This article was written by Erica Weiss, a UMass Amherst undergraduate student in Prof. Mary Carey's Journalism 300 course. In an effort to promote interdisciplinary collaboration with the variety of academic departments at the University, the Center for Research on Families frequently invites students to campus lectures and other events—to participate, reflect and write about their experience. In the spirit of this collaboration, we are pleased to share this feature written in response to one of our recent Tay Gavin Erickson lectures.
Biomonitoring and the data in the National Health and Nutrition Examination Survey (NHANES) can help identify potentially dangerous chemicals that the American public should be concerned about regulating.
This was the one of the many “take home messages” of a lecture given by Dr. Antonia M. Calafat, Chief of the Organic Analytical Toxicology Branch at the Division of Laboratory Sciences, National Center for Environmental Health of the U.S. Centers for Disease Control and Prevention (CDC). The presentation, entitled “Biomonitoring, Chemical Exposures and Human Health,” was sponsored by the University of Massachusetts Amherst's Center for Research on Families. It was held on Thursday, February 5 in the UMass Campus Center conference room 162, with approximately 50 people in attendance.
Calafat mainly discussed the use of “biomonitoring” in the CDC in order to determine the concentration of “plasticizers,” or “additives that increase the plasticity or fluidity of a material," as defined by Wikipedia, in human samples. She also focused on the use of NHANES to analyze biomonitioring data and find patterns in which chemicals were appearing and disappearing from the public. The most common plasticizers she notices in her analyses are “phthalates.”
Biomonitoring, as Calafat described, is the assessment of an internal dose of a chemical by measuring for it in a human sample, either urine or blood. When testing a human sample, a scientist looks for “biomarkers,” or different metabolites of certain chemicals that could pose a threat to a human. In order to properly search for these biomarkers, scientists need selective and sensitive instruments, clean rooms, well-trained staff members and a big budget. "It is expensive. It's not cheap, because it requires a lot of stuff," said Calafat.
Calafat explained that it is important to choose a good biomarker to measure in a biomonitoring test because people can still be infected with a chemical and not have all of the metabolites traceable in their system, even with strong technology. For example, in a study she did on the plasticizer diisononyl phthalate (DINP), Calafat observed that over 82% of the people with non-detectable amounts of the minor metabolite had detectable amounts of the major metabolite of DINP. Therefore, the impact of the chemical could be underestimated if scientists would analyze the minor metabolite as a biomarker.
Once proper biomarkers are identified, Calafat identified that the next step to evaluate human exposure to these chemicals is to use large surveys, such as NHANES, which she calls “a magnificent survey, in my opinion." NHANES, according to Wikipedia, is a Congress funded report that became annual in 1999. Through interview and physical examinations, the survey assesses the health and nutritional status of American adults and children. Calafat noted that the process of biomonitoring is important to the creation of NHANES because “we have limited amount of blood … and the collection of the urine … starts at participants six years of age.” Biomonitoring is capable of analyzing a lot of chemicals with only the “leftovers” of human specimens.
Although NHANES does collect data on widespread chemical exposures and is able to compare them based on age, race, sex, and socioeconomic status, Calafat notes that there are things that NHANES cannot do, such as interpret the data or provide health outcome analyses. “The presence of a chemical in the body does not mean it causes disease,” said Calafat.
Regardless, NHANES is usually used by the CDC to aid in risk assessment of different chemicals such as triclosan, a pesticide. In fact, the NHANES 2003-2004 data of urine samples containing triclosan was used to help the Environmental Protection Agency (EPA) make a triclosan regulation decision in 2008. NHANES is also used to monitor time trends of human exposure to different chemicals, such as perfluorooctane sulfonate (PFOS), a key ingredient formerly in 3M’s Scotchgard. Since NHANES’ inception in 1999, Calafat reported that the concentrations of PFOS in the United States have gone down by 68%.
“You stop the source, you stop exposure,” Calafat said of how chemical levels reduce in the NHANES data. However, she also notes that when “you take a compound out, another one is going to come in and take its place.” An example she provided is that diisobutyl phthalate (DiBP) levels increased as dibutyl phthalate (DBP) levels decreased after its banning in the early 2000’s. DiBP and DBP are just some of the many phthalates that Americans encounter on a daily basis.
Phthalates, a common plasticizer group, are commonly in a wide range of products that Americans use everyday, such as sunscreens, lotions, soaps, toys, electronics, furniture and flooring, according to Alternative Medicine Review. Phthalates are particularly something Americans should be concerned about, Calafat explained, because exposure to these chemicals could cause a number of developmental problems for young children.
For example, a study done at the Calafat Laboratory gave women a score based on how many phthalates were in their urine, then later measured the distance between the anus and genitals of their infant sons. Calafat and her partners found that, “the higher the score, the shorter the anogenital distance so the boys became more feminine, so to speak.”
While the CDC is not in charge of making policies for the public heath and safety of Americans, Calafat explained that the studies she completes can help legislators make the best possible decisions for their lives and the lives of their constituents.
“We try to provide the best science with which we can inform the public,” Calafat said of the CDC. She also noted that another of the CDC’s goals is to inform government officials as well so that public policy can be made.
This was the point that ended the presentation, which sent attendees to the front of the room to thank Calafat and UMass faculty member Katherine Reeves, a professor in the public health department who is currently working on a research grant to study the exposure of Americans to BPA, a common phthalate. She was the one who selected Calafat to give this lecture because it coincided with her current research. Also, in her words, “she’s the gold standard, truly an expert in her field.”
It seemed that the information provided at this lecture gave some of the attendees surprising revelations about the state of the chemicals in the environment and how data is collected on them. “I was not aware that studies on the youngest children are really unreported,” commented UMass journalism student Matt Zabik. Another UMass journalism student, Luis Fieldman, also noted that he was unaware that “inactive chemicals can still come up in people’s blood” when they are only in the coating of certain medications.