Whether breast implants float in water is determined by simple physics applied to a medical device. Implants are flexible shells filled with a specific material, and their behavior in water is governed by the same principles that determine if any object floats or sinks. Understanding the components of these devices and how they interact with water’s natural density provides a clear answer. The result depends entirely on the filler material inside the implant shell.
The Science of Buoyancy and Implants
An object’s ability to float or sink is determined by its density relative to the fluid it is placed in, a principle known as buoyancy. Density is a measure of an object’s mass contained within a specific volume, commonly expressed in grams per cubic centimeter (g/cm\(^3\)). Freshwater has a density of approximately 1.0 g/cm\(^3\), and any object with a density greater than this will sink, while an object with a lower density will float.
An object that has a density exactly equal to that of water is described as neutrally buoyant; it will neither rise nor sink but will remain suspended. The overall density of a breast implant is the average density of both the filler and the silicone shell surrounding it. Since the thin silicone shell has a density slightly higher than water, the filler material is the primary factor influencing the overall buoyancy of the implant.
How Implant Filling Affects Density
The two main types of breast implants, saline and silicone gel, behave differently due to their filling material. Saline implants are filled with a sterile saltwater solution, which is chemically similar to the salt water naturally found in the human body. The density of this sterile saline is very close to 1.0 g/cm\(^3\), which is the density of freshwater.
Because of this near-identical density, a saline implant is considered neutrally buoyant or very close to it; it will often hover in the water. The thin outer shell, made of silicone elastomer, may cause the overall density to be slightly greater than water, meaning it might sink very slowly.
Silicone gel implants, on the other hand, contain a cohesive silicone gel. This highly cross-linked gel material has a density that is consistently greater than water, typically ranging from 1.02 to over 1.07 g/cm\(^3\). Because of this higher density, silicone implants are negatively buoyant and will generally sink when placed in water.
Real World Implications for Water Activities
Despite the differences in density, the practical effect of implants on a person’s overall buoyancy during water activities is minimal. The human body is generally neutrally or slightly positively buoyant due to the volume of air in the lungs and the relatively low density of body fat. The small amount of added weight or buoyancy from the implants does not significantly alter this natural state.
For the casual swimmer, the presence of either type of implant will not noticeably affect their ability to float or swim. The main factor influencing movement in the water is the body’s shape and the resulting drag. This is only a significant consideration for competitive swimmers, as studies suggested increased breast volume could potentially create more drag.
For activities like scuba diving, the pressure changes encountered underwater are not a safety concern for the implants. The material inside the shell, whether saline or silicone gel, is largely incompressible. This means it does not shrink under pressure like the air in a diver’s lungs. Implants are safe for recreational diving within standard limits.