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Chemicals and toxins

Chemicals and toxins

Continued economic growth and industrial activity has contaminated much of the world’s fresh water supply with manufactured chemicals.

The range of contaminants includes toxic heavy metals, such as lead, mercury and cadmium, agricultural chemicals such as pesticides and fertilizers (nitrates) and volatile organic chemicals such as gasoline / petrol and solvents.

Sources of contaminants include agricultural and golf course run-off, industrial run-off from pulp mills, chemical plants, manufacturing plants, run-off from roads, acid rain from airborne pollution and leaching from landfill sites, mines and septic fields.

Generally, the more people who live in an area the greater the level of chemical pollution. Many recreational areas, and some wilderness areas, are downstream or downwind from industrial zones or agricultural areas, which ensures continuous contamination.

For example, 39% of all groundwater wells in South Dakota have levels of nitrate that exceed US national drinking water standards. The nitrate is from fertilizer contamination of aquifers and is in high enough concentrations to harm children. Across eastern Canada, the US and eastern Europe, acid rain has rendered thousands of lakes essentially lifeless. Ice core samples from the Canadian arctic and Antarctica confirm that chemicals are transported all over the world by weather systems.

Some chemicals that are now banned in North America and Europe, such as DDT, are sometimes still manufactured and used in developing countries. Even after a chemical is banned it can often persist for years, decades or potentially indefinitely in the environment of any country. Furthermore, mining or mill slag heaps, abandoned industrial areas, lake and river sludge adjacent to industrial areas and other sources will remain sources of chemical leaching into groundwater, rivers and lakes far into the future causing local and trsnboundary problems.

A Few Words on Risks

Given the proliferation of chemicals in the environment and the scale of the problem, the purpose of this section is to outline the chemicals and elements that may be present in water in recreational and wilderness areas and to assess the potential dangers of drinking such water.

It must be noted that very few chemical and elemental contaminants are found in water in recreational and wilderness areas in sufficient concentrations to cause immediate illness or death. Many of the effects are longer term and relate to organ damage and cancer.

However, the most difficult task in assessing the non-microbiological risk of drinking is determining what harmful chemicals or elements might be in the water without sending a sample to a lab.

How exactly do you assess the quality of water when you are out adventuring? The short answer is that you can’t. However you can do some research before heading out to help you predict with reasonable certainty what contaminants you might encounter and how to deal with them. The section of the website on treatment systems offers some advice on these points.

The Special Case of Nitrate

The one chemical that is often present in water at high enough levels to cause immediate harm is nitrate, which gets into the environment through chemical fertilizers, animal wastes and septic systems.

Nitrate poses a greater risk for recreational travellers than any other chemical because of widespread agriculture and livestock ranching, and the potentially deadly affect on babies.

In the digestive system of an infant, a certain type of bacteria converts nitrate into nitrite. Nitrite reacts with hemoglobin, which carries oxygen in the blood, to form methemoglobin, which cannot carry oxygen. The end result is oxygen depletion in the baby.

This illness is called methemoglobinemia, or ‘blue-baby’ disease or syndrome, and is characterized by symptoms of suffocation including bluish skin, particularly around the eyes and mouth.

The infant must be immediately hospitalized for treatment to convert the methemoglobin back into hemoglobin.

After infants reach six months of age, their stomachs usually no longer harbour large numbers of the bacteria that convert nitrate into nitrite because of an increased level of hydrochloric acid. Infants under this age should not be exposed to any water sources that have even a remote possibility of nitrate contamination, especially water from agricultural and ranching areas, golf courses or near septic fields.

Elements, Chemicals and Heavy Metal Contaminants

The following chart, derived from Health Canada and US EPA guidelines, summarizes the major chemical and elemental contaminants that have been detected in North American water supplies. Both Health Canada and the US EPA use specific terms to quantify the levels of chemical contaminants in drinking water. European systems are broadly similar if perhaps tighter following recent EU regulations on chemicals.

