Sulfur-Smelling Compost: Safe for Vegetables Yet?

Compost that smells like sulfur is not safe to use on vegetables yet. The rotten-egg odor means anaerobic bacteria are producing hydrogen sulfide and organic acids that can damage roots and contaminate edible crops. Turn the pile, add bulky browns, and cure it until it smells earthy and holds 130–150°F (54–66°C) for several days, usually 2–4 weeks.

You can smell hydrogen sulfide at roughly 5 parts per billion, which is about a hundred thousand times lower than the concentration that starts harming plant roots. That gap is why the nose is such a brutal early-warning system: by the time the pile reeks, oxygen has already dropped below the ~5% that anaerobic bacteria need to take over, and the compounds building up alongside H₂S include organic acids and mercaptans that will burn root hairs on seedlings. A pile that smells like this is almost always running cool, below 100°F (38°C), instead of the 130–150°F (54–66°C) that active aerobic decomposition should hold.

The mistake most growers make at this point is spreading it anyway and working it in, on the theory that air will fix it in the ground. It won't. Anaerobic compost applied to a bed keeps consuming oxygen in the soil pore space, and root damage shows up as yellowed lower leaves and stalled transplants two to three weeks later, long after you've stopped connecting the symptom to the amendment.

Two things decide how fast you recover. If the pile is wet and matted, break it apart, mix in straw, shredded leaves, or wood chips at roughly one part browns to one part existing material by volume, and turn it every two or three days. If it's already dry and just compacted, turning alone every other day is usually enough. Either way, the smell is your gauge, not the calendar.

• Odor threshold: Hydrogen sulfide is detectable at 0.0005 ppm (5 ppb), so any sulfur smell means the pile is anaerobic and not ready to spread.
• Root toxicity: H₂S damages plant roots at concentrations as low as 1 ppm in soil air, roughly 200,000 times the level you can smell.
• Target temperature: A working aerobic pile holds 130–150°F (54–66°C); sulfur-smelling piles typically sit below 100°F (38°C).
• Organic certification: USDA NOP rules require 131–170°F (55–77°C) for at least 3 days static aerated, or 15 days windrow with at least 5 turnings.
• Food-crop interval: FSMA guidance for biological soil amendments of animal origin sets a 120-day wait before harvesting leafy greens or root vegetables.

Why does my compost smell like sulfur and what is it doing to my vegetables?

That rotten-egg odor is hydrogen sulfide, and it is the exhaust of a pile that has run out of oxygen. When a pile turns wet and compacted, or gets buried under a crust that seals the surface, the thermophilic bacteria that need air die back and anaerobic bacteria take over. Those organisms metabolize sulfur-containing amino acids and sulfates instead of oxygen, releasing H₂S along with a family of volatile organic acids — acetic, propionic, butyric — that smell like vinegar, rancid butter, and vomit respectively. The gases are a byproduct of a decomposition pathway that also leaves behind compounds your plants cannot tolerate.

This matters because H₂S and the volatile organic acids are phytotoxic, not merely unpleasant. At concentrations well below what humans can detect — the OSHA odor threshold for hydrogen sulfide is 0.0005 ppm, or 5 parts per billion in air — these compounds damage root hairs, the fine structures that do most of the water and nutrient uptake. Seedlings germinated in fresh, anaerobic compost commonly fail to emerge, or emerge with browned, stunted roots. The damage shows up as yellowing, wilting, and poor establishment within days of transplanting.

Hydrogen sulfide production is also a reliable signal that the carbon-to-nitrogen ratio has collapsed. A well-built pile runs 25–30:1 C:N; a stinking one is often below 20:1, meaning someone has added too much grass clippings, manure, or kitchen waste and not enough dry, carbon-rich material. The excess nitrogen has no carbon to bind it, so it escapes as ammonia and feeds the anaerobic population. The smell is not cosmetic. It is a diffusive indicator that the biological conditions have shifted from the aerobic pathway that produces stable humus to one that produces organic acids, amines, and sulfides.

The practical takeaway: sulfur-smelling compost is not automatically ruined, but it is not safe for vegetables as-is. Fix the pile before it goes near food crops.

How do I know if my compost is actually unsafe or just immature?

