Semivolatile organic compounds –
from sources to the environment
Part 1: Chlorinated and
brominated compounds
What are semivolatile organic
compounds?
• Not a firm grouping
• Generally determined by vapour pressure
– typically between ~1 and 10-10 Pa
Why are they important?
• Can distribute in multiple media (gas-phase air, particlephase
air, soil, water, plants, lipids, floor dust, window
films…)
• Many are persistent, lipophilic, bioaccumulative
• Many chemicals of concern are in this group.
Well-known SVOCs
Cl
Cl
Cl
Cl
Cl
Cl
ClCl
Cl
Cl Cl
O
Cl
ClCl
Cl
Cl
Cl
Cl
Cl
Cl
DDT
(p,p’-DDT)
HCH
(Lindane)
Dioxin
(2,3,7,8-PCDD)
PCB
(PCB 118)
Main topics
COMPOUNDS:
• Organochlorine
pesticides (DDT, HCHs,
etc.)
• Polychlorinated biphenyls
(PCBs)
• Dioxins and furans
(PCDD/Fs)
• Brominated flame
retardants (PBDEs and
new use FRs)
ABOUT EACH COMPOUND:
• Source of the compound
– Industrial? Emission by-
product?
• Status
– Is the chemical still in use?
Where is it legal/illegal?
• Physical-chemical
properties, and why these
are important
• Where do we find the
chemical?
– In the environment? In
humans? How are humans
exposed?
Concepts to consider:
• Costs vs. benefits of chemicals
• What evidence is needed to show that a
chemical is safe? Or that a chemical is
dangerous?
• What is the most effective mechanism to
address concerns? How well do
regulations work?
• The role of science in decisions about
chemicals
Case study 1: DDT
ClCl
Cl Cl
p,p'-DDD
• Distinction between
“chemical DDT” and
“technical DDT”
• Chemical DDT –
dichlorodiphenyltrichloroethane,
generally p,p’-DDT – the isomer
with insecticidal properties
• Technical DDT –
mixture of p,p’-DDT,
o,p’-DDT, DDE and DDD
• DDE and DDD are
impurities in technical
mixture and breakdown
products of DDT
ClCl
Cl Cl
p,p'-DDE
ClCl
Cl
Cl Cl
p,p'-DDT
ClCl
Cl
ClCl
o,p'-DDT
What is the composition of
technical DDT?
p,p’-DDT: 63-79%
o,p’-DDT: 8-21%
p,p’-DDD: 0-4%
o,p’-DDD: 0-0.05%
Active ingredient
Impurities
DDT – a brief history
1872 – DDT was first
synthesized by Austrian
chemistry student
1939 – insecticidal
properties discovered
WW2– global use of
DDT against typhus,
malaria
1945 – DDT available
to public
1940s, 1950s – WHO
and country-specific
programs targeting
elimination of malaria
– successful in Europe
and North America,
and large reduction in
cases in India,
southeast Asia
DDT – a brief history
1959 - More than 36
million kg of DDT was
sprayed over the US
1961 - DDT use
reaches its peak.
1962 - Rachel
Carson’s
book Silent
Spring blamed
environmental
destruction on DDT.
“The toxicity of DDT to
Certain Forms of Aquatic
Life”
1945
1946:
1947:
1940s, 1950s –
Gradual increase in
number of scientific
studies identifying
negative effects of
DDT on wildlife
DDT – a brief history
1972 – DDT ban in
USA and Canada
1974 – DDT ban in
Czechoslovakia
1970s, 1980s –ban
on DDT in many
countries
2001 – Stockholm
Convention on
POPs – DDT is
banned with
limited exceptions
for malaria control
Currently
From Czech National Implementation Plan for Stockholm
Convention
Where is DDT still used?
Legally – for malaria control:
• Botswana, Eritrea, Ethiopia, India,
Madagascar, Marshall Islands, Mauritius,
Morocco, Mozambique, Namibia, Senegal,
South Africa, Swaziland, Uganda,
Venezuela, Yemen, Zambia
• Illegal use continues in limited locations?
DDT – What are the concerns
Persistence and
bioaccumulation/biomagnification!
For wildlife
- reproductive/development impairment
- Eggshell thinning in birds (DDE interferes
with reproductive enzymes affecting the
amount of calcium in shells)
- Very high sensitivity in bats
DDT – What are the concerns?
