Chemical Engineering Assessment 2022

CHEMICAL ENGINEERING
By Name
Course
Instructor
Institution
Location
Date

Contents
Executive Summary................................................................................................... 3
INTRODUCTION........................................................................................................... 4
Background................................................................................................................. 4
Project Aim and Objective.............................................................................................. 4
Objectives............................................................................................................... 4
Chemical Data............................................................................................................. 4
Routes via which the chemical is found in biosolids...............................................................5
Chemical hazard data for Benzo[a]pyrene........................................................................... 5
Hazard Assessment.......................................................................................................... 6
Hazard Identification..................................................................................................... 6
Dose-Response Assessment............................................................................................. 7
Non-carcinogenic effects............................................................................................. 7
Likely chemical concentration in biosolids/sewage sludge Inc. the product purchased.....................7
CONCEPTUAL SITE MODEL........................................................................................... 8
Potential Exposure pathways........................................................................................... 8
Exposed population....................................................................................................... 9
Depth of the risks analysis levels.................................................................................... 10
Determination of the risks............................................................................................. 10
Exposure parameters adopted...................................................................................... 11
CALCULATION OF RISK QUOTIENT.............................................................................11
Residential Exposed Population (1 Child and 2 Adults).........................................................11
Carcinogenic Risks.................................................................................................. 11
Non-Carcinogenic Risk Calculation..............................................................................12
Carcinogenic- Mutagenic........................................................................................... 13
Commercial Worker....................................................................................................... 13
Carcinogenic risk calculation...................................................................................... 13
Non carcinogenic risk calculation................................................................................14
Uncertainty analysis for exposure assessment.....................................................................14
Risk Characterization...................................................................................................... 15
Conclusion................................................................................................................... 16
Recommendations.......................................................................................................... 17
References................................................................................................................... 18

Executive Summary
Health risk analysis of soil has been suggested as a method for identification of the soil types as
well as sites that pose threat to human health. Soil screen is among the numerous methods that
should be analyzed in the determination of the level of threat of a given site to human health. The
risk analysis done in this reports is for Benzo[a]pyrene. The main pathways of exposure
identified for the site model include particulate inhalation, incidental soil ingestion, dermal
contact as well as volatilization from the soil. The exposure pathways have been treated to be
taking place at the same time in this report. The levels of risk were determined using various risk
assessment equations and the values of exposure parameters, fate of chemicals, values of
chemical toxicity being premised on default values adopted in Sydney, Australia. .
The projected risk assuming all the major exposure pathways were active was approximated at
4ppt. Going by the National Contingency Plan for the analyzed region, an allowable site specific
lifetime increase in cancer risk is in the range of a millionth to 100 millionth with risks less than
the range being perceived as protecting human health by the recommendations. The calculated
cumulative risk for the major exposure paths in this report 4ppt was found to be falling within
the provided range.

INTRODUCTION
Background
Benzo[a]pyrene (BaP) is one of the contaminants alongside other polycyclic aromatic
hydrocarbons ubiquitously occurring in the environment as a product of incomplete combustion
or even pyrolysis of organic compounds that contain hydrogen and carbon.
Benzo[a]pyrene has the chemical formula C20H12 and is one of the benzopyrenes that are formed
when a ring of benzene is fused to pyrene resulting in an incomplete combustion at temperatures
ranging between 300⁰C and 600⁰C (Ali et al., 2017). Besides natural sources of polycyclic
aromatic hydrocarbons for example forests fires, there are several man related processes of
combustion that lead to contamination of the food, water, soil, air as well as sediment.
The major sources of Benzo[a]pyrene as well as polycyclic aromatic hydrocarbons in the
environment include residential heating, industrial plants, cigarette smoke and vehicle exhausts.
Project Aim and Objective
Aim: To conduct a chemical risks assessment of Benzo[a]pyrene as per the 2012 update
Environment Health Risks Assessment
Objectives
 To determine the concentration of Benzo[a]pyrene in the soil conditioning fertilizer
 To establish the routes through which Benzo[a]pyrene is found in biosolids
Chemical Data
The melting point and boiling point of Benzo[a]pyrene are 180⁰C and 495⁰C respectively and has
a density of 1.549. The vapor pressure standards are 2.4 at a temperature of 25⁰C with the
refractive index being 1.8530 on average. The storage temperature is about 4⁰C. Benzo[a]pyrene
dissolves in toluene, benzene as well as xylene with a slight solubility noted in methanol and
ethanol. It does not dissolve in water. It is stable and not compatible with strong oxidizing agents

(Chang et al., 2019). Benzo[a]pyrene is predominantly adsorbed to particulates in air even
though it can s well exist in the form of vapor at high temperatures. The deration half-lives of
Benzo[a]pyrene in air, soil and water alongside sediment are 0.02-7, 229-309,39-71 and 196-
2293 days in that order. The figure below shows the structural formula of Benzo[a]pyrene
Routes via which the chemical is found in biosolids
Benzo[a]pyrene ended up being a biosolid as a result of ground water, wastewater as well as
sewage treatment sludge that is released on land surface. Benzo[a]pyrene may be found in
surface water, rain water, tap water, sewage sludge as well as wastewater. Manmade productions
of Benzo[a]pyrene get to the air in which sunlight changes the chemical into a dry form which
falls on to the ground and breaking down in the soil.
Chemical hazard data for Benzo[a]pyrene
 Acute Health Effects include

o irritation and burning of the eyes
o irritation and burning of the skin resulting in a burning feeling or even rash on
contact (Xu, Wang and Zhu, 2019)
o cancer hazard as a result of long exposure at some time of exposure and may go
on for numerous months or even years
 Darkening as well as thickening of the skin as well as warts as a result of repeated
exposure
 Damage to a developing fetus
 Damages to the female ovaries and male testes reproductive systems
Hazard Assessment
Hazard Identification
Possible hazards include:
 May result in cancer
 May result in skin sensitization by skin contact
 May impair fertility
 May result in heritable genetic damage
 May result in harm to an unborn child
 Extremely toxic to aquatic organisms and may result in long term and adverse impacts
within the aquatic environment