Author: Craig Bowron

Since our yard has more creeping charlie than all the kudzu in Georgia, we’ve been seriously thinking about having our lawn treated. The problem is those little green and white signs that warn “This Lawn Has Been Chemically Treated—Keep Children and Pets Off for 24 Hours.” Leery of both the chemical industry and a massive crabgrass infestation, I called the toll-free number of a major lawn-care company to ask what hazard the signs address.

“We’ve added a green dye to the treatment because some customers requested a way to recognize when their lawn had been treated,” the customer representative said. “And you don’t want to get that stuff on your kids and pets.”

“I thought it was because some of the chemicals you spray in there could be dangerous to kids,” I replied.

“Well, no. It’s so they don’t get any of that green dye on them,” she answered in Ari Fleischer style—consistent, if not entirely convincing. When I asked if she could tell me, just for kicks, exactly what chemicals my kids and pets would be playing in, she forwarded me to a local office. When the local fellow picked up, I recounted the green dye story.

“No, no, no, that’s not right,” he answered, clearly annoyed with his national coworker. “Our treatments have a fertilizer and a weed-control substance, and it’s the weed-control products that can be dangerous to kids,” he said. How dangerous—has anyone ever gotten sick? “No, we’ve never had any problem with it,” he assured me. “A kid would have to eat three times their weight to cause any harm.”

Of course, a child eating three times their weight in anything would not be healthy, but I let that slide. Instead, I made a few phone calls to the Minnesota Department of Health, where I talked with Chuck Stroebel at the Health Risk Assessment Unit in the Environmental Health Division.

He emailed me a bushel of pesticide fact sheets (broadly, pesticides include herbicides, fungicides, and insecticides). When we met at his St. Paul office a week later, I asked him what he thinks when he sees the green and white warning signs posted on a lawn.
“I think it’s just smart to minimize unnecessary pesticide exposure,” Stroebel explained. “Kids are at more risk because of their size and their hand-to-mouth activity, and pets because they tend to roll or lie in the grass.”

Looking through the pesticide safety data, I was surprised to see how well pesticides have been studied, both for acute and chronic toxicity and carcinogenic effects.

“Yeah, there’s fairly stringent regulation in pesticides in comparison to many other chemicals, because pesticides are designed to repel or kill a plant or pest. So there’s an immediate recognition that these could be dangerous.”

Naturally, it’s easy to scrutinize some toxins because of their intended use. If they are designed to kill things, we want to make sure they’re killing the right things, and experts are all over it, like flies on…well, you know. But consider PCBs. They weren’t designed to retard or kill anything, and yet we’ve found them to be harmful. “Very harmful, exactly,” he agreed.

For pesticides used in professional lawn treatments, here is the worst-case scenario: If you let the kids come out three hours later and have, say, a greased cat contest, some of the kids could develop minor skin and eye irritation.

“I think that’s accurate,” Stroebel nodded, “and you could track it into the house for a more prolonged exposure.”

So pesticide risk is a function of exposure. In other words, getting a weak solution on your feet is logarithmically safer than eating a handful of granules out in the garage. It seems like it might be safer to have a professional come out, rather than to do it myself and have the leftovers hanging around.

“Yes, and if you call a professional service, you’ve got someone who is applying the pesticide that’s a trained, licensed applicator, versus a homeowner who may be incorrectly diluting a product or putting it in the wrong area.”

Before leaving his office, I felt it my public duty to brief Stroebel on my earlier conversation, and the terrifying green dye that threatens lawn-tromping kids statewide. He did not stick up for other “experts” in this field. “It’s real hit or miss, depending on who you get,” he laughed.—Craig Bowron

Dave Neitzel’s view of the dog-eat-dog, mosquito-suck-bird world begins from his third-floor office in the faceless Minnesota Department of Health building, which sits quietly on the University of Minnesota’s East Bank campus. Neitzel is an ornithologist and entomologist who works on vector-borne and zoonotic diseases. He’s an expert on the West Nile virus.

It turns out the virus had a fairly innocuous arrival here in Minnesota last year. Slowly making its way across the state, it sent a few horses to Elysian Fields and several hundred birds went talons-up. But there were relatively few human infections.

“Fortunately, there were no West Nile virus deaths here in Minnesota,” remarked Neitzel. He said there were 48 cases, most of which resulted in not much more than a hat-stretching headache. Sixteen were more serious cases of meningitis and encephalitis, but no one died. On the wall behind him was a big state map with the 2002 West Nile data on it. I pointed to it and asked, “Any big surprise from last year’s Tote Board?”