For humans (from Eskenazi et al. 2009, Environmental Health
Perspectives – good review on DDT health effects in humans)
- International Agency for Research on Cancer (IARC) – DDT is
“possibly carcinogenic to humans” – mostly based on
evidence that DDT caused liver tumors in lab test animals
- Some epidemiological evidence of links with liver cancer in
US and Chinese populations, pancreatic cancer in Australia,
breast cancer for women exposed during childhood, puberty
- Increased risk of diabetes
- Increased risk of miscarriage in pregnant women
- Birth defects, decreased sperm count in men
- Neurodevelopmental effects – delayed development, lower
cognitive performance
- Thyroid effects, lowered immune responses
MANY SUBTLE HEALTH EFFECTS – NON-LETHAL, OFTEN DIFFICULT
TO QUANTIFY, AFFECTING A RANGE OF BODY SYSTEMS
p,p’-DDT – physicochemical
properties
• Vapour pressure: 0.00048 Pa
• Solubility: 0.00042 mol/m3
• Henry’s Law constant: 1.1 Pa m3/mol
• logKOW: 6.39
• logKOA: 9.73
From Shen and Wania, 2005
What do the physicochemical properties tell us?
Vapour pressure: 0.00048 Pa
What fraction of the compound in air is sorbed to particles?
logKOA: 9.73
Estimated from VP: 43% on particles
Estimated from logKOA: 11% on particles
Measured at Košetice in 2012-2013: 13% on particles
Vapour pressure: 0.00048 Pa
Solubility: 0.00042 mol/m3
Henry’s Law constant: 1.1 Pa
m3/mol
logKOW: 6.39
logKOA: 9.73
What are typical concentrations of DDT?
- in air -
2012-2013 at Košetice
From Degrendele et al. 2014
0
10
20
30
40
50
60
70
80
18/01/2012 18/01/2013
Airconc.(pg/m3)
p,p'-DDT
p,p'-DDD
p,p'-DDE
What are typical concentrations of DDT?
- in water In
the Indian Ocean: 9-22000 pg/L
Huang et al. 2013
In Lake Malawi, Africa
~76 pg/L
Karlsson et al. 2000
0.001-0.1 mg/kg
What are typical trends in DDTs?
SumDDT compounds in ice core
from Mt. Everest glacier
(Wang et al., Atmospheric Environment, 2008)
DDT compounds in precipitation
from North America, 1995-2005
(Sun et al., Environmental Science and Technology, 2006)
What are typical trends in DDTs?
Time 
Conc.(ng/g)
SumDDT compounds in herring fish from Sweden from 1977-1995
A. Polder , C. Thomsen , G. Lindström , K.B. Løken , J.U.
Skaare
Levels and temporal trends of chlorinated pesticides,
polychlorinated biphenyls and brominated flame
retardants in individual human breast milk samples
from Northern and Southern Norway
Chemosphere, Volume 73, Issue 1, 2008, 14 - 23
Time trend of levels of HCB, sum-DDTs and sum-PCBs in breast milk
NHANES -National Health and Nutrition
Examination Survey of the US Centre for Disease
Control
0
50
100
150
200
250
300
350
1999/2000 2001/2002 2003/2004
p,p'-DDEconc.(ng/glipid)
Sample collection year
Blood serum concentration
p,p'-DDE
Levels are ~15x lower than in 1970s, just
after ban on DDT use
Let’s look a little deeper at the
NHANES data…
0
50
100
150
200
250
300
350
400
p,p'-DDEconc.(ng/glipid)
Sample collection year
Blood serum
concentration
p,p'-DDE
0
100
200
300
400
500
600
700
800
900
p,p'-DDEconc.(ng/glipid)
Sample collection year
Blood serum concentration
p,p'-DDE
12-19
year
olds 20 years
and
older
White
americans
Black
americans
Mexican
americans
Differences by age and differences by ethnicity.
Any ideas why?
DDT – remaining questions?
ANY QUESTIONS ABOUT DDT?
Generalizing: OCPs
• OCPs = organochlorine pesticides
• What are the OCPs?
