Eliminating ants during pregnancy
September 28, 2015 11:41 PM   Subscribe

Our house is being invaded by serious quantities of ants, probably Argentine ants. Because I'm pregnant, I'm not sure what to do about it. Because we have renters, we can't just manage them and put up with it.

To date, we have tried to manage the ants. We caulked their entrances, don't leave food out, wash away their pathways with soapy water, and sprinkled cinnamon down along all their normal trails. Caulking plus cinnamon led to a solid week of peace, but now they're back. And we can't really access the renters' unit every week to clean and put down cinnamon, I don't think.

While I like the idea of baits and giving them a slow-acting poison that they can take back to the nest, it seems like in the meantime, they'll be tracking that poison across our kitchen. Because I'm pregnant, that seems to rule out borax and boric acid ("can cross the placenta, affecting fetal skeletal development and birth weight in animal studies of high-dose exposures"), and Terro.

We would ideally hand this problem over to an expert to solve, and they would ideally destroy the colony rather than just put an extra barrier in the ants' way. But the two terminators we called use heavy-duty pesticides. The exterminator that our neighbor recommends said they use Termidor (fipronil), which seems to have a number of impacts on fetal development and birth weight.

Searching the internet for solutions yields various natural methods of unknown efficacy (lemon juice! lavender!). I tried to find their nests and pour boiling water on them, but it didn't seem to help, and according to Wikipedia, "due to their nesting behavior and presence of numerous queens in each colony, it is generally impractical to spray Argentine ants with pesticides or to use boiling water as with mound building ants."

All advice is welcome. Thoughts?
posted by slidell to Health & Fitness (32 answers total) 1 user marked this as a favorite
We just have regular California ants, whatever kind those are. This two part approach has worked for us for about the last 1.5 years. A) We started keeping our kitchen trash outside on the porch. (This was annoying at first, but we adjusted before long. Occasionally the ants find their way into the trash, but they don't bother coming indoors. B) I sprinkle diatomaceous earth whenever I spot ant trails outside, especially near the house itself.
posted by ktkt at 11:51 PM on September 28, 2015 [1 favorite]

I'm not sure about Argentine ants, but the ants that try to invade my place get to perish in baking soda. (I line the walls with baking soda.)
posted by discopolo at 12:01 AM on September 29, 2015 [1 favorite]

PBO is in the Terro sprays but not the liquid ant baits. The liquid ant traps contain borax, but the research on borax is way more equivocal than the Environmental Working Group will have you believe--here is a blog post aimed towards non-scientists.

In general I would not trust anything coming out of the EWG. They willfully misinterpret studies, tailor their ratings based on whatever "green" manufacturing company is backing them, and push ingredient ratings that have little to no basis in how said ingredients are actually used or exposed to humans. They use technical scientific language to convince people without scientific backgrounds that they know what they're talking about, and like to prey on parents, especially parents of young children. I would strongly recommend taking everything they state with a grain of salt and doing your own research on Toxnet or PubMed if you feel comfortable reading and interpreting scientific literature, or checking out websites like Science Based Medicine if you do not.
posted by Anonymous at 12:06 AM on September 29, 2015

Response by poster: schroedinger's comment opens up an interesting possibility that borax might actually be okay, which would be great, given that it's one of the most commonly recommended solutions. But the blog post linked does say "The one concern is with its potential to disrupt the reproductive system. Studies have not been done in humans regarding this; however, potential reproductive issues in mice are suspected from high levels of (ingested) borax." In the toxnet studies, it looks like most studies considered impact to males? (But then, would it impact a male fetus? I really don't know how these things work.) It also includes at least one study that says "pup survival was adversely affected." And it looks like the European Chemicals Agency requires labels saying: "May impair fertility. May cause harm to the unborn child." I also don't know how to interpret the results on toxnet, since I don't know what level of mg/kg exposure I might pick up from the ants walking across my kitchen counter, dish drying rack, etc. (despite my constant wiping and re-rinsing of plates before using them). If anyone has additional comments on this or the original question, I'd really appreciate your thoughts.
posted by slidell at 1:04 AM on September 29, 2015

Best answer: Slidell, call the organization of teratology information's Mother to Baby hotline for questions like these. They'll be able to help you.

posted by discopolo at 2:01 AM on September 29, 2015

Diatomaceous earth will kill off the ants and is safe enough to eat. It scapes off the waxy cuticle on the onsects and they die of dehydration.

