The giant explosion at a fertilizer plant in West, Texas, that killed between 5 and 15 people likely released a cloud of caustic ammonia gas that could have drifted for miles, experts say.

Ammonia’s sharp odor gives a good warning of its burning properties, but thick clouds can quickly overcome victims before they can even get away. The gas can burn the lungs and eyes, causing blindness and permanent respiratory problems.

“It is a respiratory irritant of the highest order,” says Dr. Arch Carson, a toxicologist and pulmonary specialist at The University of Texas Health Science Center at Houston.

“It causes severe respiratory system damage, eye damage and incapacitates people so they are no longer able to escape from exposure and help themselves,” Carson said in a telephone interview.

“It makes it impossible to escape a cloud. They don’t know which way to go,” added Carson, a former corporate medical director for Chevron Phillips Chemical Company.

Ammonia gas is colorless and it may not ever be known how much was released in the explosion at the plant. But Carson believes a concussive blast like the one in West would have released a significant amount. “The explosion itself was fairly horrific,” he says.

Hospitals that are treating victims of the West blast say they are seeing mostly cuts, broken bones, respiratory problems and just a few burns.

John Goodpaster, director of the Forensic Sciences Program at Indiana University-Purdue University Indianapolis, says plenty of ammonia would have been released.

“If you have a fire that generates enough heat and put it (near) a tank that has ammonia gas or an ammonia gas/air mixture in it…it will spontaneously ignite and the whole container will explode,” Goodpaster said in a telephone interview.

“You are going to have a lot of ammonia left over. It is not going to be all consumed in the explosion,” said Goodpaster, an expert in bombs made from fertilizer.

Carson, who has treated people exposed to the type of anhydrous ammonia stored at the plant, says it corrodes tissue. “It’s terrible stuff and it’s all around, distributed throughout our country and our cities,” he says. Treatment would be the same as for any burn.

The chemical is used as an industrial refrigerant. “There are accidents – a forklift may back into a refrigerator piping system or someone may be exposed while servicing a refrigerator compressor,” Carson said. He’s treated patients who develop permanent respiratory damage after breathing in the gas.

Anhydrous ammonia is a thirsty gas that grabs water – and in the process can burn skin, the inside of the mouth, throat and lungs. People who breathe in the gas will know it right away – not only does it stink, but the irritation can cause choking, burning and gasping. A bad burn will bleed, causing a pink, frothy foam at the mouth. In extreme cases, victims can suffocate.

It can irritate the eyes and even blind people. Safety regulations require plants processing or using ammonia to have water stations so people can wash it away quickly if they are exposed.

There’s not much treatment beyond washing the affected area with plenty of water and then treating any burns. Carson says emergency room staff will treat victims of ammonia burns in the same way they’ll treat patients coming in with burns from the fire or smoke inhalation.

Carson says in the case of a release, people should stay inside, close doors and turn off air conditioners. “We are lucky this is a rural area,” he says. Any ammonia cloud will dissipate eventually. “Over the course of usually the first several miles, it can still be extremely hazardous,” he says.

Children are especially at risk, according to the Centers for Disease Control and Prevention. “Children exposed to the same levels of ammonia vapor as adults may receive larger dose because they have greater lung surface area to body weight ratios,” the CDC advises.

“In addition, they may be exposed to higher levels than adults in the same location because of their short stature and the higher levels of ammonia vapor found nearer to the ground.”

Even ammonia used for cleaning can be dangerous. “Contact with concentrated ammonia solutions, such as some industrial cleaners (25 percent), may cause serious corrosive injury, including skin burns, permanent eye damage, or blindness,” the CDC advises.

“The full extent of damage to the eyes may not be clear until up to one week after the injury is sustained.”

Household cleaners that contain ammonia carry a clear warning not to mix it with chlorine bleach or any other product containing chlorine. That’s because the chemicals will combine to form chloramine, a highly deadly gas. 

But ammonia isn’t poisonous and it’s not been shown to cause long-term effects such as cancer. It won’t build up in the environment.

Related:

'The whole street is gone': Bloodied eyewitnesses describe Texas explosion horror

Texas can cut off funding to Planned Parenthood's family planning programs for poor women, a state judge ruled Monday.

Judge Gary Harger said that Texas may exclude otherwise qualified doctors and clinics from receiving state funding if they advocate for abortion rights. 

The state has long banned the use of state funds for abortion, but had continued to reimburse Planned Parenthood clinics for providing basic health care to poor women through the state's Women's Health Program. The program provides check-ups and birth control to 110,000 poor women a year, and Planned Parenthood clinics were treating 48,000 of them. 

Planned Parenthood's lawsuit to stop the rule will still go forward, but the judge decided Monday that the ban may go into effect for now. In seeking a temporary restraining order, Planned Parenthood's patients could have continued to see their current doctors until a final decision was made. 

