What's your poison?

Toxicology is the study of poisons; although a more modern definition, and one that does not raise too many worried looks, is the study of how chemicals can cause harm.

Toxicologists will be knowledgeable about the likely symptoms that may be expected as a result of exposure to a given chemical. For example, if a worker develops allergic contact dermatitis and had been working with formaldehyde, the toxicologist would be able to link the symptoms, such as an allergic response, to the exposure, in this case formaldehyde. However, toxicologists will be unable to provide a medical diagnosis, unless medically trained. This is an important point and one that is commonly misunderstood by the legal profession.

For an individual to be at risk of harm or injury occurring, they have to come into contact with the chemical (known as exposure). Where there is no exposure, there is no risk of injury. Also, chemicals are specific and generally predictable in the way in which they can cause harm. For example, alcohol is a known liver and mouth or throat carcinogen and does not cause malignant melanomas.

As a toxicologist expert witness, I have been approached on several occasions by solicitors and barristers to give an opinion on their case. Typically, the conversation goes along the lines of: 'I have a client who was exposed to chemical X and has the following symptoms. Can you confirm whether or not this is as a result of her exposure to X in the workplace?' It would be nice if this was an easy question to answer, but it generally isn't for some of the following reasons:

1. A long latency period between exposure and the onset of the symptoms. A classic example of this is with the development of cancer. These types of cases are complicated simply by the fact that it may have been years since the actual exposure occurred. During which time the claimant may have been exposed to other chemical carcinogens both in the workplace and elsewhere.

2. Lifestyle factors, such as drinking, smoking, or using chemicals for DIY, can contribute to ill health, which may in turn be attributed to chemical exposure in the workplace. For example, consider the scenario where a man in his late fifties is diagnosed with oral cancer. He believes that it is as a result of his occupational exposure to polycyclic aromatic hydrocarbons (PAH), over 20 years ago, and puts in a claim against the company. However, medical case notes reveal that the man is a heavy drinker and smoker, both of which could also have been contributing factors in the development of the malignancy, and need to be taken into consideration.

3. Early signs and symptoms arising from chemical exposure can be similar to symptoms of stress and anxiety, and without additional information it can often be very difficult to differentiate between the two. In order to establish a potential link between exposure and the presenting symptoms, it is important to get an overall picture of the individual in question. This can include gaining access to any relevant medical records and work history.

Hospital and GP medical notes

Medical records can help build an overall picture of the individual, and can also help to contextualise the reported symptoms. For example, a client whose symptoms can be eloquently explained by both stress and chemical exposure may demonstrate long-term history of identical symptoms prior to the alleged exposure. Such things may be of importance and should therefore be relayed to the instructing solicitor for follow up with a medical expert.

One thing I have noticed during my time working as an expert witness is that any hospital notes have to be treated with great care. This is because the reported symptoms, such as 'terrible headache and weakness in legs', may be misinterpreted as a diagnosis, when in fact it is simply a recording of the reported symptoms.

Therefore, it is useful to have access to the full medical records and where available nursing records can help clarify what are the symptoms reported by the patient and what are objective medical findings.

Health surveillance records and work history

Health surveillance records where available will provide occupational health monitoring details. This can provide details of early warning signs of potential problems. For example, in a flour mill environment, the occupational health adviser may wish to implement lung function tests at the beginning of employment and continue at prescribed intervals throughout the duration of employment. The objective being to identify any deterioration in lung function at an early enough stage before the onset disease. If the person in question had developed asthma and wished to pursue a claim against the company, these records would be invaluable in providing evidence of any health trends leading up to the time of the claim.

This could then be used together with other information to put together a picture of whether or not the onset of asthma was due to exposure to flour dust rather than something else that was completely unrelated. In addition, the claimant's work history can also help contextualise the reported symptoms.

The best kind of relationship between a solicitor and an expert witness is one of openness and neutrality. Understandably, it is easy for an instructing solicitor to seek only an expert opinion that supports their client's case. I have had solicitors call me with the wish to instruct me only if I would support their claim, which is impossible for me to do without having first examined the case notes from an impartial viewpoint. During the case review issues may be identified that need to be addressed perhaps by another expert; or additional information required before an opinion can be given.

I have found that instructing solicitors are always grateful for any advice and guidance on the kind of information that would be required to help me assist them with their case.