Workplace Health and Safety

Importance of the Workplace

• Workplaces are significant due to the amount of time spent there, potential for intense and unique exposures, and their utility in observing environmental health links.
• Occupational settings often reveal environmental health issues before they are noticed in the general community.
• Every job carries some degree of health risk due to possible exposures.
• Studying health in the workplace is practical due to the ease of identifying the population, occupation being a good exposure indicator, and consistent work exposure patterns.
• Workplace health information is valuable for improving community health.

Occupational Health and Safety Issues

• International differences in control measures can lead to a "race to the bottom", where work is shifted to areas with less regulation to cut costs.
• Balancing the cost of workplace hazard control with the long-term benefits is a key consideration.
• Job scarcity can make individuals accept less safe working conditions.
• Precarious work, like part-time or contract positions, is associated with increased health risks, less worker control, lower wages, fewer benefits, and more dangerous tasks.

Health Impacts of Occupational/Environmental Exposures

• Pneumoconiosis is a group of lung diseases caused by particle accumulation, often from dust and fibres, leading to symptoms like persistent cough, reduced lung function, chest pain, lung fibrosis, and shortness of breath
• Pneumoconiosis, including Asbestosis, Silicosis, and Black lung, are irreversible and potentially fatal.
• Occupational cancers can be caused by sun UV radiation, Radon, Asbestos, Diesel exhaust, and Arsenic.
• Musculoskeletal disorders often affect the upper extremities or back, caused by lifting, bending, twisting, repetition, force, and vibration.
• Ergonomic risks include repetition, static position, vibration, temperature, and unnatural positions.

Asbestos

• Asbestos is a flexible, strong, durable, and incombustible fibre.
• Evidence of its health effects has been known since 1930, though it was mined in Canada until 2012 and only banned in 2018.
• Asbestos is a concern when disturbed, releasing fibres into the air, often found in tiles, fireproofing, insulation, and roofing.
• Asbestos exposure can lead to cancers such as Mesothelioma, Lung Cancer, Colon Cancer, Stomach Cancer, and Esophagus Cancer.
• Asbestosis, a pneumoconiosis, causes lung fibrosis, is irreversible, and often fatal, primarily linked to workplace exposures.

Occupational Fatalities and Injuries

• Asbestos exposure is the most common cause of occupational fatalities in British Columbia.
• Vehicle traffic accidents are the most common cause of occupational deaths in Canada.
• Each year there are 900 - 1000 occupational deaths in Canada.
• Older workers are more likely to die from asbestos exposure while younger workers are more likely to die from injury and traffic vehicle accidents.
• Falls and being struck by objects are the most common causes of occupational injuries, leading to fractures, lacerations, and concussions.
• There are an estimated 800,000 occupational injuries in Canada per year, likely underestimated.

Occupational Noise

• Noise is a leading, preventable cause of workplace illness.
• Frequency (pitch) is measured in Hertz (Hz), and amplitude (loudness) is measured in decibels (dB).
• Adverse effects of noise pollution include sleep disturbances, reproductive effects, cardiovascular effects, cognitive impairment, and noise-induced hearing loss (NIHL).
• NIHL is a sensorineural hearing loss causing a threshold shift, often worst at 4000 Hz, affecting speech detection.
• NIHL can lead to difficulty communicating, reduced work ability, psychological effects like isolation, and a reduced quality of life.

A-Weighting and Noise Exposure Regulation

• A-weighting accounts for the effect of frequency on perceived loudness and the risk of NIHL, as high frequencies pose a higher risk.
• Regulations specify a maximum noise exposure in dBA over an 8-hour period.
• An exchange rate is used to adjust the exposure time limit; for every X increase in dBA, the exposure time is halved.
• Regulation provides aids to adjust maximum exposure to the risk of noise.

Food and Health

• Food and health are linked directly through quality, quantity, and foodborne illness, and indirectly through antimicrobial resistance (AMR), pesticide use, climate change, and environmental impact.
• Diet is linked to global disease burdens like hypertension, high BMI, and iron deficiency.
• Food quantity is not the primary issue; distribution is the main concern.

