While scientists used to consider adipose tissue little more than a storage organ, in recent years researchers have learned that adipose tissue has a number of very interesting physical, metabolic, endocrine, and maybe even toxicological functions. Thus, the consequences can be serious if the functioning of adipose tissue is altered or interrupted by environmental chemicals.
Adipose tissue plays a number of roles in toxicology. One of them is a protective function, as some persistent organic pollutants (POPs) have an affinity for adipose tissue, which holds them and protects other organs from their toxic effects. This would be helpful mostly for acute exposure. The evidence for this role of adipose tissue comes from various studies in which aquatic or terrestrial animals were exposed to dioxins or other POPs. Those animals with the largest amount of fat mass had the highest levels of protection from the exposures.
Recent evidence indicates that the same effect may be seen in humans. In particular, epidemiological studies have found that if you examine death rates among people with very high levels of POPs in their blood, people who are obese have a significantly lower risk of death than thin people. Of course, among those with low levels of POPs in their blood, the obese are at a high risk of dying, but having large amounts of fat tissue does seem to have a protective effect against the toxicity of POPs.
But what happens in the long run to obese people whose adipose tissue has stored toxic chemicals? They may be protected from acute exposures, but what happens if the chemicals stored in the fat tissue are later released? It was found that obese people had significantly lower concentrations than the normal ones. In short, the POPs were distributed more diffusely in their fat tissue. However, when the total amount of POPs that an individual was carrying was calculated, the obese individuals had a significantly higher burden because they had so much more fat tissue.
Moreover, it was also established that the amount of POPs in the blood increased steadily over time in the year after the surgery. These people lose 30 or 40 kilograms of weight during the few weeks and few months after surger, but there is an increase in POPs in serum, which suggests that when you lose weight, you probably release these pollutants in your blood.
References: Ref #116