Focusing on children of farmworkers in the Salinas Valley, the group has found links between prenatal pesticide exposure and lower IQ or attention disorders. The group’s latest research centers on the health effects of flame retardants – chemicals permeating furniture, pajamas and other materials – found in Latino children.
The 15-year study began enrolling a group of pregnant women in 1999, and has followed their children, who are now 10. The researchers currently have enough funding to monitor the children to age 12, and they hope to continue through their high school years.
New America Media editor Ngoc Nguyen spoke with study coauthor Asa Bradman, associate director of the research center. Following are excerpts of this interview.
Ngoc Nguyen: Why are studies on children’s environmental health important?
Asa Bradman: Children's unique vulnerability to toxins falls at a few different levels: One, kids tend to be exposed more than adults in the same environment because they breathe more per unit of body weight, they eat more, they drink more. They also spend a lot of time on the floor, and they get dust and stuff on their hands and they put their hands in their mouths. So they just have higher exposures.
They are also developmentally changing, and if they get exposed to something that can affect neurodevelopment at a critical period, it can shift it off track. Something that is a neurotoxin like lead can interfere with what I like to call the neural architecture. [In children] that neural architecture has been changed, whereas in an adult that exposure is much less likely to have an effect.
Tell us a little about your long-term studies tracking children’s health.
Bradman: Children are more vulnerable at many levels and that understanding led to the development of this program to fund centers for children's environmental health research throughout the country. We’re one of the few funded for a full 15 years.
We wanted to focus on environmental exposure in children’s development, and the best approach to do that is to look at early exposures, starting with pregnancy and following the children over time.
In some ways, our project is also a model for a much larger national study, which is hopefully going to get of the ground and be a long-term study of 100,000 children prenatally through adulthood.
After a decade of studying the children in the Salinas Valley, what have you learned about how their health is affected by their surroundings?
Bradman: Our priority area was to look at pesticides, and we're definitely finding relationships between those early exposures and later development in the children. And, we're finding lower IQ and things like that at least at 7 years, associated with early exposures. We also know that social factors are very important. Housing quality is very poor in this population.
Pesticides are a priority research area for CERCH. What was your interest in studying flame retardant exposures in children?
Bradman: The flame retardant study came out of a particular interest in California, because there's something here called Technical Bulletin 117, which is a rule in the [California] Bureau of Furnishings that requires very specific flame retardant standard. [It] requires certain kinds of furniture to resist 12 second of open flame before igniting, like polyurethane foam.
The furniture industry has tended to use a chemical approach to meet that standard and that's why we have such high flame retardant exposures in California. There's a sense out there that there are alternatives to the use of chemicals to achieve the goals of fire safety.
There are some alternatives in terms of different kinds of fabrics, and there's also an interest in establishing a smolder standard. A lot of fires that kill people start from people smoking. There was a law [passed a few years ago] that required the cigarette industry to market cigarettes that will go out if they are not getting puffed on. That has substantially reduced the incidence of fire-related injury and death.
Certainly, from an exposure point of view, the laws in California and the way they have been met have resulted in much higher exposures to California kids and Californians in general compared to others in the country and others around the world.
Your research is the largest study of flame-retardant exposures in California children, but it’s also the first binational study of these chemicals in Latino children and Mexican children. What did you find?
Bradman: Our main study looked at participants in the Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS) -- and children in Mexico. Children in Salinas had levels in their blood that were seven times higher than the children in Mexico.
We actually went back to the regions in Mexico where the parents of the CHAMACOS children originally were from, so it would be approximately similar. So the [level of flame retardants] in Mexican-American kids were higher than the kids in Mexico by about seven and they were about three times higher than their mothers'.
We also did a study looking at levels of PBDE’s [and other] flame retardants [found] in dust. In Oakland and Salinas we found very high levels and they were generally much higher than in other studies in the U.S., and around the world.
That’s striking given that Oakland is an urban setting, and Salinas is more rural. What do these places have in common?
One, they are in California, and that’s the biggest factor. California has these flammability rules that have primarily been met by these chemicals. We [also] looked at low income neighborhoods [where] people have older furniture. It’s more likely to break down and may not be in good shape.
What about the impact of housing conditions, including poor ventilation, on flame retardant exposures?
Bradman: I do think that’s important -- definitely, separate from the flame retardant issue. There’s very poor housing quality in this population in Salinas. They have poorer parks where they don’t have a safe place to play. They tend to have higher levels. And it may be that in neighborhoods where parents don’t feel it’s safe to let their kids outside or be in the park, they are spending more time inside and therefore having more exposures.
Is newer furniture safer? What can people do to minimize exposure?
Bradman: I can’t make that recommendation, because a lot of people can’t afford to go out and buy new furniture. It seems that house dust is an important pathway of exposure, so minimizing dust in your house, vacuuming with a HEPA-filter vacuum cleaner. Make sure the furniture you have is well encased if it has foam in it. If it’s deteriorating, that’s when you should be concerned and replace it.
[The Green Science Policy Institute] suggests choosing furniture that has polyester filling or kinds of filling other than foam, which often don’t use a chemical flame retardant, or meet the flame standard by encasing rather than by chemicals.
So if you’re purchasing furniture, you can make some choices for nonchemical approaches. There are basic hygiene type things that would probably reduce exposure. For many people, especially low-income communities, that’s not so easy. For example, in Salinas, there are crowded households, multiple families living in a single home, so those suggestions are not that practical.
What explains the higher levels of the chemicals in Mexican-American children compared to those in Mexico?
Bradman: In Mexico, there’s just lower use of these materials. As you can see it translates into less exposure. There are probably other kids in the world that have very high exposures that haven’t been tested. For example, a lot of electronics are sent to the Philippines and China for “recycling,” and often it’s very low-income people who are doing that. So I’m sure there are other groups with high exposure. In California, you’re talking about a general population exposure, you’re not talking about a specific high-risk group.
What are the health effects of exposure to flame retardants?
Bradman: We found lower levels of thyroid-stimulating hormones (TSH) among women who were pregnant and have higher levels.
There’s a pretty strong inverse relationship: Those with the highest PBDE exposures have the lowest TSH levels, which would be associated with hyperthyroidism. That’s consistent with some of the theories about PBDEs being similar and potentially affecting the endocrine, the thyroid system. We haven’t found a relationship in early childhood thyroid levels, [but we] found that women who had higher PDBE levels, took longer to get pregnant.
What about health effects in children?
Bradman: So far the study by Julie Herpsman [at Columbia University] is the only one looking at early exposures in children. They looked [at people for] up to 72 months and found significant associations for psychomotor development [and other effects]. They also found some things at older ages as well. The next step is to see if these results are confirmed in other studies.
Proposed legislation (SB 147) on flame retardants sponsored by Sen. Mark Leno failed in a Senate committee vote last week, but the debate on flame-retardant exposure continues. What’s your take on this?
Bradman: If you are going to look at the issue of chemical exposures and safety, a good analogy is to pesticides. In California, there’s a push to take reduced-risk approaches (i.e. integrative pest management).
Try not to get bogged down with what is safe and unsafe with flame retardants, there’s an analogy there. If there are different ways of achieving fire safety without using chemicals, that’s an approach that should be promoted.