Foodborne Illness

• Food can cause illness through biological (bacteria, viruses, parasites), chemical (natural or man-made), and physical (glass or bone) hazards.
• Risk factors for foodborne illness outbreaks include improper handling, cooking, refrigeration, and hygiene.
• The bacterial danger zone is between 5-57°C.
• Common causes of foodborne illnesses are Salmonella, E. Coli, and Listeriosis.
• Salmonella is linked to meat, poultry, and eggs and has a high mortality rate in the elderly population.
• E. Coli is linked to undercooked beef, unpasteurized milk, and has a low infective dose; the Jack in the Box outbreak is one incidence.
• Listeriosis is linked to vegetables, soft cheese, meats, and milk, and can lead to miscarriage, premature delivery, and high fatality rates, particularly affecting pregnant women, young children, the elderly, and the immunocompromised.

HACCP

• Hazard Analysis Critical Control Points (HACCP) identifies points in the food chain where failures can occur and regulates + monitors risks by setting limits and rules
• Good record-keeping with a plan for when a point is not controlled ensures the food remains safe.
• HACCP can reduce the risk and spread of foodborne illnesses.

Global Access to Drinking Water

• Water, sanitation, and hygiene (WASH) issues cause 1.6 million deaths annually and significantly contribute to disability-adjusted life years (DALYs) in sub-Saharan Africa.
• Less than 1% of the world's water is fresh and drinkable.
• While there's progress in "improved drinking water sources", there has been limited success in sanitation.
• There are 600 million people without improved water and 2.4 million without improved sanitation.
• New, sustainable, and feasible solutions are needed, instead of transitional Western sewage systems that require too many resources and water.

Improved Water Source and Sanitation

• An improved water source is protected from outside contamination, especially fecal matter.
• Groundwater is considered a better drinking water source than surface water.
• Improved sanitation facilities hygienically separate human excreta from human contact.
• Access to improved water sources and sanitation facilities are recognized as UN human rights.

Waterborne Diseases

• Waterborne diseases are primarily caused by contamination with human or animal feces.
• These diseases pose a major health threat in low-income countries.

Walkerton, Ontario

• In Walkerton, rain washed animal feces into the local well, contaminating the drinking water with E. coli.
• The incident led to over 2300 illnesses and 7 deaths.
• Insufficient turbidity testing and chlorine residual contributed to the contamination.
• The utilities manager faced imprisonment as a result.

Water Treatment and Testing

• Water disinfection is important to kill microbes.
• Chlorine is a strong disinfectant that leaves a residue to protect water, although it has a strong smell and taste, pathogens may be resistant, and it may produce toxic byproducts that may cause cancer (IARC 2 or 3).
• Indicator tests are used to check for renewal contamination with feces.
• Coliforms are bacteria often found in animal and human feces.
• Turbidity measures water cloudiness.
• Biochemical Oxygen Demand measures how much oxygen microorganisms need to break down waste in water, where high demand indicates high contamination.

Water Contamination with Metals

• Arsenic, a ubiquitous natural element, is more concerning to health in its inorganic form.
• Chronic exposure to arsenic can lead to skin lesions, liver damage, vascular disease, and cancer (IARC 1).
• Arsenic hotspots can naturally occur, causing problems in shallow wells.
• Lead, a neurotoxin, contaminates untreated water.
• Lead can reduce child IQ, increase behavioral problems, and affect child development.
• The Michigan water crisis involved the city using untreated river water, causing high lead levels in children after its use as tap water.

Wastewater Treatment

• Wastewater treatment aims to improve water quality before discharge into waterways, protecting human health and aquatic environments.
• Treatment can be on-site (septic tank) or municipal, involving primary, secondary, and tertiary stages.

Solid Waste

• Solid waste is divided into municipal, special, and hazardous waste.
• Wealthier countries tend to produce more waste.

Types of Waste Disposal

• Landfills are the most common method in Canada.
• Open dumping is prevalent in low-income countries.
• Incineration is used when space is limited to reduce waste volume and toxicity.
• Recycling and composting are also waste disposal methods.

Problems of Landfills

• Leachate is water that passes through waste and absorbs contaminants, which it then carries into water sources.
• Toxic gases from decomposition, like methane, contribute to air pollution.
• Landfills may lead to community issues and can reduce property values.