Borax should be fine unless you are ingesting dead ants or prepare food directly on your countertops all the time.
posted by benzenedream at 2:24 AM on September 29, 2015 [6 favorites]

I have a kilo of borax sitting on my desk right now. It's fine.

They used to put borax in milk and other foods. And it did (eventually) cause all sorts of health problems - because people were ingesting it in quite large amounts. Provided you're not actually sprinlkling it on your food like salt, it shouldn't be a problem. Borax was basically used for just about everything around the home - and it's still widely used as a laundry additive.

The problem with reading studies about things, at least for the layperson, is that it's often hard to get an answer to the question 'how concerned should I be?' In this case, provided you're not actually putting the stuff in your mouth (or snorting it), you'll be fine. You'd have to be really, really stupid with the borax to risk any harm to yourself or the fetus. Obviously you should wipe up any spillage, and keep the container properly labelled and out of reach of children.

Mix something stuicky and sugary (jam/jelly) with somethink like 5-10% borax, and leave little blobs of it in cupcake cases (or other small receptacle) wherever you find ants. They'll take it back to their nests and that should wipe them.
posted by pipeski at 2:41 AM on September 29, 2015 [3 favorites]

Note the conclusion from the study comparing Turkish boric acid plant workers with exposure in rats that caused fetal effects: "this means that dose levels of boron associated with developmental and reproductive toxic effects in animals are by far not reachable for humans under conditions of normal handling and use." This was for boric acid not borax however. The borax/honey pacifier report (!!) at toxnet seems to indicate that directly feeding newborns borax is not even that toxic.
posted by benzenedream at 2:46 AM on September 29, 2015 [3 favorites]

We just dealt with these ants, using TERRO liquid bait traps. Worked quickly and cleanly. I've also used borax in laundry for years with no problem, for what it's worth.
posted by equestrian at 2:48 AM on September 29, 2015

Borax (which is terro) is used in such comically small amounts and with such fantastic success that unless younpour it in your mouth several times daily you will have zero problems. Really. Each location gets one droplet. A 3 oz bottle lasts 6-9 months with heavy continuous ant problems (central Florida).
posted by chasles at 3:49 AM on September 29, 2015 [2 favorites]

Have you seen the Earth-Kind products? All natural but meet EPA guidelines.
posted by emkelley at 3:52 AM on September 29, 2015

The studies you quote talk about "potential reproductive issues in mice are suspected from high levels of (ingested) borax" and "animal studies of high-dose exposures." It seems to me that even if you did ingest a very small amount of borax dragged by ants across a surface that later comes in contact with your food, that would still not come anywhere near being a high dose (or what would be a high dose to a mouse). I think these studies are not relevant to you. If you're worried about trails on cooking surfaces then I'd try (a) leaving liquid terra traps as close as possible to wherever it is the ants are coming from, if you can tell, and as far as possible from the kitchen; (b) wiping off counters before food preparation, and maybe if you're super worried rinsing off anything you use to prepare food or eat off.
posted by trig at 4:44 AM on September 29, 2015 [1 favorite]

It's a bit like exorcising a house, but they cannot stand the texture of talcum powder, they won't cross a line of it, it's one way to block up popular entrances.
posted by smoke at 4:54 AM on September 29, 2015

We used Orange Guard when the ants invaded the bunny room, and we frequently use it in the kitchen. Not sure if it's pregnancy safe, but it's worth a look!
posted by needlegrrl at 5:33 AM on September 29, 2015

In that Toxnet document, it clearly states that the levels of borates that would cause reproductive issues are NOT reachable by humans. Terro is a tiny amount of borax that you place where the ant trail begins to enter your home. I'm sure you're not going to be drizzling the stuff on your counters and licking them clean.

