"I am having both hips replaced and plan on making some 28" raised beds in order to allow me to continue gardening."

A 28" raised bed is much higher than is usual, but you certainly have a good reason for going that high. One word of caution in building such a bed. Pressure treated lumber frequently contains a toxic agent that can leach into the soil. Around here the pressure treated wood contains arsenic and each stick of the wood has stapled to the end a little warning sticker to that effect. Unfortunately those stickers get lost or ignored.

For example, when we moved here our front entry way has a retaining wall made of pressure treated wood, which gives the effect of a raised bed, coincidentally about 28 inches high, which makes it very convenient to work in. We were considering planting some edibles like carrots and lettuce in it in addition to some ornamentals like petunias, pansies, and coleus. I was in our local Home Depot and noticed some of the very identical landscape timbers that were used in the wall retaining that bed. And then I spotted the little red tags on their ends, with the arsenic leaching warnings. Of course, our little retaining wall had no warning stickers. We dropped the idea of raising edibles in that bed. We came rather close to raising and eating some arsenical carrots.

I'm planning on constructing some raised beds next year, much lower than yours, but so far I haven't found any pressure treated lumber that seems safe to use. Used railroad ties were popular a few decades ago for landscape use and retaining walls, but they contained creosote, a known carcinogen. The lumberyards at that time were selling pressure treated lumber saturated with pentachlorophenol, which is both poisonous and carcinogenic. But "penta" treated lumber was very popular until its human toll forced its discontinuance.

They were just hiding or ignoring the hazards of pressure treated lumber back then and apparently they still are. They were supposed to quit using arsenic in the lumber the first of this year but apparently they got some kind of "stay" from the present administration and the arsenic is still there in our Home Depot -- at least it was the last time I looked. Some woods are naturally rot resistant, but they tend to be expensive. I may look for an alternative safe building material for raised beds. I wish concrete blocks cost less, because they could be a solution. But I am quite hesitant to load our garden up with arsenic.

MM

"I couldn't find reliable information related to arsenic leaching into the soil in harmful amounts... I wouldn't be afraid to use it...and do."

Well, I guess that depends on how you define "reliable information." It's easy enough just to define information that disagrees with your viewpoint as "unreliable" but that might not be in your best interests. It would take a long time to do a thorough search on this subject, but here are a few things that turned up on the first couple of pages of a Google search:

A Connecticut Agricultural Experiment Station report - Arsenic in Pressure Treated Wood found that soil samples taken from beneath CCA-wood decks contained, on average, 20 times more arsenic, 76 mg/kg, than control soil, a level that is more than 7 times higher than the state's legal limit of 10 mg/kg and nearly twice as high as the US Environmental Protection Agency's regulatory guideline of 41 mg/kg. "Clearly, the arsenic levels pose a potential environmental problem," the study concluded. Since that report I believe the EPA has lowered their level to the 10 ppm state level. So the soil under decks was on average more than 7 times EPA's current allowable level, with some occurrences much higher. The problem is, the EPA is not enforcing their own regulations.

The wood treatment industry has lobbied the government effectively, just as the paint industry and insulation industry and tobacco industry did for decades. Thanks to their governmental lobbying we are now faced with the problem of removing lead paint and asbestos from our older schools and homes and we have a generation of smokers who started as children. And school playgrounds still abound in arsenical wood. And the lawyers are getting rich from class action lawsuits.

Online Lawyer Source - Pressure Treated Lumber

Wood Treatment Linked to Dangers

You can get arsenic on your fingers just from touching CCA-wood, it's dangerous to saw it, and if you need to dispose of it you must treat it as a toxic material, and if it catches on fire the smoke can be very dangerous.

The EPA announced CCA pressure treated wood products must be eliminated by January 1, 2004.

Home & Real Estate Archives - Pressure Treated Wood

Treated Lumber: a Consumer Arsenic Alert

Perhaps you have seen papers such as:

Treated Wood in the Garden There are alternatives to arsenical wood for the garden.

Arsenic Availability from CCA Treated Lumber and Uptake by Plants

The measurements in those two sources showed that dangerous levels of arsenic were fairly close, within an inch or so of the treated wood. Those measurements show that, on its own, arsenic moves slowly in the soil. The problem with that is that after you cultivate that soil (or earthworms do it for you), all bets are off. The arsenic gets mixed away from the border, where more arsenic concentrates.

You don't have to ingest enough arsenic to kill you to be harmed by it. Mild arsenic poisoning may cause symptoms that include, but are not limited to, nausea, loss of appetite, diarrhea.

Moderate arsenic poisoning may cause symptoms that include, but are not limited to, tingling sensation in the palms, cramped muscles, metallic taste, vomiting, stomach and throat irritation, chronic headaches, fainting, dizziness, delirium, or coma.

Long-term arsenic poisoning may result in darkening of the skin, skin rash, marks on the fingernails, wart appearing marks, and skin pigmentation changes.

I know this is still a controversial subject. There are still some people who think cigarettes are good for you. But my feeling is why use arsenic pressure treated wood when non-arsenical alternatives are available? And don't forget, arsenic is a cumulative poison.

MM

A couple of state-related pressure treated wood links:

Bush wants Florida to stop using arsenic in wood

Pressure treated wood in Maine

MM