E-Waste

• E-waste production reached 54 million tons in 2019, driven by marketing, affordability, and fast technological advancements.
• Most e-waste is shipped to low-income countries with lax health regulations for cheaper processing, with undocumented shipments.
• E-waste contains toxic and valuable components but is difficult to recycle due to the complexity of devices.
• The free market often drives waste to cheaper locations without proper regulation.
• E-waste handling can harm the health of workers and communities.

Toxic Chemicals and Endocrine Disruptors

• Impacts on the brain are measured through brain imaging, behaviour, and cognition (IQ).
• Biomarkers allow for more accurate, less biased, objective, and reliable exposure assessments, e.g., serum cotinine for tobacco exposure.

Effects of Specific Chemicals

• Lead exposure is linked to behavioral problems, lower IQ, reduced brain volume, and shorter neurite length.
• Fluoride exposure is linked to lower IQ and intellectual disability.
• Mercury exposure, through biomagnification in fish, is linked to behavioral problems and Minamata disease.
• Polychlorinated Biphenyls (PCBs) are linked to lower IQ.
• Air pollution is linked to lower IQ, ADHD, brain structure changes, and autism.
• PBDEs (flame retardants) are linked to increased anxiety.
• Pesticides (DDT) are linked to preterm birth, lower birth weight, and autism, especially when folate levels are low.

Vulnerability of Developing Brains

• The developing brains of fetuses and children are uniquely vulnerable to toxins due to a not fully formed blood-brain barrier and their lack of detoxifying enzymes.
• The long window of susceptibility during brain development increases the risk.
• Young children are more exposed due to behaviours like putting objects in their mouths and spending time on the floor.
• Fast-growing cells are more susceptible to toxins.

Low-Level Exposure and Importance of Testing

• Low-level chemical exposures significantly impact health.
• Many chemicals lack neurotoxicity testing, and effects are often recognized only after damage has occurred.
• Effects on individuals may seem small, but their cumulative impact on the population can be significant.
• The cumulative impact of multiple small risks can add up.

Endocrine Disruptors

• These are exogenous substances that disrupt the normal function of the endocrine system and lead to adverse health effects.
• Increase instance of breast cancer and testicular cancer.
• Decrease in sperm count.
• Increase instance of Hypospadias.

Estrogenic EDCs

• DES exposure can lead to rare vaginal carcinoma, infertility, breast cancer, neonatal death, and preterm delivery.
• DDT exposure can increase breast cancer risk by four times.
• BPA exposure can increase mammary gland tissue.

Androgenic EDCs

• Atrazine exposure causes feminization of frogs, less testosterone, and less sex.
• Exposure to phthalates can cause phthalate syndrome, which can cause short anogenital distance, undescended testicles, nipple retention, and Hypospadias.

Obesogens

• Obesogens promote obesity in humans and animals.
• DES promotes obesity in mice.
• BPA increases fat tissue in female rats and increases the odds of obesity in children.
• PFOAs increase BMI and fat tissue.

Healthy Community Design Principles

• Affordable housing
• Transportation alternatives
• Mixed land use
• Density
• Access to green spaces and parks
• Nutritious food
• Community centers
• Walkability/bikeability infrastructure

Consequences of Car-Dependent Communities

• Traffic-related air pollution is worst where there are steep spatial gradients; may have a direct health effect or contribute to climate change; and contributes to mortality from lung cancer and other causes.
• Traffic-related air pollution results in asthma and can badly effect bodily systems.
• Traffic related noise pollution is the biggest cause of noise pollution and can result in Diabetes mellitus, CVD, reduced birth weight, Irritation, Stress, IHD (strongest association).
• Traffic road injuries, which are the leading cause of death in the young population (15-29), resulting in 1.2 million deaths annually.
• A community that discourages walkability by relying on car dependency results in reduced physical activity and makes inhabitants less healthy as a result.

