Question: What do orcas and my butt have in common?

Answer: Plenty of blubber that houses fat-loving toxins.

Orcas, like those in our own Puget Sound, are a health indicator. Living high on the food chain, as an orca consumes food from their environment, they ingest and store higher concentrations of contaminants compared to animals lower on the food chain. This is a process known as bioaccumulation. Since many “toxins bind themselves to fat, blubber-packing…animals are particularly susceptible” to carrying high loads of toxins. These loads of contaminants, from persistent organic pollutants (POPs), to pesticides and heavy metals, persist in generations to come, passing from parent to offspring through mothers’ milk. (As it turns out, the fact that a mother orca passes on some of these contaminants is one of the primary reasons she lives longer on average than her male counterparts.)

From their vantage point at the top of the food chain, orca whales have accumulated enough PCBs and DDT to rank them the most contaminated marine mammals in the world.

But remember, humans are also pretty high on the food chain. And while my backside doesn’t quite raise a candle to the blubber packing power of an orca, I too have spent my thirty-some years on earth storing contaminants from the world around me. If I were to dive deep into my own fat reserves, I would find my fair share of persistent organic pollutants (POPs), including the same PCBs and DDT that leaves my endangered orca neighbors in quite the predicament.

When my daughter was born, my body set to work converting pregnancy weight, that good maternal fat, into a unique concoction of fats, proteins, and sugars unlike anything else found in nature or synthetically produced, meeting her specific needs. As she continued to feed, my body dug deeper into my fat stores, transforming the adipose tissue I had held on to for decades. These fat tissues contain information about my access to nutrients and details about my environment. In converting this fat and these messages into milk, my body passed down key biological lessons to my daughter, in addition to supplying her with the nutrients she needs to grow and learn.

But, like orcas, this transmission includes contaminants. One study estimated that a nursling will receive about 50 times the daily PCB intake of adults through mothers milk. There’s definitely an evolutionary reason behind this transmission, but one that doesn’t translate well in our modern age.

This translation of nutrition and information is not unique to my offspring and me. For example, women, who have sustained long periods of famine, grow to reproduce children more prone to obesity when placed in nutrient rich environments, as a result of this programming. This phenomenon is most famously observed among the Dutch Famine Birth Cohort Study. This cohort was comprised of children of pregnant women impacted by the Dutch famine of 1944. The study found that these children were smaller on average, but more susceptible to diabetes, obesity, and cardiovascular disease. And the same was true of their children, suggesting that the famine experienced by the previous generation had cause an epigenetic change, passed down to subsequent generations.

While it is believed that some of this messaging is transmitted through the genome, studies have also found that genomic messages are translated through mother’s milk. In a sense, the mother’s body sends a message to the child through breast milk, components that say, “our environment does not always provide, so make sure your body prepares to sustain starvation.” When the environment doesn’t align with this programming, problems arise. Further, when we’re passing things that we shouldn’t have absorbed into our body to begin with, we have an even bigger problem.

Today, the messages contained in our thighs and buttocks detail more than the reliability of nutrients in our environment. They pass on our exposures. DDT was banned in 1972, over a decade before I was born. But because my mother, who lived through the production, use and subsequent banning of DDT, stored this nasty chemical away in her fat stores, when she breastfed me I inherited it’s legacy. My daughter has become the third generation to put away DDT into her adipose tissue, and should she choose to have children, will likely pass the same on to her offspring.

Now, remember that can of Lysol in the lactation station? Well, that Lysol is going to make it’s way into my system, into my butt, and subsequently into my milk.

And it turns out that is a big problem.

(Stay tuned for Part 3!)