HOW CIGARETTE BUTTS AFFECT PLANT GROWTH
By: Jessica Stehr
UNST 181A
Dr. Pamela Yeh
June 1, 2011
ABSTRACT
Cigarette Butts are among the most common form of improperly disposed
refuse on streets, sidewalks, and beaches and constitute some of the most toxic
solid hazardous waste. If left untended, this waste affects all manner of animals,
fish, and plants. The group that is focused on in this research is that of plants,
specifically a particular species of beans, and marigolds. The experiment ran for
47 days and each plant was given the same amount of water, sun, and soil, however, the test groups also contained two cigarette butts each. The marigold test
group was found to be slow in germinating yet fast in growing afterwards. The
only effect observed in the bean test group was a difference in root structure, potentially some sort of mutation of the DNA. There is evidence that the butts had
some effect on the growth of the plants however the research is inconclusive
without further study. Probably the only way to ensure the health of our environment is to dispose of cigarette butts as we would other hazardous materials.
INTRODUCTION
Due to health concerns brought about by scientists in the 1950s, filters made out of cellulose acetate were added to commercial cigarettes.1 Since then the use of filtered cigarettes when
compared to their unfiltered counterparts has sky rocketed1, and only in poorer areas are rollyour-own, filter-free cigarettes still somewhat common.2
Studies have proven that cellulose acetate filters are non-biodegradable and even if they
are broken up over time, the source material will still be there it will just have diluted into the
soil. After the issue was brought in front of cigarette manufacturers, attempts to create a new,
biodegradable filter have been made. Although five were successful, they were deemed unsatisfactory by and for customers due to poor taste and aroma, poor shelf-life, and physical instability
during smoking.1
A study conducted in 2001 by John Heywood and William Murdock shows proof that
even though most people do not like to see litter, they are more likely to leave trash if there is
already litter present.3 Phillip Morris consumer research found that there is a ritualized behavior
in cigarette butt disposal1, which implies that however the group of adult smokers dispose of
their butts is how the individual will continue to do so even away from the group. From this it is
also understandable that, if the others in your group are littering, then there is little guilt involved
when following suit, potentially even when alone.
Cigarette butts make up as much as 50% of discarded waste on streets and roadways
alone, and an estimated 1.69 billion pounds worldwide per year.1 Cigarette butts make up the
highest percentage of waste on beaches due to not only littering on the beaches but also by being
brought out by storm drains when butts are dropped on the streets further inland.4
Other than the problem of littered cigarette butts, there is also the problem of their inability to degrade in landfills meaning there is an increased demand for places to dump this effectively toxic waste.1
Due to the high frequency that filters are found on beaches there have been various studies conducted on certain fish to test how they are affected by the chemicals remaining in cigarette
butts, namely nicotine and ethylphenol.4 There have also been studies conducted on the effect of
arsenic on plant tissues5 as well as the affect of polycyclic aromatic hydrocarbons (PAH) on
plant growth in an experiment to see whether certain plants would be viable for uses of phytoremediation (remediation through plants) of PAH contaminated soil.6 Arsenic is one of the most
well-known toxic ingredients in cigarettes and the PAH benzo[a]pyrene, is a carcinogen found in
cigarette smoke. As big a problem as cigarette butt litter on land is, it has not gotten as much attention by environmentalists as the problems seen on the beaches1 and very few studies have
been conducted on what affect cigarette butts and all of their various ingredients have on plant
growth.
This paper will be based purely on results from an experiment conducted in an uncontrolled, or as close to life environment as possible, to test how growth in two types of plants will
differ with and without the presence of cigarette butt contaminants. From the results of this ex-
periment it might be possible to ascertain the effects landfills containing large amounts of cigarette waste as well as day-to-day littering of cigarette butts have on the surrounding environment.
METHODS
Constants
The seeds used for this experiment were Lilly Miller Sparky Marigolds and BurpeeTM
Stringless Bush Beans. The seeds were all planted in 4” diameter X 4” tall pots. The soil used
was Miracle Grow Moisture Control potting soil. Each type of seed had two pots, one for the
control group and one for the test group. In order to assure germination of at least a few seeds;
four marigold seeds and 3 bean seeds were planted in each of their respective pots. Each pot was
placed on a balcony of a 250° (WSW) facing patio and provided the same amount of water and
heat/sun throughout the 47 days of the experiment. The photoperiod was from about 1100 till
sunset.
Test Group
One pot for each bean and marigold group was used as the test group. The cigarette butts
that were used were Marlboro brand of unknown type and had been smoked and contained some
unburnt tobacco. Two cigarette butts were placed on top of the soil and replaced every Thursday
to simulate the removal by a grounds-keeper followed by more being thrown down. This also
ensured that the chemical levels were kept high as the plants were watered through the butts regularly subsequently leading to the leaching out of such chemicals. The test group pots were given
no more and no less than two cigarette butts each, instead of a pile, in order to ensure that this
experiment was conducted in an as close to natural environment as possible as opposed to just
looking for results.
