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Comment by mrob | Hacker News Reader

It's bad reporting. The actual numbers from the abstract are "22.1 ng/kg·day" for the worst case ingested dose, and "1000 μg/mL" for the tested toxic concentration. If you assume the solvent is water (solvent isn't specified in the abstract but water is the obvious choice) and convert the units to make it easier to compare, that toxic dose is "1,000,000,000ng/kg". There's no plausible way a toddler is going to accumulate that much within "days".

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At that rate it makes cumulatively about 36 mg of nanoplastics using this pathway over the average 70 year lifetime of average 70 kg human. That would be approximately 0.6 μg/mL concentration if all would accumulate, which is very unlikely. Sounds like there is no real need to worry.

1,000,000,000ng is 1kg, so that'd would be as much plastic as solvent by mass.

1,000,000,000ng = 1g

@Omin, @mda, just a side note: I recommend using the (centuries old, I guess) established typography rule and putting a space between the number and the unit symbol. See [1] for additional info.

[1] SI Unit rules and style conventions, https://physics.nist.gov/cuu/Units/checklist.html

I never understand this pedantry. The GP is commenting on a forum, not writing a research paper. Who cares how they write, as long as they're understood?

It's just visually jarring. Do you consider your use of spaces after commas and periods and capitalizing the first word in a sentence "pedantry"? To me it's at the same level.

This is a style issue. Not at all on the same level. The ISO standard defines a space, but many, many style guides suggest otherwise. E.g. Very often you will find advice to omit space for one-letter abbreviations (i.e. '100g' not '100 g') — I believe this specific one is in the Chicago Manual of Style.

Keep being you. We all have our weird things that bother us. Apparently the spaces issue is centuries old and used a minority of the time, so you've just got a lot of convincing to do. Maybe you can multiply your effects by writing bots that, for instance, submit github pull requests. Good luck!

hey at least they're not doing something absolutely and deliberately idiotic like putting the % in front of the number like a currency symbol.

It is specifically:

#15 Unit spacing

There is a space between the numerical value and unit symbol, even when the value is used in an adjectival sense, except in the case of superscript units for plane angle.

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