cause "salicylism", as evidenced by
abdominal pain, vomiting, increased respiration, and mental disturbances.
Fatalities resulting from respiratory or cardiovascular failure are known.
Reported lethal dose in human adult of 30 mls.
Skin Contact:
May cause irritation, and skin rashes in sensitive individuals. Skin
absorption has reportedly occurred, but toxic levels are reached only when
large skin areas are covered with the drug in a suitable base (e. g.,
lanolin).
Eye Contact:
Irritant to eye and surrounding membranes. Can be severe with permanent
damage.
Chronic Exposure:
Central nervous system disturbances such as rapid breathing, confusion and
even convulsions may develop. Kidneys and pancreas can be affected by
prolonged ingestion.
Aggravation of Pre-existing Conditions:
Persons with pre-existing skin disorders or eye problems, or impaired
kidney or respiratory function may be more susceptible to the effects of
the substance.
4. First Aid Measures
Inhalation:
If inhaled, remove to fresh air. If not breathing, give artificial
respiration. If breathing is difficult, give oxygen. Call a physician.
Ingestion:
Induce vomiting immediately as directed by medical personnel. Never give
anything by mouth to an unconscious person. Call a physician immediately.
Skin Contact:
Immediately flush skin with plenty of soap and water for at least 15
minutes while removing contaminated clothing and shoes. Get medical
attention. Wash clothing before reuse. Thoroughly clean shoes before
reuse.
Eye Contact:
Immediately flush eyes with plenty of water for at least 15 minutes,
lifting lower and upper eyelids occasionally. Get medical attention
immediately.
5. Fire Fighting Measures
Fire:
Flash point: 96C (205F)
Autoignition temperature: 454.4C (849F)
Moderate fire hazard when exposed to heat or flame.
Explosion:
Above the flash point, explosive vapor-air mixtures may be formed.
Fire Extinguishing Media:
Dry chemical, foam or carbon dioxide.
Special Information:
In the event of a fire, wear full protective clothing and NIOSH-approved
self-contained breathing apparatus with full facepiece operated in the
pressure demand or other positive pressure mode. Water spray may be used
to keep fire exposed containers cool.
6. Accidental Release Measures
Ventilate area of leak or spill. Wear appropriate personal protective
equipment as specified in Section 8. Contain and recover liquid when
possible. Collect liquid in an appropriate container or absorb with an
inert material (e. g., vermiculite, dry sand, earth), and place in a
chemical waste container. Do not use combustible materials, such as saw
dust. Do not flush to sewer!
7. Handling and Storage
Keep in a tightly closed container, stored in a cool, dry, ventilated
area. Protect against physical damage. Isolate from any source of heat or
ignition. Containers of this material may be hazardous when empty since
they retain product residues (vapors, liquid); observe all warnings and
precautions listed for the product.
8. Exposure Controls/Personal Protection
Airborne Exposure Limits:
None established.
Ventilation System:
A system of local and/or general exhaust is recommended to keep employee
exposures as low as possible. Local exhaust ventilation is generally
preferred because it can control the emissions of the contaminant at its
source, preventing dispersion of it into the general work area. Please
refer to the ACGIH document, Industrial Ventilation, A Manual of
Recommended Practices, most recent edition, for details.
Personal Respirators (NIOSH Approved):
For conditions of use where exposure to the substance is apparent, consult
an industrial hygienist. For emergencies, or instances where the exposure
levels are not known, use a full-facepiece positive-pressure, air-supplied
respirator. WARNING: Air purifying respirators do not protect workers in
oxygen-deficient atmospheres.
Skin Protection:
Wear impervious protective clothing, including boots, gloves, lab coat,
apron or coveralls, as appropriate, to prevent skin contact.
Eye Protection:
Use chemical safety goggles and/or a full face shield where splashing is
possible. Maintain eye wash fountain and quick-drench facilities in work
area.
9. Physical and Chemical Properties
Appearance:
Clear, practically colorless liquid.
Odor:
Characteristic odor.
Solubility:
Sparingly soluble in water.
Specific Gravity:
1.180-1.185
pH:
No information found.
% Volatiles by volume @ 21C (70F):
100
Boiling Point:
222.2C (432F)
Melting Point:
-8.3C (18F)
Vapor Density (Air=1):
5.24
Vapor Pressure (mm Hg):
1 @ 54C (129F)
Evaporation Rate (BuAc=1):
No information found.
10. Stability and Reactivity
Stability:
Stable under ordinary conditions of use and storage.
Hazardous Decomposition Products:
May produce acrid smoke and irritating fumes when heated to decomposition.
Hazardous Polymerization:
Will not occur.
Incompatibilities:
Can react with oxidizing materials.
Conditions to Avoid:
Heat, flames, ignition sources and incompatibles.
11. Toxicological Information
Oral rat LD50: 887 mg/kg. Irritation data: skin rabbit 500 mg/24 Hr
Moderate; eye rabbit 500 mg/24 Hr Mild. Investigated as a mutagen,
reproductive effector.