Sulfur smell tells you the pile has gone anaerobic, not that it is poisoned. Hydrogen sulfide is detectable at 0.0005 ppm (5 ppb) in air, which is far below any concentration that would harm plants, so your nose is flagging a process failure long before the material itself becomes a hazard. The real question is whether the pile can be brought back into the thermophilic range, 113–160°F (45–71°C), where the bacteria you want outcompete the ones producing volatile organic acids and H₂S.

Work through the criteria below in order. Smell and temperature you can check today with a $15 compost thermometer; C:N and maturity need either a lab or a Solvita test kit, roughly $30–60 for a 4-pack of gel paddles.

Rows 1 through 3 landing in the left column means the pile is immature, not dead — turn it every 3–5 days per UC Cooperative Extension guidance, add browns until C:N is back at 25–30:1, and expect odor to clear in 2–4 weeks. Row 4 is the deciding factor for food crops: a Solvita index of 7 or higher (respiration under 2 mg CO₂-C per gram OM per day) is what you want before spreading on lettuce, carrots, or anything harvested within 120 days, because immature compost can still carry E. coli O157:H7 or Salmonella and FSMA's 120-day interval for untreated biological amendments exists for exactly that reason. The flip case is ornamentals and established perennials: immature compost at Solvita 4–5 is fine as a mulch there, since phytotoxicity from volatile organic acids matters most for germinating seed and young transplants. Only row 6 pushes you to discard outright — synthetic contamination does not compost out, and no amount of turning fixes painted lumber or PFAS-bearing biosolids. Even then, that is a contamination problem, not a sulfur problem, and the pile you are worried about this morning is almost certainly the fixable kind.

What steps will fix a sulfur-smelling compost pile fastest?

This plan assumes a pile that still has recognisable feedstock in it, not a finished product you are trying to rescue. If the material is already dark and crumbly and only smells when you dig into the centre, you have less work to do than someone with a wet, matted pile that has never been turned. The fix is mechanical and biological: get oxygen in, get the carbon-to-nitrogen ratio back above 20:1, and hold the pile in the thermophilic range long enough for the anaerobes to lose. Budget two to four weeks of active management and one or two bales of straw or a few bags of shredded leaves.

1. Turn the whole pile and break up the wet core. Not a cosmetic shuffle. Fork the material from the outside to the centre and the centre to the outside, and smash any matted clumps with the back of the fork. A 3x3x3 ft (roughly 1 m³) pile takes 20-40 minutes by hand; a windrow takes a tractor bucket. If the bottom six inches are sludgy and grey-black, scrape that layer out and spread it thin somewhere to dry before putting it back.
2. Add bulky browns and mix them in, not on top. Straw, dry leaves, shredded cardboard, wood chips, or sawdust. Aim for a C:N ratio of 25-30:1. In practice, if the pile smells like sulfur, your C:N is probably below 20:1, so you are correcting an excess of nitrogen rather than hitting a target from scratch. For a 1 m³ pile, two or three 5-gallon buckets of dry leaves or one bale of straw is a reasonable starting dose. Sawdust is slower to break down and can lock up nitrogen if overdone; leaves and straw are more forgiving.
3. Check moisture by the squeeze test. Pick up a handful and squeeze. It should feel like a wrung-out sponge and leave a faint sheen on your palm, around 50-60% moisture by weight. Over 65% and the air spaces fill with water and you are back to anaerobic conditions within a day. Too dry and the pile stalls, which is a different problem but not one that causes sulfur smells.
4. Rebuild the pile and poke air channels through it. Push a crowbar, a length of rebar, or a fence post vertically through the mound in four or five places and wiggle it to open a hole. This buys you a couple of days of passive aeration between turnings and costs nothing.
5. Take the temperature daily with a 20-inch (50 cm) compost thermometer inserted to the core. You want 130-150°F (54-66°C). That is inside the thermophilic band of 113-160°F (45-71°C) where the bacteria doing the work actually function. Below 104°F (40°C), anoxic pockets persist and hydrogen sulfide keeps forming; H₂S is detectable by nose at five parts per billion, so your nose will notice long before the pile looks wrong. If the pile heats past 160°F, turn it to shed heat and avoid killing the biology.
6. Turn again every 3-5 days. This is the University of California Cooperative Extension guidance for odor control, and it is the single most important number in this list. More frequent turning than every three days does not speed things up much and costs you moisture and heat; less frequent and the pile goes anoxic in the interior between events. Expect the sulfur smell to drop sharply after the second or third turning and to be gone by the fourth or fifth.
7. Keep turning until the temperature stops spiking after each turn and settles below 110°F (43°C). At that point the thermophilic phase is over and you are in the curing phase. Stop adding fresh material during curing; adding greens restarts the whole cycle and can reintroduce the problem.
8. Confirm maturity before it goes near a food crop. The Solvita test (or a lab CO₂ evolution test) should read below 2 mg CO₂-C per gram of organic matter per day. If you cannot test, wait another three to four weeks after the smell is gone. Immature compost can be phytotoxic even when it no longer stinks, because volatile organic acids break down on a slower timescale than hydrogen sulfide.

