Looks like more of a "Challenge" than a deal breaker, IMO. Let's examine some excerpts from your article/link.
Toxic Mars: Astronauts Must Deal with Perchlorate on the Red Planet
The pervading carpet of perchlorate chemicals
found on Mars may boost the chances that microbial life exists on the Red Planet
— but perchlorates are also perilous to the health of future crews destined to explore that way-off world.
Perchlorates are reactive chemicals first detected in arctic Martian soil by NASA's Phoenix lander that plopped down on Mars over five years ago in May 2008.
It is likely both of NASA's Viking Mars landers in 1976 measured signatures of perchlorates, in the form of chlorinated hydrocarbons
. Other U.S. Mars robots
— the Sojourner, Spirit and Opportunity — detected elemental chlorine. Moreover, orbital measurements taken by the Mars Odyssey spacecraft show that chlorine is globally distributed
And more recently, NASA's Curiosity rover found perchlorates
within Gale Crater, where it landed in August 2012. [Missions to Mars: Robotic Invasion of Red Planet (Infographic)
Hydrocarbons in any form can be a "good thing" as they are components in organic life and if no life is present ~ or past ~ on Mars, these compounds mean less material to transport there for sustaining the life of any future human explorers~colonists.
Finding calcium perchlorate "was one of our most unexpected results," said Peter Smith, the Phoenix principal investigator at the University of Arizona in Tucson.
"Perchlorate is not a common word in the English language; all of us had to go and look it up," Smith said during Spacefest V, a conference held May 24-27 in Tucson, Ariz. "Perchlorate has become an important component of the soil … and half a percent is a fair amount," he said.
Smith said microbes on Earth use perchlorate for an energy source. They actually live off highly oxidized chlorine
, and in reducing the chlorine down to chloride, they use the energy in that transaction to power themselves. In fact, when there's too much perchlorate in drinking water, microbes are used to clean it up
, he said.
Furthermore, seasonal flow features seen on Mars may be caused by high concentrations of the brines of perchlorate, which has a strong attraction to water and can drastically lower its freezing point, Smith told SPACE.com.
"Anybody who is saying they want to go live on the surface of Mars better think about the interaction of perchlorate with the human body," he warned. "At one-half percent, that's a huge amount. Very small amounts are considered toxic. So you'd better have a plan to deal with the poisons on the surface."
Any humans exploring Mars, Smith said, will find it hard to avoid the finest of dust particles. "It'll get into everything…certainly into your habitat."
Given Mars has nearly no magnetic field and a very thin atmosphere (@1/100th as thick as Earth's), humans on mars will likely spend most of their time living "under" Mars, using it's surface material/"soil" to cover their habitats. Initial and early human habitation on mars wil be much like our "bases" on/in Antarctica. Antarctic bases being an excellent starter template for what would be needed for human habitats on Mars.
But Smith also noted that perchlorate is used within the pyrotechnics industry, and ammonium perchlorate is also a component of solid rocket fuel. "So maybe you can mine it as an on-the-spot resource," he said.
There's a plus side. Might be able to refuel rockets used to get there, providing Earth bound propellent.
Perchlorate has made, and continues to make, the search for organics on Mars all but impossible
, said astrobiologist Chris McKay of NASA's Ames Research Center in Moffett Field, Calif.
"Its presence is good news for the possibility of life on Mars
…but very, very bad news for humans, McKay told SPACE.com. "Once again, Mars is full of surprises."
"It's bad for astronauts because it is toxic for humans, as it interferes with the thyroid," he said.
The research emphasizes that perchlorate is widespread in Martian soils at concentrations of between 0.5 to 1 percent. There are dual implications of calcium perchlorate on Mars. On one hand, at such concentrations, perchlorate could be an important source of oxygen.
But it could also become a critical chemical hazard to astronauts.
In the forthcoming paper, the researchers propose a biochemical approach for the removal of perchlorate from Martian soil that would not only be energetically cheap and environmentally friendly, but could also be used to obtain oxygen both for human consumption and to fuel surface operations.
An indicator/product of life perhaps, makes finding life difficult or worse, and could "food" for microbial life. Seeming contradictions here, but bottom-line looks as if the "biochemical approach" might be something to work into the "artificial biosphere" portion of any long term habitats where recycling air, water and waste while trying to grow food would be essential life-support systems.
In many ways, managing calcium perchlorate exposure on Mars
is viewed as no different than managing for example, uranium, lead or general heavy-metal-contaminated areas in modern mines, where dust suppression, dust extraction and regular blood monitoring are employed. Other ideas suggested by the study team include a wash-down spray that can clean suits and equipment of dust deposits.
More proposals are on the table, too. For instance, Mars suits could be kept on the outside of extravehicular activity rovers or habitation modules.
The astronauts would climb into their suits through a bulkhead opening, and then the suits would be sealed from within. Thus, Mars crews avoid coming into contact with outside materials.
Again, we see some work-arounds, solutions for how to deal with and/or make use of this condition.
NASA has identified key strategic knowledge gaps that need to be addressed before humans can be sent to Mars. Two key areas are the potential hazards to humans, and the existence of resources that can support human and robotic operations
"I'd put it in the category of, this is exactly why we do robotic exploration before sending humans,"
Doug Archer, a scientist with the Astromaterials Research and Exploration Science Directorate of NASA's Johnson Space Center in Houston, said of the perchlorate research.
Archer said perchlorate's existence on Mars would have posed an even larger problem had it not been discovered.
"But now that we know it's there, I am confident we will be able to design around it,
" he said. "I have a lot of co-workers here at Johnson Space Center who work in the human exploration side of things, and none of them seem to think perchlorate is a showstopper.
So sending robotic explorers as precursors to human exploration is shown to be a very useful strategy."
So some more problems/challenges/issues to deal with, which don't look like dealbreakers, suggest some useful work arounds, and underscore the value of more remote-rover survey's while fleshing out what sort of gear and habitat structures would be needed on Mars ... when the time comes ... likely decades from now ... for humans to make that voyage.