Drinking Water and Health Exam 3

Heavy Metals of interest

Arsenic, Fluorine, lead, cadmium, chromium

Arsenic reservoir

Earth’s crust, soils, and minerals

Arsenic transportation

wind-blown dust, runoff, leaching (water soluble), fish and shellfish

Arsenic route of exposure

contaminated water for drinking, food prep, industrial

contaminated food

tobacco

What is arsenic used for

alloying agent

hide tanning

Acute arsenic poisoning symptoms

vomiting, abdominal pain, diarrhea, cramping, death

Long term arsenic exposure symptoms

skin lesions, cancers

in utero: cognitive issues

Arsenic WHO guideline value

10 ug/L

Most reliable arsenic test

urine test

What are the positives of fluorides

prevent cavities

Fluorine transport

drinking water

Excess flourine effects

Fluorosis:

dental effects first

skeletal problems more severe

Fluoride WHO guideline value

> 1.5 mg/L

Fluorine reservoir

geologic origin

water at the foot of mountains

Acute fluorine symptoms

abdominal pain, excessive saliva, nausea

EPA fluoride mcl

4 ppm

Fluoride levels in public water in US

0.7-1.2 ppm

Fluoride global distribution

“Fluoride belts”

syria through jordan, egypt, nothern africa

Turkey, Iraq, China

IQ trends for arsenic and fluoride exposure in China

Exposed groups (especially high arsenic exposure) more likely to have lower IQ than control group

Fluoride exposure and IQ levels

IQ decreased when exposure was less than 4 and 2 mg/L

How does exposure to heavy metals effect risk for cardiovascular diseases and stroke

Arsenic, lead, and cadmium showed increased risk

mercury showed no association

copper showed increased risk, but no dose-response association

T/F: heavy metal exposure cases are common

F: they are rare

Where is lead naturally occurring

Earth’s curst

Where does lead contamination come from

smelting, mining, manufacturing, recycling

in some countries: paint, gasoline/fuel

What is unique about lead in the body

affects multiple body systems

distributed into brain, kidneys, liver, bones

Level of exposure to lead that is safe

none, no lead exposure is without harmful effects

Concentrations of lead known to decrease intelligence in children

5 ug/dL

Transport sources of lead

ingestion and inhalation

Symptoms of lead exposure

In children: permanent health effects developmentally,

In adults: high blood pressure, kidney damage

In pregnant woman: miscarriage, stillbirth, premature

Why are children more vulnerable to lead exposure

absorb 4-5 times as much as adults

What policies have helped reduce lead exposure

safe drinking water act

lead and copper rule

What year for houses being built are considered safe from lead

1986

Unique aspect of testing for lead exposure

There is a latency period

builds up in the system over time

What kind of error impacts precision

random error

what kind of error impacts accuracy

Systematic

Most frequent sites of exposure to environmental chemicals

gastrointestinal, respiratory, skin

What kind of error is type 1

false positive

What kind of error is type 2

false negative

What kind of error is more important to reduce

Type 1

Where does cadmium come from

earth’s crust

usually as a mineral combined with other elements

Heavy metal that is highly carcinogenic

Cadmium

What parts of the body is cadmium especially harmful for

lungs, bones, and kidneys

What has increased cadmium in the environment

human activity

Where are most of the cadmium exposures from

workplace

cigarette smoke

contaminated food

Cadmium exposures for children

toys, jewelry, plastics, disposal of electronics

T/F: cadmium effects a limited list of organ systems

F: cadmium effects a large list of systems

Cadmium symptoms

damage to lungs

stomach irritation

kidney disease

fragile bones

EPA standards for chromium

100 ppb

What fish has higher mercury levels

Large, predatory fish:

shark, tuna, mackerel

Pesticide definition

substances used to kill, repel, or control any plant or animal life considered to be a pest

