Environmental Engineering Assignment: Ally Alcohol HQ Analysis

This assignment focuses on calculating the Hazard Quotient (HQ) for ally alcohol in drinking water, a key aspect of environmental toxicology and risk assessment. The student utilizes a formula adapted from James et al. (2000) to determine the HQ, considering a concentration of 50 µg/L. The calculation incorporates several assumptions, including ingestion rate, exposure frequency, duration, body weight, and safe human dose (RfD) from the EPA. The assignment breaks down the formula, calculating the intake rate (I) and subsequently the HQ value, which is found to be 5.714. The conclusion highlights the implications of the HQ value, indicating that the higher the HQ, the greater the environmental risk. The document provides a detailed step-by-step guide for the calculation.

Running head: ENVIRONMENTAL TOXICOLOGY 1
Environmental Toxicology
Name of institution
Date

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ENVIRONMENTAL TOXICOLOGY
Calculation on the Hazard Quotient for Drinking Water Containing Ally Alcohol
Exposure Quotient (HQ) is the often used to determine the risk of exposure to a given
chemical or substance in the environment. Waters et al. (2015, p. 105) defines HQ as the “rate of
exposure point estimate per the occupational exposure limit”.
However, According to James et al. (2000), the best formula for calculating the HQ is;
HQ = D  or
HQ = SHDD 
This assignment illustrates the calculations of the Exposure Quotient of the ally alcohol
based on formula that is described by James et al. (2000). The concentration is given to be
concentration of 50 μg/L (according to the Environmental Protection Agency). The assumptions
are indicated below:
Ingestion rate of 2 L/day
Exposure frequency at 365 days/year
Exposure duration of up to 10 years
Body weight = 70 kg
Averaging time = 3,650 days
Safe human dose = 0.005 mg/kg-day (RfD from EPA)
Below is the breakdown of the formula.
HQ = D × RfD-1 or HQ = SHDD RfD-1

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ENVIRONMENTAL TOXICOLOGY
Where SHD is the Estimation of a safe human dose and D is the rate of change of intake
as a function of the average body weight.
In other instances, the rate of intake is denoted by the symbol I. Therefore, using the first
formula, the equation translates as;
HQ = I (for the noncarconogenic substances only)/ RfD
Ally alcohol is a potential carcinogenic substance and so there is a need to calculate the intake
rate (I).
Therefore, I = C × {(CR × EF × ED)/ (BW × AT)}
Where: C = Concentration of the ally alcohol
CR = the exposure frequency (2 L/day)
EF = the concentration per year (365 days per year)
EF = Exposure duration (10 years)
BE = the average body weight (70 kgs)
AT = the average time of exposure (365 d/year × 30 years)
Plotting the figures into the formula gives the intake rate (I) shown below;
I = 50 μg/L × {(2 L/day × 365 days/year ×10 years)/70kg × 365d/years ×10 years)}
Computation of the figures in the formula gives the value of I as 0.02857
I = 0.02857 mg/ (kg/d)

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ENVIRONMENTAL TOXICOLOGY
From the above calculations of the value of ‘I’, it becomes easier to calculate the value
for the Exposure Quotient. This is calculated as shown below;
HQ = I/RfD
I = Intake rate (0.02857 mg/ (kg/d))
RfD = the oral reference dose (mg/kg /day); fresh ingestion (0.005 mg/kg-day).
Therefore HQ = {0.02857 mg/ (kg/d)}/ {0.005 mg/kg/day}
HQ = 5.714
Note: The exposure quotient gives the ration, and therefore, doesn’t have any unit.
As a conclusion and an inference of the implication of the HQ value, I would indicate
that whereas the HQ values that are less than one (1) are considered to be environmentally
acceptable for the non-carcinogenic substances, the parameter does not exist for the carcinogenic
substances. However, the higher the HQ values the higher the risks involves in the environment.

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ENVIRONMENTAL TOXICOLOGY
References
Phillip, L. W., Robert, C. J. and Stephen, M. R. (2000). Principles of Toxicology: Environmental
and Industrial Applications, Second Edition. Edited by John Wiley & Sons, Inc.
Waters, E. and McKernan, L. et al. (2015). Exposure estimation and interpretation of
occupational risk: Enhanced information for the occupational risk manager. Journal of
occupational and environmental hygiene, 12, s99-s111