I think pregnancy is eating your brain, like it does, and making you super stressed (-speaking as a Formerly Pregnant Person who has Been There). Just use the Terro and wash your hands. It will be ok.
posted by PorcineWithMe at 5:59 AM on September 29, 2015 [4 favorites]

Oh, and if you've never seen the Terro baits in action let me just say-
Whatever is in those things, it's like crack for ants. The little junkies FAR prefer the bait over anything else in your house. Put the bait over the trail, they will swarm it and head back to their Lair of Evil and never even continue on their former pathway.
posted by PorcineWithMe at 6:04 AM on September 29, 2015 [3 favorites]

Your body is strong enough to protect your baby from the miniscule amount of toxins that you come in contact with every day. Good for you on not using a commercial pesticide, which no one should use. Borax or ant baits will be fine. Have someone else put them out and deal with them.
posted by myselfasme at 6:15 AM on September 29, 2015 [2 favorites]

We used diacetamous earth in a similar situation and it worked for us.
posted by EmilyClimbs at 6:31 AM on September 29, 2015 [2 favorites]

Having done battle with ant super colonies for years, the only effective long term solution we've found are the borax baited ant traps. They are so non-toxic to higher forms of life that a toddler, dog, or wild scavenger (raccoon, opossum) can eat the entire contents of the trap and not be harmed. I'm really struggling to see how you would come into contact with the poison once the traps are placed - the ants eat the bait and immediately return to the colony to share it, no further roaming around your house. I used them as a pregnant person with nary a worry.
posted by Wavelet at 8:09 AM on September 29, 2015 [2 favorites]

That Toxnet page mentions 9.6 mg/kg bw/day as a "no observed adverse effect level." That's roughly 10/1000, or 1/100. As a conservative estimate, if you weigh only 100 lbs, that would be a pound of borax per day. I used liquid Terro traps a few years ago to get rid of ants and I don't think the entire package (cardboard box, plastic traps, plus the liquid) even weighed half a pound. And you're not going to be consuming the entire contents of the Terro trap...
posted by needs more cowbell at 8:14 AM on September 29, 2015 [2 favorites]

The Terro liquid baits are amazing - you'll easily be able to find where the ants are coming in because there will be loads of them trekking back and forth, so just put the bait trap right by the entrance and the ants won't go anywhere else in your kitchen.

Once they've completely gone (took a day or so watching a river of ants) caulk up the entrance and you're done. Like others have said up thread there is nothing at all to worry about.
posted by zeoslap at 8:25 AM on September 29, 2015

Where is your renters' unit compared with your own?

Could someone who is not you put down borax in their place? If it's your partner, could they do it and then shower afterwards?

It seems unlikely that borax in a different apartment on your property is going to somehow get into your body, cross the placenta, and damage your child.

YMMV if your renters are roommates rather than tenants, or if there's a shared kitchen, or the units aren't well separated such that borax in their kitchen would drift into yours.

Also, different tack, but I've used talcum powder against Argentine ants in the past. It has worked OK, though not as good as when my landlord used heavy pesticides to eradicate the entire colony. This might be a better alternative for your own living space during your pregnancy.
posted by Sara C. at 8:50 AM on September 29, 2015 [1 favorite]

Response by poster: One question about reading these studies. When people are talking about what would be a high dose to me, should I also be doing the mg/kg math on the fetus, which is currently tiny? Or do the studies just care about the mother's weight?
posted by slidell at 8:54 AM on September 29, 2015

That Toxnet page mentions 9.6 mg/kg bw/day as a "no observed adverse effect level." That's roughly 10/1000, or 1/100.
No, a kg is 1 million times a mg, so 9.6 mg/kg is 10 in a million, not 10 in a thousand.

