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Is the food industry missing a major food safety risk? A look at intake of food chemicals other than by oral ingestion

Published: 2 Dec 2014

By Tony Zipper (C Chem, ARMIT (App.Chem.), FAIFST, FRACI, FoodLegal Food Chemist)

FoodLegal Lawyers and Consultants

© Lawmedia Pty Ltd, December 2014


A recent article published by the Journal of the American Medical Association reported the results of a literature review which held certain chemicals to pose a public health risk when inhaled. Many of these same chemicals are permitted to be added to food or oral ingestion without much regulation. But, as this article illustrates, there are considerable opportunities for food chemicals to be absorbed into the human body by means other than ingestion. This article queries whether ingestion should be the only accepted means of food intake when food regulators prescribe acceptable levels of food chemicals.

Does food law consider intake other than oral ingestion?

The Australia New Zealand Food Standards Code (the Food Standards Code) references its definition of ‘food’ from Food Standards Australia New Zealand Act 1991 and then Section 5 of the same legislation utilizes the word “consumption” which is used to describe the act of ‘eating, drinking, devouring’ (Macquarie Dictionary). The Food Standards Code does not define the term “consumption”, nor any of its synonyms.

The Food Standards Code also tends to ignore ‘odour’ / ‘aroma’ one of the 5 basic senses (taste, smell, touch, sight, hearing) used by humans in their appreciation of food. The major references to ‘odour’ in the Food Standards Code are in Standard 1.3.1 Schedule 5 where a ‘Flavouring’ is described by reference to “taste or odour”, and a ‘Flavour Enhancer’ which includes “taste and/or odour”.

Yet, despite these narrow definitions for ‘food’ or ‘flavour’ or ‘consumption’ when used by regulators and food scientists working with the Food Standards Code, it is now clearer that the human body can ingest, inhale, absorb, etc substances that are defined as ‘food’ by the Food Standards Code, or substances that are part of medicines as permitted by the Therapeutics Goods Administration (TGA) or ingredients in cosmetics using materials from a permitted list, apart from being substances that are loosely regulated, if at all.

It is irrelevant whether these substances have any nutrient, medical or aesthetic value when they enter the body either through the digestive system or are otherwise assimilated internally.

A case study example raised by the Journal of the American Medical Association

Diacetyl is a permitted flavour (FEMA 2370) as per Standard 1.3.1 Clause 11. Diacetyl has a strong buttery flavour and odour and is found naturally in fermented beverages, which sometimes can be regarded as beneficial to the flavour profile. Diacetyl is used as a flavour component in many dairy and margarine products that require a ‘butter’ flavour and also in many flavoured popcorns.

However Diacetyl – as was highlighted by the Journal of American Medical Association article(*) - has a dark side when present at reasonably high concentrations in the atmosphere of its manufacturing plants. Workers in these plants have been diagnosed with a serious lung disease ‘bronchitis obliterans’ which can be fatal.

Neither the Food Standards Code nor SUSMP – Standard for the Uniform Scheduling of Medicines and Poisons make any reference to the restriction of the use of Diacetyl in any circumstance. The USA Department of Labor – OSHA has published “Hazard Communication Guidance for Diacetyl and Food Flavorings Containing Diacetyl”. A similar OH&S warning for Australia could not be found. This could be because Diacetyl is used in small quantities in flavour manufacture.

Oral Ingestion of Food

Oral ingestion is currently the only legally permitted route for food intake under the Food Standards Code. In normal circumstances, food orally ingested must “be fit for purpose” and must not have any toxic effect. Excess consumption beyond oral ingestion is a choice that is not a consideration covered by the Food Standards Code, although there are discussions re mandating serve sizes, etc and some Food Standards do require labelling of daily limits.

Food chemical intake other than by ingestion

This article explores the different methods of direct ingestion of volatile materials by various human organs i.e. via the mouth, nose and skin. The materials include food chemicals permitted as processing aids or additives by the Food Standards Code and other substances that may fall under product categories within the regulatory standards that cover foods, therapeutics, cosmetics and aerosol sprays.

