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Environmental Health: How Complex Health Issues May Be Linked to Our Air, Food and Water

Author: Patricia Nicholson

According to the World Health Organization’s 2006 report Preventing Disease through Healthy Environments, almost one-quarter of the global disease burden can be attributed to environmental factors. In addition to broad contributors to health such as income, social supports and health services, environmental factors include chemicals and contaminants in our air, soil, food, water and the products we use.

Patients from across Ontario are referred by their physicians to the Environmental Health Clinic at Women’s College Hospital in Toronto for assessment of chronic conditions linked to environmental factors. Dr. Alison Bested, one of the clinic’s doctors, said some of the most common diagnoses found in referred patients are myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), fibromyalgia and multiple chemical sensitivities (MCS).

Dr. Bested and Dr. Lynn Marshall, also from the Environmental Health Clinic, gave a presentation on environmental health issues at Medical Grand Rounds on May 19, 2010 at Women’s College Hospital.

ME/CFS, fibromyalgia and MCS were diagnosed in 440,000 patients in Ontario in 2005, Dr. Bested said, adding that Canada loses an estimated $2.5 billion per year in productivity due to ME/CFS alone.

Environmental illnesses may begin after an incident such as a viral illness, motor vehicle accident or chemical spill, but may also arise after multiple exposures to various factors over time. Clinicians who diagnose and treat these conditions require a detailed patient history, including asking the patient about their home, their community, their job and hobbies, their personal life, their diet, and what medications they take.

Because of the multiple issues involved in environmental health, it’s important to identify the most common hazards and potential hazards that may be present, where those hazards come from, who may be affected, and ways to protect ourselves, Dr. Marshall said.

Our changing environment

If it seems that environmental illnesses are more common now than they were a century ago, that may be true. Dr. Marshall explained that World War II was a change point, when chemists became adept at synthesizing chemicals during the war effort.

‘There were brand new chemicals we’d never been exposed to,’ Dr. Marshall said.

New chemical production has continued over the past 65 years. In Canada, between 500 and 1,000 new chemicals have been examined for their health and environmental effects every year since 1994. However, prior to that, thousands of chemicals were used in high volumes for 20 years or more without being screened for toxicity. When some of these chemicals were eventually tested, they were found to have toxic properties, Dr. Marshall said.

Children, infants and developing fetuses are the most vulnerable to environmental toxins because they take in more of them, relative to their size, than adults. At the same time, their physiology is still developing, and so they may be unable to break down toxins and get rid of them as readily as adults.

You are what you eat . . . and drink

People are exposed to chemicals in the environment through three main channels, Dr. Marshall explained: by eating or drinking them, through skin contact, and by inhaling them in the air.

Groundwater can become contaminated through many routes, from many sources. Contaminants can come from landfills, industrial or farm waste such as sludge or manure, sewer and septic systems, contaminated lakes or rivers, or wastewater ponds. They can seep down into the water table through permeable soil, cracks in rock, gravel, cracked sewage pipes and even wells drilled for drinking water or for testing groundwater.

Water can be contaminated with microbes such as bacteria like E. coli or campylobacter, viruses like Norwalk or hepatitis A, protozoa like giardia or cryptosporidium, and toxic types of algae. Chemicals that can leach into water include industrial chemicals, pesticides, pharmaceuticals and heavy metals such as lead and mercury.

Similarly, foods can carry bacteria, viruses, fungi and parasites, can be exposed to radiation, and can contain chemicals ranging from PCBs and pesticides to heavy metals.

Dr. Marshall explained that some fruits and vegetables tend to have higher pesticide levels than others. The highest levels are often found in strawberries, bell peppers, spinach, cherries, peaches, cantaloupe, celery, apples, apricots, green beans and cucumbers. Produce on this list is the best place to spend extra on organic products.

Fruit and vegetables that tend to have the lowest levels of pesticide include pineapple, plantains, mangos, bananas, plums, kiwi, blueberries, grapefruit, avocados, cauliflower, Brussels sprouts, asparagus, broccoli, onions and cabbage.

Some contaminants, such as mercury, become more concentrated as they move up the food chain, a process called biomagnification. For instance, when mercury escapes from industrial processes into wastewater, it ends up in our lakes where it is taken up by algae. The contaminated algae and other small organisms that eat algae are then eaten by small fish. Larger fish then eat the small fish. The larger fish are then eaten by people. By eating the larger fish, we are consuming all the mercury from the algae, the small fish and the larger fish, and it has become more concentrated at each step up the food chain. Certain fish that are large and live a long time – such as marlin, shark, swordfish and certain species of tuna – have higher mercury content than other fish.

The things you use and the air you breathe

Consumer products can also affect our environmental health. Products that we use to store and cook food and drinks, to make toys and furniture and build homes and vehicles often contain plastic. Some plastics contain harmful additives such as bisphenol A (BPA) and phthalates that may leach from products such as baby bottles, food can linings, toys, bibs and teething rings. Other toxic substances that can leach from some types of plastic include cadmium and lead.

Personal care and cleaning products can be a source of inhaled irritants and toxins, Dr. Bested said. Ingredients in perfumes and scented products have been linked to asthma symptoms, and sometimes appear on lists of hazardous or toxic chemicals.

Other air pollutants that may be found in homes include cigarette smoke, moulds, carbon monoxide from an attached garage, paint and solvent fumes, combustion gases from wood-burning stoves and fireplaces, and chemicals used in building materials and home furnishings,

Going outdoors for a breath of fresh air isn’t always a solution. Industrial processes and transportation result in emissions of smog-producing pollutants such as particulates, ozone, sulfur dioxide and nitrogen dioxide.

People who have the highest health risks related to air pollution include those with respiratory or heart conditions, elderly people, those who do sports or strenuous activities outdoors, and children.

Improving your own environment

We can’t control all of the elements of our environment, but there are some practical steps that can be taken to improve environmental health, Dr. Bested said.

  • avoid pesticides by eating organic when possible
  • reduce mercury exposure by following fish consumption advisories
  • use glass or ceramic containers, not plastic, to store and heat food
  • use glass baby bottles instead of plastic to avoid bisphenol A exposure
  • if your home’s pipes or the connector pipes to the municipal water supply are old and may contain lead, run the tap until the water is cold to avoid drinking lead-contaminated water that has been standing in the pipes
  • consider using a water filter
  • use fewer or no scented products
  • adjust outdoor activities according to Environment Canada’s Air Quality Health Index
  • keep your home well ventilated
  • fix water leaks promptly and use a dehumidifier as needed to avoid dampness and mould growth
  • reduce use of cleaning products with chemical hazard warning labels
  • use a carbon monoxide detector
  • avoid off-gassing new carpets, furniture and building materials

These steps help to keep intake of toxins to a minimum by reducing exposure to harmful or potentially harmful chemicals, by diluting their concentration in air, water or food, and by substituting safer alternatives.


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