What does herbicide target

weeds/unwanted vegetation

What does insecticide target

insects

What does fungicides target

molds and mildew

What does disinfectants target

spread of bacteria

How is dose expressed

in reference to body weight and time

Which dose is harder to quantify

absorbed dose harder than exposure dose

Why is absorbed dose harder to quantify

requires information about how animals absorb agents through various routes of exposure

target organ dose def

amount that reaches the site where adverse effects occur

aka biological effective dose

What are organic chemicals of interest

VOCs and SOCs

VOCs def

volatile organic chemicals

release “off-gas” at room temp

SOCs def

synthetic organic chemics

Atrazine

Endocrine disruptors

chemicals (natural and man made) that mimic or interfere with hormones

Common endocrine disruptor of interest

PFAS

fire fighter foam, non stick pans, paper, textile coatings

Chemical mixtures: additivity

effect of mixture = sum of exposure levels

1+1=2

Chemical mixtures: synergism

effect of mixture = greater than estimated for additivity

1+1=3

Chemical mixtures: potentiation

one component that does not have toxic effect increases the effect of second chemical

0+1=1.5

Chemical mixtures: Antagonism

effect of mixture less than that estimated for additivity

1+1=1.5

Chemical mixtures: inhibition

one component that does not have toxic effect decreases the effect of second chemical

0+1=0.5

what makes PFAS dangerous

very persistent in the environment and human body

“forever chemicals”

EPA health advisory for PFAS

70 ppt

What states have higher populations served with PFOA and PFOS

north Carolina, new jersey, Kentucky

What population has higher concentrations of PFAS

chemical production workers

Classes of pesticides

Organophosphates & carbamates

Organochlorines

Pyrethroids

Organophosphates & carbamates

Contact and systemic insecticides in agriculture and homes

Organochlorines

“legacy” pesticides that used to be used for crops

many banned in the US

DDT

Pyrethroids

Synthetic versions similar to extract from chrysanthemum flower

Pesticide impacts

potentially toxic to humans for acute and chronic health issues

many older, cheaper pesticides remain in soil and water for years

What was the 2001 Stockholm Convention

many pesticides were banned or restricted (POPs): persistent organic pollutants

long range transport, stay in the environment

Pesticides reservoir

homes (insect repellent, cleaning products, weed killer)

agricultural use

What affects the symptoms of pesticides

toxicity of the pesticide

age (children more at risk)

T/F: insecticides are more toxic to humans than herbicides

T: they target animal bodies vs plants

Who is responsible for approving pesticides and health risks

EPA

How prevalent are pesticides in the US

very

1.1 billion lbs used every year

20,000 products on market

Are pesticide exposure cases common

no they are not

What did case control study on children exposure to pesticides show

positive association for childhood brain tumors in indoor exposure to insecticides

FORMAL exposure-response relationship not established due to rarity of cases

Who is at the most risk for pesticide exposure

workers who apply pesticides

more than workers who make it

What is atrazine

common name for herbicide used to kill weeds

odorless, white power

will dissolve in water

T/F: atrazine is unrestricted to buy

F: in its concentrated form, it is restricted to certified users

How persistent in the environment is atrazine

Most cases: broken down in soil in one season

IF washed into streams, will stay for a long time

Why are MCLs not set to zero

they set an achievable goal with the best available treatment technology

Atrazine WHO and EPA regs

WHO: 0.1 mg/l

Where is atrazine used in the US

midwest

What is the legality of atrazine in the US and the world

banned in the EU, but still legal in the USA

EPA dismisses WHO cancer agency’s claim it is probably carcinogenic

What are disinfection by products

when chlorine (or chlorine based variant) mix with water

create strong oxidizing agents

What are THMs

disinfection by products

THMs of concern

Chloroform

BDCM

DBCM

WHO classification on THMs of concern

Possible human carcinogens

How are humans exposed to DBPs

drinking water and oral/dermal/inhalation with chlorinated water

Water treatment steps

aeration

coagulation and flocculation

sedimentation

filtration

thermal

chlorination

ozonation

ionizing radiation

Adsorption def

soluble molecules removed by attachment to substrate