As a young food chemist in the early 1970’s I can recall spilling a drop of a food flavour chemical Dimethyl Sulphoxide on my finger and within less than one second I could taste a foreign flavour on the tip of my tongue even though my finger never touched my tongue. Although I was working with many flavour chemicals at the time, the association was only confirmed with repeating the experiment in isolation.

The conclusion I drew was that the chemical could have been absorbed through my skin. Yet at that time, the chemical industry believed that skin was to be considered to be impervious to chemical absorption even though a chemical could be detected by sensory organs in the mouth apparently through skin absorption.

At the time, I also raised a question about lipstick and the then Chief Chemist of the State of Victoria replied that “there was nothing to worry about, because the lipstick components could not penetrate the skin”.

In more recent decades, the mechanism of chemical absorption into the bloodstream has not just been proven but has been thoroughly explored and commercially exploited in medical terms, through transdermal patches for delivery of medicines and pharmaceutical substances, such as for nicotine, pain relief, heart conditions, and other similar applications. The level of oxygen in the blood stream is also now measurable through the skin. Skin as the largest organ in the human body, is now well understood to be porous to many substances that come into contact with it.

One can be sure that there are companies exploring the opportunities for delivering essential nutrients by transdermal means such a ‘patch’ similar to a nicotine patch.

Transdermal transfer will depend on numerous factors, including the molecular size of the particular chemical, volatility, use of solvents/carriers, dose required, and other possible variables.

Defining Volatile Substances

Volatile substances, without having the reader know too much chemistry, are either solids or liquids that at ambient (room) temperatures or slightly higher, exhibit some noticeable aroma/odour to humans. The main volatile substances under discussion are Flavourings, Solvents, Fragrances and other Volatile Organic Compounds (VOCs).

Volatile substances are often but not always sensed by the nose. The ability to smell is the least understood and appreciated sensory function, not only for food aromas but also because it is used as a warning instrument or a memory stimulating device, etc. The capabilities of the nose are highly underrated at the best and not understood at the worst. Many of the nose’s attributes are yet to be discovered and appreciated, much less exploited.

Often volatile substances do not exhibit any odour but can still have an effect on the human metabolic system, even if harmless and may be absorbed and duly excreted through the digestive system or through perspiration or through respiration (e.g. garlic).

Vapours are often not only Volatile Organic Compounds (VOCs) but are the result of another process and generated either naturally (i.e. Sulphur from volcanoes, etc.) or manmade (i.e. burning wood or plastic, etc).

Food Chemicals

There are many volatile substances permitted by the Food Standards Code, primarily ‘Flavourings’ (Standard 1.3.1 – Food Additives, Clause 11, Schedules 1 [Section 0.1], 2 & 5) and their Solvents (Standard 1.3.1 Schedule 1 Section 0.1). There are many food substances that have an associated aroma both individually and when combined. All odours are perceived by consumers and end up in the respiratory system (lungs) where they are metabolised and distributed through the blood system to end up in various organs and bodily systems.

Adventitious Inhalation of Odours & Vapours

There are very many sources of odours and vapours in our environment, some of which are deliberately added to the atmosphere for marketing reasons, i.e. the smell of “fresh coffee” or “fresh bread” in food outlets, cafes, etc to induce custom. “Odour fatigue” is a well-researched subject that is used to exploit repeated applications.

There are many vapours that are inhaled, knowingly (through perception of the associated odour) and unknowingly (these substance, usually gases at room temperature and pressure, do not have any odour. Examples can include: refrigeration coolants such as the now superseded CFCs [Chlorofluorocarbons] but replaced by Hydroflurocarbons with a history still to be written; aerosol fumigants (used in food plants); cigarette smoke (those that are smoked deliberately and “other peoples” smoke). This latter group now includes “electronic cigarettes” which burn/heat/vaporise flavourings either with or without nicotine and often include Diacetyl – see above.