The step people botch is step two. Dumping browns on the surface without mixing them through does nothing, because the anaerobes are in the middle of the pile where the oxygen is not, and that is where the carbon needs to go. A pile that has been "fixed" with a top dressing of straw and no turning will still smell like rotten eggs a week later, and the grower concludes that the advice does not work. Mix or don't bother.

One more thing, and it matters if you plan to spread this on lettuce or carrots. Even compost that passes the maturity test is not automatically compliant with food-safety rules. Under the FDA's Food Safety Modernization Act (2015), untreated biological soil amendments of animal origin require a 120-day interval between application and harvest of crops that contact the soil. If your pile contained manure and never reliably held 131°F (55°C) for three days, the FSMA interval applies, and pathogens including E. coli O157:H7 and Salmonella can survive a pile that is merely warm rather than properly thermophilic. Compost made only from plant material carries none of that requirement, but it is still not safe to use until the smell is gone.

Can I use sulfur-smelling compost on vegetables if I wait a few weeks?

Waiting helps only if the pile is actively managed during those weeks. Hydrogen sulfide has an odor threshold of roughly 0.0005 ppm in air, so a faint whiff means the compound is still being produced somewhere in the pile, not that it is lingering from last month. Anaerobic bacteria keep generating H₂S and volatile organic acids as long as oxygen is scarce, so a pile left untouched in a wet corner will smell the same in October as it did in September. The clock starts after the last turning, not after you first noticed the smell.

The practical target is 2–4 weeks of turnings every 3–5 days, per University of California Cooperative Extension guidance on odor control, until two conditions hold at once: the pile smells earthy and the internal temperature has dropped and stayed below 104°F (40°C) without climbing back. That drop signals the thermophilic phase has finished and the material has entered curing, not that it has gone cold and dead. Then leave it undisturbed for another two to four weeks so the remaining volatile organic acids break down. Total timeline from a sulfur-smelling pile to something you would spread on a bed: about six to ten weeks in most home setups, longer in cool weather.

What "ready" actually means before it touches a food crop

Maturity is a separate question from pathogen safety, and both matter. Run a Solvita maturity test — a mature sample scores 7 or higher, corresponding to a respiration rate below 2 mg CO₂-C per gram of organic matter per day. Immature compost below that threshold will tie up nitrogen as microbes scavenge for carbon and can injure seedlings through residual phytotoxicity. On the safety side, FSMA's produce rule requires a 120-day interval between applying untreated biological soil amendments of animal origin and harvesting crops that contact the soil, and 90 days for crops where the edible portion does not touch the ground. Compost that has completed a validated thermophilic process meeting USDA NOP standards (7 CFR 205.203(c)(2)) — 131–170°F for at least 3 days in a static aerated pile, or 15 days with 5 turnings in a windrow — is treated differently, but a backyard pile that went anaerobic is not that compost.

So the honest answer for the two cases: if the pile has been turned on schedule and now smells earthy with a stable temperature, wait out the curing period and then apply it to fruiting crops like tomatoes and peppers with reasonable confidence, keeping it away from leafy greens and root crops unless 120 days will pass before harvest. If it still smells like rotten eggs after a month of proper turning, do not gamble on it for anything you plan to eat raw — spread it on ornamental beds or a fallow section this season, let it finish there, and rebuild your C:N ratio toward 25–30:1 before the next batch.

What if I already spread sulfur-smelling compost on my garden?

How much work you have ahead depends on three things: how much material you spread, how deep it went, and whether the crop is already in the ground. A thin surface dressing on a dormant bed in October is a different problem from two inches of wet, matted compost worked into the rows where you plan to set out lettuce in three weeks. Work through the list in order. Most people can stop after step three.