Health Canada’s levels are based upon an average daily intake of one and a half litres of water by a 70 kilogram adult and a large safety factor of up to ten is considered when determining the levels. Important definitions for the chart are: Health Canada’s Maximum Acceptable Concentration (MAC), which is the maximum level of concentration permitted for ‘substances that are known or suspected to cause adverse effects on health.’

The US EPA’s equivalent term, Maximum Contaminant Level (MCL), which ‘is the highest amount of a specific contaminant allowed in the water delivered to any customer of a public water system.’

When possible the Health Canada MAC or US EPA MCL is provided. Most importantly, a brief description of the possible sources of contamination and possible health effects is given. This should help you to assess the quality of water sources based on geographic location and make judgement calls about the risks of drinking water that may contain possible contaminants.

Elements and Inorganic Chemicals
MSC / MCL in mg per litre
Potential Health Effects
Sources of Contamination
Antimony – / 0.006 Cancer Fire retardants, ceramics, electronics, fireworks, pipe-solder
Arsenic 0.025 (IMAC) / 0.05 Skin and nervous system toxicity Natural deposits, smelters, glass, electronic wastes, orchards
Asbestos – / 7 (million fibres/litre) Cancer Natural deposits, asbestos cement in water systems
Barium 1.0 / 2 Affects circulatory system Natural deposits, pigments, epoxy sealants, burned coal ash
Beryllium – / 0.004 Damage to bones and lungs Electrical, aerospace, defence manufacturing
Cadmium 0.005 / 0.005 Affects kidneys Galvanized pipe corrosion, natural deposits, batteries, paint
Copper – / 1.3 Gastrointestinal irritation Natural and industrial deposits, wood preservatives, plumbing pipes
Chromium 0.05 / 0.1 Liver, kidney and circulatory systems disorders Natural deposits, mining, electroplating, fertilizer
Lead 0.01 / 0.005 Damage to kidneys and nervous system Natural deposits, pipe-solder, leaded gasoline car exhaust
Mercury 0.001 / 0.002 Kidney and nervous system disorders Agricultural run-off, natural deposits, batteries, electrical switches
Nitrate 45 / 10 Methemoglobulinemia (blue baby disease) Animal faeces, fertilizers, septic fields and natural deposits
Nitrite – / 1 Methemoglobulinemia (blue baby disease) Animal faeces, fertilizers, septic fields and natural deposits
Selenium 0.01 / 0.05 Liver damage Natural deposits, mining, smelting, coal and oil burning
Thallium – / 0.002 Kidney, liver, brain, intestinal damage Electronics, drugs, alloys, glass
Organic Chemicals
Contaminant MSC / MCL in mg per litre Potential Health Effects Sources of Contamination
Acrylamide – / – Cancer, affects nervous system Polymers used in sewage treatment
Adipate – / 0.4 Weight loss Synthetic rubber, food packaging, cosmetics
Alachlor – / 0.002 Cancer Herbicide run-off from corn, soyabean and other crops
Atrazine – / 0.003 Breast tumors Herbicide run-off from corn and other crop and non-crop fields
Carbofuran 0.09 / 0.04 Affects nervous and reproductive systems Soil fumigants on corn and cotton
Chlordane – / 0.002 Cancer Leaching from termite insecticide
Chlorobenzene – / 0.1 Affects liver and nervous sysetm Waste solvent from metal degreasing
Dalapon – / 0.2 Affects kidneys and liver Herbicides on orchards, beans, lawns and road and railway ditches
Dibromochloropropane – / 0.0002 Cancer Soil fumigant on soybeans, cotton and orchards
o-Dichlorobenzene –       0.6 Liver, kidney, and blood cell damage Paint, engine cleaners, dyes and chemical wastes
trans-1,2-Dichloroethylene – / 0.1 Affects liver, kidneys and nervous and circulatory systems Waste from industrial extraction solvents