For a 50kg or 100lb person, this is about 0.5g (i.e. a thousandth of a lb). Which is still more than a person would plausibly ingest unless they were shaking Borax on their food like salt. But it's not 1 lb.
posted by caek at 9:33 AM on September 29, 2015 [1 favorite]

Borax is about as toxic as table salt, gram for gram. Main difference is that borax is slower to eliminate from the body, so chronic or repeated exposure is much more of an issue for borax than for table salt. But if you make up a sugar and honey syrup containing about 5% borax, and you put a bottle cap full of that somewhere near where your trail of ants is coming in, then they won't be tracking it all over your kitchen; most of their little footyprints will stay in the trail.

Even if they were to track a tiny amount of 5% borax syrup over, say, your cutting board: you'd be washing that down before you used it anyway, because ants! and that will get rid of the borax along with everything else that might have been on their little feet. You're not going to ingest a measurable amount.

If you keep on replenishing that capful of syrup until the ants stop coming (which might take a week before the last staggering little stragglers keel over), you can be pretty confident that you have in fact killed the colony. And seriously, borax would have to be about the least toxic chemical you could possibly employ for that job.
posted by flabdablet at 11:29 AM on September 29, 2015 [1 favorite]

Best answer: You can't project toxicity data used on adults male rats to effects on a male fetus in a human. Ideally your study is specifically aimed towards monitoring fetal development and is not solely targeting acute toxicity (i.e. at what point does the fetus die).

There are too many variables going into the how the animal is dosed, what route the compound takes to the fetus (if at all), and the stage of the pregnancy, etc. Not to mention compounds have different effects at different stages of pregnancy. For example, Fetal Alcohol Syndrome is a broad term that refers to a whole host of effects that manifest very differently (if at all) depending on the stage of pregnancy in which they occur. The biggest danger is in the early stages of pregnancy, especially in the first trimester where there is the potential for severe developmental effects depending on what organs were developing when alcohol was ingested. But by the third trimester, when the embryo is a full-blown fetus and basically just needs to get bigger, the fetus is resilient enough that only daily drinking or very heavy drinking episodes are likely to do any serious harm.

There is little done on low-dose effects of borate compounds on fetal development. But human case studies cited in some of the survey papers illustrate the variability of the compound's effects. In one case study a woman ingested a woman ingested 70 g during the 34th week and the the child did not survive. But in another a woman ingested 250 g of borax during her 18th week of pregnancy and she bore a healthy, full-term baby with no developmental effects.


That said, 9.6mg/kg/day is the smallest dosage in these papers where there's evidence of toxicity to any gender or age of rats or mice. All human studies of toxicity require much higher dosages than this to see effects. But as 9.6 mg/kg/day seems to be the number that's sticking out in this discussion, let's use it to estimate how much Terro you would need to consume to hit that amount.

cm3 = cubic centimeter = cc
1 mg = 0.001 g
0.45 kg = 1 lbs
1 cc = 0.20 tsp

Initial values
Density of borax = 1.73 g/cm3 = 1.73 g/cc
Borax concentration in Terro liquid traps = 5.4%
Amount of liquid in each trap = 11 cc

Let's say you are 100lbs. How many mg of borax would you need to ingest to hit that 9.6 mg/kg value?

100lbs × 0.45 kg/lbs = 45 kg
45 kg × 9.6 mg/kg = 432 mg
432 mg × 0.001 g/mg = 0.432 g

So if you weigh 100 lbs, you would need to ingest 0.432 g of borax per day to reach that 9.6 mg/kg threshold. If you are 150 lbs, that translates to 0.648 g of borax, 200 lbs that's 0.864 g, etc.

But Terro traps are not 100% pure borax. How much pure borax is in each trap? First, let's translate that 0.432 g quantity into volume.

0.432 g ÷ 1.73 g/cc = 0.250 cc pure borax

Now calculate the amount of borax per trap.