"We are pleased the court rejected Planned Parenthood's latest attempt to skirt state law," attorney general spokeswoman Lauren Bean said. "The Texas Attorney General's office will continue to defend the Texas Legislature's decision to prohibit abortion providers and their affiliates from receiving taxpayer dollars through the Women's Health Program." 

Ken Lambrecht, president and CEO of Planned Parenthood of Greater Texas, said he brought the lawsuit on behalf of poor women who depend on its clinics. 

"It is shocking that once again Texas officials are letting politics jeopardize health care access for women," Lambrecht said. "Our doors remain open today and always to Texas women in need. We only wish Texas politicians shared this commitment to Texas women, their health, and their well-being." 

Planned Parenthood has brought three lawsuits over Texas' so-called "affiliate rule," arguing it violates the constitutional rights of doctors and patients while also contradicting existing state law. 

Republican lawmakers who passed the affiliate rule last year have argued that Texas is an anti-abortion state, and therefore should cut off funds to groups that support abortion rights. Gov. Rick Perry, who vehemently opposes abortion, has pledged to do everything legally possible to shut down Planned Parenthood in Texas and welcomed the court's ruling. 

"Today's ruling finally clears the way for thousands of low-income Texas women to access much-needed care, while at the same time respecting the values and laws of our state," Perry said. "I applaud all those who stand ready to help these women live healthy lives without sending taxpayer money to abortion providers and their affiliates." 

The Texas Health and Human Services Commission has spent the last nine months preparing to implement the affiliate rule. But federal officials warned it violated the Social Security Act and cut off federal funds for the Women's Health Program, prompting the commission to start a new program using only state money. 

State officials have also scrambled to sign up new doctors and clinics to replace Planned Parenthood. Women who previously went to Planned Parenthood clinics will now have to use the agency's web site to find a new state-approved doctor. 

On Friday, HHSC officials acknowledged they are unsure whether the new doctors can pick up Planned Parenthood's caseload in all parts of the state. 

Linda Edwards Gockel, a spokesman for the Texas Health and Human Services Commission, said Monday that the new state program will launch as planned on Tuesday. 

"We have more than 3,500 doctors, clinics and other providers in the program and will be able to continue to provide women with family planning services while fully complying with state law," she said. "We welcome Planned Parenthood's help in referring patients to providers in the new program." 

Democratic lawmakers continued to question whether women will have to wait longer for appointments and services. 

"I vehemently disagree with the state's efforts to blacklist a qualified provider and, thereby, interfere with a woman's right to choose her own provider," said state Rep. Donna Howard, D-Austin. "I will be submitting a letter to the Texas Health and Human Services Commission, requesting a list of approved providers to gauge the outreach of the new program, and ensure that all qualified women throughout the state have access to its services." 

Another hearing is scheduled with a different judge for Jan. 11, where Planned Parenthood will again ask for an injunction to receive state funding.

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West Nile virus is now in 48 states, has made nearly 1,600 people ill and killed 66 of them, federal health officials said on Wednesday. But don’t expect Hurricane Isaac, which is now dumping tons of rain on Louisiana, to make matters any worse, they said.

The case count keeps 2012 on track to be the worst year for West Nile since the virus first came to the United States in 1999, the Centers for Disease Control and Prevention said. And some of the sickest people will never fully recover, the CDC says.

“As of August 28, 2012, 48 states have reported West Nile virus infections in people, birds, or mosquitoes. A total of 1,590 cases of West Nile virus disease in people, including 66 deaths, have been reported to CDC,” the agency says.

“Over 70 percent of the cases have been reported from six states (Texas, South Dakota, Mississippi, Oklahoma, Louisiana, and Michigan) and over 45 percent of all cases have been reported from Texas.”

Health officials are not sure why West Nile is so bad this year or why Texas has been so hard-hit. The very hot summer may have been a factor, but viruses like West Nile have complicated and hard-to-follow life cycles, they said.

West Nile is spread by infected mosquitoes, which breed in water. But CDC officials said they doubted Hurricane Isaac would worsen the epidemic, because mosquitoes like stale, standing water, which is likely to be washed away by a hurricane.

The CDC’s Dr. Lyle Petersen, an expert on mosquito-transmitted disease, says the virus has to pass from mosquitoes to birds and back to mosquitoes to take hold in an area, and big storms mess up that cycle of transmission. “The end result is that hurricanes and floods do not have a major impact,” Petersen told reporters in a conference call.

“Heavy rainfall can certainly eliminate breeding sites rather create them,” he added. But in the weeks after a storm, pools of water can form and make new sites for the insects, he added. After Hurricane Katrina struck the Gulf coast in 2005, a few more cases of West Nile were reported but that was more likely because so many people were outside, repairing homes and cleaning up debris, he said.