Walkable Neighborhood Characteristics

• High street connectivity (small blocks and many intersections)
• Medium to high density
• Mixed land use
• Diversity and concentration Commercial use close to residential area
• Compact urban form

Green Spaces and Health

• Shortens gallbladder surgery recovery time.
• People that Live in green spaces have better birth outcomes, with highest birth weight even after adjusting for air and noise pollution.
• Green spaces have an independent positive impact on heath.
• Leads to less preterm births, less diabetes, less CVD mortality, less all cause mortality, lower heart rate.

Community Development Trends

• Suburban areas grow faster than urban areas.
• Most of the global population lives in urban areas, with an increase expected.
• High-density areas and zoning are common.
• Dependence on cars and separated-use zoning increase social, environmental, and health problems.
• Higher rates of population growth, car numbers, and vehicle miles traveled from 1940-2000 in California.

Environmental Justice Goals

• Everyone receives the same degree of protection from environmental and health hazards.
• All have equal access to the decision-making process to live and work in a healthy environment.

Key Considerations in Environmental Justice

• Spatial distribution of environmental goods and bads
• Distribution of effects of environmental goods and bads
• Access to policy making
• Administration and enforcement of environmental protection programs

Warren County PCB Disposal Controversy

• PCBs were disposed of in Warren County soil, inspite of residents of the county opposing.
• The outcome led to media attention, inspiring research into "unfair" siting of toxic waste facilities.

Criticisms of Environmental Justice Research

• Proximity vs Exposure vs Impact
• Cause vs Result
• Mobility difference - wealthy move aways, property prices decline and poor move in - disproportionate siting may be unavoidable.

Environmental Justice Issues in Canada

• Mercury was dumped mercury in river upstream of the Grassy Narrows community, which resulted in economic and health consequences - mercury levels elevated in fish and people after 40 years.
• First Nations communities had drinking water under boil water advisory for years or even 3 decades, due to government failure on multiple levels.

Climate Change Facts

• The greenhouse effect is well understood since the 1800s.
• Climate-altering pollutant concentrations in the atmosphere are rising.
• The climate is changing.
• Lack of knowledge is not the primary barrier to addressing climate change.
• Climate change involves more than just temperature, and includes storms, extreme weather, wind, and precipitation.
• Climate differs from weather.
• Climate variability is important.

Climate Change Threat Perception

• Strongly associated with ideology, worldview, values, and political orientation.
• Less associated with education, sex, subjective knowledge, and experience.
• Belief in climate change does not predict willingness to change.

Greenhouse Pollutants

• CO2, methane, and nitrous oxide
• Many pollutants have a worse climate-warming potential than CO2, but CO2 concentration is so high that it is the major issue.

Climate Change and Health Links

• A direct health link is heat.
• Heat increases mortality, especially in those 65+ and 50+, by straining the heart - planting trees and living in green spaces can mitigate adverse effects of heat waves.
• High spatial variation in heat is dependent on urban, suburban, and rural areas.
• Indirect health links include reduction in food security
• Indirect health link includes loss of biodiversity, floods, pests, heat waves, impact to productivity of agricultural lands, harm to farm workers.

Wildfires and Air Quality

• Wildfires have increased and will become more frequent and intense in the future, reversing 25% of multi-decadal progress in air quality improvements.

Cause and Impact Disconnect in Climate Change

• Those who cause the most greenhouse gases and contribute the most to climate change are not those who are most affected by the adverse consequences.
• Generational and current (Low vs High income countries) injustice.

Environmental Risk Transition

• As a country develops, environmental burdens shift from local to global and health issues shift from acute to chronic.

Epidemiological Transition

• In the age of pest and famine, there are high rates of infectious diseases and malnutrition.
• There is better sanitation, nutrition, and medical advances in the age of receding pandemics.
• In the age of man-made diseases, chronic diseases are the leading cause of death.

Historical Figures and Discoveries

• Richard Doll discovered that asbestos causes lung cancer and fibrosis and he conducted the physician smoking study which concluded that smoking causes lung cancer.
• Marie Curie discovered that Radium is Radioactive, and some of the workers that worked with Radium developed necrosis of the jaw.
• Percival Potts discovered the first carcinogen - chimney sweepers cancer.

Pollution and Health

• Pollution is the world's greatest threat to health, causing 9 million premature deaths annually (16% of total deaths), most in low- and middle-income countries.
• About ⅕ of deaths are caused by toxic chemicals.
• Environmental exposures and issues vary in severity between low- and high-income countries.
• Most chronic diseases are man-made and preventable, though trade offs between beneficial changes and environmental hazards remain.

