Biomonitoring

Biomonitoring is the measurement of chemicals in a person's body in order to understand the combined chemical burden carried by the body from sources such as air, dust, food, and soil.

Biomonitoring is the scientific measurement of chemicals in a person's body to assess exposure to a various natural and synthetic chemicals. The idea behind biomonitoring is that chemicals enter the body and leave markers or trace elements behind. By analyzing these traces, scientists can better understand the chemicals to which people are exposed.

Biomonitoring is different from toxicity tests because it only tells researchers that a person has been exposed to a particular chemical but not how much the person is exposed to on a daily basis or where the exposure came from (e.g., the air, dust, food, soil). Additionally, whereas toxicity tests assess adverse effects, biomonitoring does not. Just because a person has been exposed to a certain chemical does not mean that it is a health threat. The advantage of biomonitoring is that it measures total exposure from all sources. It also gives researchers a solid measurement of level of individual exposure, not just an estimate of which chemicals or their concentration from a particular source Therefore, biomonitoring gives researchers information that can lead to the discovery of trends and possibilities for the direction of future research and remediation to exposure.

Biomonitoring is not limited to humans. Aquatic biomonitoring is quite common throughout the world. Samples are taken from both water sources and the organisms that live there. Biomonitoring can also be done on animals and plants. These versions of environmental biomonitoring give researchers insight into the types and levels of chemicals to which organisms and resources in the environment are exposed.

Although there is a record of biomonitoring taking place as far back as the early nineteenth century, principals of biomonitoring were not applied in a widespread and systematic way until the late 1800s in Europe. At this time, there was a large group of well-trained scientists with the basic technology needed to measure chemical levels within the human body. Over time, technological advances and a greater interest in the field of biomonitoring has significantly increased the number of chemicals analyzed and the number of biomonitoring studies taking place around the world.

The National Biomonitoring Program of the Centers for Disease Control and Prevention continues to increase the size and scope of its research. As of 2012, the program measured more than 450 environmental chemicals and nutritional indicators in humans. It also cooperates with a large number of American governmental agencies, universities, state and local health departments, and both community and international organizations. The National Children's Study is the largest national study of the effects of the environment in child and adult health ever planned in the United States. The study will follow 100,000 children from before birth to age 21. A pilot study, known as the Vanguard Study, began in the summer of 2009 and took place in 40 study locations. The goal of the Vanguard Study was to evaluate the acceptability, cost, feasibility, and recruitment strategies that will be later used in the National Children's Study.

As scientific methods and technology improve and the importance of chemicals in the environment and their impact on human health is better understood, the number and size of biomonitoring programs continue to grow. Organizations throughout the world work together to better understand the trends discovered through biomonitoring programs and what these results mean for human health.

The purpose of biomonitoring is to better understand the number and level of chemicals that get into the human body from various sources, such as air, dust, food, and soil. Results from biomonitoring allow researchers to do the following:

The purpose of human biomonitoring programs is similar to the goals of environmental biomonitoring of animals, plants, and water sources.

Biomonitoring starts when researchers choose the group of subjects they are going to test. For the most accurate results, subjects must vary regarding geographical location, age, sex, ethnic identity, and state of health. The larger the sample size, the more likely a greater variety of people will be chosen, and the samples analyzed will reflect a picture of the general population.

Once the people are selected, samples must be taken. The most common substances used are blood and urine; however, bone, breast milk, expelled air, fat, hair, meconium (the first feces of a newborn), nails, saliva, semen, and other tissues may also be collected and analyzed for the presence of certain chemicals.

Collected samples are then analyzed for the presence or absence of a selection of chemicals. The National Biomonitoring Program can analyze samples for 450 environmental chemicals and nutritional indicators, from acetochlor to xylenes. Depending on the goal of the biomonitoring study, the samples may be analyzed for the presence of many fewer chemicals. The results are then recorded, analyzed, and interrupted to determine trends, develop reference ranges for physicians and scientists, assess the success of current public health efforts, and set priorities for future research.

Biomonitoring done on animals, plants, and water sources follow similar procedures to biomonitoring done on humans. The types of samples collected may be different (such as water samples from a water source) and the chemicals analyzed may vary.

Results from biomonitoring studies tell if chemicals are present in people at high enough levels to be detected and the relative levels of these chemicals. These results can be used to develop future research, set reference ranges, as a basis for the development of legislation, and to assess the effectiveness of public health programs, such as the campaign to reduce exposure to secondhand smoke. Trends can also suggest researchers where exposure may come from, if, for example, people who live in a city have higher levels of a certain chemical than people who live in rural areas.

Biomonitoring in an occupational setting can determine if workers are being exposed to higher than acceptable levels of certain chemicals. This can lead to changes in health and safety measures used in the workplace in order to better protect the health of workers. Overall, the results from biomonitoring programs can be used in a number of ways, depending on the goal of the program and the data collected.

Biomonitoring is expensive and resource intensive. For this reason, it is not always possible to use as large a sample as wished for by researchers. Small sample groups may affect results because samples from one particular area or age group may give different results from samples from a wide range of people from various locations. Additionally, biomonitoring studies can only be done at a few times, making it impossible for researchers to determine how often, how long, and how much chemical exposure people experience on a daily basis. This is different from typical toxicity studies, which focus on the relationship between the negative effects of a daily dose of a certain chemical. This also means that in biomonitoring research, any amount of chemical in a person's body cannot be directly linked to causing adverse effects.

Tish Davidson, AM