Coastal Chemistry Corner: Not What the Doctor Ordered

To Pee or Not to Pee

By now it’s well-established that sunscreen chemicals harm corals by reducing their tolerance to heat, as well as their ability to feed and reproduce, even when those chemicals are present at very low concentrations in the water. In response, product bans and public awareness campaigns promote mineral-based sunscreen and sun protective clothing to avoid contaminating reefs. 

But what about the chemicals in other skin care products that wash off of swimmers? Or the chemicals in pharmaceuticals that get excreted through urine and sweat? 

There’s a growing scientific consensus about the harms to marine life caused by chronic exposure to low levels of many ingredients in pharmaceuticals and personal care products like contraceptives, antibiotics, pain killers, and even caffeine. Studies document impacts to marine life ranging from growth abnormalities and behavior changes to entire population collapses after the feminization of male fish chronically exposed to synthetic estrogen. 

As animals, corals share parts of our underlying biological architecture, which means that drugs designed for a specific effect in humans—like halting reproductive processes—can just as readily disrupt their biological functioning. Some chemicals, like the stimulants in coffee and chocolate, are problematic for animals that lack the specific enzymes required to break them down before they accumulate to toxic levels (a fact well-known to most pet owners). 

Wastewater systems offer a first line of defense to remove many of these chemicals before they reach the ocean when they are flushed down household drains. But in heavily used swimming areas, those chemicals are directly released into the ecosystem through contact with the water, and are excreted through both sweat and urine. Up to 90% of the active ingredients in some medicine passes through the body without being changed or taken up, after which they can linger in the environment for weeks or months, especially in calm areas and enclosed bays. 

Water quality sampling by ʻĀkoʻakoʻa scientists has revealed measurable levels of ten pharmaceuticals and personal care products in West Hawaiʻi bays, some of which have been documented to build up within coral tissue. Keeping these chemicals out of the ocean as much as possible will give our corals a better chance to survive impending heat waves and help restore healthy reefs.

What you can do: 

• Don’t pee in the water. Use the lua (bathroom) before swimming, especially if you recently took medicine or drank caffeine. See the table below for how long it takes your body to process chemicals. 
• Never flush unused or expired medications. The best option for disposal is the pharmacy drop-off locations at Long’s Drugs or Safeway. 
• Use sun protective clothing, and only mineral-based sunscreen. Always check the label and avoid anything that contains active ingredients besides zinc oxide or titanium oxide. 

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