Chemical intolerance and hypersensitivity

We come now to one of our BIG topics, albeit it a highly controversial one: the question of chemical “allergy” or intolerance. I am not talking here merely about chemical “pollution” in the atmosphere but contact with substances common in the home and that release fumes which we breathe on a daily basis. Some of this chemical exposure is deliberate and part of our modern living style: cosmetics, detergents, aerosols and even medical drugs are all intentional chemical exposures. I particularly object to the concept of spoofily-named “air fresheners”, when all they do is add more chemicals to the air, in an attempt to disguise existing contaminants. It is rather like taking dirty trench water to wash away stains — “Not logical”, as Mr Spock (Leonard Nimoy, not the paediatrician) would have said.

It is surprising to most people to learn that indoor chemical pollution is often many times the allowed safety limits allowed at work. A 5-year-study carried out by the US Environmental Protection Agency (EPA) found that peak concentrations of 20 toxic compounds monitored were 200-500 times higher inside some homes than those outdoors. Formaldehyde and toluene (from paints and varnish) are good examples of dangerous indoor pollutants. Formaldehyde, given off by many home substances, from PVC to particle board, is a known carcinogen. Toluene, released by fresh paint, dissolves brain tissue and causes permanent brain damage. There is a move to ban it in industry as a health hazard but homes have no such protective legislation. In the di-isocyanate form (tdi= toluene di-isocyanate), released by wet varnish, it is notorious for sensitizing people to allergens. Pronounced exposure to this latter chemical has been the start of a descent into Allergy Hell for many individuals.

[SPECIAL NOTE: sometimes the products which harm us are not initially present in the product and may not appear on the label, so the danger is overlooked. For example diethanolamine (DEA), triethanolamine (TEA) and monoethanolamine (MEA) are relatively non-toxic substances added to soap and personal hygiene products. Who can object? Well, everyone should! In the presence of nitrates, which are present in many manufactured food products, these “innocent” compounds form dangerous nitrosamines. Most nitrosamines are known to be carcinogenic]

Human canaries

Increasing numbers of people simply cannot accommodate the everyday load of ambient chemicals and it begins to undermine their health in many unsuspected ways. In my radical 1986 book ALLERGIES: WHAT EVERYONE SHOULD KNOW (London, Unwins) I introduced the term “human canaries”. The phrase seems to have caught on. This likens chemically sensitive people to the canaries taken down mines in olden days. If the bird fell dead it meant that the air was dangerous and a warning to humans to get out fast. It seems to me that we have many human canaries today but few people are heeding the warnings.

Something like 6 million new chemicals have been manufactured since the 1960s, when the chemical boom got under way worldwide. Of these, upwards of 100,000 are in production or have been until recent years. We call these synthetics xenobiotics (foreign to life). This is not an idle word: it implies that our bodies do not know how to deal with these substances. Nature did not endow us with the necessary enzyme equipment to safely detox them because they are not naturally occurring compounds. This increases their danger considerably.

In my view it is unarguable that we will all go under if we don’t soon start to reduce the total chemical load in our environment. This is not merely green politics but an out and out survival issue. There is dirty work afoot and that, of course, means Big Business dollars getting in on the act and perverting truth. We are told we need most of this chemical junk, that pesticides save lives and help grow more crops, which we need to feed the planet, and so on. I am not in the agribusiness, I’m a doctor. My take on this is very simple and very blunt:

the word “pesticide” is a con trick. Plant and animal physiology does not recognize human value judgements, such as “useful” and “nuisance” life forms. The correct word is biocide, which means that it kills any life, not just pests.

the idea of “responsible” or “controlled use” of toxic substances and talk of “reducing” usage levels is meaningless and dishonest: chemicals in the environment persist. Last year’s out put is added to that of the year before, to this year’s, next year’s and so on. It’s cumulative.

There are already enough xenobiotic substances in our environment, working their way through the water table and eco-system to keep us all ill for decades, even if output was curtailed tomorrow, a pretty unlikely event in any case.

