Realist review of policy intervention studies aimed at reducing exposures to environmental hazards in the United States

Supporting legislative action: Urinary levels of phthalates and phenols among influencers in the 'Plastics in the spotlight' advocacy initiative

BACKGROUND

Society-wide initiatives to prevent human exposure to plastic residues include laws and policies. Such measures require citizens' support, which can be increased by honest advocacy and pedagogic projects. These efforts must have a scientific basis.

OBJECTIVE

To assist the 'Plastics in the spotlight' advocacy initiative raise awareness among the general public of the presence of plastic residues in the human body, and to increase citizens' support for legislation on plastic control in the European Union.

METHODS

Spot urine samples of 69 volunteers with cultural and political influence from Spain, Portugal, Latvia, Slovenia, Belgium, and Bulgaria were collected. Concentrations of 30 phthalate metabolites and phenols were determined through a high-performance liquid chromatography with tandem mass spectrometry and ultra-high-performance liquid chromatography with tandem mass spectrometry, respectively.

RESULTS

At least 18 compounds were detected in all urine samples. The maximum number of compounds detected per participant was 23, and the mean, 20.5. Phthalates were detected more frequently than phenols. Median concentrations were highest for monoethyl phthalate (41.6 ng/mL, adjusted for specific gravity), and maximum concentrations were highest for mono-iso-butyl phthalate (1345.1 ng/mL), oxybenzone (1915.1 ng/mL), and triclosan (949.6 ng/mL). Most reference values were not exceeded. Women had higher concentrations of the 14 phthalate metabolites and oxybenzone than men. Urinary concentrations were not correlated with age.

DISCUSSION

The study had three main limitations: method of subject selection (volunteers), small sample size, and limited data on determinants of exposure. Studies on volunteers do not pretend to be representative of the general population and are no substitute for biomonitoring studies in representative samples of the populations of interest. Studies as ours can only illustrate the existence and some aspects of the problem, and can raise awareness among citizens concerned by the evidence that the studies provide in a group of subjects who are humanly appealing.

CONCLUSIONS

The results illustrate that human exposure to phthalates and phenols is widespread. All countries appeared to be similarly exposed to these contaminants, with higher levels in females. Most concentrations did not exceed reference values. The effects of this study on the objectives of the 'Plastics in the spotlight' advocacy initiative deserve a specific analysis from policy science.

The "realist search": A systematic scoping review of current practice and reporting

The requirement for literature searches that identify studies for inclusion in systematic reviews should be systematic, explicit, and reproducible extends, at least by implication, to other types of literature review. However, realist reviews commonly require literature searches that challenge systematic reporting; searches are iterative and involve multiple search strategies and approaches. Notwithstanding these challenges, reporting of the "realist search" can be structured to be transparent and to facilitate identification of innovative retrieval practices. Our six-component search framework consolidates and extends the structure advanced by Pawson, one of the originators of realist review: formulating the question, conducting the background search, searching for program theory, searching for empirical studies, searching to refine program theory and identifying relevant mid-range theory, and documenting and reporting the search process. This study reviews reports of search methods in 34 realist reviews published within the calendar year of 2016. Data from all eligible reviews were extracted from the search framework. Realist search reports poorly differentiate between the different search components. Review teams often conduct a single "big bang" multipurpose search to fulfill multiple functions within the review. However, it is acknowledged that realist searches are likely to be iterative and responsive to emergent data. Overall, the search for empirical studies appears most comprehensive in conduct and reporting detail. In contrast, searches to identify and refine program theory are poorly conducted, if at all, and poorly reported. Use of this framework offers greater transparency in conduct and reporting while preserving flexibility and methodological innovation.

Systematic Review: A Method at Risk for Being Corrupted

The production of systematic reviews is increasing, but their credibility is under threat. Although systematic reviews are an important tool for policymaking, their influence can be weakened by methodological problems and poor policy relevance. Using Cochrane as an example, I address standards for systematic reviews, the influence of special interests on these reviews, and ways to increase their relevance for policymakers.