Passive exposure to flame retardant chemicals in preschool children

Relation

S. Lipscomb, M.M. McClelland, M. MacDonald et al. Cross-sectional study of preschool children's social behavior and exposure to flame retardants.Environmental health. 2017;16(1):23.

Objective

To assess associations between exposure to flame retardants and differences in social behavior in children aged 3 to 5 years.

Draft

Cross-sectional observational study

Participant

From October 2012 to January 2013, 92 children between the ages of 3 and 5 years were recruited from 28 preschool classrooms in 2 geographic areas of Oregon. Each child was given a passive silicone sampler to wear continuously on their wrists or ankles for 7 days to detect exposure to flame retardant chemicals. Of the 92 participants, 77 returned the silicone bracelets; Of the 77 who returned the bracelets, 5 were excluded due to a significant deviation from the protocol (bracelet was never worn by the child, was lost at school for several days, or went through the laundry) and 3 chose not to answer questions on the sociodemographic questionnaire, leaving a final sample size of 69 children eligible for analysis.

Study parameters assessed

The returned bracelets were removed and analyzed for 41 different flame retardant compounds using gas chromatography-mass spectrophotometry. Children's parents completed a series of structured questionnaires to capture sociodemographic information (e.g., household income, parental education, race) and home learning environment. The questionnaires allowed researchers to control (in statistical analysis) for key psychosocial stressors that negatively influence behavior. The children's preschool teachers completed the Social Skills Improvement Systems Rating Scale (SISS-RS)—a standardized assessment of social skills and problem behaviors that has strong psychometric properties and measures both normative and clinically relevant variation.

Target parameters

The primary outcomes were the prevalence of positive social behaviors (cooperation, assertiveness, and self-control) and negative or externalizing social behaviors (hyperactivity, inattention, aggression, and oppositional behavior) among children with varying levels of exposure to brominated diphenyl ethers (BDE). and organophosphate-based flame retardants (OPFR).

Using a HEPA air filter, wet wiping fabrics and electronics, and regularly cleaning air ducts to reduce exposure of house dust to flame retardant sources can reduce available contaminated dust in the environment.

Concentrations of flame retardants were summed before natural log transformation to total BDE and OPFR exposure. Separate generalized additive models were used to assess the relationship between 7 subscales of the SISS and total BDE or total OPFR, adjusting for age, gender, adverse social experiences, and family context.

Key insights

All children in the study were exposed to a mixture of flame-retardant compounds. Researchers observed a dose-dependent relationship between total OPFR and 2 subscales, with children with higher exposures being rated by their preschool teachers as exhibiting less responsible behavior. In addition, children with higher overall BDE levels were rated by teachers as less assertive.

Practice implications

Does exposure to flame retardants affect children's behavior? The evidence is inconclusive. Although researchers were able to find a statistically significant correlation between less responsible and less assertive behavior and exposure to OPFRs and BDEs, respectively, they were unable to demonstrate a significant correlation between exposure to flame retardants and hyperactivity, aggression, cooperation, self-control, or oppositional behavior. Additional research is needed to examine the possible relationship between OPFR and BDE exposure and adverse social behavioral outcomes.

Because the aim of this study was to focus on current exposure to OPFRs and BDEs, it does not address factors such as maternal toxic exposure during pregnancy and exposure through breast milk, which are known to influence blood toxin levels in children at birth and early developmental stages.^1.2

It would be clinically applicable to conduct future studies that address the short-term effect of current exposure to flame retardant chemicals. When exposure is removed, are there significant improvements in responsible and assertive behavior? A study by Toms et al. in 2008 found that infants and children ages 0 to 4 had higher blood concentrations of BDEs than older children, suggesting that these chemicals do not remain in the circulation once exposure is reduced.³For now, we can only assume that the chemicals will be eliminated as children age, and we can act to reduce young children's exposure to these chemicals in the built environment.

The researchers controlled for potential confounding factors such as age, gender and traumatic experiences using multiple regression analysis, a strength of this study. However, they did not collect data on other factors known to influence social behavior, such as diet,^4.5other health conditions or history of maternal nutritional deficiency during pregnancy.⁶

Although the use of silicone wristbands as passive collection devices is a start in estimating children's exposure to flame retardants, researchers acknowledge that this indirect measurement of exposure may over- or underestimate actual body burden. It is reasonable to assume that the wristbands do not account for additional exposure to ingested OPFRs and BDEs from hand-to-mouth activity, which is common in children, and therefore may underestimate the overall exposure in some or all participants. Since the pharmacokinetics of different OPFR and PBD compounds also vary,⁷Current exposure may not accurately reflect total body burden and the true effects of exposure in the long term. Future studies examining blood levels or urinary metabolites of OPFRs and BDEs may show a greater association between actual body exposure to these chemicals and social behavior.

The results of this study provide good reason to consider methods to reduce exposure to and aid in the elimination of these chemicals in young children. Sources of exposure to these chemicals include furniture, nursing pillows, carpets, electronic devices, strollers, car seats, and vehicles. Some companies have started offering furniture that is free of flame retardant chemicals. However, this does not guarantee the elimination of other chemical contamination of furniture components, such as: B. Formaldehyde, which is used in chipboard. It has been suggested that used furniture has less exposure to these chemicals because it has had time to “off-gas.” However, I couldn't find any studies on this topic. It is likely that older furniture continues to be a significant source of flame retardant chemicals as the foam padding degrades and releases more dust.

Some electronics and furniture companies have committed to eliminating the use of BDEs, but in many cases BDEs have been replaced by OPFRs.⁸A more proven option to reduce exposure would be to reduce exposure to dust particles, which are vectors for flame retardant chemicals.⁹For example, using a HEPA air filter, wet wiping fabrics and electronics, and regularly cleaning air ducts to reduce exposure of house dust to flame retardant sources can reduce available contaminated dust in the environment.

However, the majority of exposure among study participants and among preschool children in general may come from outside the home. Previous studies have shown that levels of organophosphate chemicals in public buildings are four times higher than levels in most domestic environments.¹⁰Plausible recommendations to reduce exposure in public spaces, such as: Some areas, such as schools, include regular cleaning of air ducts and reduction of other dust reservoirs. Aside from stricter regulations regarding materials allowed in public buildings or avoiding these spaces, there is not much that can be done to reduce exposure outside the home, particularly at an individual level.

A more practical solution might be to offer parents suggestions about what they can do to promote biotransformation and elimination of these compounds in their young children. Animal studies suggest that increased dietary fiber intake significantly increases the fecal excretion of other lipophilic toxicants such as polychlorinated biphenyl ethers (PCBs) and organophosphate pesticides, with rice bran fiber and spinach being the most potent forms studied.¹¹It seems reasonable to extrapolate these results and conclude that fiber may also increase the excretion of OPFRs and BDEs.

Additionally, physicians should emphasize the importance of ensuring the child has good nutritional status to support the metabolism of these chemicals. Docosahexaenoic acid (DHA) has been shown to cross the blood-brain barrier and protect against oxidative damage caused by organophosphate pesticides and improve symptoms in disorders such as attention deficit hyperactivity disorder (ADHD), which have symptoms similar to those that correlate with exposure in the present.^12,13It is reasonable to recommend DHA supplementation as both prevention and treatment for exposure to OPFRs and BDEs.

Again, we should be reassured, and we should reassure our patients, that research shows that younger children have higher circulating concentrations of flame-retardant chemicals than older children, suggesting that they can effectively clear these toxins from the circulation once exposure is reduced.³