--------\Cancer Lists\---------------------------------------------------
---
---NTP Carcinogen---
Ingredient Known Anticipated IARC
Category
------------------------------------ ----- ----------- ----------
---
Benzoic Acid, 2-hydroxy-, Methyl No No None
Ester (119-36-8)
12. Ecological Information
Environmental Fate:
When released into the soil, this material is expected to readily
biodegrade. When released into the soil, this material is expected to
leach into groundwater. When released into the soil, this material is
expected to quickly evaporate. When released into water, this material is
expected to readily biodegrade. When released into water, this material is
expected to have a half-life between 10 and 30 days. This material has an
estimated bioconcentration factor (BCF) of less than 100. This material
has a log octanol-water partition coefficient of less than 3.0. This
material is not expected to significantly bioaccumulate. When released
into the air, this material is expected to be readily degraded by reaction
with photochemically produced hydroxyl radicals. When released into the
air, this material may be removed from the atmosphere to a moderate extent
by wet deposition. When released into the air, this material is expected
to have a half-life between 1 and 10 days.
Environmental Toxicity:
No information found.
13. Disposal Considerations
Whatever cannot be saved for recovery or recycling should be managed in an
appropriate and approved waste disposal facility. Processing, use or
contamination of this product may change the waste management options.
State and local disposal regulations may differ from federal disposal
regulations. Dispose of container and unused contents in accordance with
federal, state and local requirements.
14. Transport Information
Not regulated.
15. Regulatory Information
--------\Chemical Inventory Status - Part 1\-----------------------------
----
Ingredient TSCA EC Japan
Australia
----------------------------------------------- ---- --- ----- ------
---
Benzoic Acid, 2-hydroxy-, Methyl Ester Yes Yes Yes
Yes
(119-36-8)
--------\Chemical Inventory Status - Part 2\-----------------------------
----
--Canada--
Ingredient Korea DSL NDSL Phil.
----------------------------------------------- ----- --- ---- -----
Benzoic Acid, 2-hydroxy-, Methyl Ester Yes Yes No
Yes
(119-36-8)
--------\Federal, State & International Regulations - Part 1\------------
----
-SARA 302- ------SARA 313--
----
Ingredient RQ TPQ List Chemical
Catg.
----------------------------------------- --- ----- ---- ----------
----
Benzoic Acid, 2-hydroxy-, Methyl Ester No No No No
(119-36-8)
--------\Federal, State & International Regulations - Part 2\------------
----
-RCRA- -TSCA-
Ingredient CERCLA 261.33 8(d)
----------------------------------------- ------ ------ ------
Benzoic Acid, 2-hydroxy-, Methyl Ester No No
No
(119-36-8)
Chemical Weapons Convention: No TSCA 12(b): No CDTA: No
SARA 311/312: Acute: Yes Chronic: Yes Fire: No Pressure: No
Reactivity: No (Pure / Liquid)
Australian Hazchem Code: No information found.
Poison Schedule: No information found.
WHMIS:
This MSDS has been prepared according to the hazard criteria of the
Controlled Products Regulations (CPR) and the MSDS contains all of the
information required by the CPR.
16. Other Information
NFPA Ratings: Health: 1 Flammability: 1 Reactivity: 0
Label Hazard Warning:
WARNING! HARMFUL IF SWALLOWED, INHALED OR ABSORBED THROUGH SKIN. CAUSES
IRRITATION TO SKIN, EYES AND RESPIRATORY TRACT. AFFECTS THE KIDNEYS AND
CENTRAL NERVOUS SYSTEM.
Label Precautions:
Avoid breathing vapor.
Keep container closed.
Use only with adequate ventilation.
Avoid contact with eyes, skin and clothing.
Wash thoroughly after handling.
Label First Aid:
If swallowed, induce vomiting immediately as directed by medical
personnel. Never give anything by mouth to an unconscious person. If
inhaled, remove to fresh air. If not breathing, give artificial
respiration. If breathing is difficult, give oxygen. In case of contact,
immediately flush eyes or skin with plenty of water for at least 15
minutes. Remove contaminated clothing and shoes. Wash clothing before
reuse. In all cases call a physician.
Product Use:
Laboratory Reagent.
Revision Information:
MSDS Section(s) changed since last revision of document include: 1.
Disclaimer:
***************************************************************************
*********************
Mallinckrodt Baker, Inc. provides the information contained herein in good
faith but makes no representation as to its comprehensiveness or accuracy.
This document is intended only as a guide to the appropriate precautionary
handling of the material by a properly trained person using this product.
Individuals receiving the information must exercise their independent
judgment in determining its appropriateness for a particular purpose.
MALLINCKRODT BAKER, INC. MAKES NO REPRESENTATIONS OR WARRANTIES, EITHER
EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION ANY WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE WITH RESPECT TO THE
INFORMATION SET FORTH HEREIN OR THE PRODUCT TO WHICH THE INFORMATION
REFERS. ACCORDINGLY, MALLINCKRODT BAKER, INC. WILL NOT BE RESPONSIBLE FOR
DAMAGES RESULTING FROM USE OF OR RELIANCE UPON THIS INFORMATION.
***************************************************************************
*********************
Prepared by: Environmental Health & Safety
Phone Number: (314) 654-1600 (U.S.A.)
Try the links in the MadSci Library for more information on Neuroscience.