# Tomato plants grown on human waste water effluent OK to eat? **URL:** \ **Category:** Factual Questions\ **Created:** [September 1, 2002, 6:06pm UTC](https://boards.straightdope.com/t/tomato-plants-grown-on-human-waste-water-effluent-ok-to-eat/126579 "2002-09-01T18:06:04Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![astro](https://avatars.discourse-cdn.com/v4/letter/a/9dc877/32.png) [@astro](https://boards.straightdope.com/u/astro)\ **Post date:** [September 1, 2002, 6:06pm UTC](https://boards.straightdope.com/t/tomato-plants-grown-on-human-waste-water-effluent-ok-to-eat/126579/1 "2002-09-01T18:06:04Z")
Because tomato seeds have a gelatinous coating they can survive a trip through the intestine and the sewer system and are often seen in the spray fields of waste water treatment facilities where the waste water sludge is treated and sprayed on fields as a nitrogen enhancer and more bio-friendly way of breaking down the waste. Not that these would be the first tomatoes of choice, but if I were hungry and desperate to wat them could these tomatoes potentially carry any pathogens, heavy metals or other harmful substances to the person consuming it because of the medium on which they were grown? [At the treatment plant](http://www.citywestwater.com.au/schools/cleaning.htm) > [@](#): > > While often undigested tomato plants and pumpkin vines sprout out of the sludge [EHUF 411 - PLANT PROPAGATION](http://www.cfr.washington.edu/classes.uhf.411/thought_provokers/thought_1_answers.htm) > [@](#): > > What happens to tomato seed which you “eat” when they pass through your body? > > - nothing, it passes through the human digestive tract intact and ends up ready to grow Example, when Gas Works Park was built, they were in the early years of starting to compost and use sewage sludge as an organic soil amendment. Many of the “mountains” there were filled and shaped with Seattle sewage sludge. The following year, the ground was covered with a terrific cover of tomato plants. We no longer encourage the use of sewage sludge for areas where you are going to be planting edible crops. ---
**Author:** ![Tuckerfan](https://avatars.discourse-cdn.com/v4/letter/t/eada6e/32.png) [@Tuckerfan](https://boards.straightdope.com/u/Tuckerfan)\ **Post date:** [September 1, 2002, 8:06pm UTC](https://boards.straightdope.com/t/tomato-plants-grown-on-human-waste-water-effluent-ok-to-eat/126579/2 "2002-09-01T20:06:48Z")
I would think that it depends upon how well the waste water is treated beforehand. There’s a city in California that uses basically a series of ponds, marshes and plants to purify its waste water to a high degree. (It’s located in a popular park!) I would imagine that plants grown in some of the later parts of that kind of treatment system would be safe to eat. Also, I doubt that if you were only going to eat one or two of the tomatoes from another site that didn’t clean its waste as well, you’d have anything to worry about. ---
**Author:** ![Hirsel](https://avatars.discourse-cdn.com/v4/letter/h/8c91f0/32.png) [@Hirsel](https://boards.straightdope.com/u/Hirsel)\ **Post date:** [September 1, 2002, 8:33pm UTC](https://boards.straightdope.com/t/tomato-plants-grown-on-human-waste-water-effluent-ok-to-eat/126579/3 "2002-09-01T20:33:10Z")
Hey my girlfriend is just doing a project about this question. This will be a report for the Danish government about, whether it is save to use human waste as fertilizer. The most important question is the question of human parasites, such as cryptosporidium. If you eat your tomato then chances are that you infect yourself with a human parasite, which gets passed on again and again. The parasites will die if there was enough time between sowing the tomato and bringing out the manure, but in the described case this was not the case. ---
**Author:** ![handy](https://avatars.discourse-cdn.com/v4/letter/h/b5a626/32.png) [@handy](https://boards.straightdope.com/u/handy)\ **Post date:** [September 2, 2002, 12:18am UTC](https://boards.straightdope.com/t/tomato-plants-grown-on-human-waste-water-effluent-ok-to-eat/126579/4 "2002-09-02T00:18:08Z")
My neightbor in California used it in the 70’s. He bought it at the store, its called MILORGANITE. Yes, they dry it & then you buy it in a bag. He had the best growing plants I ever saw & I ate a lot of them too. As a matter of fact, this is well covered right here dude: [http://www.milorganite.org/uses/pro\_faq.htm](http://www.milorganite.org/uses/pro_faq.htm) Or [http://www.milorganite.org](http://www.milorganite.org) They are kind of gentle about what’s in it & what it’s made of: “However, because Milorganite is a by-product of a wastewater treatment process, it must meet additional quality and safety standards not imposed on traditional fertilizers, and is further regulated by the U.S. Environmental Protection Agency and the Environmental regulatory agencies of individual states.” Yeah, believe it or not. ---
**Author:** ![Ringo](https://avatars.discourse-cdn.com/v4/letter/r/779978/32.png) [@Ringo](https://boards.straightdope.com/u/Ringo)\ **Post date:** [September 2, 2002, 8:21am UTC](https://boards.straightdope.com/t/tomato-plants-grown-on-human-waste-water-effluent-ok-to-eat/126579/5 "2002-09-02T08:21:43Z")
Correct me if I’m wrong **astro** , but I believe your question is _not_ whether or not it is safe to use human waste as fertilizer (which the Japanese have done without problem for a long time), but rather whether tomato seeds that have passed through a human digestive system produce fruit that is safe from contamination. ---
**Author:** ![AskNott](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/asknott/32/5790_2.png) [@AskNott](https://boards.straightdope.com/u/AskNott)\ **Post date:** [September 3, 2002, 12:38am UTC](https://boards.straightdope.com/t/tomato-plants-grown-on-human-waste-water-effluent-ok-to-eat/126579/6 "2002-09-03T00:38:46Z")
I’ll reply on two tracks: First, effluent from your city’s sewage plant probably should not be used for food fertilizer. The reason, changed in recent years, is that industrial waste contains metallic ingredients which can find their way into your tomato. The processing probably, probably kills bacteria before it can hurt you. Second, human waste that hasn’t been that thoroughly processed should not be used for growing food, ever. My older brother got hepatitis from eating the native food in S. Korea several years ago. The Koreans used human dung as fertilizer, directly. Folks would crap in the streets, and dung sellers would gather it to sell to farmers. Hepatitis survives digestion, and it finds its way into food plants. My brother spent months in the hospital. ---
**Author:** ![Spiratu](https://avatars.discourse-cdn.com/v4/letter/s/47e85d/32.png) [@Spiratu](https://boards.straightdope.com/u/Spiratu)\ **Post date:** [September 3, 2002, 5:17am UTC](https://boards.straightdope.com/t/tomato-plants-grown-on-human-waste-water-effluent-ok-to-eat/126579/7 "2002-09-03T05:17:36Z")
Sewage sludge used as fertilizer is called “biosolids.” According to my introductory Soils textbook (_Soil Science & Management_, Plaster, 1997), the main risks are from heavy metals that accumulate in human waste, such as lead, arsenic, and cadmium. There is no recorded case, according to the book, of a disease outbreak from pathogens in biosolids. Supposedly, up to 80% of the sewage sludge applied to land is used in agriculture nowadays (the rest going to landfills, i suppose). That said, however, my book also goes on to note that biosolids need to meet certain requirements before they can be used to grow plants for human consumption; that is, they have to be tested for heavy metals and pathogens before they can be applied. So, unless the sludge in question is already being used to grow some sort of crop, it’s probably a pretty good idea to assume that it’s not safe.