Environmental Exposure and Health

• The link between environmental exposure and health is rarely obvious due to long latency periods.
• DALYs considers lost years due to premature death and disability.

Global Burden of Disease (GBD)

• Quantifies health loss of hundreds of diseases, injuries, and risk factors.
• Provides information on upstream and downstream factors, as well as the population attributable fraction (PAF).
• Determining PAF requires exposure data, exposure-response relationships, counterfactual scenarios, and burden estimates for the outcome.
• Limitations of GBD estimates:
  • Does not consider all exposure outcome pairs
  • Uncertainties in exposure assessment and exposure response relationships
  • Climate change is difficult to incorporate
  • Disability weights are difficult to set
  • Categorizing health on a continuum is difficult
• Uncertain estimates are better than no estimates.

Prevention Paradox

• A large number of people at a small risk produce more cases than a small number of people at a high risk.
• Individual effects may be small, but the effect of the total population is huge.
• Air pollution is the second leading risk factor for early death, causing 8 million deaths annually, and it is the leading contributor to DALYs globally.

Clinical vs. Population Strategy

• Clinical strategy involves diagnosing signs and symptoms and treating with drugs or surgery.
• Population strategy involves identifying and reducing upstream factors to prevent disease.

Curve Shifting

• A small shift in the population distribution can lead to substantial effects for the population.
• Moderate achievable change can produce high population health benefits.
• There is no biological reason why populations should not be as healthy as the best.
• Many diseases are man-made and avoidable.

Precautionary Principles

• Insufficient evidence should not stop action when there is a serious threat to human health or environment.
• Banning public smoking reduces heart attacks in non-smokers.
• Toxic metals like lead increase the risk of CHD, enhance atherosclerosis, contribute to CHD and CVD mortality, and all-cause mortality even at low levels.
• Lead causes 5.5 million deaths annually and ⅓ of CVD/CHD mortality in the USA.

Exposure Assessment and Environmental Epidemiology

• Epidemiology finds associations between exposure and health.
• Impact assessment determines how much death and disease the exposure causes.
• Surveillance tracks how exposure changes over time.
• Identification of the exposure source leads to develop upstream interventions.
• Comparisons with regulations are made to make rules and ensure compliance.

Routes of Exposure

• Include dermal, inhalation, ingestion, and vertical routes.
• The importance of each varies by exposure and population.

Exposure Pathway

• Pollutant emission - Movement of pollutant - Exposure- Dose - & Effect.
• It's best to act as early as possible in this pathway.

Exposure Control Hierarchy

• Elimination is the most effective.
• Other control measures include substitution, engineering controls, administrative controls, and personal protective equipment (PPE), though people do not like to change their behaviour, and it may result in error.

Exposure Assessment Methods

• Direct methods include biomarkers and personal measurements, which are accurate and expressive but place a high burden on participants and are not feasible for large samples.
• Indirect methods include area measurements, questionnaires, and models, which are less accurate but good for large samples and have a low burden on participants, and are cheaper.
• Biomarkers involve measuring pollutants or their metabolites in biological material, but can be intrusive, difficult to interpret, and cannot distinguish between different routes of exposure.
• Experimental designs are uncommon in environmental health due to ethical concerns, long latency periods, blinding issues, questions about external validity, and difficulties assigning interventions.

Key Ideas in Environmental Epidemiology

• Correlation is not causation.
• Not every case is due to the exposure of interest, and not every exposure results in a case.
• Effect estimates can be misleading; individual impact and relative risk/odds ratio may be low, but population impact can be massive.
• A population strategy only makes sense if many are exposed.
• The high-risk strategy vs. the population strategy are used.
• Curve needs to be shifted.

Shifting the Curve

• A shift in total population exposure can have a significant effect on the amount of disease produced while only resulting in a small change in individual risk.
• Mostly affects the end of the curve where disease cases are.
• May be good or bad, depending on the hazard reduction or increase.

