As I mentioned last week, Marketplace is a 22 minute show and they did a 10-product countdown, giving them approximately 2 minutes per product, so they had to leave a lot of information out.
So, first things first: the Simple Green MSDS.
The ingredients of Simple Green All-Purpose Cleaner are:
|Ingredient||CAS Number||Percent Range|
|Ethoxylated Alcohol||68439‐46‐3||≤ 5%|
|Tetrapotassium Pyrophosphate||7320‐34‐5||≤ 5%|
|Sodium Citrate||68‐04‐2||≤ 5%|
|Fragrance||Proprietary Mixture||≤ 1%|
|Colorant||Proprietary Mixture||≤ 1%|
2-butoxyethanol is a general-purpose solvent that's good at lifting stuff that isn't water soluble, while itself being water soluble.
Ethoxylated Alcohol is a detergent and emulsifier. Not sure which of its roles it's supposed to be here for, or maybe it's both.
Tetrapotassium pyrophosphate is an emulsifier as well.
Sodium citrate is probably a buffering agent, used to keep the pH stable. It's also used in food as a preservative, but since this isn't a food, it's probably being used for its pH effect.
The fragrance and colorant I can't say anything about because it's proprietary, so they probably wouldn't tell me even if I asked. Apparently the smell is supposed to be sassafras. I don't think I've ever smelled real sassafras, so I don't know how accurate it is.
The Simple Green product claims of interest to somebody looking for greenwashing are: "An environmentally-sensitive non-toxic cleaner/degreaser [...] non-toxic and biodegradable".
CBC Marketplace says that Simple Green contains a toxic substance, the 2-butoxyethanol, which is listed by Environment Canada as a toxic health hazard that can damage red blood cells, and therefore the "non-toxic" claim is greenwashing.
Naturally I go see what EC has to say about this, and I found both the fact sheet and the regulation (plus a later update to the regulation) on 2-butoxyethanol. (Note: the fact sheet was written before the work was complete on the regulation, and has not been updated since to judge by the "regulation is expected to be released" date years in the past.)
So the fact sheet says, "Based on investigations in experimental animals, the risk assessment report concluded [in 2003] that chronic exposure to 2-BE could cause alterations in blood that are associated with hemolytic anemia." In the regulation that was developed, the limit for "any other non-aerosol cleaner" is 6%. The Simple Green MSDS says the 2-butoxyethanol concentration is less than 5%, and the company statement said it was 3.8%. So, well within what Environment Canada said was a safe concentration for indoor household use.
Just how toxic is 2-butoxyethanol, though? The assessment report that EC got has quite an extensive section on toxicity testing, which I'll try my best to summarize here.
Short term effects in all the animals tested started with reduced red blood cell count, with rats the most sensitive showing effects at oral doses of 100mg/kg body weight per day for a few days, but mice much less sensitive as they started to show effects at 500mg/kg per day. These effects reversed themselves once the dose was stopped and the body cleared itself of 2-butoxyethanol. To be pessimistic, we'll take the rat dose as being the dose at which the red blood cell count starts to be affected, and use an average adult human body weight of 62kg. This works out to 0.1g * 62kg = 6.2 grams swallowed to get a decrease in red blood cells, the first of the symptoms. Since Simple Green is 3.8% 2-butoxyethanol, you'd have to drink 6.2g/0.038 = 163g of the cleaning solution to get that dose. Note that this is pessimistic; the rats were by far the most sensitive of the animals tested, and test-tube trials of samples provided by humans and rats showed that human samples were also much less sensitive than rat samples. If human response is closer to the mouse response, you'd have to drink five times more to get a dose that would start to affect your red blood cells. You'd have to drink more again to get into changes in the internal organs.
Long term effects were basically the same, starting with low red blood cell count. Again, with rats being the most sensitive, the oral dose that caused female rats (but not males—it took about double the dose for male rats) was 82mg/kg per day over thirteen weeks. For the same "average person" of 62kg, this is 0.082g * 62kg = 5.1 grams pure or 5.1/0.038 = 134g of the cleaning solution every day for three months to get that dose. As above, this is the dose at which female rats start showing symptoms, and the other animals including humans are less sensitive.
