Better knowledge of dangerous substances can prevent life-long allergies

Allergenic substances are constantly present in our everyday lives. To respond to the growing problem of allergies in society, Yolanda Hedberg calls for increased cooperation between chemists and dermatologists.
Published Feb 24, 2020

An estimated 4,300 common chemicals in society can trigger an allergic reaction on contact.
“Chemists and dermatologists need to work together to tackle the growing problem with allergies,” says Yolanda Hedberg, a researcher at the Department of Chemistry and docent at KTH.

A contact allergy is a life-long disease. Once your skin has reacted to a molecule, your body remembers this for the rest of your life.
KTH researcher Yolanda Hedberg  has contributed to a chemically refined diagnostic method for skin allergies, in cooperation with Region Stockholm.

“We have investigated allergic reactions caused by everyday products such as cosmetics, implant materials, clothes and shoes,” she explains.
“Diagnoses are determined via tests using so-called patch test chambers, that we have analysed and refined at the Occupational and Environmental Medicine Centre Centrum för Arbets- och Miljömedicin .

Together with research colleagues, Hedberg has also been supporting the European Chemicals Agency for the last couple of years in lobbying for legislation to protect consumers against harmful substances in products.

Despite measures such as the Registration, Evaluation, Authorisation and Restriction of Chemicals in the EU, REACH , there has been an explosive growth in allergy cases in society.
“It's difficult to entirely avoid allergy invoking substances today, they are found almost everywhere,” she says.

Yolanda Hedberg examines a cosmetic cream that can be the source of an allergic reaction via infrared spectroscopy.

Demanding work to find the cause of a contact allergy

According to Hedberg, an estimated 35 percent of all women and 17 percent of all men currently have developed a nickel allergy.

“Nickel allergy is the commonest form of contact allergy. If you have it, you can get dermatitis from contact with the metal in objects such as glasses, watches, belts, tools and keys. And we must not forget that a further 4,300 chemicals in our society can trigger contact allergies …

A contact allergy always arises where the substance has been in contact with the skin, but often only a couple of days or even weeks later. This means it can take a bit of detective work to work out what has caused the allergy.

“We need to raise public awareness of what a delayed contact allergy actually means. Many people think they have suffered a direct allergy when they get a skin rash, but in the case of contact allergies, the reaction can be delayed several weeks,” says Hedberg.

“My best advice is always to perform allergy tests as recommended on the packaging before any beauty treatment such as hair colouring, piercing, false nails, false eyelashes, face masks or getting tattoos. You also need to wait at least a couple of days to see whether you have a possible allergy. Serious allergic reactions can be life threatening in the worst case.”

How skin allergies are diagnosed via a patch test

• A small amount of the chemical substance the patient is suspected of being allergic to is inserted in a so-called chamber that is taped to the skin for 48 hours.
• After four to seven days, a dermatologist will examine the area to see if there has been an allergic reaction.
• Tests have shown that the material the chamber itself is made of can react with the chemical substance and affect the diagnosis. This new knowledge, that Hedberg has contributed to, is increasing the number of correct diagnoses.

She also stresses that it can be difficult for doctors and dentists to determine if it is a case of a delayed contact allergy from an implant, for example.


“That’s why closer cooperation is needed between care providers and chemists. As researchers, we are already helping many sectors when it comes to occupational allergies today, such as preventing chromium allergy that can be caused by cement and work gloves. Not many people are aware that leather often contains chromium, and shoes can also cause severe allergic discomfort,” Hedberg explains.

The beauty industry is particularly vulnerable to powerful allergy invoking substances, and the problem is especially common in hairdressing salons and nail bars.

“Everyone who gets a rash from substances they use on a daily basis as part of their job, must make sure they take protective measures in good time, as once you have developed a contact allergy, you can be forced to change your job.”
Hedberg is currently supervising a Vinnova financed student project on substances in tattoo inks that are hazardous to health, that is expected to be completed in May 2020.

Katarina Ahlfort
Photo: Håkan Lindgren

What a delayed contact allergy does to your body

• The substance reacts with a protein, which changes form and is detected by a receptor in a cell.
• The cell communicates with another cell that goes to lymph nodes, a process that can take about a week.
• It can take 30 days from initial contact with an allergy invoking substance before the body shows symptoms of a contact allergy.
• The allergic reaction consists of a skin rash and swelling.
• The inflammation that arises will not go down if you continue to expose your body to the substance – the inflammation will remain and become chronic. Your immune system will continue to subject the material in question to constant attack.

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Last changed: Feb 24, 2020