• Get the material off the surface first. If the compost is still sitting in a visible layer, rake or shovel it back off. Even a partial removal helps, because the worst phytotoxicity comes from volatile organic acids and hydrogen sulfide concentrated in the top few centimetres of soil. Dump what you scrape up back into the active pile, where aeration and another thermophilic pass will finish it.
• Aerate the soil you already contaminated. Till, fork, or broadfork the top 15–20 cm to break up the smeared, compacted layer that anaerobic compost leaves behind. The goal is oxygen back into the root zone. In a no-till bed, push a garden fork in at 30 cm intervals and rock it back and forth rather than inverting the soil.
• Wait 2–4 weeks before planting anything. Hydrogen sulfide disperses fast once air returns, but the volatile organic acids that accompany it break down more slowly, and both suppress root growth while they last. If you can smell rotten eggs at the soil surface after two weeks, you have not waited long enough.
• Test pH and soluble salts before you commit a crop. Send a sample to a lab or use a home test kit; expect pH to run low and electrical conductivity to run high. Soluble salts above roughly 4 dS/m will burn germinating seedlings and young transplants. If salts are high, irrigate heavily two or three times and retest.
• Plant a cover crop if the contamination was heavy. Cereal rye, winter wheat, or annual ryegrass will grow through mildly phytotoxic soil and hold it while it recovers. Treat the season as lost for edible production and turn the cover crop in the following spring. Do not graze it or feed it to livestock if you applied the compost at a rate high enough to worry you.
• Check the 120-day rule if food crops are involved. Under the FDA Food Safety Modernization Act, untreated biological soil amendments of animal origin applied to crops that contact the soil require a 120-day interval before harvest (FDA, 2015). Sulfur-smelling compost has not completed a thermophilic cycle, so it does not qualify as treated. Restart that clock from the date you last applied it.
• Watch for pathogen risk, not just plant damage. Anaerobic piles never reached the 131–170°F (55–77°C) for three days that USDA National Organic Program standards call for (7 CFR 205.203(c)(2)), so E. coli O157:H7 and Salmonella may survive. Root crops, leafy greens, and anything eaten raw deserve the full waiting period and then some.

The step people skip is the soil test. It is also the one that decides everything downstream. A gardener who waits three weeks and plants into soil with pH 5.2 and soluble salts at 5 dS/m will lose the crop and blame the compost, when a $20 lab test would have caught it and a couple of irrigations would have fixed it.

How does compost maturity testing work and when should I do it?

Maturity is measurable, and the cheapest field tool is a Solvita gel test kit. A measured sample of compost is sealed in a jar with a color-changing gel paddle, incubated at room temperature for four hours, and read against a chart of CO₂ respiration. The result runs on a 1–8 index. Below 5 means the pile is still actively consuming oxygen and will keep pulling nitrogen and oxygen out of your root zone; 7–8 is mature, corresponding to a respiration rate under 2 mg CO₂-C per gram of organic matter per day. Kits cost roughly $30–$60 per set of paddles in 2026 and each set does two or more tests, so it is worth splitting a set with a neighbour.

If you do not want to buy anything, seal a cup of compost in a clean glass jar with a lid and leave it on a counter for 24 hours. Open it and smell it, not the room — put your nose at the mouth of the jar. Rotten-egg or vinegar notes mean volatile organic acids and hydrogen sulfide are still being produced, and the material is not finished. A jar that smells like damp forest floor, or like nothing much, passes. This is the same logic commercial labs use when they run an odor panel, minus the panel. Do the jar test before the Solvita test, not instead of it; smell tells you whether anaerobic pockets remain, respiration tells you whether microbial activity has dropped far enough that the compost will not damage young roots.

When the DIY tests are not enough

For vegetable beds, especially if the compost contains manure or food scraps, send a sample to a soil lab. Ask for two things: the ammonium-to-nitrate ratio and a phytotoxicity bioassay. The ratio matters because immature compost carries high ammonium, which burns seedlings; a finished pile has converted most of it to nitrate. The bioassay is more direct — labs germinate cress or lettuce seed in a compost extract and compare root length against a control. Root elongation under about 80% of the control is a fail, regardless of what the pile smells like.