“Yeah, there was,” he explained. “About three-quarters of our human cases were out in western or central Minnesota, and only a quarter of the cases were in the seven-county metropolitan area. That’s different than in the East, where most cases occurred in urban areas.” Down in Illinois, they had almost 900 cases—and most were right in Chicago.

It turns out that the mosquito that carries the virus is different here than down there. “Once you get west of the Mississippi River, the main bird-feeding mosquito becomes Culex tarsalis, a much more rural mosquito that develops in plains and semi-open country,” he explained. “We have some of those bugs that get into the metro, but mostly they’re out farther west.” I suppose they hate the traffic and vote Republican like everyone else.

This summer the Department of Health is asking Minnesotans to report any birds they believe may have died under what they call on their web site “unusual circumstances.” Now, short of flying kamikaze into the picture window, I wonder whether the public knows what the usual circumstances of avian death might be. “Right, it was kind of hard to word that,” Neitzel chuckled. “We certainly appreciate the help from the public—this surveillance is public-driven. But there has to be an understanding that we can’t test every bird. I had one guy in particular who was very mad because we didn’t pick up a crow he had seen on the side of Highway 394. And I tried to explain that was a bird that was most likely hit by a vehicle, and he said, ‘Well, it may have been sick and unable to avoid the vehicle…’” Neitzel trailed off, sensing the ridiculousness of the conversation all over again. But he was just getting warmed up.

“We had one person request that we test a mosquito they had found.” Neitzel laughed. “Another guy wanted information on Chronic Waste Nile Disease.”—Craig Bowron

Having seen all the news reports on the outbreak of Severe Acute Respiratory Syndrome, or SARS, I sat down with two physician colleagues of mine who specialize in infectious diseases and asked them the obvious: Are we all going to die?

“Yes,” they answered in unison and without hesitation. “Of course everyone dies,” Dr. Dan Anderson explained helpfully. He and Dr. Jason Sanchez work in Abbott Northwestern’s Infection Control department. “We just don’t know when or what from.”

Maybe this SARS thing is becoming an epidemic of hysterical proportions? “There’s some of that,” said Dr. Sanchez. “A patient asked me if they should cancel their trip to Washington D.C., so people do take leaps. The lay public is afraid to travel here in the U.S., and I don’t think anybody has told them to be. People came to those conclusions on their own,” he added. “But it is a serious, front-page issue.”

Definitely serious. It’s an infection with lethal potential, after all. But not even the World Health Organization is giving us any sense of proportion. Right now, the talk is all numerator, not denominator, and you need both to calculate risk. “There have been 80 or 90 deaths now, out of almost 4,000 suspected cases. But that’s 4,000 people who got sick enough to come to somebody’s attention,” noted Dr. Anderson. “But maybe it’s 90 deaths out of 10 million this year; no one knows.”

Here’s what the experts do know: The SARS virus is a member of the coronavirus family, whose members generally cause only mild respiratory illnesses. So why is SARS acting more like a Gambino family virus? “Take influenza for example,” Dr. Sanchez said. “Some of the major pandemics in the past are not just from minor mutations in the virus, what we call antigenic drift, but from a major re-assortment of the virus’ DNA that the population will not have immunity to. That’s called antigenic shift.”

So a few weeks back, maybe a coronavirus somewhere in China slipped into a genetic Glamour Shots, got a complete make-over, and walked out the door nearly unrecognizable to our immune system. If that happened, it would give a virus like SARS the chance to really get going before our bodies’ defenses could react.

But antigenic drift—the reshuffling of the genetic deck—has been going on since the beginning of time. What’s really revolutionized the infection world is, of course, the travel industry. More people flying more often to more places. Viruses are hitchhikers, and hitching a ride—a really fast ride—has never been easier. A SARS offspring can catch a 5 p.m. flight out of Hong Kong and be touching down at Heathrow by day’s end. That beats a sneeze of just about any magnitude.

“Read The Demon in the Freezer by Richard Preston,” suggested Dr. Anderson. “Part of it reviews how people like D.A. Henderson eradicated small pox in the 1960s and 70s. When they identified a case, they would treat or isolate everyone who had had contact with that person in the last two weeks. In Pakistan, in the late 1960s, how far might that net be cast—15 miles, 50 miles? And how far might that be today?”

Until we develop more rapid ways to identify new viruses (or the airline industry tanks, and we all agree to travel on foot), global health alerts, travel restrictions, and a bit of fear and loathing are here to stay. If the SARS virus does end up getting to the Pandemic Hall of Fame, we’ll have antigenic drift, the Wright brothers, and your local travel agent to thank for it.—Craig Bowron