11 cc liquid per trap × 0.054 = 0.594 cc volume of borax per trap
0.250 cc ÷ 0.594 cc/trap = 42.1% of each trap

You would need to be drinking 42.1% of each liquid trap per day to hit that cutoff. How many teaspoons is that?

11 cc × 0.421 × 0.20 tsp/cc = 0.93 tsp

40% of the trap is nearly an entire teaspoon of Terro per day, and that's if you only weigh 100 lbs. If you weigh 150 lbs we're talking nearly half a tablespoon of Terro. 9.6 mg/kg/day is the worst-case scenario based on the research out there, and there is no way you will accidentally consume that much!


I hope this sets your mind at ease. As an addendum, while looking this stuff up I found many agricultural extensions and entomology studies recommend much lower concentrations of borax than are found in commercial traps like Terro--only 0.5% to 2% borax, rather than a whopping 5.4%. The suggestion is that a lower dose allows the ants to survive long enough to carry the poison back to their nest. Here is a handout and here is an actual study. That handout recommends a 1 part Terro to 4 part water dilution to get the borax concentration down to 1.08%.

If you do that you might not only get a trap that's more effective long-term, the amount of ant bait you'd need to drink to reach the 9.6 mg/kg/day value goes up to 4.65 tsp/100 lbs person. Fewer ants and worries!

You've got to hand it to Terro. By using that higher concentration you get happy consumers because all the visible signs of infestation--the workers--are quickly killed off. But the nest never gets affected, so your consumer will keep buying more of your traps because the ants will come right back once the number of workers has been replenished. I am now really annoyed with how many traps I've used to deal with my ongoing ant problem.
posted by Anonymous at 11:29 AM on September 29, 2015

should I also be doing the mg/kg math on the fetus, which is currently tiny? Or do the studies just care about the mother's weight?

Toxicity level is related to concentration in the bloodstream, so go by the total weight of the mother/foetus system.
posted by flabdablet at 11:30 AM on September 29, 2015 [1 favorite]

The suggestion is that a lower dose allows the ants to survive long enough to carry the poison back to their nest.

My standard ant killing syrup recipe is around 5% borax (2 tsp borax per cup of syrup), and the marching column always lasts a few days; there's no doubt at all in my mind that most of that syrup is making its way back to the nest. The army does not generally appear to get the staggers until about day 3.
posted by flabdablet at 11:34 AM on September 29, 2015

Another vote for looking into diatomaceous earth as a physical deterrent, as it's worked well for me -- you'd want the food-grade version, rather than the stuff used in pools.
posted by Iris Gambol at 11:38 AM on September 29, 2015

My standard ant killing syrup recipe is around 5% borax (2 tsp borax per cup of syrup), and the marching column always lasts a few days; there's no doubt at all in my mind that most of that syrup is making its way back to the nest. The army does not generally appear to get the staggers until about day 3.

I am not an entomologist and defer to the scientific research. Obviously if 5% works for you then no need to change, but a lower concentration will use less product and may leave OP less nervous.
posted by Anonymous at 12:06 PM on September 29, 2015

Response by poster: Thank you! Borax it is! I hope all the other anxious people out there googling for solutions find this thread as reassuring and useful as I did. Many thanks for doing the math, schroedinger! All the other input was very helpful, too.
posted by slidell at 2:54 PM on September 29, 2015 [1 favorite]

Response by poster: The exciting conclusion is that we bought the Terro liquid baits for the tenants. I really appreciated the smart analysis recommending we mix it ourselves, but the tenants were losing their patience, and we were too busy for a few weekends there. Next year!

The ants had already been disappearing, so after so much worry, almost zero ants were in our apartment during the entire time they had baits out. I had to laugh. We probably could've used anything, as far as my personal exposure went.

But after a micro-invasion yesterday and finding an ant floating in my almost-empty coffee cup this morning, I was again grateful for all of your input and for schroedinger's math about how much I'd need to consume to hit that lowest level of statistically observable impact. Thanks!
posted by slidell at 1:38 PM on October 18, 2015

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