permaculture

["Lawrence F. London, Jr." <lfl@intrex.net>]

Robert Waldrop wrote:
> I visited a community garden project today (a new garden, just being created) and I was shocked to find railroad ties forming the outer border.  

It is a raised bed garden, the beds will be about 8 inches tall.  The creosote-soaked railroad ties will be about 1 ft 
from the sides of the beds.

he area between the beds and the railroad ties will be mulched.
> The people said that they thought the railroad ties would be OK because they are in contact with the plants.  I pointed out that it would rain, 

chemicals would leach into the water, and some of the water would probably be wicked up into the beds.  They did not 
seem convinced.
> Any ideas out there for me to use to convince them that this is a bad idea?

Just google it (see sample hits from my search below) or look in some of my old archives 
http://www.ibiblio.org/ecolandtech/pesticide-education/ for more information.

How much convincing do they need when it is common knowledge that creosote 
and CCA treated lumber should never be used
near plants or people? Both have been banned and are not for sale except as 
large timbers intended for industrial use.
One reference below shows that there is potential risk of ingestion through handling or being in close proximity to 
creosote-laden soil and that ultraviolet rays potentiate the health risks of exposure to creosote, a good reason for 
gardeners to avoid contact with this toxic substance. These two facts alone should be enough to convince them to abandon
use of RR ties in their food gardens.

The new nontoxic pressure treated lumber is OK for gardening and construction 
use. Other containment options include
slow-decomposing wood such as cedar, oak, walnut, locust, fir and others. A 
disadvantage to using anything other than
masonry products, native soil and/or quarry rock dusts to build height in raised garden beds is that the beds will drain 
too well and dry out much faster.

They should use the RR ties for a retaining wall, steps or some other landscaping use away from sensitive plant material 
or food cropping. Why can't they double dig their gardens? They will achieve the same height plus if they add rock dusts 
free from local quarries they can remineralize their soil and add fertility and tilth at the same time as they increase 
the overall volume of dirt in the garden to achieve bed height.

The creosote in the ties will leach out and harm any plants in the bed. I do not know if creosote or any of its chemical 
constituents can be uptaken by plants but it is carcinogenic and if in the soil it will be in contact with gardener's 
skin. Not a good idea.

Here are a few documents to show them:

Creosote:
What Is It? What Are the Risks?
http://www.tceq.state.tx.us/files/gi-285.pdf_4007152.pdf

Creosote: What is it? What are the risks?
Explains the dangers of creosote and how to reduce the risk.
http://www.tceq.state.tx.us/comm_exec/forms_pubs/pubs/gi/gi-285.html

U.S. Environmental Protection Agency
Pesticides: Topical & Chemical Fact Sheets
Preliminary Risk Assessment For Creosote
http://www.epa.gov/pesticides/factsheets/chemicals/creosote_prelim_risk_assess.htm

A Probabilistic Assessment of
Cancer Risk in Creosote Workers
http://www.risktrace.com/pra/Long.pdf

The Environmental Risks Associated With The Use Of
Pressure Treated Wood In Railway Rights-of-Way.
http://www.rta.org/pdf/short_tie.PDF

http://www.atsdr.cdc.gov/HAC/PHA/creosote/cre_p2.html
HEALTH CONSULTATION
FEDERAL CREOSOTE SITE
MANVILLE, MIDDLESEX COUNTY, NEW JERSEY
DISCUSSION

The recent sampling conducted by EPA/ERT confirms earlier findings that show creosote, and its constituent PAHs, at 
elevated levels in the subsurface. As stated by ATSDR in a previous Health Consultation, if the creosote contamination 
is unearthed, it may pose an acute contact threat causing irritation and burning of the skin and eyes [4]. The 
ultraviolet rays of the sun may intensify the effects of the exposure.

Long-term exposure to creosote has been shown to induce skin cancer in animal studies, but evidence of cancer in humans 
is less definitive. Some studies of workers showed an association between long-term exposure to creosote and the 
development of skin cancer. However, other studies suggest there is no association between exposure to creosote and 
other coal tar products and cancer in humans [6]. Since creosote used for wood treatment contains a mixture of several 
carcinogenic PAHs, it is prudent to assume that there may be an increased risk of cancer associated with long-term 
exposure to creosote.

Non-cancerous adverse effects have also been associated with exposures to PAHs [7]. Mice fed high levels of the PAH, 
benzo(a)pyrene (B(a)P), during pregnancy had difficulty reproducing. Also, the offspring of mice fed high levels of 
B(a)P had an increased incidence of birth effects and decreased body weight [6]. There are no studies that indicate 
these effects occur in people, and the doses that cause these effects are considerably higher than those likely to be 
experienced through environmental exposures.

Exposure to PAHs in the soil is most likely to occur through incidental ingestion of soil or dust. Some dermal 
absorption of PAHs may occur through direct contact with skin. However, PAHs bind to organic matter in the soil, which 
decreases its bioavailability through skin absorption.

The following health evaluations are based on the highest concentrations of 
PAHs detected in on-site surface soils.

Non-cancer assessment:

The EPA and ATSDR have derived health-based guidelines for several PAHs. These guidelines are defined as estimates of a 
daily oral exposure of humans, including sensitive sub-populations, that are likely to be without an appreciable risk of 
deleterious effects (non-cancer). Such guidelines are not thresholds for toxicity, but are useful for screening to 
determine if more detailed evaluations are necessary. The EPA guidelines are referred to as a Reference Dose (RfD), and 
the ATSDR guidelines values are Minimal Risk Levels (MRLs).

Assuming a worst case scenario, a 3-4 year old child (weight-16 kg) ingesting 200 mg of soil per day while playing on 
the property with the swing set (total PAHs-758 ppm), the child would receive a dose of 0.0094 mg/kg/day. This dose is 
10-100 times below any screening values used by ATSDR, and several thousand times lower than levels that have caused 
effects in animals.

Cancer Assessment:

Several PAHs have been shown to have a carcinogenic potential. The potencies of the individual PAHs vary, so mixtures of 
PAHs are evaluated by expressing their carcinogenic potential as B(a)P equivalents. The following two scenarios assess 
cancer risks for adults and children who are exposed to PAH mixtures.

--
Lawrence F. London, Jr.
Venaura Farm
lfl@intrex.net
http://market-farming.com
http://market-farming.com/venaurafarm
http://venaurafarm.blogspot.com/
http://www.ibiblio.org/ecolandtech