Chapter 26 – Infographic descriptions

26.0a Hay Fever & Hay Fever Medications

The cause of hay fever: trees, grass, weed pollens.

• 10-15% of the UK population is affected by hay fever.
• 90-95% of hay fever sufferers are allergic to grass pollen

The allergic response:

1. Pollen exposure results in the body misidentifying it as a threat; antibodies are released to combat it.
2. The antibodies produced bind to two types of cell in tissues – mast cells and basophils.
3. These release several chemicals, including histamine, which produce an inflammatory response.
4. Symptoms of this response include a runny nose, itching, sneezing fits, and nasal congestion.

Antihistamines for hay fever:

• Cetirizine and loratadine block histamine action, prevent most symptoms.
• Nasal sprays.

All oral formulations for treatment of hay fever are antihistamines. These bind to H₁ histamine receptors instead of histamine, preventing the effects produced by the allergic response – although they may be clear blocked noses.

First generation antihistamines can cause undesirable effects, including sedation. Second generation are less likely to exhibit sedative effects, particularly loratadine, Peak levels of antihistamines are generally reached one hour after taking.

Take when hay fever symptoms are expected, rather than when they have already started. This is because they cannot reverse the effects of histamine already binding to the H₁ receptors, and so will not provide relief.

Sodium cromoglycate prevents release of histamine. Commonly used in eye drop solutions, sodium cromoglycate prevents hay fever symptoms by stabilizing mast cells, and preventing them from releasing histamine. Unlike anti-histamines, it is effective at remedying itchy eyes even after symptoms have started.

Corticosteroids prevent the inflammatory symptoms of hay fever. Prevent nasal symptoms more effectively than antihistamines, and also relieve itchy eyes. They act to reduce inflammation, rather than directly blocking or preventing the action of histamine.

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26.2a The Chemicals in Cigarette Smoke & Their Effects

• Estimated number of chemical compounds in cigarette smoke: 7,357.
• Number of these compounds with confirmed carcinogenic activity: 70

The compounds shown below are all found in cigarette smoke. The mass figures, given in [latex]\mu[/latex]g, take into account both mainstream (inhaled) and sidestream smoke. 1 [latex]\mu[/latex]g is equal to 1 million of a gram. Amounts of these compounds vary in different brans of cigarettes – these figures are approximate.

Nicotine:

• Approx. 9.19[latex]\mu[/latex]g per cigarette
• Addictive
• Increases heart rate
• Increases blood pressure
• Increases blood glucose
• Lethal dose: around 500-1000mg

N-Nitrosamines:

• Large class of compounds
• Several are tobacco-specific
• Known human carcinogens
• Most carcinogenic: NNK & NNN
• NNK: approx. 0.3[latex]\mu[/latex]g per cigarette
• NNN: approx. 2-50[latex]\mu[/latex]g per cigarette
• May cause reproductive damage

Benzene:

• Approx. 46-272[latex]\mu[/latex]g per cigarette
• Known human carcinogen
• Damages bone marrow
• Lowers red blood cell count
• May harm reproductive organs

Aromatic Amines:

• Large class of compounds
• Includes 2-aminonaphthalene:
  • Known human carcinogen
  • Linked with bladder cancer
  • Approx. 0.04[latex]\mu[/latex]g per cigarette

Acetaldehyde:

• Approx. 680-1571[latex]\mu[/latex]g per cigarette
• Known animal carcinogen
• Probable human carcinogen
• Irritant to skin and eyes
• Irritant to respiratory tract

1,3-Butadiene:

• Approx. 36-191[latex]\mu[/latex]g per cigarette
• Known human carcinogen
• Suspected human tetratogen
• Irritant to eyes and skin
• Irritant to upper respiratory tract

Acrolein:

• Approx. 69-306[latex]\mu[/latex]g per cigarette
• Possible human carcinogen
• Known DNA mutagen
• Irritant to skin and nasal passages
• May contribute to heart disease

Polyaromatics:

• Large class of compounds
• Includes benzo[a]pyrene:
  • Known human carcinogen
  • Known DNA mutagen
  • Affects reproductive capacity
  • Up to 0.14[latex]\mu[/latex]g per cigarette

Read more about “The Chemicals in Cigarette Smoke & Their Effects [New tab]” by Andy Brunning / Compound Interest, CC BY-NC-ND.

26.2b RTC Week 2015 – #3: Nitrogen-Containing Atmospheric Pollutants

Dr. Nadine Borduas, department of chemistry at University of Toronto did research on how various nitrogen-containing amine compounds react when released into the atmosphere.

Organic nitrogen compounds enter our atmosphere from a variety of sources, both natural and industrial.

Amines: sources are: industrial, farming, forest fires, cigarette smoke.  [latex]R= \text{various groups}[/latex]

[latex]{\normalsize \text{Amines}\xrightarrow[Hours]{+\cdot OH{+O_{3}}}\text{Amides}\xrightarrow[Days/Weeks]{+\cdot OH}\text{Isocyantes} \normalsize}[/latex]

[latex]{\scriptsize \text{Ammonia \& Carbon Dioxide}\xleftarrow[Seconds/Days]{+H_{2}O}\text{HNCO (dropl)}\xleftarrow[Days/Years]{}\text{Isocynaic Acid (type of isocynanate)} \scriptsize}[/latex]

Ammonia reacts with chemicals in air to form particulates which can have human health issues, contribute to smog, and impact climate. Nitrogen deposition in soils can also affect ecosystems.

