Toxicology

This article discusses pollution, contamination, environmental pollutants, and pesticides like DDT and their effects on the environment and human health. It also includes solved assignments, essays, and dissertations on toxicology.

Running Head: Toxicology 1
Toxicology
Name
Institutional affiliation

Toxicology 2
QUESTION 1
Explain the difference between pollution and contamination. Discuss a specific
environmental pollutant that has had a negative effect on the environment. How did the
pollutant affect the environment? How was the pollutant introduced and transferred
throughout the environment? Your response should be at least 300 words in length.
The environment may be altered by a diverse range of stressors that are not necessarily of
chemical origin. For example, pollution may be a result of the introduction of new species.
Pollution is brought about by the presence of toxicants or toxins that result in considerable
biological effects on the habitat. All pollutants can be classified as contaminants. This is because
pollutants are unwanted substances in a system that causes adverse biological or environmental
impact. Contaminants are unwanted substances found in a biological or system that don't
necessarily lead to harmful effects. (Chapman, 2007). Therefore, all contaminants cannot be
classified as pollutants. Hence, contamination is the presence of substances where they are not
required or the presence of these substances in relatively unacceptable concentrations. Pollution
is, therefore, the presence of contaminants the lead to adverse health or environmental effects.
Environmental pollutants include those substances that have extreme effects on the
habitat. The habitat consists of air, soil, plants, water, and human beings or animals. It also
encompasses the pollution that alters the interrelationships that exist between the habitats.
Industrialization and the tremendous increase in the population of human beings have led to a
significant increase in the amounts of waste by-products. The discharge of chemical effluents
into water bodies, disposal of solid wastes, such as plastics, and the release of harmful gases are
examples of environmental pollutants. An example of an environmental pollutant is Methyl-
Mercury pollution in Minamata, Japan.
Methyl mercury is produced in the process of manufacturing acetaldehyde. In Japan, the
factories that were using Mercury as a catalyst dumped the waste products in rivers. Methyl

Toxicology 3
mercury, which has the capabilities of bio-accumulation and bio-concentration, found its way
into marine life. Fishes and shellfishes concentrated the compound. Fish served as the staple food
for most of the fishing families in Japan. People who consumed the fish from contaminated
methyl-mercury contracted a disease that came to be known as the Minamata disease (Harada,
2003). The pollutant was introduced into water bodies through chemical by-products, it
accumulated in fish and later transferred to humans.
QUESTION 2
A population of individuals was exposed to lead contamination in drinking water at the
concentration of 27 parts per billion (ppb). The following represents a small sample set
from the population indicating the level of response to the contaminant rated on a scale
from 1–20. Within your response, please explain how you calculated your answer (1
indicating minimal effects and 20 indicating maximum effects to the lead exposure). Given
the data set 9, 12, 7, 15, 8, 9, 10, calculate the following results: a. mean, b. mode, c. median,
and d. standard deviation. Your response should be at least 300 words in length.
a) Mean
The mean of the response level is ten. The value is calculated by adding up the numerals
that indicate the level of the responses to get the total value. The total value is the divide by the
number of respondents that was given towards the level of contamination to get the mean level.
The calculation is as shown below:
9+12+7+15+ 8+9+10
7 =10
b) Mode
The mode will be indicated by the value that is given by the largest number of
respondents. In this case of lead poisoning, the numeral that attracted the greatest number of
respondents as the level of contamination is nine.
The responses that were given in no particular order are; 9, 12, 7, 15, 8, 9, 10. First, I
arranged the numeric responses in ascending order: 7, 8, 9, 9,10, 12, 15. From the arranged

Toxicology 4
numeric terms, we see that level nine of contamination was felt by two of the seven respondents,
which is higher than other levels. Therefore, the numeric term 9 is the mode.
c) Median
The total number of responses determines the median, and it involves picking the
numeric terms that fall in the middle. In the case of lead poisoning, our median is nine. This
means that the number of responses that indicated the response as being equal to or higher than
nine is the same as the number of responses that indicate the level as being equivalent to or less
than nine. I got the answer in the following manner;
Arrange terms in ascending order: 7, 8, 9, 9, 10, 12, 15. And because this series is from
seven respondents, which is an odd number, the middle numeral is nine. If the number of
respondents was even then, the average of the middle two numbers would have been my median.
d) Standard deviation
The standard deviation is used to measure the spread of data that has the same mean
value. A lower standard deviation would mean that the data is spread out while a high standard
deviation means that the numerals are almost the same. The standard deviation of the responses
is 2.51.
x 7 8 9 9 10 12 15
(x−x̅  )2 9 4 1 1 0 4 25
The formula of calculating standard deviation is; Whereby: σ is the standard deviation
∑ is the Sum of
n is total responses
x is the contamination level
x is the mean

Toxicology 5
Therefore; when we add the (x−x̅  )2 and divide by n and finally squaring it off, we get our
standard deviation to be 2.51.
QUESTION 3
A family goes fishing at a weekend getaway and has a fish fry with their catch. Several of
the family members fall sick, and when they were screened in the emergency room, test
results show that benzene was consumed by the family members. The fish that were
consumed evidently came from a lake that was contaminated. The following data set
represents the level of benzene (in micrograms) that each member consumed. Within your
response, please explain how you calculated your answer. Given the data set 215, 501, 305,
298, 345, 305, 465, calculate the results below: a. mean, b. mode, c. median, and d. standard
deviation. Your response should be at least 300 words in length.
a) Mean
The mean level of benzene consumed is; 347.71 micrograms. I calculated the mean by
adding the data representing the concentrations each family member took and after that, divided
by the number of family members.
The mean = (215+501+305+298+ 345+305+465)
7
which gives 347.71 micrograms.
a) Mode
The mode number of concentrations taken by the family members is 305 micrograms. I
got the mode to be 305 by taking the concentration that was reported in most of the patients. 305
micrograms were reported in 2 family members, while each of the remaining concentrations was
reported in one family member.
b) Median