Now that’s said, let’s get back to chemical sensitivity:

Arguments I have heard against this phenomenon are frankly absurd:

Many otherwise sound clinicians refuse to accept that small traces of chemical substances can make an individual ill. Yet the toxicologists, who have very precise and quantitative scientific techniques, know it and have written tens of thousands of papers on what I have termed “low grade poisoning” – susceptible individuals who feel the ill effects at doses that are supposed to be safe in normal circumstances. Confusion may stem from the fact that it may be long term exposure which causes the trouble, as the chemical accumulates in the tissues (especially the brain). Allegedly safe levels don’t count if you are storing the toxin.

Small simple molecules don’t command an antibody response, is another ridiculous assertion. We all know that people can be highly sensitized to nickel: that’s just one atom! You can’t get simpler than that. But experts should know also about haptens. These are small molecules which plug in to an antigen-antibody pair and excite a reaction which might not otherwise have happened.


The key to chemical intolerance of this type is the matter of individual biological variation. It is no good measuring averages or the mean when it comes down to the fact that most people are not at all average and some individuals are very far from average. Is it right to condemn and ignore individuals who are extremely poorly tolerant, or accusing them of making it up, when we know (for sure) that there are individuals equally far from average in the opposite direction, who can tolerate very large exposures apparently without harm? An enlightened and compassionate medical science must include everyone and not dismiss those who don’t fit the reductionist demographic formula.

Dr Theron Randolph, who first pioneered chemical susceptibility in a massive seminal book Human Ecology and Susceptibility to the Chemical Environment (Springfield, IL, Charles C Tuttle, 1962), points to this major difference between conventional medicine and the allergy/ecology approach: the one is for the mass, the other is for the individual. He called these two approaches endogenous and exogenous medicine. It is worth tabulating the key differences.




Treats the averageBlames the patient


Sees averages

Over-rides nature in the cure

Treatment adds burden

Treats the individualBlames exterior causes


Sees uniqueness

Seeks to enlist nature in curing

Treatment by reducing burden

The point is that, sooner or later, everyone reaches their threshold limit and from then on, symptoms escalate. It matters not whether we call it susceptibility or overload; the result is the same.

When to suspect chemical intolerance and overload.

Suspect chemical intolerance or overloading when you develop the following signs:

  • Symptoms worse in closed spaces (shopping malls, long car journeys)
  • Symptoms worse on week days (chemicals at work)
  • Symptoms better on holiday (fresh air!)
  • Worse in an urban environment
  • Gasoline or gloss paint gives you a headache
  • Acute sense of smell to chemicals
  • Lost sense of smell or it comes and goes
  • You get a “lift” or liking for certain chemical odours
  • Intolerant of synthetic fabrics (sneezing, skin rash, irritation)
  • Others similarly ill in the home or workplace
  • Illness began after moving to present location or current employment

Does the idea of a “lift” or buzz from chemicals sound crazy? Why should it? Think about glue and solvent sniffers. They do it on purpose – but just because they are too stupid to realize the dangers that doesn’t mean it is not pleasurable brain stimulation.

Note that with exposure at work symptoms may not begin till Tuesday or Wednesday, as the cumulative effect builds up. Similarly, symptoms may not clear by Saturday morning but could linger through till later. Yet you may get the worst reaction on Monday and Tuesday, as your body is challenged by chemicals which have gassed out over the weekend.

Why would someone develop chemical intolerance?
I have learned of at least four reasons a person becomes chemically sensitive. Others may come to light in time:

  • Chronic over-exposure (as in the workplace)
  • Sudden massive over-exposure (as in a contamination incident)
  • Metabolic (enzyme) deficiency
  • Overload

Once intolerance to one chemical substance is established, it tends to spread rapidly to other substances. We call this the spreading effect.

Causes of chemical exposure- what to look for
SCOTT-MUMBY’S RULE OF THE NOSE: I have a maxim, based on decades of experience, which is that if there is enough substance present to cause an odour, there is enough to cause symptoms. Some chemical substances, of course have no odour.

There are many other chemical contacts, of course: plastics, urban atmospheric pollution, perfumes and cosmetics, cleaners, solvents, aerosol sprays, paints and food additives, to name but a few. Most of these are derived, ultimately, from petroleum and the whole group we call “hydrocarbons” from their chemical structure. Interestingly, all petroleum (and coal) products originated as pine trees in carboniferous forests millions of years ago. Yet we find pine and its terpene derivatives today are quite potent allergens! Is there a connection?

