Zika and DDT - What's the science say?

[Katy]

Is anyone here well versed in DDT science?  I mean the actual science, not just the fear mongering in Silent Spring (which I read and fully believed until recently).  I've read enough medical studies to know that journalists don't often get science right. Oftentimes I've been curious about a medical study after a news bit only to discover the abstract came to the exact opposite conclusion the journalist said it did.

 

So when I read DDT might be brought back to fight Zika, I'm left wondering.  Many of the articles indicate it wasn't nearly as bad as it was made out to be, or at least it could be less dangerous if more carefully managed - small quantities on home walls rather than spraying entire fields with it, etc.  But I don't believe journalists, and I don't want to spend two weeks researching, so I'm hoping someone here is already well versed and can share their nuanced opinion with us.

[Matryoshka]

All I know is that when I grew up, I never saw a single raptor.  No falcons, no hawks, no eagles, no vultures.  Not a single one.  

 

Now I see multiple ones daily.  I remember being so excited the first time I saw one sailing over the highway.  Now it's commonplace.

 

Raptors were supposed to be one of the populations most affected by DDT (because it softened their eggshells and the babies wouldn't survive - top of the food chain got the most cumulative effect vs. smaller or seed-eating birds).  Really... zero for years and years on end, to multiple sightings of multiple species per day.

 

PS.  I have not moved since I was a kid.  Still live within 30 miles of where I grew up - so that's not it.

Edited August 2, 2016 by Matryoshka

[Lanny]

On the 6 P.M. (EDT) news show from the USA that I just finished watching (02 August 2016), they had a segment, about the Zika problem in Miami, FL, USA.  They are not sure that what they are spraying at this time is effective against the Mosquitoes with Zika.  They are not sure whether or not the Mosquitoes are resistant to what they are spraying. They are considering or contemplating Aerial Spraying in that section of Miami. The UK government has issued a Travel Warning, for Pregnant women, or women who are trying to get pregnant, for the Miami area.  So, I think the answer to your question about Zika and DDT doesn't have a proven answer at this time.   

[TravelingChris]

They used way too much DDT back then.  It was more than what was needed.  I don't know what they are going to do about the mosquitoes.  If I was a pregnant woman, I would be drenched with deet, I guess, but who knows what that would do?  Be inside all the time except for the short walk to the car and to the next indoor place you need to be?  And not only do the pregnant woman have to do this but their husbands have to do this before their wives get pregnant (at least six months before according to the latest recommendations).  

[Sk8ermaiden]

All I know is that when I grew up, I never saw a single raptor.  No falcons, no hawks, no eagles, no vultures.  Not a single one.  

 

Now I see multiple ones daily.  I remember being so excited the first time I saw one sailing over the highway.  Now it's commonplace.

 

Raptors were supposed to be one of the populations most affected by DDT (because it softened their eggshells and the babies wouldn't survive - top of the food chain got the most cumulative effect vs. smaller or seed-eating birds).  Really... zero for years and years on end, to multiple sightings of multiple species per day.

 

PS.  I have not moved since I was a kid.  Still live within 30 miles of where I grew up - so that's not it.

 

We had a presentation at a state park by a well known and respected birds of prey sanctuary, and they explained the ways in which DDT seriously endangered the raptors. 

 

I don't know anything beyond that really.

[Ausmumof3]

It was more environmental than health risk related wasn't it? In pretty sure the bird decimation factor was pretty major.

[Guest]

I'd take completely extinct species of birds as an alternative to the hundreds of thousands of people dead from malaria, or the physical ravages of zika and other similar infections. The studies on the deleterious effects of ddt on humans and animals aren't as substantiated as reports make them out to be (though it has been a decade or so since I last seriously looked and new data may be out). But given the consequences of mosquito borne illness? Very little outweighs the direct correlation between less mosquitos and less loss of human life from what they carry and spread.

 

That's my .02, others obviously disagree.

Edited August 3, 2016 by Arctic Mama

[Katy]

It was more environmental than health risk related wasn't it? In pretty sure the bird decimation factor was pretty major.

 

The reported health issues have to do with theoretically killing nerve tissue and lowering fertility, at least in the handful of recent articles I read.  There didn't seem to be anything substantiated, but again, never trust science reports from journalists.

[Melissa in Australia]

I vaguely remember there was some major detrimental effect on cattle- or the ability to sell cattle. that was directly related to DDT.

[Ausmumof3]

I vaguely remember there was some major detrimental effect on cattle- or the ability to sell cattle. that was directly related to DDT.

Yeah I think my dad said there was a huge decline in bird population where they were. I get the human life is more important argument but often mass impact on some part of the bio cycle does impact on human life at some point in time.

[Melissa in Australia]

quite frankly I am completely shocked that there is even a discussion on bringing back DDT use. IS this something proposed in USA? DO people not learn form recent history at all????????

