Statistics show occupational skin disease to be one of the most common causes of occupational ill health. Given that in addition to skin disease we must consider systemic toxic effects on body organs and systems due to skin uptake, perhaps it is time to consider whether our traditional approach to managing skin exposure in the working environment properly reflects the latest scientific knowledge about the skin and how it interacts with our immediate environment.

This interaction is almost unimaginably complex. There is also much we do not yet fully understand about how this works. This article takes a brief look concentrating on some of the factors that we need to include in our approach to creating and maintaining a ‘skin safe’ workplace.

Workplace exposure to chemicals

Basically, there are three main routes by which human exposure to chemicals in a workplace can occur. These are inhalation, ingestion and dermal. Each has its own particular characteristics affecting how the risk of damage to health is assessed. Until now it has been common practice to consider each separately. This article will challenge this practice and explain why we frequently need to integrate the three routes if we are to produce a valid risk assessment for a particular task or workplace situation. It will then review what methods currently exist to achieve this and their limitations and suggest what needs to be done to ensure that risk assessments for chemical exposure reflect the total picture.

The routes of exposure

Inhalation – taken into the respiratory system via the nose or mouth. Substances must be airborne and in the breathing zone. Particle size must allow them to enter the respiratory system either as ‘inhalable’, i.e. able to reach the upper parts of the respiratory system, or ‘respirable’, i.e. able to penetrate through to the gas exchange region of the system (alveoli), where they can be absorbed into the blood stream to cause or contribute to systemic toxic effects and allergic reactions.

“we must consider systemic toxic effects on body organs and systems due to skin uptake”

Ingestion – taken into the digestive system either directly through the mouth or indirectly, for example by redirection from the respiratory system due to mucociliatory transportation, then swallowed.

Dermal – contact with the skin, such as through the hands.

Injection – a fourth possibility, i.e. through sharp objects penetrating the skin and allowing a chemical or micro-organism to enter the body. However, in the context of the interaction between the three main routes this is not of significance and will not be discussed further.

Effect on health

Inhalation – if inhalable, a chemical (be it dust, fume or aerosol) may cause irritant damage to the upper part of the respiratory system, if respirable there can be entry into the blood stream then transmission to a target organ or system. The alveoli is about 70m2 and is the region where the gas exchange vital for life occurs. It is extremely vulnerable to damage should any harmful chemicals reach it, either in gas or particulate form. Ingestion – a chemical will enter the digestive system – possibly in modified forms due to metabolisation in the skin or subsequently in the liver. It can then enter the blood stream and finally reach a target organ or system. Case studies show that this can result in allergic reactions such as dermatitis. Dermal – the chemical may cause direct local damage through denaturing of skin cells (corrosion, irritation), systemic effects through absorption into the skin and initiating a response from the immune system (allergy) or penetration and causing or contributing to damage to internal organs or systems. There is potential for metabolisation in the skin causing either an increase or decrease in toxic properties.

Risk assessment is task based

When considering the risks to health from the presence and use of chemicals in a workplace the risk assessment forms the basis on which decisions will be made regarding the need to eliminate or adequately control any exposure of the person to these.

A simple definition of what constitutes a risk assessment is:

“A risk assessment is nothing more than a careful examination of what, in your work, could cause harm to people, so that you can weigh up whether you have taken enough precautions or should do more to prevent harm.” – European Agency for Safety & Health at Work.