Toxicology 6
The median range is 305. The number total number of individual concentrations is seven,
which is an odd number. First, I arranged the concentration figures from the lowest to the
highest. The middle number is the median.
215, 298, 305, 305, 345, 465, 501.
c) Standard deviation
The standard deviation of the concentration in micrograms of benzene taken is 93.35.
x 215 298 305 305 345 465 501
( x−x ) 2 17611.9 2471.10 1824.14 1824.14 7.34 13756.94 23497.82
By applying the formula below, the standard deviation becomes 93.35.
QUESTION 4
Discuss the pesticide dichlorodiphenyltrichloroethane (DDT). What was DDT initially used
for, and how does it work as a pesticide? Explain the benefits of DDT, and then discuss how
DDT moves through the environment. Your response should be at least 300 words in
length.
Dichlorodiphenyltrichloroethane (DDT) is an insecticide that belongs to the
organochloride-based group of insecticides. DDT was synthesized for the first time in 1874 by a
chemist called Zeidler. The insecticide is used in agriculture to control insect pests. It is also used
Whereby: σ is the standard
deviation
∑ is the Sum of
n is total responses
x is the concentration
x is the mean

Toxicology 7
in the control of lice and mosquitoes to curb the spread of malaria in some countries. The United
States banned the use of this chemical in 1972. The government banned the use of DDT partly
due to its long half-life in the environment and tissues of animals or human beings who come
into contact with it. DDT also has adverse effects on human health.
DDT functions by disrupting the physiology of the peripheral nervous system,
which means that it is a neurotoxic chemical. DDT toxic effects arise after a series of processes.
In the peripheral nervous system, it prevents the deactivation of the sodium ion gates found on
the axon. The sodium channels usually open during membrane polarization or activation and
thereafter close to stabilize the membrane potential. Failure to deactivate leads to the leaking of
sodium ions through the membrane of the affected nerves. The result is negative membrane
afterpotential. Therefore, the activation of the nerve results in the repetitive discharge of sodium
ions after a single stimulation of the neuron.
DDT is one of the most effective tools used in the control of malaria. Malaria
accounts for over one million deaths annually and poses a threat to 3.3 billion others (Susmita,
2012). Due to the chemical’s duration of activity and insecticidal activity, it kills more
mosquitoes effectively than other insecticides. DDT is relatively cheap compared to most
insecticides. It also has a broad spectrum of actions, which may as well serve to be a
disadvantage. The chemical has low toxicity in mammalian tissue. The chemical is highly
effective in controlling crop pests over a long period, which translates to higher yields.
DDT biomagnifies in a food chain. Due to its long half-life and residual
activity, it means that the chemical persists in the environment for long periods. When sprayed
on crops, the chemical can find its way into water bodies if washed by the rain or irrigation
water. In water, DDT bioaccumulates in fish and other water life. Animals accumulate DDT

Toxicology 8
when they feed on the affected plants and fish. DDT can also be absorbed into animal tissues via
breathing or touching contaminated compounds. In the body, DDT is broken down into
metabolites such as DDE (dichlorodiphenyldichloroethane). DDT and its metabolites are stored
in the adipose tissues. In pregnant animals, the compounds can be passed on to the fetus.
Journal entry III
After conducting a research on Bisphenol (A), it is clear that it has serious health effects on
humans. Bisphenol is a chemical that is used in the manufacture of polyvinyl chloride (PVC)
which is used in making plastic products. Plastic has become very popular in the manufacture of
home products. The popularity of the plastics as the main material used in manufacture of home
products is attributed to its flexibility which enables it to be shaped into different products.
Plastic products are also lighter and cheaper when compared to similar products made from other
materials.
Phenolic structure interacts with oestrogen receptors. This interaction affects the endocrine
system causing male and female infertility, early puberty, hormone associated tumours, and other
metabolic disorders. Having considered the potential effects of the chemical on the body, I agree
with U.S. Food &drug Administration (FDA) that the chemical should not be used to
manufacture products used by babies such as toys and utensils (Konieczna et al., 2015).
The concern on the baby products is of concern because the children are most affected in the
case of toxicity. The chemical also affects the endocrine system in children which is
underdeveloped. Exposure to the toxin could therefore damage the endocrine system resulting in
endocrine associated disorders such as precocious puberty. Having done a research on the

Toxicology 9
toxicity of BPA, I would not let my baby use any products made with the chemical (Vogel,
2009).
References
Chapman, P. M. (2007). Determining when contamination is pollution — Weight of evidence
determinations for sediments and effluents. 33, 492–501. https://doi.org/10.1016/j.envint.
2006.09.001

Toxicology
10
Harada, M., & Ph, D. (2003). Minamata Disease and the Mercury Pollution of the Globe. 4–7.
Susmita Dasgupta:https://blogs.worldbank.org/developmenttalk/health-costs-and-benefits-of-ddt-
use-in-malaria-control-and-prevention
Konieczna, A., Rutkowska, A., & Rachon, D. (2015). Health risk of exposure to Bisphenol A
(BPA). Roczniki Państwowego Zakładu Higieny, 66(1).
Vogel, S. A. (2009). The politics of plastics: the making and unmaking of bisphenol a “safety”. American
journal of public health, 99(S3), S559-S566.