Fluorinated chemicals (FCs) have been used since the 1950s in many industrial and
commercial applications because of their unique properties such as chemical inertness,
resistance to heat and their ability to repel water and oils. Concerns regarding potential
environmental or human health risk from FCs exposure have emerged due to these chemicals
being persistent in the environment and can bioaccumulate in animal tissues. Early life stages
are often sensitive to chemical insult, so it is essential to determine if FCs are developmentally
toxic. 41 structurally diverse FCs, including perfluorooctanoic acid (PFOA) and
perfluorooctane sulfonate (PFOS), were screened for potential developmental toxicity using an
embryonic zebrafish bioassay. In initial studies, developmental responses to waterborne
exposure to FCs were determined using a range of concentrations (0.01-200 ng/mL), including
levels that are relevant to the environment. The majority of the FCs tested did not elicit any
adverse developmental responses. However, increased embryonic malformations were
observed in animals exposed to 17 FCs. Since the embryonic dose cannot be inferred from
waterborne exposures, six FCs that are most commonly studied were also microinjected into
the embryonic zebrafish with three doses (0.00002, 0.00024, 0.00245 mg/kg). Three of these six FCs (PFOA, PFDA and PFHxA) elicited embryonic malformations, including mortality and head defects only at certain concentrations. A subsequent microinjection study at higher concentrations was conducted to determine if a structure-response relationship exist. Exposure to three carboxylated and two eight-carbon FCs did lead to embryonic malformations, but not a definite structure-response relationship. These results demonstrate that FCs are generally not developmentally toxic. Collectively, these studies indicate the
power of the zebrafish model to conduct structure- and dose- response relationships and developmental toxicity studies.
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