Start with one afternoon, because everything on this page happened in one.
A boy comes out of a house in the summer of 1976 and does not go back in until he is called. He drinks from the garden hose, thumb over the nozzle, water warm from an hour in the grass. Somebody’s mother hands out biscuits on the step and one goes on the ground, and he picks it up, blows on it, eats it. A single bottle of Coke goes round four children and comes back with a quarter left in it. The dog licks his face and later licks the plate. He makes a mud pie and tastes it, because that is what a mud pie is for. He comes in at six, runs his hands under the tap for about a second, and sits down to eat.
Nobody in that story did anything unusual. That was a Tuesday.
To see the video, go here.
What was going into him
We know what was going into that boy, which is the strange part, because at that exact moment the government was finding out.
Between 1976 and 1980 a national survey drew blood from American children, and among those aged 1 to 5, 88.2% came back at or above 10 micrograms of lead per decilitre. The average for that age group was 15.2. By 2011 to 2016 the same measurement gave 0.83, and the level at which an American child’s blood lead is now considered worth a phone call is 3.5. (EPA Report on the Environment; Environmental Health Perspectives, 2021; CDC reference value, 2021.)
Nine children in ten were carrying a burden that would empty a school today. And the road it took into them was that Tuesday: hands, dust, soil, mouth. The Environmental Protection Agency puts a young child’s intake at roughly 100 milligrams of soil and household dust a day, and rates its own confidence in the figure as low, because measuring it means chasing tracer elements through a toddler. (Exposure Factors Handbook, chapter 5.)
So that is the thing worth sitting with. The afternoon is now sold back to us as a prescription, dirt as medicine, the dog as an immune booster, and I have made that argument myself. But the medicine and the poison came down the same pipe, through the same hands, in the same mouthful. Only one of them was being measured at the time.
The part that holds up
Children who grow up on working farms, with animals moving in and out of the house, have strikingly less asthma and allergy than children who do not. That result is real, it has been found repeatedly, and the best study of it put early farm animal exposure at an odds ratio of 0.47 for asthma at age 7, which is a halving. (Fall and colleagues, JAMA Pediatrics, 2015.)
That is the strong end of this literature, and it is strong. Hold on to it, because almost everything else is softer than it sounds.
The part that does not
The family dog is not the farm. The same Swedish study followed 276,298 school-age children and found that a dog in the house during the first year of life gave an odds ratio of 0.92, about 8%, not the third that gets quoted. Among preschool children it also found dogs came with a slightly raised risk of pneumonia, 1.13. (the findings, summarised.) And families who already have asthma in them are less likely to get a dog at all, which bends every study of this kind before it starts.
The hose is worse than nostalgia allows. When somebody bought 32 garden hoses and tested them, 7 had at least 100 parts per million of lead in the plastic, 2 of those above 50,000. Water left standing in them came back at 13, 19 and 20 parts per billion of lead against a federal action level of 15, one sample carried BPA at 87 ppb, and phthalates turned up in 56% of the hoses, including 3 of the 10 labelled safe for drinking water. (Ecology Center, 2016.) Those were hoses sold in 2016 and water that had sat for two days, so be fair to the 1975 nozzle. But the modern parent buying the filtered bottle is not being squeamish. She is being right.
The five-second rule has been tested properly, which almost nothing in this argument has. A laboratory at Rutgers dropped watermelon, bread, buttered bread and gummy sweets onto steel, tile, wood and carpet at under a second, 5 seconds, 30 and 300, 2,560 measurements in all. Transfer happened instantly in every combination, and the wet food picked up as much as 97%. Moisture and surface mattered. Time barely did. (Applied and Environmental Microbiology, 2016.)
Hand sanitiser cannot be the villain, on dates alone. Purell was invented in 1988 and shops would not stock it for consumers until 1997, by which time childhood asthma and allergy had been climbing for over a decade. (History News Network.) It is a symbol of a sealed world, not a cause, and I have caught myself letting it play both parts.
And the friendly soil bacterium everyone mentions, Mycobacterium vaccae, has been through a proper trial in people. 210 patients with advanced lung cancer got it alongside chemotherapy and 209 did not. Median survival was 223 days against 225. Quality of life held up better, which matters. The survival line is flat. (Annals of Oncology, 2004.)
The other ledger
There is a column on the far side of that Tuesday that nostalgia never opens.
Before the vaccine arrived, invasive Haemophilus influenzae type b ran at about 20,000 cases a year in American children, meningitis in half to two thirds of them. Roughly 1 child in 200 got it before their fifth birthday. Between 3% and 6% of the meningitis cases died with correct treatment, and 15% to 30% of the survivors came out with hearing loss or permanent neurological damage. It is now down by more than 99%, and in 2018 there were 38 cases in the whole country. (CDC Pink Book, chapter 8.)
That is the bottle going round the step. Four mouths, one bottle, in a country where 1 child in 200 was going to get bacterial meningitis before they started school.
What the afternoon actually was
Both things came through the same door, and the boy chose neither. He was not taking a treatment and his mother was not neglecting him. He was simply outdoors in a world that had not yet been tested, and when the testing started it found a teacher and a neurotoxin sitting in the same handful of dirt. We pulled out the lead, which was the right call and is the single greatest public health achievement of his lifetime. We also sealed the house, and that bill arrived later, in a different currency, and is still being argued over.
The farm evidence is the piece to take seriously. The rest of that Tuesday is a good story, and I would rather tell you where the story runs ahead of the evidence than let it run.
Two things worth knowing if this is the first page of mine you have read. The allergy science itself, the hygiene hypothesis and what became of it, the peanut trial, the Amish work and the studies that argue against all of it, is laid out in full on the page for 70s Americans Didn’t Have Allergies. And the number you will have heard, 1 in 13 American children with a food allergy, comes from a survey of 38,408 households in which only 61% had a confirmed diagnosis. It is not a CDC figure, whatever you have been told.
The video this comes from: 6 Disgusting Reasons 70s Kids Never Got Allergies · the channel
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