Frequently Asked Questions

Questions that are commonly asked at community meetings or through our communications are listed below. In order to see the answer to any particular question please click on the banner with the question and the answer will open up below. 


In 1976, the Michigan Department of Health and Human Services (MDHHS) enrolled approximately 4,000 farmers, chemical workers, and others with PBB exposure risk to participate in the Michigan Long-Term PBB Study. The data collected as part of this study is now referred to as the Michigan PBB Registry. All original study participants and their children and grandchildren are eligible to be in the registry. In 2011, MDHHS was no longer able to maintain the registry and transferred it to Emory University.

If you or a parent/grandparent were a part of the original Michigan Long-term PBB Study conducted by the state, you might be a part of the original PBB Registry. To find out, please call us at: 1-888-892-0074. Individuals who want to stay in the PBB Registry must provide consent to transfer their PBB records from the Michigan Department of Health and Human Services (MDHHS) to Emory University. By transferring your health records to Emory University, you will receive up-to-date information on study findings and have opportunities to guide future research priorities. To get more information about how to transfer your records, please click here


If you or your parent/grandparent were a part of the original registry, you may join the registry by providing consent to transfer your PBB records from the Michigan Department of Health and Human Services (MDHHS) to Emory University. To get more information about how to transfer your records, please click here

The Emory Michigan PBB Registry team, along with local partners, are currently conducting PBB health research. Click here to learn more about our ongoing studies. If you are interested in participating, please fill out our Health Research Interest Form

Some of the health effects of the PBB exposure may take many years to develop and will only be found by continued research. The study findings can help you and your doctor decide if you need more frequent tests for certain conditions. Our research has also shown health effects among the sons and daughters of women who ate contaminated food. It is important to continue to study the health of these children as they grow up and have children who are now adults as well as their children, who may also have been affected by their parents' exposure to PBB. 

PBB Exposure

Due to the PBB contamination incident in 1973, people throughout Michigan were exposed to PBB by eating contaminated food. Because PBB stays in the body for a long time, the children of women who ate contaminated food may have been exposed in the womb and through breastfeeding.

You may have been exposed to PBB if you or your mother:

  • lived or worked on a farm in Michigan in 1973-1974;
  • Ate contaminated beef, pork, dairy products, chicken, or eggs during 1973-1974; or
  • Worked for the Michigan Chemical Company/Velsicol or lived near the plant.

To detect the level of PBB in the body, blood is drawn and analyzed. However, blood testing for PBB is not a routine test available at doctor’s offices and is not a standard laboratory procedure. The Emory PBB research laboratory analyzes blood for PBB with research participation. If you are interested in participating in PBB research, please complete the

Health Research Interest Form

Blood testing for PBB is not a routine test available at doctor’s offices and is not a standard laboratory procedure. The Michigan PBB Registry Team conducts research studies to investigate the health effects of PBB exposure, and as part of the research, participants’ blood is tested for PBB. If you are interested in participating in future research studies, please complete the Health Research Interest Form

PBB levels are reported in parts per billion (ppb). Among Michiganders that we have tested in recent years, the average blood level is 0.24 parts per billion. Although a part per billion is a very low concentration, it’s important to understand that our natural hormones exert their effects at similar low concentrations:

  • Estradiol, the primary form of estrogen, in reproductive-age women, is present in concentrations of 0.02-0.4 parts per billion.
  • Testosterone in adult men is present in concentrations of 2.4-9.5 parts per billion.

Recent PBB testing reflects the use of new analytical methods, which are able to detect a lower concentration of PBB than previous methods and is also more accurate.  In addition, there are several different forms of PBB. The Firemaster mixture was mostly PBB-153. Measurements from 1990 to the present are reported as the concentration of PBB-153 detected in the blood. Previous PBB measurements were based on different mixtures of PBB types and are not directly comparable to each other or to the PBB-153 measurements. Because of the advances in laboratory science, the most recent measurements are the most accurate.

Yes, gradually. On average, it takes about 15 years for half of the PBB in the body to be eliminated.  There is currently no medical treatment that will lower PBB levels in the human body.

We are currently conducting a weight loss study to determine whether weight loss, with the aid of a weight loss pill that reduces body fat, can increase the speed that PBB is eliminated from the body. Participants take a study pill (active ingredient or placebo), follow a low-fat diet, and exercise some over six months. PBB levels are assessed at the beginning and at the end of the study to determine whether PBB has been eliminated from the body.

For more information about the PBB weight loss study click here

Yes, PBB can be transferred from mother to child in the womb and through breastmilk. For more about these research findings please click here




Health Effects

PBB exposure has been associated with a variety of health outcomes including a higher risk of certain cancers (breast, lymphoma, and gastrointestinal) as well as thyroid problems. Adult daughters born to exposed women had higher levels of miscarriages while the sons reported more urinary and genital conditions.

Click here for an infographic of our health findings and click here for more information about all of our research findings

Yes, we have created a fact sheet for physicians about PBB and the associated health effects of PBB exposure. Click here to see the fact sheet.

In addition, we are currently working to develop an online Continuing Medical Education course for physicians to learn more about environmental exposures and endocrine disrupting hormones, using PBB as an example.


Participation in the PBB research study includes a blood draw and completion of a health questionnaire. If you are interested in participating, please fill out the Health Research Interest Form.

PBB community members have helped the research effort in multiple ways. For example, they have helped us find locations to host community meetings and research appointments. They have shared information regarding PBB community meetings with family, friends, and neighbors. They have contacted state and federal officials to advocate for support of the PBB research. To learn more, click here.

It typically takes up to a year after a blood draw to receive your PBB results. This is because the PBB analyses must be conducted in large batches of at least 100 samples. The calibration and set-up of the sophisticated instruments used to measure PBB takes several weeks. The laboratory must conduct this critical process for each batch of samples. However, due to COVID restrictions the laboratory is currently operating at a lower capacity due to the limitations on the number of staff allowed in the laboratory at one time. This will cause analyses to take longer than usual. 




Contaminated livestock were buried at two state-owned sites in Michigan, one in Kalkaska and another in Mio. Livestock were also buried on private land by some farmers. For the state-owned sites, the geology, hydrology, and typology of the site were evaluated prior to selection. In addition, groundwater observation wells were installed and monitored by the Michigan Department of Natural Resources for several decades. It is our understanding that the groundwater levels of PBB measured were low and below levels of concern. Click here for a journal article from 1978 that provides additional details. 

PBB tends to bind to the soil and stay put. PBB is lipophilic, meaning it dissolves much more easily in fats than in water. This means that PBBs are highly sorbed to soil surfaces and organic matter, persistent in soil, and less likely to move in water. However, PBB has been detected at low levels in groundwater near the Gratiot County Landfill, where they disposed of over 150,000 lbs of PBB.


Over 500 farms were quarantined across the state (click here for a map). While farms across the state were contaminated, some areas were more affected than others, including Newago, Mecosta, and Missauki counties. St. Louis, Michigan was also highly affected because the manufacturer of PBB disposed of it in local landfills, and many of the residents worked at the facility. In fact, most Michiganders living in the state during the early to mid-1970’s are likely to have consumed contaminated meat, eggs, and dairy products. In addition, our research has shown that children born to mothers with high levels of PBB were also exposed in the womb and through breastmilk.