Exposure Assessment

• Identifying, measuring, and evaluating the extent of exposure.
• Measuring concentration over space and time and monitoring people.
• Exposure can be chronic or acute.
• Exposure assessment identifies and quantifies exposure-health relationships, informs and evaluates public health decisions, improves health, and identifies risk populations.

Toxicology and Risk Assessment

• How toxic substances interact with the body: ADME.
• Absorption: Substance enters the body and is absorbed.
• Distribution: Distributed in the body
• Metabolism: Metabolized to be more water-soluble, and/or more toxic.
• Excretion: Gets rid of it.

LD50

• It quantifies acute toxicity rather than death outcomes, chronic effects, presence or absence of the threshold.

NOAEL and LOAEL

• NOAEL is the no observed adverse effect level.
• The lowest observed adverse effect level (LOAEL).
• ADI (Acceptable daily intake) and Rfd (Reference dose).

ADI

• Acceptable daily intake as a fraction of NOAEL (divide NOAEL by UF)
• Use Uncertainty factors due to animal experiments, data limitation, and variability between humans - = provides safety margin.

Threshold

The lowest exposure at which no adverse effect is observed (below = “safe”).

Characteristics of Dose-Response Relationships

• Presence of zone of homeostasis, where some levels may be better then minimal level.
• Changes in exposure have higher effects at low doses then high doses.

Risk Assessment

• Hazard identification: connect hazard to health outcome
• Dose-response assessment: derive slope factors or RfD
• Exposure assessment: determine current exposure in population Risk characterization: put all the information together to understand the risk

Perceived vs. Technical Risks

• Technical risk is calculated by scientists.
• Perceived risk: Influenced by choices, intuitive judgement, policy.
• Often do not align.

IARC (International Agency for Research on Cancer) Classifications

• Group 1 = Carcinogen (there has to be enough epidemiological and experimental evidence from human studies, says nothing about risk of cancer) -Group 2A = Probably carcinogenic
• Group 2B = Possibly carcinogenic
• Group 3 = Not carcinogenic
• Group 4 = Probably not carcinogenic

Hazards vs. Risk

• Hazard = something capable of causing an adverse effect on health
• Risk = probability a hazards will cause adverse health effects under specific circumstances - A function of hazards, exposure , susceptibility

Dimensions of Toxicity

• Factors that influence the likelihood and severity of toxic effects:
  • The toxicant and the target organ
  • The dose
  • The route of exposure
  • Timing of exposure
  • Duration of exposure (in utero (pregnant animal) windows of susceptibility)
  • Individual susceptibility (age, sex, health status, genetics...)

Air Quality

• Smaller particulate matter are worse, get deep into alveolar, not threshold and supralinear relationship, Number 1 threat to human health.
• Sharp spatial gradient
• Burning unprocessed solid fuel for cooking with poor ventilation.
• Carbon monoxide: Colourless, odorless, tasteless gas from combustion
• Radon: Only concern when no ventilation and in basement, no concern outside because it dilutes in the large air volume

Criteria Air Pollutants

Most common and most commonly controlled air pollutants that are known to cause harm to human health PM, Ozone, Carbon Monoxide, Nitrogen oxides, Sulfur Dioxide

Burden of Air Pollution

• Largest burden of PM2.5 comes from the effect on CVD (Maternal, neonatal, diabetes…)
• Effect the entire body not just lungs
• Ozone only contributes to chronic lung disease
• Air pollution causes preterm birth and low birth weight. Development in utero can influence entire life health trajectory in man system of the body (windows of susceptibility).
• Air pollution is the leading contributor to DALY and second leading cause of early death.

Harvard 6 City Study and American Cancer Society Study on Air Pollution

• Probability of survival declines as air pollution increases and that long term exposure increases risk for all cause mortality.
• Study indicated that PM2.5 increases risk for all cause mortality.

Pesticides

• Designed to prevent, repel mitigate and kill living things/ pests and are hazardous chemicals that are intentionally added to our environment.

Organochlorine Insecticides

• Persistent, Bioaccumulation, Half life of 2-5 years, Fat soluble, High toxicity

Organophosphate Insecticides

• Designed to prevent, repel mitigate and kill living things/ pests and are hazardous chemicals that are intentionally added to our environment.