Since this product is for cleaning and one generally doesn't drink cleaning solutions, the more likely way to get a dose of any size is either by inhaling vapour or by absorbing through the skin. The dose at which the first symptoms appeared was again in female rats, breathing air containing 31ppm of 2-butoxyethanol for 14 weeks. For male rats this was four times higher, and again, rats were the most sensitive. The US OSHA has set an exposure limit for workers of 50ppm for people working with the stuff for 8 hours per day, 40 hours per week. This is higher than what female rats living in it 24/7 showed effects at, but lower than what caused the first effects in all the other test animals exposed 24/7.
The actual maximum concentrations in the air during cleaning (and other uses) was measured and found to be well below the 8-hour exposure limit (page 166) for all tested applications except silkscreening and applying varnish. The concentrations of 2-butoxyethanol for the cleaning solutions most likely to be used in the home are below 3.8% (0.3% for the floor cleaning example), but Simple Green does say it's concentrated and that it should be diluted for most uses. Looks like a 1:10 dilution (about 0.3-0.4%) is a reasonable floor scrubbing solution, and exposes you to an average non-detectable and maximum 1/5th of the 8-hour exposure limit, flagged as an outlier. There was no information on ventilation in that table, so the 1/5th outlier value could very well be a small room with the door closed and no ventilation. The same document indicates that studies on humans showed eye irritation at 113ppm and headache at 100ppm, double the 50ppm 8-hour exposure limit (page 172) and 50 times more than the maximum exposure during floor washing. Red blood cell effects were not measurable at 195ppm, nearly double the concentration at which you get a headache. The same page indicates that in humans, effects on the blood are only seen in people who drank 30-60g of 2-butoxyethanol—or the equivalent of 789g of Simple Green. I can't imagine that would taste very good.
After looking at the toxicity data, it sounds like this stuff is quite safe even in its concentrated form, but if you have a pet rat that tends to chew through things it shouldn't, you might want to keep it safely separated from the bottle so it doesn't eat a hole in it and get a Simple Green bath.
It seems to me that the "non-toxic" claim that Simple Green makes about its formulation is true. I have only looked at the one ingredient that CBC Marketplace said was toxic, thus assuming they couldn't find anything about the other ingredients to get scared about and so they weren't toxic. As far as the "biodegradable" claim, many of the references I linked above also mentioned that 2-butoxyethanol degrades within a couple of days in air or water, so that would also be true.
Regarding the CBC Marketplace claims that 2-butoxyethanol is a toxic ingredient, yes, pure 2-butoxyethanol is toxic. However, they completely miss the concept of a dose response.
To use a different chemical as an example, oxalic acid vapour causes irritation above 1-2 mg/m3, where the 50ppm limit for 2-butoxyethanol is 242mg/m3 and irritation starts at about double that. The LD50 for oral oxalic acid in rats is 375mg/kg which is in the range of first symptoms for 2-butoxyethanol (100-ish for rats, 500-ish for mice), nowhere near killing them.
The reason I mention oxalic acid? Well, it's substantially more toxic than 2-butoxyethanol, and yet at a low dose, we eat it regularly. There are many healthy foods that contain oxalic acid, some up to a couple of percent. 2-butoxyethanol at 3.8% concentrated Simple Green solution vs. the orders of magnitude more toxic oxalic acid at 0.5-2% in swiss chard, spinach, rhubarb, parsley...
Oxalic acid—it's what's for dinner.
Obviously I'm not advocating drinking Simple Green. It's not food. But even getting a splash in your mouth isn't going to make you sick. (Although it might taste bad.)
My bottom line? I think next time I need to buy some cleaners, I may buy some Simple Green to see if it cleans as well as they say it does. It's definitely less toxic than the bleach-based cleaners currently in my cupboard. I'm getting more and more disappointed in CBC Marketplace as this show goes along.
10: Raid EarthBlends Multi-bug killer
9: Sunlight Green Clean Laundry Detergent
8: Obusforme EcoLogic Contoured pillow
7: Simple Green All-Purpose Cleaner
6: Eco Collection Bath Mitt
5: Vim PowerPro Naturals
4: Organic Melt Ice Remover
3: T-fal Natura frying pan
2: Biodegradable J Cloth
1: Dawn Antibacterial Hand Soap