Evaluation of the developmental toxicity of perfluorooctanesulfonate in the Anuran, Silurana tropicalis

Abstract

A 150-day post-metamorphosis (dpm) partial lifecycle study exposing Silurana tropicalis to <0.03 (control), 0.06, 0.13 0.25, 0.5 and 1.0 mg/L perfluorooctanesulfonate (PFOS) was conducted. A subset of specimens from the control and each treatment were evaluated at metamorphic completion. A significant increase in the median metamorphosis time was observed in the 1.0 mg/L PFOS treatment relative to the control. A modest increase in the occurrence, but not severity, of mild follicular hypertrophy was found in thyroid glands from organisms exposed to the 0.62 and 1.1 mg/L PFOS treatments. At 150 dpm, a concentration-dependent increase in whole body PFOS residues was measured ranging from 29.6 to 163.5 mg/kg in the 0.05 and 1.1 mg/L PFOS treatments. Decreased body weight and snout-vent length were noted in specimens exposed to 1.1 mg PFOS/L at the completion of metamorphosis. Body weight was reduced in the 1.1 mg/L PFOS concentration; however, snout-vent length was not affected by PFOS exposure at 150 dpm. An increased proportion of phenotypic males were noted in the 0.62 and 1.1 mg/L PFOS treatments. Abnormal ovary development characterized by size asymmetry, necrosis and formation of excessive fibrous connective tissue was identified in females exposed to 0.29 and 1.1 mg PFOS/L. Asymmetrically misshaped testes were found at 1.1 mg/L PFOS. Results suggested that PFOS is capable of interfering with S. tropicalis growth before metamorphic completion and growth and gonad development during juvenile development.

Chronic Per‐/Polyfluoroalkyl Substance Exposure Under Environmentally Relevant Conditions Delays Development in Northern Leopard Frog (Rana pipiens) Larvae

“…Most toxicity testing for aquatic species focuses on water exposure alone. Our results suggest that environmental PFAS exposure can cause adverse effects at aquatic concentrations as much as 100 times lower than those previously reported (0.06 vs ≥10 ppb; Ankley et al 2004; Hoover et al 2017; Flynn et al 2019; Fort et al 2019). There are several possible explanations for our findings.…”

Effect of perfluorooctanesulfonate exposure on steroid hormone levels and steroidogenic enzyme activities in juvenile Silurana tropicalis

“…Fort et al () found that exposure to 1.1 mg PFOS/L for 150 dpm increased the proportion of phenotypic male frogs. Hermaphroditic development was not noted, however.…”

“…Breeding was performed using human chorionic gonadotropin (Sigma Chemical Company, St. Louis, MO, USA; CAS no. 9002‐61‐3; 5000 IU [CG‐5], lot number SLBQ3937V) (~100 IU immediately before introduction to breeding chambers) (Fort & Rogers, ; Fort et al, ).…”

“…Specifically, CYP17, aromatase and 5α-reductase activities were measured in the differentiating gonad, in conjunction with plasma E 2 , testosterone and DHT levels in PFOS-exposed S. tropicalis. As a phenotypic male skewing was noted by Fort et al (2019), and gonadal CYP17, aromatase and 5α-reductase activities were measured in the present study; only gonadal testosterone levels were determined to evaluate de novo androgen synthesis.…”

“…Previously, a partial life cycle study exposing S. tropicalis to varying concentrations of PFOS 0.06, 0.13, 0.25, 0.50 and 1.0 mg PFOS/L [nominal]) was conducted through 150 days post‐metamorphosis (dpm) (Fort, Mathis, Guiney, & Weeks, ). A concentration‐dependent increase in whole body PFOS residues was measured ranging from 29.6 to 163.5 mg/kg in the 0.05 and 1.1 mg/L PFOS treatments.…”