Internal and Maternal Distribution of Persistent Organic Pollutants in Sea Turtle Tissues: A Meta-Analysis

Abstract

We aimed to identify patterns in the internal distribution of persistent organic pollutants (POPs) and assess contributing factors using sea turtles and their offspring as a case study of a long-lived wildlife species. We systematically synthesized 40 years of data and developed a lipid database to test whether lipid-normalized POP concentrations are equal among tissues as expected under steady state for lipophilic compounds. Results supported equal partitioning among tissues with high blood flow or perfusion including the heart, kidney, muscle, and lung. Observed differences in the brain, fat, and blood plasma, however, suggest the physiological influence of the blood–brain barrier, limited perfusion, and protein content, respectively. Polybrominated diphenyl ethers partitioned comparably to legacy POPs. Polycyclic aromatic hydrocarbons, meanwhile, partitioned more into the lung, colon, and muscle compared to the liver under chronic and acute field exposure. Partitioning ratios of individual POPs among tissues were significantly related to the lipophilicity of compounds (as estimated by K ow ) in half of the observed cases, and significant differences between juveniles and adults underscore physiological differences across life stages. The comprehensive tissue partitioning patterns presented here provide a quantitative basis to support comparative assessments of POP pollution derived from biomonitoring among multiple tissues.

Chlorinated Persistent Organic Pollutants (PCDD/Fs and PCBs) in Loggerhead Sea Turtles Stranded along the Central Adriatic Coast

“…Conversely, more studies focused on other POPs [ 29 , 46 , 47 , 48 ]. However, these studies were very heterogeneous regarding the analyzed matrices (liver, muscle, blood, or fat tissue), the classes of investigated contaminants (from organochlorine pesticides to PCBs or PBDEs), and the expression of results (wet weight, lipid weight, or WHO-TEQ) [ 49 ]. Moreover, since little is known about the levels of contaminants in sea turtles, sometimes different congeners from the same group of POPs were examined, and biometric characteristics, sex, and sexual maturity were not always specified, as well as the evaluation of the nutritional status.…”

The ATTAC guiding principles to openly and collaboratively share wildlife ecotoxicology data

“…In a follow-up, Muñoz et al. [59] succeeded in the integration of 26 studies covering 40 years of biomonitoring data, thereby allowing for a comparative analysis of the internal distribution of persistent organic pollutants (POP) among all extant sea turtle species. Similarly, based on a meta-analysis, Ratier & Charles [75] proposed a new and promising method to assess the bioaccumulation capacity of chemical substances accounting for the uncertainty on the bioaccumulation metric estimates; an innovative approach that could replace the current use of a single median to do so as required in regulatory documents (e.g., [30] , [65] ).…”

“…The ATTAC workflow progressively emerged from experiences and earlier applications in Muñoz & Vermeiren [61] , and Muñoz et al. [59] , and has been further consolidated when building an integrated database to investigate the maternal transfer of chemical substances across reptile species. The new, extended, and improved ATTAC workflow presented in this paper includes refinements based on further discussion among the authors in gathering ecotoxicological data to support quantitative meta-analyses and modeling from both academic and regulatory perspectives.…”

“…For example, the development of a lipid content database by Muñoz et al. [59] allowed comparison among multiple studies and tissues of sea turtles, even when lipid content information for individual studies was missing. In addition to pollutant concentrations, data on toxic effects in wildlife are often heterogeneous and measured against a variety of endpoints for a range of timeframes.…”

“…For example, data regarding biological characteristics of sampled individuals such as sex, size and body condition (e.g., approximated as a size-weight quantitative relationship or a qualitative description of health), as well as basic data regarding time, date, and location (and potentially experimental or field conditions) of capture are of high importance as they can influence the exposure, uptake and effects of pollutants within individuals. For example, females can offload some of their pollution burden via maternal transfer, while males do not have this elimination pathway, hence resulting in differences in bioaccumulation patterns between sexes [59] . Additionally, physiological rates such as metabolic, breathing, and heart rates are known to differ between sexes, which can influence toxicokinetics [ 12 , 53 ].…”