If you didn’t have food allergies as a child, is it possible to develop them as an adult? The short answer is yes. But the reasons why are much more complicated.

Preschoolers are about four times more likely to have a food allergy than adults and are more likely to grow out of it as they get older.

It’s hard to get accurate figures on adult food allergy prevalence. The Australian National Allergy Council reports one in 50 adults have food allergies. But a US survey suggested as many as one in ten adults were allergic to at least one food, with some developing allergies in adulthood.

What is a food allergy

Food allergies are immune reactions involving immunoglobulin E (IgE) – an antibody that’s central to triggering allergic responses. These are known as “IgE-mediated food allergies”.

Food allergy symptoms that are not mediated by IgE are usually delayed reactions and called food intolerances or hypersensitivity.

Food allergy symptoms can include hives, swelling, difficulty swallowing, vomiting, throat or chest tightening, trouble breathing, chest pain, rapid heart rate, dizziness, low blood pressure or anaphylaxis.

IgE-mediated food allergies can be life threatening, so all adults need an action management plan developed in consultation with their medical team.

Here are four IgE-mediated food allergies that can occur in adults – from relatively common ones to rare allergies you’ve probably never heard of.

1. Single food allergies

The most common IgE-mediated food allergies in adults in a US survey were to:

• shellfish (2.9%)
• cow’s milk (1.9%)
• peanut (1.8%)
• tree nuts (1.2%)
• fin fish (0.9%) like barramundi, snapper, salmon, cod and perch.

In these adults, about 45% reported reacting to multiple foods.

This compares to most common childhood food allergies: cow’s milk, egg, peanut and soy.

Overall, adult food allergy prevalence appears to be increasing. Compared to older surveys published in 2003 and 2004, peanut allergy prevalence has increased about three-fold (from 0.6%), while tree nuts and fin fish roughly doubled (from 0.5% each), with shellfish similar (2.5%).

While new adult-onset food allergies are increasing, childhood-onset food allergies are also more likely to be retained into adulthood. Possible reasons for both include low vitamin D status, lack of immune system challenges due to being overly “clean”, heightened sensitisation due to allergen avoidance, and more frequent antibiotic use.

2. Tick-meat allergy

Tick-meat allergy, also called α-Gal syndrome or mammalian meat allergy, is an allergic reaction to galactose-alpha-1,3-galactose, or α-Gal for short.

Australian immunologists first reported links between α-Gal syndrome and tick bites in 2009, with cases also reported in the United States, Japan, Europe and South Africa. The US Centers for Disease Control estimates about 450,000 Americans could be affected.

The α-Gal contains a carbohydrate molecule that is bound to a protein molecule in mammals.

The IgE-mediated allergy is triggered after repeated bites from ticks or chigger mites that have bitten those mammals. When tick saliva crosses into your body through the bite, antibodies to α-Gal are produced.

When you subsequently eat foods that contain α-Gal, the allergy is triggered. These triggering foods include meat (lamb, beef, pork, rabbit, kangaroo), dairy products (yoghurt, cheese, ice-cream, cream), animal-origin gelatin added to gummy foods (jelly, lollies, marshmallow), prescription medications and over-the counter supplements containing gelatin (some antibiotics, vitamins and other supplements).

Tick-meat allergy reactions can be hard to recognise because they’re usually delayed, and they can be severe and include anaphylaxis. Allergy organisations produce management guidelines, so always discuss management with your doctor.

3. Fruit-pollen allergy

Fruit-pollen allergy, called pollen food allergy syndrome, is an IgE-mediated allergic reaction.

In susceptible adults, pollen in the air provokes the production of IgE antibodies to antigens in the pollen, but these antigens are similar to ones found in some fruits, vegetables and herbs. The problem is that eating those plants triggers an allergic reaction.

The most allergenic tree pollens are from birch, cypress, Japanese cedar, latex, grass, and ragweed. Their pollen can cross-react with fruit and vegetables, including kiwi, banana, mango, avocado, grapes, celery, carrot and potato, and some herbs such as caraway, coriander, fennel, pepper and paprika.

Fruit-pollen allergy is not common. Prevalence estimates are between 0.03% and 8% depending on the country, but it can be life-threatening. Reactions range from itching or tingling of lips, mouth, tongue and throat, called oral allergy syndrome, to mild hives, to anaphylaxis.

4. Food-dependent, exercise-induced food allergy

During heavy exercise, the stomach produces less acid than usual and gut permeability increases, meaning that small molecules in your gut are more likely to escape across the membrane into your blood. These include food molecules that trigger an IgE reaction.

If the person already has IgE antibodies to the foods eaten before exercise, then the risk of triggering food allergy reactions is increased. This allergy is called food-dependent exercise-induced allergy, with symptoms ranging from hives and swelling, to difficulty breathing and anaphylaxis.

Common trigger foods include wheat, seafood, meat, poultry, egg, milk, nuts, grapes, celery and other foods, which could have been eaten many hours before exercising.

To complicate things even further, allergic reactions can occur at lower levels of trigger-food exposure, and be more severe if the person is simultaneously taking non-steroidal inflammatory medications like aspirin, drinking alcohol or is sleep-deprived.

Food-dependent exercise-induced allergy is extremely rare. Surveys have estimated prevalence as between one to 17 cases per 1,000 people worldwide with the highest prevalence between the teenage years to age 35. Those affected often have other allergic conditions such as hay fever, asthma, allergic conjunctivitis and dermatitis.

Allergies are a growing burden

The burden on physical health, psychological health and health costs due to food allergy is increasing. In the US, this financial burden was estimated as $24 billion per year.