– DDT
– Hexachlorobenzene (HCB)
– Pentachlorobenzene (PeCB)
– Hexachlorocyclohexanes (multiple isomers)
– Heptachlor/heptachlor epoxide
– Aldrin/dieldrin/endrin
– Chlordane (multiple isomers)
– Endosulfan
– Mirex
– …
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Mirex
HCHs
α β γ
Cl
Cl
Cl Cl
Cl
PeCB
Cl
Cl
Cl
Cl
Cl
Cl
HCB
Endosulfan
Aldrin
Dieldrin
Endrin
cis-chlordane
trans-chlordane trans-nonachlor heptachlor
OCPs under the
Stockholm Convention
“compounds recognized as causing
adverse effects on humans and the
ecosystem”
• Aldrin
• Chlordane
• DDT and metabolites
• Endrin
• Dieldrin
• Endosulfan
• α-, β-, γ-HCH
• HCB
• PeCB
• Toxaphene
• Mirex
Global emissions of α-HCH and its mean concentrations in Arctic air from 1979 to 1996 assembled from published data
Rainer Lohmann , Knut Breivik , Jordi Dachs , Derek Muir
Global fate of POPs: Current and future research directions
Environmental Pollution, Volume 150, Issue 1, 2007, 150 - 165
Phys-chem properties
• Vapour pressure
VP= 0.01 Pa (PeCB) to 0.0002 Pa (β-endosulfan)
• Octanol-water partitioning coefficient:
logKOW = 5.5 (dieldrin) to 6.9 (p,p’-DDE)
• Octanol-air partitioning coefficient: logKOA
= 6.7 (PeCB) to 10.0 (p,p’-DDD)
• Air-water partitioning coefficient:
logKAW = -1.5 (PeCB) to -4.7 (β-endosulfan)
Chemicals divided according to partitioning
properties
From Wania, 2003, Environmental Science and Technology
Any questions about OCPs?
Polychlorinated biphenyls - PCBs
31
Use
•Discovery of
compound, of useful
properties
•Spread of use
Concern
•Increasing number of
scientific studies
identifying concern
•Push-back from
industry
•Weight of evidence
Consequences
•Regulation
•Phase-out
•Environmental problem
-High chemical and physical stability, even at high
temperatures
Desirable property!
-Industrially produced in 10 countries for a range
of uses
- Can also occur as a by-product of some industrial
processes, esp. cement production and pulp and
paper industries
- First detected in environment in Swedish fish in
1966, many more reports followed
- Concerns about environmental persistence and
bioaccumulation
- Production and new use banned by many
countries in 1970s, 1980s
- Banned under Stockholm Convention
But...PCBs remain in use in old building
equipment, electrical equipment, etc.
PCBs – chemical structure
Cl
Cl
Cl
Cl
Cl
• 209 possible congeners
• 1 to 10 chlorines
• only 130 were used commercially
• Classified based on degree of chlorination
2,3',4,4',5-Pentachlorobiphenyl
PCB 118
Indicator PCBs – 7 congeners: PCB
28
PCB
52
PCB
101
PCB
118
PCB
153
PCB
138
PCB
180
PCBs – Physical-chemical
properties
• Trend in phys-chemical properties with
chlorination
0.000001
0.00001
0.0001
0.001
0.01
0.1
1
10
-10
-8
-6
-4
-2
0
2
4
6
8
10
0 100 200 300 400 500 600
Molar mass
log Kow
log Solubility
Vapour
Pressure
From Paasivirta et al. 2009
LogKOW,solubility
VapourPressure
What were PCBs used for?
• Transformers and capacitors
• Other electrical equipment including voltage regulators, switches,
reclosers, bushings, and electromagnets
• Oil used in motors and hydraulic systems
• Old electrical devices or appliances containing PCB capacitors
• Fluorescent light ballasts
• Cable insulation
• Thermal insulation material including fiberglass, felt, foam, and cork
• Adhesives and tapes
• Oil-based paint
• Caulking
• Plastics
• Carbonless copy paper
• Floor finish
Sanexen Environmental Services
Building sealants?
 Caulking material used to
waterproof joints between
masonry/concrete parts of
buildings
 PCBs added as plasticizer
to caulking to allow for
expansion during
temperature change
 Added at a concentration
of at least 10 mg/g (1%)
(Kohler et al., 2005)
35
PCB production
over 1 million tonnes globally
PCB use in North America
Hafner and Hites, ES&T, 2003
Why are PCBs still in use?