Chemicals at work and school

Don’t forget the work environment as a source of chemical exposure. In some trades there are specific hazards and the monitoring of these exposures since the Health and Safety at Work Act of 1974 has come under the control of the Environmental Safety Officer (ESO) in the Environmental Medical Advisory Service (EMAS). However, to pretend this system is working efficiently and protecting workers properly is to be foolish and gullible in the extreme. Only a very small percentage of workers – those employed in larger factories and offices – effectively come under this sort of umbrella. Although the Act supposedly covers all offices, factories and places of work, in actual fact it is impossible to monitor the countless small businesses that this represents. Only if the individual worker complains is any action likely to be taken in the event of a hazard and many workers are reluctant to report breaches of the codes for fear of losing their jobs, either as retribution or indirectly because the works are closed down due to not being able to afford all the safety procedures required.

It may be obvious to you that you are working with major chemical toxins. Elaborate precautions and safety instructions would tell you that. However, many chemical allergens at work are much more insidious and difficult to detect unless you consider the possibility. Problems can come from photocopier fluids, solvents, aerosol, powerful cleaning agents and detergents (common where contract cleaners are employed), air purifiers and, fast but not least, the fabric of the building and its furnishings (formaldehyde particularly). If your office has that new ‘plastic’ smell, this could be a problem. Air conditioning often makes matters far worse by circulating indoor pollution.

The Allergy Handbook

This problem can be so bad that we have begun to pinpoint what is called the Sick Building Syndrome. Some modern buildings have such a high internal accumulation of these obnoxious substances, that almost everyone feels ill to some degree. Headaches, sore eves and runny nose, fatigue and inability to concentrate are almost the norm. The effect on work efficiency is disastrous and absenteeism runs sky-high.

Since it is costing industry money in lost man-hours, you may be sure (especially if you are cynical, like me) that a lot of money is now being spent on researching this problem.

In the meantime, the answer is simple. Open the windows! The problem is made far worse by the modem craze for energy efficiency. For allergy sufferers at least, draughts are good news. They help to circulate air and keep down internal pollution. This applies in the home also – double glazing and draught-proofing may be disastrous to those who suffer within the home environment.

The list below gives pointers towards allergies in the work environment.

  • The presence of any known hazards (eg. Toluene diisocyanate, formaldehyde)
  • You feel better at weekends
  • Symptoms clear up on holidays
  • Co-workers affected (‘sick’ building syndrome)
  • Reaction started when you started your present employment
  • Worst on Monday and Tuesday
  • Keep in mind potential physical factors eg. VDU’s and back or eye-strain (not necessarily an allergy)

Cleaning up your chemical environment

It makes good sense to clear your environment of as many unnecessary chemicals as possible. This will reduce your overall environmental burden. We choose the home for this because it is something you can control to a great extent. You can’t do much about what is beyond your doors and windows (except move if you are down-wind from a factory or such) but, unless you have a particularly unsympathetic and selfish family, you should be able to effect enough changes indoors to produce a worthwhile improvement. Some substances you will be able to replace with safer substitutes. Many you will be able to dispense with altogether. Some you will need and no substitutes can be found. The answer is to recognize the danger, use them as infrequently as possible, preferably get someone else to carry out the task involved and store these substances outside the house, for instance in the garage

I usually get patients to comb the whole house, room by room, cupboard by cupboard and shelf by shelf, listing all the chemicals found. Sometimes, the list itself is a shock and this is salutary. To pinpoint all potential trouble, I get them to supplement what can be seen with what can be smelled. Most chemical allergics have a very sensitive sense of smell; others have none and will need to enlist the help of someone else – I call this a nose survey: if you can smell it, it can make you ill. That is, if there is enough to cause an odour, there is enough to cause symptoms.

The list of potential chemical allergens shown below will help you search out trouble. Store, replace or throw out as much as possible of what you find.

Aerosols. We all know about the effect aerosol propellants (CFCs) have on the environ­ment. What is more important and often forgotten is that they have a bad effect on humans too! Also, beware of so-called ‘ozone friendly’ products. These simply contain alternative chemicals. Remember that ozone friendly doesn’t mean ‘bio­friendly’.

Air fresheners
Tap water
Cavity wall insulation

Urea-formaldehyde foam insulation (UFFI) is a cause of considerable health problems; so much so that it was banned some years ago in the US — although we are still being told it is safe here in the UK.