Data Collection
From day 1, starting with planting, information on plant growth and any changes to pots,
such as cigarette butt replacement was recorded in a journal. Growth of stems and leaves was
measured with a ruler, in millimeters, semiweekly in conjunction with photographs taken to
show plant color and any normal or abnormal growth observed. At the end of the experiment the
plants were placed in an oven at 37°C and left to dry over the course of 3 days and then weighed
in order to clearly show any differences in the entire plant including the roots.
RESULTS
Germination
Visible plant growth was observed in the Control Marigold pot two weeks after planting
on April 25th. In the Test Marigold pot plant growth was first observed on May 4th, almost a full
month after planting. After planting pre-germinated bean seeds into both the test and control pots
on May 5th, visible growth was observed in the Test Bean pot on May 19th. On May 23rd visible
growth was first observed in the Control Bean pot. Due to lack of comparable growth, no data
was collected for beans other than the date that sprouts first appeared.
Data Collected
Figure 1a shows the growth patterns of the stems, smooth leaves, and toothed leaves for
all four plants, in the control and test groups, from day of planting till the end of the experiment.
Figures 1b – d show the growth patterns for each of the measured plant parts from the day they
were planted. On the graphs, the second date indicated is where the first visible plant growth appeared, continuing in semiweekly measurements till the end of the experiment. In Figures 1b – d,
2 and 3, the test pots are indicted as dashed grey and black lines and the control pots are indicated as solid blue and green lines. In Figures 1b-d it is easy to see that the seeds in the test pots
germinated over a week after those in the control pots and that the secondary toothed leaves for
both groups developed over a week after that. Due to the fact that both pots received the exact
same soil, sunlight/heat, and water, and both seeds in either pots germinated at the same time, it
is plausible to deduce that the chemicals in the cigarette butts actually retarded the process of
germination in the test pots causing them to sprout over a week later than those in the control
pots.
Comparative Analysis of Leaf Growth
In Figures 2 and 3 the time periods have been skewed so that the start of growth in both
plants matches up. The last set of data for the control group was removed to better illustrate the
data. What these graphs show is that, although the test group of marigolds germinated later than
the control group, once the test group did germinate, the sprouts actually grew faster than those
in the control group and with time might have surpassed those in the control group. One possible
explanation for this is that the control group germinated when external temperatures were still
quite cold and cloudy, while the test group had warmer and often sunnier weather. Another pos-
sibility is that, as in humans, the chemicals in the cigarette butts excel the aging process of the
plants and causes them to grow faster.
Other Observations
Plant
Control Bean
Test Bean
Back Control Marigold
Front Control Marigold
Left Test Marigold
Right Test Marigold
Weight (Grams)
0.3101
0.3707
0.0793
0.0400
0.0259
0.0178
The roots of the bean plants, when compared, were very different. Although, as mentioned previously, the sprout in the control bean pot had visible growth a full week after that of
the test bean pot, the roots of the control pot sprout were actually slightly more developed than
those of the test bean’s roots. Being a dicotyledonous plant (having two seed leaves) the roots of
beans are supposed to be in a tap-root formation, where the central root is longer and lets off
many smaller roots and root hairs.7 This was observed to be so in the control pot. The sprout in
the test pot, however, had roots like splayed fingers, all equal in width and length with no central
root structure. It is possible that the test bean roots developed this way due to the carcinogens in
the butts causing a mutation in the DNA which altered the growth of the tissue and possibly prohibiting the formation of a normal taproot.
Improvements and Future Experiments
Use pre-germinated seeds to ensure growth of more subjects. Grow seeds in bag, outside
of soil, to record root growth data with and without cigarette contaminants. Continue experiment
until plants reach maturity to observe how cigarette butts affect flower and fruit production. Another possible experiment would be to cover the soil in butts or to bury several butts in the soil to
simulate the environment in a landfill where several thousand pounds of cigarette waste can be
found.
Why It’s Important
Everyday, everywhere you go there is litter present and cigarette butts occupy the highest
percent of it.8 As big a problem as cigarette butt littering is, the problems caused by cigarette
waste collected in landfills is often just as bad. As previously mentioned the components of a
cigarette butt filter are not biodegradable and will never completely break down. This means that
if the areas that landfills occupy were ever to be cleaned up, there’s a potential that plants could
never properly grow there again. If we are to ensure the health of our environment then it may be
necessary to dispose of cigarette butts in a way similar to industrial hazardous material.