Read more about “RTC Week 2015 – #3: Nitrogen-Containing Atmospheric Pollutants [New tab]” by Andy Brunning / Compound Interest, CC BY-NC-ND

26.3a A Guide to Simple Heterocycles in Organic Chemistry

A heterocycle in organic chemistry is a ring of connected atoms, where one or more of the atoms in the ring are elements different from carbon. Heterocycles with oxygen, nirtrogen, and sulfur are the most prevalent; selenium, boron, arsenic and phosphorus can also be incorporated.

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26.3b Today in Chemistry History: Gertrude B Elion and drug discovery firsts

Gertrude B Elion born 23 January 1918 and died 21 February 1999. Elion was jointly awarded the 1988 Nobel Prize in Physiology or Medicine for work on the development of drugs, based on biochemical differences between human and pathogen cells. Working both alone and George Hitchings and she discovered new drugs against a variety of diseases. Her name appears on 45 different patents, and she was awarded 25 honorary doctorates.

Mercaptopurine, first treatment for leukemia; Azathioprine, to prevent transplant rejection; Trimethoprim, antibiotic; Allopurinol, treatment for gout; Aciclovir, antiviral for herpes infections; Pyrimethamine, for malaria and toxoplasmosis; Nelarabine, treatment for cancer.

Read more about “Today in Chemistry History: Gertrude B Elion and drug discovery firsts [New tab]” by Andy Brunning / Compound Interest, CC BY-NC-ND,

26.3c Why is Coffee Bitter? – The Chemistry of Coffee

Chlorogenic acids account for up to 8% of the composition of unroasted coffee beans. More than 40 different varieties have been identified in green coffee beans, with 5-caffeoylquinic acid the most prevalent. Chlorogenic acid content decreases when coffee beans are roasted, as they react to form quinolactones, phenylindanes and melanoidins. These contribute to flavour and bitterness.

The caffeine content of coffee is variable but approximately 100mg in a cup. Caffeine works by blocking the action of a group of brain chemicals called adenosines, which work to naturally trigger tiredness. The amount of caffeine in your bloodstream peaks 15 to 45 minutes after ingestion.

Read more about “Why is Coffee Bitter? – The Chemistry of Coffee [New tab]” by Andy Brunning / Compound Interest, CC BY-NC-ND

26.3d Toxicity & Aphrodisia – The Chemistry of Chocolate

Phenylethylamine occurs naturally in the brain, often referred to as ‘the love drug’ due to its ability to produce feelings of well-being and contentment. It is present in significant concentrations in chocolate, it is broken down during ingestion and is ruled out as causing significant aphrodisiac effect.

Tryptophan is a chemical in the brain linked to production of serotonin, the neurotransmitter that produces feelings of elation. It is present in small quantities in chocolate, it is unlikely that it causes any aphrodisiac effect.

Theobromine is a mild stimulant, similar to caffeine, found in chocolate. It is harmless to humans at levels found in chocolate and would require eating tens of kilograms of milk chocolate. However, theobromine has a more potent effect in cats and dogs; small doses can lead to vomiting and diarrhea and 50g of dark chocolate could kill a small dog.

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26.5a Chemical Concerns – Does Acrylamide in Toast & Roast Potatoes Cause Cancer?

Acrylamide is a chemical formed in reactions that occur when carbohydrate-rich foods are cooked at high temperature. Low levels of it are found in foods including roast potatoes, toast, and potato chips. It’s also found in roasted coffee beans and in cigarette smoke.

When carbohydrate-rich foods are cooked at high temperature (above 120 degree Celsius) amino acids can combine with reducing sugars (such as glucose) to form a range of products. The amino acid asparagine, combines with sugars to produce acrylamide. Higher temperatures and longer cooking times produce more acrylamide.

Acrylamide is classified as a probable human carcinogen; however, the amounts in  food are very low:

• Toasted bread: 4.8 micrograms (assumes 1 slice is 24 grams)
• Potato chips: 12.4 micrograms (assumes packet is 32.5 grams)
• AV. daily intake: 30 micrograms (assumes body weight of 75kg)
• Max. Recommended daily intake: 195 micrograms (assumes body weight is 75kg).

Dietary levels of acrylamide are a minor concern for a small increased lifetime risk of cancer. This is based on animal studies -evidence for increased risk in humans is currently minimal. Increases in cancer risk associated with regularly drinking alcohol or smoking are much higher. The latest advice recommends cooking foods a little less brown to reduce acrylamide content.

In short: acrylamide hasn’t been decisively linked to increased cancer risk at levels found in cooked foods.

Read more about “Chemical Concerns – Does Acrylamide in Toast & Roast Potatoes Cause Cancer? [New tab]” by Andy Brunning / Compound Interest, CC BY-NC-ND

Attribution & References

Compound Interest infographics are created by Andy Brunning and licensed under CC BY-NC-ND

Except where otherwise noted, content on this page has been created as a textual summary of the infographics used within our OER. Please refer to the original website (noted below each description) for further details about the image.