“We continue to preach the message of making sure you are raining your yards,” said Texas state health commissioner Dr. David Lakey.

Heat could be a factor, also, if it incompletely dries up pools of standing water. “There has been a lot of speculation about the heat wave this year and could this partially have caused this effect, and the answer is yes,” Petersen said. But, he added, other heat waves have not led to outbreaks.  

 Officials in the Dallas area have been spraying pesticides to kill mosquitoes and Lakey and Peterson both said that should start cutting reported cases of West Nile there. It takes a few weeks for cases to be reported, so they said the number of reported cases will probably rise before it starts to fall.

More than half the cases reported so far this year have been of neuroinvasive disease – meaning the brain and spinal cord are affected. Peterson said it’s unlikely there’s an unusually high proportion of severe cases compared to years past. He notes that 80 percent of people infected with West Nile never even feel particularly sick, and it’s the serious cases that are more likely to get noticed and counted.

But people with neurological symptoms can be in serious trouble. There are three types – meningitis, which is inflammation of the spinal cord; encephalitis, which is when the brain is infected and inflamed; and acute flaccid paralysis, caused when both the brain and spinal cord are damaged. About one in 150 people infected with West Nile develop severe illness, according to the National Institutes of Health.

Patients with meningitis must be hospitalized but usually recover, Petersen said. About 10 percent of patients with encephalitis die, and those who survive may have subtle neurological effects long term. Patients who develop paralysis are in the worst trouble – a third recover, a third have some weakness long term and a third never recover, Petersen said. Some patients have had paralyzed limbs for years now.

Lakey says people of all ages have been affected, but the older people are, the more likely they are to be seriously ill. People with damaged immune systems, such as cancer patients, are at higher risk.

By the time patients with neurological symptoms get to the hospital, the virus has already invaded the nervous system, Petersen says. There’s no drug to treat West Nile virus anyway, and this effect makes it hard to develop one, because it’s hard to make a drug that can penetrate the central nervous system.

And because West Nile is so spread out and sporadic, it’s hard to even try to develop a drug or vaccine to fight it, Petersen said. Drug companies need lots of guaranteed cases of a disease to test whether a new vaccine or drug actually works.

“We are dealing with a low-incidence disease most years, (with) cases that are widely dispersed,” Petersen said. “The thought of trying to produce a phase 3 clinical trial to show efficacy is fairly daunting."

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As cases of West Nile virus continue to mount in what may be record numbers, government health officials are urging people -- particularly those in the worst-affected states -- to cover up, use insecticide and remove the standing water that helps fuel the mosquito-borne infections.

Cases of West Nile virus in the U.S. are about three times higher than normal for this time of year, officials with the Centers for Disease Control and Prevention said Tuesday, with at least 1,118 illnesses in what's being described as one of the worst outbreaks since the virus was detected here in 1999.

About half of the cases have been in Texas, where drought and heat, followed by rain, have contributed to the outbreak that has killed 19 people in that state. Forty-one have died nationwide, CDC says.

In normal years, fewer than 300 cases are reported in the U.S. by mid-August, with most illnesses typically reported in late August and September. It's difficult to tell how this season will progress, officials said.

CDC

Pesky mosquitoes are behind one of the worst-ever outbreaks of West Nile virus, health officials say.

A handful of states have seen the most infections, including Texas, Louisiana, Mississippi, Oklahoma, South Dakota and California -- but the virus can occur anywhere, CDC officials said.

West Nile virus, which is most often spread through the bites of infected mosquitoes, usually isn’t deadly. Only about 20 percent of infected people even realize they have it. Those who do develop symptoms of West Nile fever typically complain of headache, fever, tiredness and, sometimes, a rash.

But 1 percent of cases develop into severe disease, usually meningitis, an inflammation of the spinal cord.  They may die quickly or result in nerve damage.

The severe cases usually strike the elderly and those with impaired immune systems, but it’s important to prevent West Nile infection when possible.

Here are CDC’s top tips for avoiding West Nile virus.

• Use insect repellents that contain an EPA-registered active ingredient whenever you’re outdoors.
• Wear long-sleeved shirts and long pants outdoors at dawn and dusk, or consider staying indoors during those times, when mosquitoes are most active.
• Install or repair screens on windows and doors to keep mosquitoes out.
• Remove the standing water that allows mosquitoes to breed. That includes small pools of water in unlikely places such as flower pots, buckets and barrels. Change the water in pet dishes and replace the water in bird baths weekly.
• Drill holes in tire swings so that water drains out. Keep children’s wading pools empty and on their sides when they’re not being used.

