title: Protocol For a Systematic Evidence Mapping of Exposure to Chemicals in Personal Care Products and Fetal Growth
Creators: name: Silva, Raquel
name: Walker, Vickie R
name: Taylor, Kyla
name: Rooney, Andrew
name: Bommarito, Paige
name: Kembra Howdeshell
name: Hall, Samantha
name: Blain, Robyn
Publisher: name: OSF Registries
Year: 2025
Subjects: subject: Toxicology
subject: Environmental Health Life Sciences
subject: Pharmacology, Toxicology and Environmental Health
subject: Life Sciences
subject: Birth weight
subject: Class-based approach
subject: Endocrine disrupting chemicals
subject: Fetal Growth
subject: PFAS
subject: Paraben
subject: Personal care products
subject: Phenol
subject: Phthalate

description: Fetal growth is an important risk factor for later life outcomes. For example, abnormally low birth weight is associated with higher rates of infant death, lower intelligence quotient (IQ), and higher incidence of neurodevelopmental disorders. Conversely, abnormally large birth weight is associated with increased risk of respiratory distress, obesity and insulin resistance throughout development among other outcomes. Fetal growth is influenced by maternal and paternal genetics, maternal nutrient intake and placental nutrient transport, maternal metabolic function, fetal epigenetics and endocrine activity in the mother, placenta, and fetus. In addition, exposure to environmental chemicals can influence fetal growth through several proposed mechanisms (e.g., endocrine disruption, effects on metabolism and nutrient availability, inflammation, and oxidative stress). 
The use of personal care products (PCPs) represents an important close contact exposure to environmental chemicals for pregnant people. PCPs contain a variety of non-persistent and persistent organic chemicals, including parabens, phthalates, phenols and perfluoroalkyl substances. Patterns of PCP use and concentrations of those chemicals have been reported to differ by race and ethnicity, sex, and education, and have been hypothesized to be effect measure modifiers. Although some chemicals in PCPs have short half-lives, exposure to them is likely chronic due to their widespread use in PCPs. Indeed, chemicals and their metabolites derived from PCP exposure are frequently detected in the urine of pregnant women, as well as placental and fetal tissues. 
Hazard identification and risk assessment evaluations have traditionally been conducted on a single chemical. Class-based approaches are proposed as a more efficient method for hazard identification or risk assessment by grouping chemicals based on common characteristics such as structural similarity, mechanism of action, biological function, and/or toxicity to the same tissue/organ system. Considering that there are over 1,000 chemical constituents of PCPs, a class-based approach may represent a time- and resource-efficient approach for hazard identification and risk assessment of the chemicals in PCPs.
The extent, availability, and characteristics of the human and animal literature related to the relationship between chemicals to which humans are exposed through PCP use and fetal growth are unclear. Thus, the Division of Translational Toxicology (DTT) will develop a Systematic Evidence Map (SEM) to establish the extent of evidence published on this topic, characterize the evidence by study design, fetal growth-related health endpoints, and exposures categorized by chemical classes and individual chemicals studied. The SEM will be used to identify data-rich areas, data-poor areas, and knowledge gaps, which are first steps in addressing public health challenges. Specifically, the information contained in this SEM, and the associated summary of the evidence, will serve as a resource to inform decision making on PCP and fetal growth, such as) whether the extent of evidence by classes of related chemicals is sufficient to support a class-based assessment of effects of PCP on fetal growth. Secondly, the SEM may be used to direct future studies, such that the identification of poorly studied chemicals could target chemicals for exposure assessment in cohort studies or new experimental animal studies, or, regarding well-studied chemicals, where new studies should be questioned or justified for added value in grant applications and by institutional research boards to avoid duplicative research. Thirdly, the SEM will inform whether there is information sufficient to reach informative synthesis conclusions (e.g., full systematic review) on the association between exposure to chemicals in PCPs, on an individual chemical- or chemical class-basis, and fetal growth.