

But it’s a nothing comment. Water has an LD50. It’s 90ml/kg. LSD has no known LD50 and has not been the sole cause of any known death. Drowning in it would not mean you died from LSD toxicity, you would die from asphyxiation. Sand doesn’t have a lethal dose but can still kill you. But it wouldn’t be from sand overdose.
Seconds is based on speed though. It’s literally how speed is defined. Distance over time. At 60mph you travel 88 feet per second. So if you count out the seconds between when the car ahead passes say a road sign and you pass the same road sign and it’s two seconds, there’s roughly 176ft between your two vehicles. If you’re going 25 mph, then two seconds equates to 73ft of space.
Which really gives you more space than car lengths per 10mph, so it’s safer. 10mph=~14fps. The average length of a car is 14ft. So you end up giving double the space if you count out 2 seconds.