Adult food allergy needs to be taken seriously and those with severe symptoms should wear a medical information bracelet or chain and carry an adrenaline auto-injector pen. Concerningly, surveys suggest only about one in four adults with food allergy have an adrenaline pen.

If you have an IgE-mediated food allergy, discuss your management plan with your doctor. You can also find more information at Allergy and Anaphylaxis Australia.

Clare Collins, Laureate Professor in Nutrition and Dietetics, University of Newcastle

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Today’s news coverage reports potentially unsafe levels of “forever chemicals” detected in drinking water supplies around Australia. These include human-made chemicals: perfluorooctane sulfonate (known as PFOS) and perflurooctanic acid (PFOA). They are classed under the broader category of per- and polyfluoroalkyl substances or PFAS chemicals.

The contaminants found in our drinking water are the same ones United States authorities warn can cause cancer over a long period of time, with reports warning there is “no safe level of exposure”.

In April, the US Environmental Protection Agency (USEPA) sent shock waves through the water industry around the world when it announced stricter advice on safe levels of PFOS/PFOA in drinking water. This reduced limits considered safe in supplies to zero and gave the water industry five years to meet legally enforceable limits of 4 parts per trillion.

So, should the same limits be enforced here in Australia? And how worried should we be that the drinking in many parts of Australia would fail the new US standards?

What are the health risks?

Medical knowledge about the human health effects of PFOS/PFOA is still emerging. An important factor is the bioaccumulation of these chemicals in different organs in the body over time.

Increased exposure of people to these chemicals has been associated with several adverse health effects. These include higher cholesterol, lower birth weights, modified immune responses, kidney and testicular cancer.

It has been very difficult to accurately track and measure effects of different levels of PFAS exposure on people. People may be exposed to PFAS chemicals in their everyday life through waterproofing of clothes, non-stick cookware coatings or through food and drinking water. PFAS can also be in pesticides, paints and cosmetics.

The International Agency for Research on Cancer (on behalf of the World Health Organization) regards PFOA as being carcinogenic to humans and PFOS as possibly carcinogenic to humans.

Our guidelines

Australian drinking water supplies are assessed against national water quality standards. These Australian Drinking Water Guidelines are continuously reviewed by industry and health experts that scan the international literature and update them accordingly.

All city and town water supplies across Australia are subject to a wide range of physical and chemical water tests. The results are compared to Australian water guidelines.

Some tests relate to human health considerations, such as levels of lead or bacteria. Others relate to “aesthetic” considerations, such as the appearance or taste of water. Most water authorities across Australia make water quality information and compliance with Australian guidelines freely available.

What about Australian PFOS and PFOA standards?

These chemicals can enter our drinking water system from many potential sources, such as via their use in fire-fighting foams or pesticides.

According to the Australian Drinking Water Guidelines, PFOS should not exceed 0.07 micrograms per litre in drinking water. And PFOA should not exceed 0.56 micrograms per litre. One microgram is equivalent to one part per billion.

The concentration of these chemicals in water is incredibly small. And much of the advice on their concentration is provided in different units. Sometimes in micrograms or nannograms. The USEPA uses parts per trillion.

In parts per trillion (ppt) the Australian Guidelines for PFOS is 70 ppt and PFOA is 560 ppt. The USEPA’s new maximum contaminant levels (enforceable levels) are 4 ppt for both PFOS and also PFOA. Previous news reports have pointed out Australian guidelines for these chemicals in drinking water are up to 140 times higher than the USEPA permits.

Yikes! That seems like a lot

Today’s news report cites PFOS and PFOA water tests done at many different water supplies across Australia. Some water samples did not detect either chemicals. But most did, with the highest PFOS concentration 15.1–15.6 parts per trillion from Glenunga, South Australia. The highest PFOA concentration was reported from a small water supply in western Sydney, where it was detected at 5.17–9.66 parts per trillion.

Australia and the US are not alone. This is an enormous global problem.

One of the obvious challenges for the Australian water industry is that current water treatment processes may not be effective at removing PFOS or PFOA. The Australian Drinking Water Guidelines provide this advice:

Standard water treatment technologies including coagulation followed by physical separation, aeration, chemical oxidation, UV irradiation, and disinfection have little or no effect on PFOS or PFOA concentrations.

Filtering with activated carbon and reverse osmosis may remove many PFAS chemicals. But no treatment systems appear to be completely effective at their removal.

Removing these contaminants might be particularly difficult for small regional water supplies already struggling to maintain their water infrastructure. The NSW Auditor General criticised the planning for, and funding of, town water infrastructure in regional NSW back in 2020.

Where to from here?

The Australian water industry likely has little choice but to follow the US lead and address PFOS/PFAS contamination in drinking water. Along with lower thresholds, the US committed US$1 billion to water infrastructure to improve detection and water treatment. They will also now require:

Public water systems must monitor for these PFAS and have three years to complete initial monitoring (by 2027) […]

As today’s report notes, it is very difficult to find any recent data on PFOS and PFOA in Australian drinking water supplies. Australian regulators should also require ongoing and widespread monitoring of our major city and regional water supplies for these “forever chemicals”.

The bottom line for drinking tap water is to keep watching this space. Buying bottled water might not be effective (2021 US research detected PFAS in 39 out of 100 bottled waters). The USEPA suggests people can reduce PFAS exposure with measures including avoiding fish from contaminated waters and considering home filtration systems.

Correction: this article previously listed the maximum Australian Drinking Water Guidelines PFOA level as 0.056 micrograms per litre. The figure has been updated to show the correct level of 0.56 micrograms per litre.

Ian A. Wright, Associate Professor in Environmental Science, Western Sydney University

This article is republished from The Conversation under a Creative Commons license. Read the original article.