No free lunch with phthalates on the menu

Americans love going out to eat. In fact, two-thirds of the U.S. population dine out daily, according to our new study. While many of us know that dining out establishments typically serve larger meals that contain more butter, salt, and oil than foods we might prepare at home, how many of us know that chemicals with the potential to harm reproductive health and child development (called phthalates, or “thal-ates”) are also on the menu – even in our school cafeterias?

Our study found that people who dine out at restaurants, cafeterias, and fast food outlets have higher levels of multiple endocrine disrupting phthalates in their bodies. On average, nearly 35% higher than people who eat only at home.

This is especially of concern for pregnant women, young kids and teenagers, who are more sensitive to endocrine disrupting chemicals, which can interfere with hormone action during various stages of development. While phthalates are associated with many health impacts across a lifetime, including infertility, preterm birth, neurodevelopmental problems, obesity, diabetes, and cancer, the National Academy of Sciences (NAS) recently identified certain phthalates as presumed human reproductive hazards, and previously acknowledged their ability to collectively increase risk of genital malformations and other reproductive tract abnormalities in baby boys.

To reflect this reality in our new study, we assessed multiple phthalates in combination by accounting for some being more toxic than others, which is reflective of modern-day exposures and associated health risks.

We found that children 6-11 years old had the highest overall cumulative phthalate levels. Teenagers who consumed the highest percent of their total calories from dining out at restaurants, cafeterias, or fast food outlets had up to 55% higher phthalate levels than teens who strictly ate food from home (which was most likely purchased from the grocery store).

JV Figure 1

Phthalates are used widely in everyday consumer and personal care products, ranging from perfume to vinyl flooring, and some are restricted in children’s toys. However, most of our phthalate body burden comes from food. Phthalates are not intentional food ingredients but instead contaminate food products by migrating from various food contact materials along the food production supply chain (e.g. from conveyer belts, industrial tubing, food handling gloves, takeout food containers, and other food packaging materials).

While we knew that phthalate sources include fast food and many household food products, such as meat/poultry, dairy products, olive oil, and even spices, we didn’t know whether other dining out sources may contribute to phthalate levels or how dining out compares to eating at home. Our study found that full-service restaurants and cafeterias are probable sources of phthalates exposure and that dining out is associated with higher phthalate levels than consuming food from the grocery store.

Cafeteria sources of phthalates exposure are particularly relevant for children and adolescents, many of whom depend on the National School Lunch Program as a vital source of nutrition. The program provides 30 million school lunches daily across 95% of U.S. public and private schools.

Fast food, restaurant, and cafeteria food appear to contribute about equally to teen’s phthalate levels. The cafeteria food contribution was relatively low in children (15% compared to ≥ 45% in adolescents), despite more children consuming cafeteria meals than teenagers or adults. Different lunch options and food choices may partially explain this discrepancy; teenagers are typically served and often choose  lower quality foods than younger kids in the lunch room, which may increase phthalate levels.

JV Figure 2

Our study suggests that other sources besides dining out contribute to high phthalate levels in children, but our findings also show that school lunches may provide unique opportunities to reduce exposure in children and teens.

As a scientist, I know we need more research. As a mother of a two year old son, I want to act on what we do know. Phthalates have no place (or purpose) in our school cafeterias. Many schools are outsourcing meal preparations off-site, where fresh ingredients undergo processing into less healthy alternatives, which may increase school lunch contamination. Overly processed deep-fried meals can be modified to include healthier, fresh ingredients.

Ultimately, adequate, nutritious meals are the most important factors in healthy development. Other benefits include healthier diet preferences, reduced risk of obesity, and improved test scores. While our findings are not a reason for kids to avoid the school cafeteria – they are a reason for policy makers, food service providers, and others to take action and eliminate phthalates from school lunches.

Many phthalates are already banned from children’s toys; why are we serving them to kids at lunch?

My co-authors on this study were: Rachel Morello-Frosch at the University of California, Berkeley, School of Public Health, Tracey Woodruff, Director of the Program on Reproductive Health and the Environment (PRHE) at the University of California, San Francisco, and Ami Zota at George Washington University, Milken School of Public Health.

PRHE’s Toxic Matters brochure provides practical tips on how to reduce potentially harmful chemical exposures in everyday life.

1+1>2: Evaluating how risks of pollutants and stressors stack up

Constant exposure to environmental pollutants can sicken our bodies, and social stressors such as poverty and psychological burden can further aggravate the health effects. For example, traffic-related air pollution has been linked to the onset of childhood asthma. However, if children exposed to air pollutants also experience violence, their risks of developing asthma can be doubled or tripled. Researchers and Scientists consider ‘cumulative risks’ (details here) as the elevated risks from the combined effects of multiple environmental and social stressors or agents, in this case air pollution and exposure to violence.

Understanding cumulative risk is important because we know very little about how synergistic interactions of multiple chemical exposures and social factors can increase risk of severe diseases, even though we are exposed to numerous chemicals via air, water, soil and consumer products on a daily basis. Until recently, a systematic-review of human and animal evidence confirmed the cumulative adverse effects of prenatal-exposure to chemicals and psychosocial stress on fetal growth. Individuals and different health organizations can take more effective actions to address such health issues once we can gain better knowledge relevant to cumulative risks.

The number of cumulative risk and impact studies increased tremendously over the past decade, but the relevant modeling methods have been underdeveloped to evaluate the joint exposures. Proper selection and use of statistical modeling techniques will generate accurate scientific results, which will contribute to sound environmental and public health policies.

To summarize modeling methods utilized to quantify the cumulative effects of multiple stressors in previous studies, we performed the first ever review on statistical models used to evaluate cumulative risks. I conducted a systematic search to identify original peer-reviewed research articles published between Jan 1, 2012- June 21, 2017 that evaluated both environmental and social stressors, and analyzed their health effects. We focused on human subject studies that provided quantitative method information. Eventually, we identified 31 eligible articles– the majority used simple regression models and focused on air pollutants and socio-economic status (SES) with various health outcomes, as shown in the table below.

Chemical Stressors Measured Social Stressors Measured Health Effects Studied
Air pollutants, drinking water pollutants, climate indicators, metals, silica, BPA SES, race, neighborhood features, psychological factors, physical disorder, material hardship, education, employment, housing, urbanization, neighborhood features, access to health services, health prevention program, violent crime Mortality, morbidity, nutritional status, IQ, cancer risk, child behavior, heart defects, blood lead level, blood pressure, respiratory disease, autoimmune disease, diabetes hospitalization, pregnancy outcomes

We found that simple regression models, including multivariable and logistic regression models, are commonly used in cumulative risk studies, especially evaluating the combined effects of both chemical and non-chemical stressors. However, we wondered whether regression methods can properly cover all the combinations of different possible research settings such as research questions, study designs and data. Unfortunately, no. We found that regression methods, similar to other modeling techniques, has its own advantages and limitations (details here), and concluded that no single modeling technique can be applied universally to all cumulative risk studies.

With increasing knowledge in exposure science and the advent of more quantitative tools in the era of ‘big data’, we recommend that other data mining and machine learning techniques such as deep learning be considered in cumulative risk research, particularly when it comes to understanding the combined risks of multiple stressors. To provide public health protection for vulnerable populations such as pregnant women and children, risk assessment can take advantage of the established modeling methods while more approaches are being developed. Other authors on the study include Drs. Aolin Wang, Rachel Morello-Frosch (UC Berkeley), Juleen Lam, Marina Sirota, Amy Padula and Tracey Woodruff.