A relatively unknown area is the inhalation of nanomaterials from many newly developed materials. It is presumed that nanoparticles may have different volatility properties from their none-nano equivalents. This is a subject of much current research. (See also previous FoodLegal Bulletin articles about nanotechnology: ‘The growth of nanotechnologies in the food industry and the regulatory issues’ (May 2014) and ‘Is nanotechnology the new GM?’ (October 2008))

Packaging is now known to emit odours which can be absorbed (within the matrix of the goods held in a package) or adsorbed (onto the surface of the packaged goods). Although this an important but negative factor in food packaging, Food Standards Australia New Zealand (FSANZ) have only recently released FSANZ Proposal P1034 – “Chemical Migration from Packaging into Food” and will be preparing a report after considering industry submissions.

Volatile substances in food and the effects of reflux

One relatively new health concern is the now quite common health condition known as reflux, whereby ingested food is expelled back up through the esophagus into the mouth and often volatile substances (and sometimes solid food particles) will enter the lungs. This could also occur with burping when volatile material re-enters the oral cavity and may be drawn into the lungs via subsequent breathing.

The PBS drug rankings for Nexium or the like (Esomeprazole) show that there are now huge numbers of Australians who are taking medication to prevent reflux and possibly worse side effects such as aspiration pneumonia caused by bacterial pneumonia and chemical pneumonitis. Aspiration pneumonia results from inhalation of stomach contents or secretions of the oropharynx leading to respiratory tract infections.

Short-term effects of reflux and subsequent lung ingestion of volatile compounds are known to include secondary health problems such as temporary breathing difficulties.

Over the past 30-40 years all new food substances have undergone a variety of mandated toxicity tests (refer to FSANZ Application Handbook). These tests can establish with a very high degree of certainty, that any detrimental long-term health effects of ingestion of volatile substances from permitted foods into the lungs and thence into the blood stream or remain within the lung lining, have been studied and eliminated as causes of any toxicity. With regard to volatile food substances, with aroma often being a characterising parameter, toxicity testing from inhalation is a mandated testing factor refer JECFA (CODEX) – Joint Expert Committee of Food Additives.

However, the related issues that might be missing and that FSANZ ought to consider for further study are the interactions of a mixture of volatile compounds with each other or with other food components to form a new compound during digestion, followed by reflux and also the composition of the metabolic breakdown products of VOCs after partial ingestion followed by reflux.

Furthermore, similar toxicity studies ought to be required for any substance to be accepted into the Australian Register of Therapeutic Goods (ARTG). Existing permitted substances ought to be reviewed by similar studies.

Nasal Ingestion

The nasal route of permitted food ingestion is also not discussed in the Food Standards Code although there are some foods that would be regulated by Standard 2.9.5 - Foods for Special Medical Purposes that could be used for nasogastric feeding for special needs patients.

While the nasal passages are used primarily for odour/aroma detection as described above, some volatile food chemicals and food substances are likely to affect breathing and may be of concern to consumers with respiratory conditions.

Transdermal Ingestion

For food, this may be a future route of ingestion for micronutrients i.e. vitamins, nutritive substances but it does not seem feasible to use this method for macronutrients such as protein or fats, etc.

The chemical that I mentioned earlier in this article, Dimethyl Sulphoxide, is a solvent and a permitted flavouring.

Are food regulators missing a potential food safety risk by only considering oral ingestion?

All materials have established limits of ingestion and these limits are included on the Material Safety Data Sheet (MSDS) that should accompany every batch of raw material so that manufacturers, retailers and users of the material have access to these limits.

The actual health effects of flavours and aromas on humans can vary depending on many factors, including dosage, age, weight, health status, other substances ingested at the same time and more.

There are apparently some beneficial effects of flavours and  aromas such as inducement to eat or as a complement to eating, as the ingestion organs (mouth and nose) are physiologically joined and the flavour of the ingested food and its associated  aroma are usually detected simultaneously.

However, if inhaling a food chemical associated with a non-nicotine e-cigarette is to be viewed as unhealthy(*), a similar review should be undertaken in relation to similar chemicals that are accepted by the food industry but are capable of being absorbed into the human body by means other than ingestion by eating or drinking. 

* REFER: "Flavorings in Electronic Cigarettes. An Unrecognized Respiratory Health Hazard?" Jessica L. Barrington-Trimis, PhD, MS, MA; Jonathan M. Samet, MD, MS; Rob McConnell, MD in The Journal of the American Medical Association (JAMA) . Published online November 10, 2014