Run these tests on the day you plan to spread, not on the day you think the pile looks done. Compost that passes on a Monday can slide backward if you turn it, water it, or add fresh material, so retest after any disturbance. If the sample passes both the Solvita 7–8 threshold and the germination test, it is safe for food crops under USDA NOP and FSMA rules; if it fails either one, it is fine for ornamentals and tree mulch but belongs back in the pile for active management. Expect 2–4 weeks of turning every 3–5 days before a sulfur-smelling pile reaches that point.

What causes sulfur smell in compost and how can I prevent it next time?

The fix for a pile that already reeks is covered elsewhere. The more useful question is why it happened, because a sulfur smell is almost always a recipe error rather than bad luck. Every one of the levers below is something you control at the moment you build the pile or add the next bucket of scraps. Get two of them right and you will rarely smell hydrogen sulfide again.

• Keep the C:N ratio between 25:1 and 30:1 by weight. Sulfur odors typically show up when the ratio drops below roughly 20:1, which means nitrogen has run ahead of the carbon available to bind it. Two parts dry leaves or straw to one part grass clippings by volume lands close to target; a pile that is mostly clippings and kitchen scraps does not. If you are guessing, guess toward more browns.
• Stop dumping fresh grass clippings in thick slugs. A 3-inch layer of clippings mats into an airless slab within a day, and that slab is where anaerobic bacteria get their foothold. Spread clippings no more than an inch thick, or let them dry on the lawn for a day and rake them in as brown-tinged material.
• Build in porosity with a coarse bulking agent. Wood chips, shredded branch prunings, or chopped straw at roughly 20–30% of pile volume keeps channels open for oxygen even when the pile is wet. Particle size matters more than most guides admit: material under half an inch compacts, material over three inches sheds water and slows decomposition.
• Turn on a schedule, not on a smell. University of California Cooperative Extension recommends turning at least once every 3–5 days during active composting for odor control. Turning after the smell arrives means you are already 48 hours behind. For windrow composting, USDA National Organic Program standards (7 CFR 205.203(c)(2)) require 15 days at 131–170°F with five turnings; a static aerated pile needs 3 days at that temperature.
• Keep moisture between 50% and 60%, and check it with your hand. Squeeze a fistful: it should feel like a wrung-out sponge, with maybe a drop or two released. Above 60% water fills the pore spaces that oxygen needs, and below 104°F (40°C) anaerobic conditions begin to dominate. Cover the pile in a wet autumn and leave it open in a dry July.
• Feed the thermophilic phase and let it finish. Thermophilic bacteria work between 113°F and 160°F (45–71°C). A pile that never gets over 100°F is not hot enough to drive off the volatile organic acids (VOAs) that cause both the sour smell and phytotoxicity. A $20 compost thermometer with an 18-inch probe tells you more than any visual inspection.
• Screen and cure before the pile touches a vegetable bed. Run finished material through half-inch hardware cloth, then cure it in a loose, uncovered heap for 3–4 weeks. A mature pile tests below 2 mg CO₂-C per gram of organic matter per day on the Solvita maturity test, and it smells like damp forest floor, not eggs.

The mistake people make most often is getting the C:N ratio roughly right and then wrecking it with one addition. A single 5-gallon bucket of wet coffee grounds, brewery mash, or fish emulsion poured onto a 3x3x3 pile can push the local ratio under 20:1 for days, and that is enough time for anaerobic bacteria to establish a population that outcompetes the thermophiles even after the material balances out again. If you generate a lot of one high-nitrogen waste stream, stockpile it and add it in thin layers mixed with browns rather than in a weekly dump.

Worth knowing: prevention and pathogen safety overlap more than most gardeners assume. A pile that stays hot and aerated reaches the temperatures that knock down E. coli O157:H7 and Salmonella, which matters because FSMA's produce safety rule requires a 120-day interval between applying untreated biological soil amendments of animal origin and harvesting soil-contact crops (FDA, 2015). A cold, soggy, sulfurous pile fails both tests at once. The EPA's compost guidance and the Rodale Institute's field trials converge on the same point: manage for oxygen first, and the odor, the pathogen risk, and the phytotoxicity all resolve together.

Does compost that smelled like sulfur ever become safe for organic certification?