• Because they are so useful for their
purpose!
• Where they were used was not well-
documented
• Challenges with removing all PCBs from
use – current legislation only requires
PCBs to be removed at >50 ppm
CN Tower, Toronto, Canada
CN Tower
Built 1972
Had transformer
containing PCBs
Transformer is located in viewing area, 342 m
high Had to be cut apart by hand
Too big to be taken down elevator Packed piece-by-piece into steel drums, removed by
elevator
From PCBs Elimination Network Magazine, Stockholm Convention, 2010
Chemko Strážske, Slovakia
Conc. in μg/g
Typical soil levels in Brno: 0.1-14 ng/g
Temporal trends of α- and β-HCH, ∑ 10 PCBs and ∑DDT in ringed seal blubber from Lancaster Sound in the Canadian Arctic archipelago.
Rainer Lohmann , Knut Breivik , Jordi Dachs , Derek Muir
Global fate of POPs: Current and future research directions
Environmental Pollution, Volume 150, Issue 1, 2007, 150 - 165
Any questions about PCBs?
Dioxins and furans
Dioxins in the news...
Dioxins and furans
Polychlorinated dibenzodioxins
Polychlorinated dibenzofurans
2,3,7,8-TCDD
Chemical Structures
O ClCl
Cl
Cl
Cl
Cl
O
Cl
ClCl
Cl
Cl
ClCl
O
Cl
ClCl
Cl
Cl
Cl
Cl
Cl
O
Cl
ClCl
Cl
ClCl
O
Cl
ClCl
Cl
ClCl
O
Cl
ClCl
Cl
Cl
Cl
O
Cl
ClCl
Cl
Cl
O
Cl
ClCl
Cl
O
O
Cl
Cl
ClCl
Cl
ClCl
Cl
O
O
Cl
Cl
ClCl
Cl
ClCl
O
O
Cl
Cl
ClCl
Cl
Cl
O
O
Cl
Cl
ClCl
Cl
Cl
O
O
Cl
Cl
ClCl
Cl
Cl
O
O
Cl
Cl
ClCl
Cl
DioxinsFurans
Physical-chemical properties
Dioxins and
Furans
Molar Mass Vapour Pressure (Pa) logKoa Particle Fraction
2378-TCDF 306 0.0017 9.9 0.09
12378-PeCDF 340 0.00024 11.4 0.76
23478-PeCDF 340 0.00019 11.5 0.80
123478-HxCDF 375 0.000071 12.0 0.92
123678-HxCDF 375 0.000069 12.0 0.92
234678-HxCDF 375 0.000055 12.1 0.94
123789-HxCDF 375 0.000040 12.2 0.95
1234678-HpCDF 409 0.000055 12.1 0.93
1234789-HpCDF 409 0.0000079 12.3 0.96
OCDF 444 0.0000013 12.8 0.99
2378-TCDD 322 0.0020 10.0 0.11
12378-PeCDD 356 0.00018 10.4 0.25
123478-HxCDD 391 0.00088 12.2 0.95
123678-HxCDD 391 0.000052 12.2 0.95
123789-HxCDD 391 0.000045 12.3 0.96
1234678-HpCDD 425 0.00077 11.5 0.81
OCDD 460 0.0000014 13.0 0.99
Beyer et al. 2002, Paasivirta et al. 1999, Harner et al. 2000
Chemicals divided according to partitioning
properties
From Wania, 2003, Environmental Science and Technology
Sources of PCDD/Fs
• Unintentionally produced
• During inefficient/incomplete combustion,
especially waste burning
• By-product from chemicals manufacturing
• Major sources are: waste incineration,
automobile emissions, metal industries, burning
of peat, coal, wood
• Listed under Annex C of Stockholm Convention:
“Parties must take measures to reduce
the unintentional releases of chemicals listed
under Annex C with the goal of continuing
minimization and, where feasible, ultimate
elimination.”
PCDD/F Source Inventory
Fielder et al.
Chemosphere
, 2007
Temporal trends of PCDD/Fs
What do you think the temporal trends are? Increasing?
Decreasing? Any guesses?
