Altrenogest photochemistry: influence of pH and nucleophiles on transformation product formation via reversible photohydration

Iowa is home to 25 million pigs (more than 7 times the number of people) and is the nation’s leading pork producer. With such intensive livestock operations, managing breeding cycles efficiently is crucial for farmers. To achieve this, they widely use artificial hormones like altrenogest to synchronize breeding in pigs. However, when these potent hormones wash into waterways and soil from farms, they don’t simply disappear – they transform in ways that could change what they target, and threaten environmental and human health.

When some of these hormones enter the environment, sunlight changes them into different compounds. Previous research has found that sunlight transforms altrenogest into new substances that cycle back and forth depending on whether it’s day or night, however, we don’t know if any new products are formed or how they behave in real environmental conditions. To investigate this, I studied what happens to altrenogest under different conditions that mimic natural environments such as varying pH levels and presence of other reactive chemicals. I discovered that over time, and with varying sunlight exposure, these hormones eventually form “dead-end” products that no longer cycle between different forms.

Interestingly, the day-night cycling behavior increased how much of these dead-end products form and this process is further sped up by the presence of other naturally present reactive chemicals. My findings show that hormone-derived chemicals can stick around in the environment along with likely conserved biological activity, posing risks to ecosystems and human health.