Cleaning materials

There are always simpler alternatives, even if they do call for a little more manual effort. Sodium bicarbonate or borax can often be made to serve where more powerful alkaline agents would be used. Avoid ‘biologicals’ like the plague. Especially avoid fabric ‘conditioners’ which seem to cause strong reactions in some.

For personal washing use Simple, Castille or Neurragena soaps. For household duties try soft green soap (that’s its name!) obtainable from chemists.

Cooking utensils

Allergics should avoid using non-stick pans with Teflon-type coatings. Nor is aluminium cookware recommended, due to toxicity problems. Glass and enamel are best.


Most people are better off in natural fabrics, such as wool and cotton. Man­made fabrics all give off fumes long after they are new. Of course some people are allergic to natural fabrics, especially wool, and trial and error is required to find what suits you best.


Chimney flues may present problems as they can leak and give off serious fumes. The only safe course is to have the flue lined with a modern flexible flue liner which, although expensive, can be passed up the chimney with the minimum disturbance and mess.

Better still, change to electrical radiators and eliminate gas or open fires.

Garages, integral

Petrol fumes are a common concern; I find. It is far better (and safer!) to park the car outside and to use the garage to grow mushrooms or for a model workshop.


All chemically-sensitive patients should get rid of gas from their homes if it is at all practicable and economically viable to do so. Avoid open gas fires. Do not use gas for cooking, even if you have to retain it for heating purposes.

A final word of warning: Under no circumstances whatever be tempted to use the free-standing butane gas heaters which can be wheeled from room to room. These give off very toxic fumes.


Avoid ducted air systems, fan heaters and, to a certain extent, open bar electric fires. Best are central heating radiators or, for portable use, small oil-filled electric radiators, such as the Dimplex type.


Cosmetics are generally biologically unfriendly. Try to get the hypoallergenic kind but remember there is no such thing as non-allergenic.


Paints can cause many unpleasant symp­toms. There are a number of ‘organic’ paints coming onto the market. These are watersoluble and free of the toxic solvent fumes. If you don’t want to use water-based paints, latex paint is said to be best for allergics. Stir in sodium bicarbonate until the paint stops bubbling. Richard Mackarness suggests about 100 g to 5 litres of paint.


Toothpaste may contain ammonia, ethanol, artificial colours and flavours, formaldehyde, mineral oil, saccharin, sugar and carcinogenic PVP plastic.

Weleda (Ilkeston, Derbyshire) do a simple salt gel or plant gel paste, safer than any others. For the exquisitely sensitive, try oil of cloves.

Don’t forget car and upholstery are potential hazards. Nowadays, most are treated with complex stain-repellent and preservative chemicals. You may not want to throw out your nice new carpet or sofa but at least if you can diagnose that’s where the trouble is coming from, you will feel less distressed. Things will probably improve in time. However, for an unlucky few, the truth is simple, if bleak – they will never be well until the luxury wall-to-wall hazard is disposed of!

 Organic foods

It pays to avoid food additives and eat only wholefoods, although it must be said there is some hysteria about ‘E numbers’ at present. Only a very small percentage of the population can never eat foods containing them. For the rest of us, it is a matter of prudence and need not be magnified to become a fear of poisoning.

Probably the greatest hazard is from chemicals sprayed on our foods before harvesting. This can include fertilizers, weedkillers, insecticides, fungicides and others. According to official figures, 98 per cent of green leaf crops, 94 per cent of orchard crops and 95 per cent of root crops are treated with chemicals. Sometimes foods are sprayed after gathering, to assist in storing. All of this poses a serious long-term health threat that has not been properly evaluated.

Foods grown without such chemicals are christened ‘organic’ or ‘organically grown, and developments in this area are a welcome, fast growing trend. Those with serious chemical allergies are advised to eat only organically grown food. However, it is difficult to get supplies and, fortunately, most people don’t need to be strict in this regard.

A few weeks’ experimentation will elimination and carefully judged challenge tests, comparing organic with non-organic ordinary commercial supplies, should settle the matter.

For years, we have recommended a company called Allergycare Ltd. Henry Doubleday Research Association lid publishes a book listing organic food suppliers, but it suffers from going out of date too quickly. Finally, Action Against Allergy will usually be able to supply names and addresses of organic food suppliers and other chemical-free or allergy-safe household goods.


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