[rose]

When I was in college I did a research paper on DDT. As far as I can remember the harmful effects are all in animals. There have actually been reports of people unsuccessfully trying to consume large amounts of DDT to commit suicide and have been unsuccessful. My mother remembers running through clouds of DDT behind her fathers tractor as a child. Now, she not exactly a poster child for health but her sisters are much healthier and they did the same thing.

 

I feel a little sad that the issue of DDT use has come up now that Zika has hit US soil. I've thought for years that if malaria was in the US killing thousands upon thousands of US children each year DDT would be available at every corner store. We have friends that are missionaries in Papua New Guinea and they've ravaged by constant malaria. It affects everybody in their community on an ongoing basis. Malaria is much worse than Zika and yet it's largely ignored because it's old news. I definitely think that this issue should be revisited with compassion in mind.

[Guest]

When I was in college I did a research paper on DDT. As far as I can remember the harmful effects are all in animals. There have actually been reports of people unsuccessfully trying to consume large amounts of DDT to commit suicide and have been unsuccessful. My mother remembers running through clouds of DDT behind her fathers tractor as a child. Now, she not exactly a poster child for health but her sisters are much healthier and they did the same thing.

 

I feel a little sad that the issue of DDT use has come up now that Zika has hit US soil. I've thought for years that if malaria was in the US killing thousands upon thousands of US children each year DDT would be available at every corner store. We have friends that are missionaries in Papua New Guinea and they've ravaged by constant malaria. It affects everybody in their community on an ongoing basis. Malaria is much worse than Zika and yet it's largely ignored because it's old news. I definitely think that this issue should be revisited with compassion in mind.

 

You're not alone in this.

[EmseB]

After so long I can't believe we still don't use DDT. And that people still believe Rachel Carson's "science".

[Bluegoat]

I think the science shows pretty clearly that DDT has serious ecosystem effects, and that isn't just about animals.  We live in the ecosystem as well.

 

OTOH, in general there can be a big difference between using a dangerous chemical in a very limited, directed, and careful way, and using it the way chemicals were applied in the first half of the 20th century and Victorian period. 

 

I do feel like there is a lot of hysteria going into decision making about Zika though, which doesn't tend to make for good decisions, or careful ones.

[ktgrok]

I think the science shows pretty clearly that DDT has serious ecosystem effects, and that isn't just about animals.  We live in the ecosystem as well.

 

OTOH, in general there can be a big difference between using a dangerous chemical in a very limited, directed, and careful way, and using it the way chemicals were applied in the first half of the 20th century and Victorian period. 

 

I do feel like there is a lot of hysteria going into decision making about Zika though, which doesn't tend to make for good decisions, or careful ones.

 

Yes, this. And sometimes using a "less dangerous" chemical is larger amounts does even more harm. Coating mosquito nets or whatever is different than spraying it EVERYWHERE. I think we could do some science on this and find a safe way to use it. 

 

Of course, I'm currently pregnant and living in the only state with native Zika cases, so I may be biased. I live in Orange County, which doesn't have native cases YET, but is the third highest county regarding travel cases. It's a matter of time, honestly. I'm just trying to stay indoors and avoid touristy areas, as I figure the less people I'm around the less likely a mosquito that bit an infected person will bite me. 

[prairiewindmomma]

Time, Newsweek and other "legitimate" publications had pieces on bringing back DDT early this spring. Personally, I think it would be prohibitively detrimental to do so. There are other strategies out there (like releasing genetically modified sterile mosquitos to lower breeding rates, environmental cleanup, etc.) that are proven and more likely to bring success.

 

It is fairly well known that A. Aegypti are becoming DEET resistant, but permethrin and a couple of other pesticides are still effective.

[Bluegoat]

Time, Newsweek and other "legitimate" publications had pieces on bringing back DDT early this spring. Personally, I think it would be prohibitively detrimental to do so. There are other strategies out there (like releasing genetically modified sterile mosquitos to lower breeding rates, environmental cleanup, etc.) that are proven and more likely to bring success.

 

It is fairly well known that A. Aegypti are becoming DEET resistant, but permethrin and a couple of other pesticides are still effective.

 

Yes, it's always important to talk about what the other options are, and also I think to remember to consider what the longer term outcomes might be of doing nothing.  Sometimes nature will resolve issues in the middle-long term and interfearing will only compromise that.

 

A vaccination might be better than any kind of environmental solution.

 

Given that we don't really know or understand much about Zika, it seems hard to say what the long term outcomes of doing nothing would be.

[prairiewindmomma]

I agree, Bluegoat. Any time a new virus enters an environment, it tends to cause a lot of disease and disruption and after the populace is exposed and gains immunity an equilibrium sets in. We just need to ride out this next year or two.