Yes, but the bar is higher than most people assume, and passing a maturity test is not the same as passing a pathogen test. The USDA National Organic Program at 7 CFR 205.203(c)(2) sets two acceptable processing routes for compost made from manure or other animal material: a static aerated pile held at 131–170°F (55–77°C) for at least 3 consecutive days, or a windrow turned at least 5 times with the same temperature range held for 15 days. Sulfur smell is the signal that neither route happened as written. Below 104°F (40°C) anaerobic conditions take over, thermophilic bacteria stall out, and H₂S sits at detectable levels down to 0.0005 ppm, so the pile can smell like rotten eggs long before a thermometer would tell you anything useful.

If your pile never reached that temperature band, the honest answer is that it does not qualify as certified compost under NOP rules — not as-is, and not after a week of turning. You have two paths. Either treat it as raw manure, which under FSMA means a 120-day interval between application and harvest for crops that touch the soil (FDA, 2015), or run it through a fresh thermophilic cycle and document it. Cornell's Waste Management Institute data is useful here: you need the pile above 113°F (45°C) with enough oxygen to keep thermophiles dominant, which usually means rebuilding the pile with a C:N ratio near 25–30:1 and turning every 3–5 days (UC Cooperative Extension, 2023). Anaerobic material with a C:N under 20:1 will not self-correct just by sitting; the excess nitrogen keeps feeding the same problem.

For certification — whether you are pursuing NOP status or just want compost that would pass if inspected — write the remediation down. Date, internal temperature readings at 6–12 inches depth, turning dates, moisture checks, and a final Solvita maturity test showing respiration below 2 mg CO₂-C per gram of organic matter per day. That respiration figure is the one that matters most for phytotoxicity; compost can be pathogen-clean and still burn seedlings if volatile organic acids are still present. A pathogen panel for E. coli O157:H7 and Salmonella costs roughly $60–120 through most state university labs and is worth running if the compost is headed for leafy greens or root crops.

The one thing certified growers get wrong here: they assume "cured" means "compliant." It does not. A pile that sat for six months and smells fine may still fail NOP because it never hit the thermal kill step. Temperature logs, not nose or calendar, are what an inspector asks for.

Frequently Asked Questions

Is compost that smells like rotten eggs still usable?

Yes, eventually, but not straight out of the pile. Hydrogen sulfide at even 1-2 ppm means the center has gone anaerobic, and immature compost carrying it can burn roots. Turn the pile, mix in two or three parts dry browns by volume for every part wet greens, and keep it aerated. After 2-4 weeks of proper curing it is usually fit to spread.

How long does it take for sulfur smell to go away from compost?

Two to four weeks is typical once you fix the air and carbon balance. A 1 cubic metre pile turned every 3-5 days in 20°C weather clears in about 14-18 days; a small unturned bin in cold October can drag on for six weeks. Pile size, moisture above 60%, and how often you turn drive the timeline more than anything else.

Can I put sulfur-smelling compost on my tomato plants?

No. Tomatoes are unusually sensitive to the volatile fatty acids and hydrogen sulfide still present in anaerobic compost, and roots exposed to them brown off, stunt, and set less fruit. Wait until the earthy smell returns and a cress or bean germination test shows at least 80% sprouting. Fresh manure-heavy anaerobic material can drop tomato yields by a third.

What is the fastest way to fix anaerobic compost?

Turn the whole pile, not just the top, and fold in dry straw, shredded leaves or wood chips until moisture squeezes out at about 50-60% like a wrung sponge. Then turn every 3-5 days and watch the core hit 130-150°F (54-66°C) on a compost thermometer. If it stays below 100°F (38°C) after a week, add more carbon and keep turning.

Does hydrogen sulfide in compost kill plants?

At high enough concentrations, yes. Hydrogen sulfide is phytotoxic to roots above roughly 0.1-1 ppm in the root zone, causing root tip death, blackened tissue and stunted shoots. The good news is that the gas escapes quickly once the pile is aerated, so finished compost that smells earthy carries essentially none of it.

Is sulfur-smelling compost safe for vegetable gardens after curing?

Yes, provided it has fully cured. Safe compost smells earthy like forest floor, holds together loosely, shows no recognizable food scraps after 8-12 weeks, and reaches 130-150°F during the thermophilic phase. If it still reeks of sulfur or ammonia, or a bean germination test fails, leave it another two weeks and turn again before it touches anything you plan to eat.