The following was published in the Biddeford-Saco?Journal Tribune Sunday edition, 10/2/2016, and?Making It At Home's 10/5/2016 issue.

When my wife, sons, and I went away to our annual family reunion over Labor Day Weekend, we never expected to return home to find a party raging at our house. Wed left our cat, Greenberry, in charge of the homestead. When we got back from our trip, she was playing host to hundreds of obnoxious guests.

Fleas.

Somehow, our indoor-only cat had picked up a parasitic army. They were everywhere: in our carpets, in our books, on our cat, on our legs. Jumping, crawling, biting, reproducing. The battle for our home began.

First, we had to get them off of our hapless Greenberry. The vet recommended Capstar, a little white pill to make her blood temporarily toxic to fleas. What kind of chemical could do that, I wondered, but not kill the cat? Nitenpyram is in the same chemical family as pesticides sprayed on farms across America, the nefarious ones Id read so many environmental journal articles about. Are neonicotinoids killing our bees? Quite possibly. Well, theyre killing fleas too, so this week, Im a fan.

My sister, a synthetic organic chemist at the University of California in San Diego, offered this assessment: Thats a cool molecule. Lots of weird $%#&. I was sold. Within minutes, the fleas were fleeing, jumping from Greenberry like first-class passengers off the Titanic. Unfortunately, theyd still made themselves quite comfortable in the carpets and between the cracks of our hardwood floors. On to Phase II of campaign Rolling Thunder.

Foggers, the insecticidal grenades one used to throw and run from, are of limited effectiveness in rooms containing furniture. Nowadays, modern exterminators (and farmers too) apply the principles of integrated pest management to attack, and beat back, bugs throughout their different life stages. Timing is everything. There are now chemicals to hit eggs, larvae, and adults; one can even buy them online in one delicious cocktail spray.

It was a roll call of superheroes: Pyriproxyfen, the growth regulator! Pyrethrin, the nerve agent derived from chrysanthemums! Permethrin, the favorite tick repellent of an old bird banding friend! We carpet bombed our carpets with them all.

And then we started vacuuming, for hours a night, every night, a new bag every night. Thats what youre supposed to do, said the professionals. Knock em back with poison, then suck em up with the hose. I like the vacuuming tactic: its the most physical approach, and after the all the chemicals wed dropped, easily the most organic. Also, our house has never been cleaner.

But the fleas  the shameful, mortifying, aggravating fleas  they remain. Weve killed off the weak ones, surely, but natural selection is inescapable: the fleas that are left are stronger, faster, and possibly even immune to the toxins. Its been weeks of this war, but the white socks I wear around the house to test our progress still collect passengers. We have not won yet, and meanwhile, what exactly have we been breathing in?

How much do we really know about what goes into our bodies? What do we take for granted as safe? Is non-toxic completely so, or just as far as we know, in limited amounts?

My younger son recently had a Glow Stick accident and splashed his mouth and eyes with phosphorescent liquid. After the screaming and the face washing were over, I looked up the ingredients. Hydrogen peroxide and dibutyl phthalate  irritating, not poisonous, but still surprising to a parent whod never considered the possibility that those sticks could be dangerous. (Apparently, every Halloween poison control centers are inundated with calls about Glow Stick incidents.)

The Kennebunks will put their water districts fluoridation policy to a vote this Election Day. Some people, including the director of the water district, believe that fluoride causes more harm than good; others contend that it is still the most effective and economical way for communities, and especially their less fortunate members, to prevent tooth decay. The facts are out there that make convincing arguments for both sides. How to decide?

Im a science person. I enjoy learning about, and benefiting from, technologys advances. Im skeptical about the supposed dangers of GMOs, vaccines, and many pesticides, given the regulatory gauntlet those substances have to run and the lack of evidence for many claims of their horrors. Im even, it seems, OK with filling my home with synthetic organic neurotoxins.

The substances we allow into our homes, our bodies, and even our body politic, need to scrutinized and evaluated, but at some point, one must act, even without a set of complete facts. At some point, a leap of faith is required.

In the meantime, as the standup comic canine once quipped in a Far Side cartoon: Take my wifes& fleas.

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Nik Charov is president of Laudholm Trust, the nonprofit partner of the Wells National Estuarine Research Reserve in Wells, Maine. His occasional column, Between Two Worlds, ventures forth from the intersection of art and science, past and present, molecule and compound. More at wellsreserve.org/twoworlds.