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• West Nile outbreak in U.S. surpasses 1,100 cases
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Texas state health officials, alarmed by the worst outbreak of West Nile virus since the infection first hit the United States in 1999, started spraying insecticide from airplanes Thursday night.

Years of research show the poisons being used in the spray are safe for humans — and certainly safer than the virus, health officials said. But blogs and social media lit up with concerned comments from people afraid the insecticide might hurt them, their children or other creatures in the environment. 

“This is not science. It is ignorance, fueled by chemical corporations seizing the opportunity to poison everyone,” Judith Winchester, a Dallas-area designer, posted on the North Texas Poison Center 's Facebook page.

The poison center and state health officials, as well as the Centers for Disease Control and Prevention and the Environmental Protection Agency, say the spray being used is about as safe as an insecticide can be. Called Duet, it’s made up of two products, both synthetic versions of a chemical made by chrysanthemum flowers.

AP Photo/courtesy the Northwestern Mosquito Abatement District

Culex pipiens, left, is the primary mosquito that can transmit West Nile virus to humans, birds and other animals. The bite of this mosquito is very gentle and usually unnoticed by people. At right is an Aedes vexans. It is a very aggressive biting mosquito but not an important transmitter of disease.

“Risks with aerial spraying are very, very low, especially compared with the risk of disease,” said Carrie Williams, a spokeswoman for the Texas State Department of Health Services. “We believe it is a safe and very effective approach for Dallas.”

Insecticides first got a bad name back in the 1960s, when it became clear that DDT was killing birds by thinning their eggshells. Then it turned out it was a likely cause of human cancer, too, and it was banned in the U.S. in 1972.  And because so many insecticides are nerve agents, they have worried doctors, environmentalists and the public. There’s one class of pesticides called organophosphates that do appear to damage the nervous systems of people who get exposed to high amounts — farm workers, for example.

But the pyrethrins in Duet — that’s their chemical name – are formulated differently and work through a different mechanism. They kill mosquitos in very low doses. And they don’t affect mammals, humans included, in the same way they affect insects.

According to the National Pesticide Information Center (NPIC), a joint venture between Oregon State University and the EPA, pyrethrins work by blocking the nerve activity of insects and they kill adult mosquitos by direct contact. But they’re not as dangerous to bigger creatures, even birds.

“Pyrethrins are one of the least poisonous insecticides to mammals," the center says on its website. They break down quickly into inactive forms in the body and don’t build up in the soil. They do, however, kill honeybees and can poison fish and other aquatic life. That’s one reason that Texas is spraying at night – to minimize the effects on bees, butterflies and other beneficial insects.

They are used in pet flea and tick preparations and in lice control shampoo for humans. The EPA says they don’t cause cancer and don’t hurt pregnant women or their unborn babies.

Compare this to West Nile, which has made 30,000 Americans sick since it arrived in the New York City borough of Queens in 1999. “The 693 cases reported thus far in 2012 is the highest number of West Nile virus disease cases reported to CDC through the second week in August since West Nile virus was first detected in the United States in 1999,” the CDC says.

“Over 80 percent of the cases have been reported from six states (Texas, Mississippi, Louisiana, Oklahoma, South Dakota, and California) and almost half of all cases have been reported from Texas.”

West Nile itself isn’t especially deadly — only about 20 percent of infected people even know they have something, other than perhaps a mild cold. And most who develop symptoms get what’s called West Nile fever, which has the typical symptoms of many viruses — fever, headache, tiredness and, sometimes, a rash.

But 1 percent of cases get severe disease, usually meningitis, an inflammation of the spinal cord, or encephalitis, which is inflammation of the brain. These are usually older people are patients with suppressed immune systems. These symptoms can kill quickly or leave people with nerve damage such as paralyzed limbs.

There is no human vaccine for West Nile — there’s one for horses — and no real treatment. People with severe infections get supportive care such as IV fluids to make sure they don’t die of dehydration and breathing support if the nerve damage affects their ability to breathe.

The other chemical used as a defense against West Nile is DEET, an ingredient in the most effective insect repellents. It seems to stop mosquitoes from smelling their human victims. The NPIC says it’s very safe for people. “Nearly all of the DEET that is taken in through the skin is eliminated by the body within 24 hours of applying it,” the center’s website says. It also does not cause cancer and has been used safely by pregnant women.

Williams says the state health department is trying to address fears. “People have kids, they have pets,and we completely understand that people may be feeling apprehensive about this,” she says. “We have relied on the science to help us make the decision.”

And the department says spraying is only part of the answer to the problem. People need to cover up, use insecticide and,most of all, control standing water to stop mosquitoes from breeding. Even a small amount of water in a potted plant can provide a breeding ground for mosquitoes.

Related links:

• Texas sprayed as West Nile virus spreads
• Tenth West Nile death confirmed in Dallas
• West Nile virus on the rise