Sediment core data from Baltic Sea:
Assefa et al. 2014, Environmental Science & Technology
Spatial patterns of PCDD/Fs
• Higher concentrations closer to sources,
in highly developed, industrialized areas
• Concentrations patterns in air, soil,
sediment and biota mirror each other
• Trends on a large scale – globally – and
small scale - locally
Local scale – PCDD/Fs
in soil around an
incinerator
Goovaerts et al. 2008
Bignert et al. 2007
Regional scale –
PCDD/Fs in fish from
the coast of Sweden
Global scale – PCDD/Fs
Morales et al. 2014
PBDEs
• Polybrominated diphenyl ethers
• Flame retardants
• Classified by either technical mixture or
congener group
– Confusing!! E.g., penta-BDE can refer to
either the technical mixture called “Penta”
or could refer to a PBDE with 5 bromines
– Commercial mixtures sometimes
distinguished as “c-penta”
PBDE naming - congeners
BDE-99
Pentabromodiphenyl ether
BDE-47
Tetrabromodiphenyl ether
BDE-153
Hexabromodiphenyl ether
BDE-154
Hexabromodiphenyl ether
BDE-100
Pentabromodiphenyl ether
BDE-183
Heptabromodiphenyl ether
BDE-209
Decabromodiphenyl ether
BDE-28
Tribromodiphenyl ether
PBDE naming – commercial
mixtures
C-
pentaBDE
~40%
BDE-47
~2%
BDE-85
~45%
BDE-99
~10%
BDE-100
~5%
BDE-153
~2%
BDE-154
c-
octa
BDE
0.1-8%
BDE-
153
~1% each
BDE-154,
171, 180
13-42%
BDE-
183
3-10%
BDE-
196
11-22%
BDE-
197
4-8%
BDE-
203
1-8%
BDE-
206
~12%
BDE-
207
1-50%
BDE-
209
From La Guardia et al. 2006
c-
deca
BDE
91-96%
BDE-209
2-5%
BDE-206
0.1-4%
BDE-207
Polybrominated Diphenyl Ethers: Uses
Penta Textiles, PUF, paint, household
plastic products, automotive parts
banned under Stockholm Convention
Octa ABS plastic for computers, casings,
circuit boards, small appliances
banned under Stockholm Convention
Deca Electrical & electronic equipment,
casings for TVs, computers, textile
backings (e.g., carpets)
Still in use in some areas, phased
out in Europe, North America
Estimated
Historical
Consumption
Of Penta BDE in
Europe
Prevedouros et al. 2004
Environ Sci Technol
38:3224-3231
Estimated
Consumption
Of BDEs in North
America
Abbasi et al. 2015
Environ Sci Technol
Global distributions of PCBs and
PBDEs
From Pozo et al. 2006
PBDEs
PCBs
Human health concerns for
PBDEs
• Thyroid active agents
– Neurological impairments
• Maturation
– Delay in puberty
• Developmental neurotoxicity
– Impaired spontaneous motor behaviour,
nonhabituation behaviour
• Learning & memory
– Worsen with age
Review: Birnbaum & Staskal 2004 EHP 112:9-17.
Hites 2004 Environmental Science & Technology
Temporal trends of PBDEs
San Francisco Bay sediment and water:
Sutton et al. 2014, Environmental Science &
Technology
Where are we in the temporal
trend of PBDE exposure?
Harrad and Diamond, 2006
5 10 15
OCP
PCBs
PCDD/Fs
PBDEs
logKOA
4 6 8 10 12 14
OCP
PCBs
PCDD/Fs
PBDEs
logKOW
-7 -6 -5 -4 -3 -2 -1 0
OCP
PCBs
PCDD/Fs
PBDEs
logKAW
1E-10 1E-09 1E-08 0.0000001 0.000001 0.00001 0.0001 0.001 0.01 0.1 1
OCP
PCBs
PCDD/Fs
PBDEs
VP
Vapour
pressure
logKOA
logKOW
logKAW
Using phys-chem props, interpret how a different
chemical would behave relative to DDT
“EMERGING” COMPOUNDS NEXT
WEEK:
OCPs, PCBs, PCDD/Fs and PBDEs are now all regulated – lots of
compounds are not. How do we identify which compounds we
should be concerned about? What are those compounds? Where do
we find them? What levels are they at in the environment? What
about human exposure?