 

Chikungunya, Dengue, and a variety of other vector borne diseases are affecting the US now as our climate changes and international travel is so common. We need to think about longer term options (and actually fund them!)

[Dmmetler]

The problem is that it's all one ecosystem. Remove raptors as collateral damage due to use of DDT to reduce mosquito borne infections, and you have likely really increased rodent borne ones, like Hantavirus, Lyme disease (carried by insects carried by rodents) and Bubonic plague due to an absense of predators. Things like this are what gives ecologists (and public health specialists) grey hairs, because it's not "people are more important than animals" or vice versa-it's that changes can have catastrophic effects down the road. And small scale studies (which indicate DDT may be manageable with little effect on the larger Avians) don't necessarily scale up well.

Edited August 3, 2016 by dmmetler

[MistyMountain]

Wiping out a species into extinction to use one pesticide is not something that is a good solution. I do not trust humans to not mess up. We do not have a good track record. We are heading into the 6th major extinction because of human actions and climate change. A animal on the top of the food chain like birds of prey are very important for an ecosystem. Killing them puts others off balance. There are other ways to address the Zika virus. Humans should not have the right to destroy our planet. Diseases will come and mutate but there are other ways of addressing that.

Edited August 3, 2016 by MistyMountain

[Lanny]

Not about DDT, but on the 6 P.M. Evening News from the USA tonight they reported that the State of Texas is going to provide Pregnant women with something (obviously not DDT) that will hopefully protect them.  There are about 90 cases of Zeka in Texas, all travel related.  Here in Colombia I believe the worst of the Zika thing is over and that it is subsiding.

[hjffkj]

Not about DDT, but on the 6 P.M. Evening News from the USA tonight they reported that the State of Texas is going to provide Pregnant women with something (obviously not DDT) that will hopefully protect them. There are about 90 cases of Zeka in Texas, all travel related. Here in Colombia I believe the worst of the Zika thing is over and that it is subsiding.

Pregnant women who receive Medicaid will be covered with 2 cans of bug repellant a month in Texas. As far as I can tell it is only pregnant women who have Medicaid.

[EmseB]

Silent Spring came out in 1962 or some such.  It was filled with questionably done science and anectdotal evidence.  It is part of the reason that, today, in 2016 a lot of people think anything with "chemicals" in it is bad.  Reading even parts of it remind me of the anti-vaxxers of today.  Technology for application and general knowledge have increased exponentially since she came out with her book, which was not well done in the first place.  Science has proven that to continue with a total ban is just based out of fear, not out of any actual danger of destroying an ecosystem or species.

 

I seriously cannot believe people think that there is no room for judicious application of a substance that is known to solve the problem because of environmental fear mongering from the 1960's.  Yes, birds of prey are part of the ecosystem, but so are those babies born with microcephaly.

[MistyMountain]

The effects of DDT on the eggs of birds of prey is well known and not just from Rachel Spring. It did cause the decline of many birds of prey. In warm tropical areas mosquitos have developed a resistance to DDT since their season is longer and they have time to develop a resistance to it.

Edited August 4, 2016 by MistyMountain

[ktgrok]

The resistance thing makes the idea probably moot. I heard yesterday on NPR that the mosquitoes in some areas did start to develop a resistance to DDT, which is why the Malathion isn't working well either....that all the chemicals we have are similar in structure chemically to DDT and the mosquitos are resistant to all of them as a result, that what we really need are NEW chemicals, but no new ones have been developed in years and years. 

 

Also, as an aside, here is a link to the rankings of repellants by Consumer Reports..you can see how many hours they are effective against various mosquitos, including the Aedes mosquito. Many popular brands are MAYBe an hour of protection! Also, they said lemon eucalyptus (they being the scientists on NPR yesterday) said NOT to use lemon eucalyptus on children under 2 years old, but you could use DEET safely on children as young as 10 months. One of those cases where natural doesn't mean safer. 

 

http://www.consumerreports.org/cro/health/beauty-personal-care/insect-repellent/insect-repellent-ratings/ratings-overview.htm

[Katy]

In Oklahoma our backyard was filled with bugs.  After we got lime disease in the backyard we tried a yard spray called Cutter Natural that's made of essential oils like lemongrass and rosemary oils (I think there were like 8 oils).  We could find it at Walmart or Home Depot. The bottles screw onto a hose, and you can spray the yard with it.  You could see swarms of mosquitoes and the like flying away as the lawn was sprayed.  The only problem was it would only last until the next heavy rain - not ideal for summertime in Florida where, at least in North & Central Florida, it is likely to rain almost every summer afternoon for 20 minutes to two hours.  Perhaps it's more dry in South Florida, I've never looked into it.

 

Now I'm told this stuff is completely safe, but since some of the oils have estrogenic effects the rule was that no one could go outside for three hours after the lawn was sprayed, and DH would take a shower as soon as he came inside.