Temporal and Spatial Evaluation of Mono(2-ethylhexyl) Phthalate (MEHP) Detection in Common Bottlenose Dolphins (Tursiops truncatus) from Sarasota Bay, Florida, USA

Abstract

Phthalates are endocrine-disrupting chemicals added to plastics, personal care products, cleaning solutions, and pesticides. Extensive use has led to its exposure to wildlife, including common bottlenose dolphins (Tursiops truncatus) from Sarasota Bay, Florida, USA; however, there are gaps in knowledge regarding whether sample timing or geographic location influence exposure. Dolphins were evaluated for temporal and spatial variability in urinary mono(2-ethylhexyl) phthalate (MEHP) detection (2010–2019). Significant fluctuations in detectable MEHP concentrations were found across the dataset. All samples from 2014 and 2015 (n = 12) had detectable MEHP concentrations; thus, data were classified into cohorts to explore the significance of prevalent MEHP detection (“Cohort 1” (n = 10; 2010–2013), “Cohort 2” (2014–2015), and “Cohort 3” (n = 29; 2016–2019)). Compared to Cohorts 1 and 3, Cohort 2 had higher detectable MEHP concentrations (Dunn’s; p = 0.0065 and p = 0.0012, respectively) and a greater proportion of detectable MEHP concentrations (pairwise comparisons using Benjamini–Hochberg adjustments: p = 0.0016 and p = 0.0059, respectively). MEHP detection also varied across spatial scales. Dolphins with detectable MEHP concentrations had ranges primarily within enclosed embayments, while dolphins with nondetectable MEHP concentrations extended into open waters, potentially indicating geographically linked exposure risk. This study suggests that researchers and management agencies should consider a population’s ranging pattern, geographic habitat characteristics, and sample timing when assessing small cetacean health in relation to contaminant exposure.

Assessment of Phthalate Esters and Physiological Biomarkers in Bottlenose Dolphins (Tursiops truncatus) and Killer Whales (Orcinus orca)

“…Our findings align with previous studies where DEP and DEHP are the most common compounds found in cetacean species, independent of the matrix or area of study [30,31,70]. Moreover, studies assessing PAE metabolite concentrations have also detected DEP and DEHP metabolites in different cetacean species [31][32][33][34]36,37,71,72].…”

“…After a thorough review, we were only able to identify one study that has attempted to correlate phthalate exposure with physiological responses in cetaceans. In this study, Dziobak et al (2022) have described a positive relationship between blood thyroid hormone concentrations (free thyroxine) and urinary MEHP (mono(2-ethylhexyl) phthalate), a DEHP metabolite, for both adult female and male dolphins. They suggest that DEHP exposure may be impacting thyroid hormone homeostasis.…”

“…In the marine environment, marine mammals have been widely utilized as efficient indicators of environmental chemical pollution and its consequences due to their higher position in the food chain and long lifespan [27][28][29]. Prior research has found exposure to different phthalate compounds in varied cetacean species, including bottlenose dolphins (Tursiops truncatus [30][31][32][33][34][35][36][37]), killer whales (Orcinus orca [38]), sperm whales (Physeter macrocephalus [38]), long-finned pilot whales (Globicephala melas [38]), short-finned pilot whales (Globicephala macrorhynchus [30]), white-beaked dolphins (Lagenorhynchus albirostris [38]), harbour porpoises (Phocoena phocoena [38]), Risso's dolphins (Grampus griseus [30,31]), striped dolphins (Stenella coeruleoalba [30,31]), pygmy sperm whales (Kogia berviceps [30]), Fraser's dolphins (Lagenodelphis hosei [30]), and fin whales (Balaenoptera physalus [31]).…”

Consequences of in vitro benzyl butyl phthalate exposure for blubber gene expression and insulin-induced Akt activation in juvenile grey seals

“…In addition, the bioaccumulative and biomagnification potential of HMW phthalates (World Health Organization & International Programme on Chemical Safety, 1999;Beltifa et al, 2017) may mean top predators with large fat stores, such as pinnipeds, are exposed to phthalates through the food chain even without direct plastic ingestion. Most studies in marine species have investigated the concentration of phthalate metabolites (such as mono(2-ethylhexyl) phthalate (MEHP) and monoethyl phthalate (MEP)) in urine (Hart et al, 2020;Dziobak et al, 2021;Dziobak et al, 2022), which have been found in cetaceans (Fossi et al, 2012;Rian et al, 2020;Hart et al, 2020;Montoto-Martínez et al, 2021). However, recent studies have confirmed the presence of HMW phthalates (both parent compounds and their metabolites) in cetacean and polar bear blubber (Baini et al, 2017;Routti et al, 2021), including BBzP and its major metabolites (Baini et al, 2017).…”