Frequently Asked Questions

What is "Biomonitoring"? 

 Biomonitoring is a scientific technique to assess a person's exposure to and uptake (absorption into the body) of chemicals by taking samples of their blood, urine, breast milk, fat, hair or other tissues and analysing them for the chemical(s), their metabolites (break down products) or other markers.

What can Biomonitoring tell us?

It can tell us what kinds of chemicals people have been exposed to and to what extent. For example, it may be able to determine who has been exposed to a chemical after a chemical spill or accident, so we can build a picture of the extent of exposure.

Biomonitoring can be used to determine the "background" or normal level of a chemical in the general population. In this way, results from individuals can be placed in context and those with higher or lower than "average" levels can be identified. Biomonitoring can also be used to reveal trends in exposure within a population to see if exposure is changing over time and to identify variability between locations i.e. geographical differences in exposure. This is particularly useful if we want to find out whether laws put in place to control exposure to toxic chemicals are working.

What chemicals are being looked for?

In readiness for responding to chemical incidents in the future, the HPA has developed guidance for the use of human biomonitoring, where appropriate, to measure exposure to and uptake of some of the most common substances involved in chemicals incidents as well as a number of other chemicals of interest. Many of these chemicals have the potential to harm health. The chemicals were selected due to their involvement in incidents, rather than their suitability for being detected by biomonitoring analysis. Therefore, for some chemicals there is no reliable way to measure them in human samples and this is stated in the protocols.

For studies of background exposure, chemicals such as metals, organochlorines and phyto- and xeno-oestrogens are being measured as part of a study being carried out at the MTC (Medical Toxicology Centre - a collaboration between HPA and the University of Newcastle) called the "Reference Range Study".

Investigations of exposure and uptake of certain chemicals following chronic exposure are also planned.

From whom will samples be collected following an incident?

If biomonitoring is considered appropriate and feasible following a chemical incident, samples will be collected from people directly involved in the incident or people living near the site of the incident. Health Protection Units (HPUs), A&E hospitals and incident management centres will be supplied with sample collection kits and guidance on what samples to collect (blood, urine, saliva etc) and how to collect them following an incident.

What kind of samples will be taken from people and why?

In most instances, blood and possibly urine samples will be taken, as these can be related to exposure and uptake more easily. Hair is easy to collect, but is also more easily contaminated and is more difficult to analyse accurately. For some chemicals hair analysis is not well validated with respect to effects on health. For example, neurological effects of lead (Pb) are well correlated with blood lead levels, but not levels in hair.

Why is this being done?

The HPA is involved in human biomonitoring to better understand the background levels of chemicals in the general population and also as a possible tool in measuring exposure and uptake following chemical incidents. Research in this area could also be helpful in other ways, for example in refining estimates of exposure in epidemiology studies.

What does the presence of a chemical in a person's urine/blood/hair/breast milk mean for their health?

For most chemicals, it is not yet possible to predict what a level measured in a person's body actually means for their health. This is currently one of the major limitations of biomonitoring. Our ability to detect chemicals and their metabolites is now so advanced that extremely small amounts can be detected in human samples. These may be detectable in most of the population but do not by themselves indicate that any adverse health effects would be expected. Only for relatively few substances (such as lead, mercury and cadmium) is there reliable enough information on the health effects at certain levels of exposure for health risks to be predicted following a chemical incident.

What is a "normal" level of exposure? Is it possible to put an individual's results into context to see if they are higher or lower than "average"?

At the moment, this is difficult to answer. Without a good background set of data on levels of chemical exposure and uptake it is not possible to say accurately whether a person's results are low, high or about average for the population. This is a major reason why reference range biomonitoring studies  are being carried out - to establish the range (lowest to highest) of exposure in a population. When there is more information available for background levels of chemicals it will be possible to put individual results into context.

Can biomonitoring be used to estimate the risk of developing cancer due to chemical exposure?

Biomonitoring can provide information on whether a person has been exposed to and absorbed a chemical that is believed to cause cancer. However it is usually not possible to estimate quantitatively what level of risk this poses. This is because with chemical carcinogens we rarely have reliable information on how dose relates to health impacts at low dose levels (such as those experienced by the general public, through their environment) to enable accurate predictions of cancer risk to be made. There is also a long period, 20-30 years in most cases, between exposure to chemical carcinogens and the possible onset of cancer. This makes it difficult to interpret the significance of biomonitoring data with regard to cancer. Repeated exposure is usually required for chemicals to induce carcinogenic effects and the risk from a single exposure, if any, is likely to be very small.
It is also worth remembering that although certain chemicals are known to increase a person's risk of cancer, a person's lifestyle is very important. Not smoking, eating healthily (with plenty of fruit and vegetables), drinking alcohol in moderation, exercising regularly and maintaining a healthy weight are the best ways to reduce the risk of cancer.

If I have provided samples following an incident can I find out what I have been exposed to and to what extent?

This will depend on who has requested the sample
i) If the sample was requested by your GP, or you have consulted your GP.  You would be able to discuss the interpretation of your results with your GP. 
ii) If the sample was requested as part of a population survey; when you are asked to give a sample you will be informed whether you can obtain your own results or if the results will be reported as population averages.  These aspects will be explained to you when you consent to give a sample. 

 

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Last reviewed: 15 July 2011