(Bloomberg) -- President Donald Trump returned to the lectern Thursday after a government scientist’s presentation about studies showing that sunlight, humidity and disinfectants kill the coronavirus on surfaces -- in some cases within seconds.
What Trump suggested next later sparked warnings from doctors and manufacturers of household cleaners.
Bill Bryan, an undersecretary at the Homeland Security Department, told reporters during the White House’s daily task force briefing that research had shown bleach could kill the virus in saliva or respiratory fluids in five minutes and isopropyl alcohol could kill it even more quickly.
“The disinfectant knocks it out in a minute. One minute,” Trump said in response to the presentation. “Is there a way we can do something like that by injection inside?” He said it would be “almost a cleaning. It gets in the lungs and does a tremendous number on the lungs.”
On Friday morning, the maker of Lysol and Dettol, Reckitt Benckiser Plc, issued a statement that “under no circumstance” should its disinfectant products be administered into the human body, through injection, ingestion or any other route. The company said it was issuing the guidance after it was asked whether internal administration of disinfectants “may be appropriate for investigation or use as a treatment for coronavirus,” amid recent speculation and social media activity.
The office of Maryland governor Larry Hogan — a Republican — said a state government hotline was flooded with calls Friday morning from people asking about the president’s comments.
The calls prompted the state to issue a warning to residents not to ingest disinfectant.
ALERT🚨: We have received several calls regarding questions about disinfectant use and #COVID19.— Maryland Emergency Management Agency (MDMEMA) (@MDMEMA) April 24, 2020
This is a reminder that under no circumstances should any disinfectant product be administered into the body through injection, ingestion or any other route.
Warnings were echoed by doctors and researchers. Bleach is a toxic chemical, and inhaling it could damage the lungs.
“Inhaling chlorine bleach would be absolutely the worst thing for the lungs,” said John Balmes, a pulmonologist at Zuckerberg San Francisco General Hospital, and a professor of medicine at the University of California, San Francisco. “The airway and lungs are not made to be exposed to even an aerosol of disinfectant.”
“Not even a low dilution of bleach or isopropyl alcohol is safe,” Balmes said in a telephone interview. “It’s a totally ridiculous concept.”
Mayor Marty Walsh was asked about Trump’s comments Friday. Walsh said he didn’t see the briefing but heard about the comments, which he called “scary.” No elected official, Walsh said, should be “passing information like that along” or “even insinuating” a remedy like that. He said elected officials should defer to public health specialists when it comes to giving medical recommendations.
Following the backlash, President Trump and the White House offered conflicting explanations for his comments.
White House press secretary Kayleigh McEnany scolded the media for “negative headlines” and said his comments were taken out of context.
“President Trump has repeatedly said that Americans should consult with medical doctors regarding coronavirus treatment, a point that he emphasized again during yesterday’s briefing. Leave it to the media to irresponsibly take President Trump out of context and run with negative headlines," she said Friday morning in a statement.
But Friday afternoon, Trump shifted again and tried to suggest his comments were meant to be sarcasm.
“I was asking a question sarcastically to reporters like you just to see what would happen," he said.
Thursday’s coronavirus briefing from the White House began innocuously enough. More than 870,000 people in the U.S. have been confirmed infected with Covid-19 and more than 49,000 have died. About 20,000 new cases were added on Thursday.
Bryan said that new U.S. research showed the coronavirus doesn’t last as long on door handles and other nonporous surfaces when it’s exposed to sunlight, higher temperatures and humidity.
He suggested “increasing the temperature and humidity for potentially contaminated indoor spaces” in order to kill the virus on surfaces. At a temperature of 70 to 75 degrees Fahrenheit and 80% humidity in the summer sun, for example, the research showed the virus would last just two minutes on a porous surface. Dry environments, Bryan said, may require “extra care.”
Trump has previously expressed interest in whether summer weather would end the outbreak of the virus, suggesting in February that warmer spring temperatures could eliminate cases by this month.
Trump appeared intrigued by the research after Bryan’s presentation.
“Suppose we hit the body with a tremendous ultraviolet or just very powerful light,” Trump said, following Bryan’s presentation. “I think that hasn’t been checked but you’re going to test it.”
Researchers could also bring “the light inside the body” Trump said, “either through the skin or in some other way.”
The World Health Organization has warned against using UV lamps to sterilize any part of the body, saying it can cause skin irritation.
Disinfecting surfaces is an important practice in infection control. The coronavirus is fragile outside the body, and is essentially a packet of genetic information wrapped in a packet of lipids. Hand washing with soap is particularly effective in cleaning it and stopping transmission.
The U.S. Centers for Disease Control and Prevention has warned Americans to be careful with cleaning products in their rush to use cleaners and disinfectants, which have been snapped up from store shelves and are still hard to find at many retailers. Poisonings related to cleaners and disinfectants rose significantly in March, according to the CDC. In one case, a woman was sent to the hospital after filling her sink with bleach solution, vinegar and hot water to soak her vegetables.
As some U.S. states begin planning to roll back social-distancing restrictions, an important question has become whether summer heat might affect the virus — and whether the fall might bring a new outbreak, as some experts inside and outside the government have suggested.
Weather and UV rays are often an important factor in the transmission of infectious diseases. Transmission of the flu, for example, is often correlated with cold temperatures and dry air. One study found that in northern Europe, low temperature and low UV indexes coincided with peaks of the flu virus in the period between 2010 and 2018.
“We know that respiratory viruses are quite seasonal. Coronaviruses are also respiratory viruses, and we had hope and anticipation it would be, too,” said William Schaffner, an infectious disease professor at Vanderbilt University in Nashville, Tennessee. But, he said, not all coronaviruses show strong seasonal variation, and it’s not clear that this one will.
Scientists continue to research the new coronavirus, and the pathogen has circulated in parts of the world with high, humid temperatures. Singapore is experiencing a surge of cases despite hot, humid weather. And in the developed world, many people spend much of their time indoors in controlled, cooler, drier environments without direct sunlight.
Anthony Fauci, the National Institutes of Health scientist on the White House task force, said in an April 9 television interview that, “one should not assume that we are going to be rescued by a change in the weather. You must assume that the virus will continue to do its thing.”
Studies of other coronaviruses have suggested that certain types of UV light may act as a sort of disinfectant. Sunlight contains three types of ultraviolet light, and one of them, UVC is often used to sterilize medical equipment. In China and Italy, robots that disinfect using UVC light have reportedly been deployed in hospitals.
Some studies, however, have suggested the opposite. One recent study of cities in Southern China, for example, found that heat and UV rays seemed to have no impact on the virus.
Christina Prignano and Travis Andersen of the Globe staff contributed to this report.