cis-1,2-Dichloroethylene – / 0.07 Damage to liver, kidneys, and nervous and circulatory systems Waste from industrial extraction solvents
Dichloromethane 0.05 / 0.005 Cancer Paint stripper, metal degreasers and propellants
trans-1,2-Dichloropropane – / 0.005 Cancer and liver and kidney damage Soil fumigant and industrial solvents
Dinoseb 0.01 / 0.007 Damage to thyroid and organs Herbicide run-off from crops
Dioxin – /  0.00000003 Cancer Chemical production byproduct, pulp-mills, herbicide impurity
Diquat 0.07 / 0.02 Affects liver, kidneys and eyes Herbicide run-off from land and aquatic weeds
2, 4-D – / 0.07 Damage to liver and kidneys Herbicide run-off from wheat, corn, rangelands and lawns
Organic Chemicals continued
Contaminant MSC / MCL in mg per litre Potential Health Effects Sources of Contamination
Endothall – / 0.1 Liver, kidney and gastrointestinal problems Herbicide on crops and land and aquatic weeds
Endrin – / 0.002 Damage to heart, liver, and kidneys Pesticide (currently restricted in the US)
Epichlorohydrin – / - Cancer Water treatment chemicals, epoxy resins
Ethylbenzene – / 0.7 Damage to liver, kidneys and nervous system Gasoline, insecticides, waste from chemical manufacturing
Ethylen edibromide – / 0.00005 Cancer Leaded gasoline additives, soil fumigant
Glyphosate 0.28 /
IMAC) 0.7
Damage to liver and kidneys Herbicide run-off from grass, weeds and brush
Heptachlor – / 0.0004 Cancer Termite insecticide leaching
Heptachlor epoxide – / 0.0002 Cancer Biodegradation of heptachlor
Hexchlorobenzene – / 0.001 Cancer Pesticide manufacturing byproduct
– / 0.05 Damage to kidney and stomach Pesticide production byproduct
Lindane – / 0.0002 Affects liver, kidneys, and nervous, immune, and circulatory systems Incesticide used on cattle, lumber, and gardens (restricted since 1983)
Methoxychlor 0.9 / 0.04 Affects growth, liver, kidneys, and nervous system Insecticide run-off from fruit, vegetable, alfalfa crops, and livestock
Oxamyl (Vydate) – / 0.2 Kidney damage Insecticide run-off from apples, potatoes and tomatoes
PAHs (benzo(a)pyrene) – / 0.0002 Cancer Tar coatings, ashes from burning organic matter, fossil fuels
PCBs – / 0.0005 Cancer Coolants from electrical transformers and plasticizers
Pentachlorophenol 0.06 / 0.001 Cancer and affects liver and kidneys Wood preservatives, herbicides and cooling tower waste
Phthalate (di(2-ethylhexyl)) – / 0.006 Cancer PVC and other plastics
Picloram 0.19 / (IMAC) 0.5 Damage to liver and kidneys Herbicide run-off from broadleaf and woody plants
Organic Chemicals continued
Contaminant MSC / MCL in mg per litre Potential Health Effects Sources of Contamination
Simazine – / 0.004 Cancer Herbicide run-off from sod, some crops and aquatic algae
Styrene – / 0.1 Damage to liver and nervous system Plastics, rubber, resins, drug manufacturing, leachate from city landfills
Tetrachloroethylene 0.03 / 0.005 Cancer Dry-cleaning solvents
Toluene – / 1 Damage to liver, kidneys, and nervous and circulatory systems Gasoline additive, fabric seam-sealant, solvents
Toxaphene – / 0.003 Cancer Insecticide run-off from cattle, cotton, soybeans (restricted in the US since in 1982)
2,4,5-TP – / 0.05 Damage to liver and kidneys Herbicide on crops, right-of-ways, and golf courses (restricted in the US since 1983)
1,2,4-Trichlorobenzene – / 0.07 Damage to liver and kidneys Herbicide manufacturing and dyes
1,1,2-Trichloroethane – / 0.005 Kidney, liver, and nervous system damage Solvent in rubbers, and chemical manufacturing waste
Xylenes – / 10 Damage to liver, kidneys, and nervous system Byproduct of oil refining, paints, inks and detergents
Volatile Organic Chemicals
Contaminant MSC / MCL in mg per litre Potential Health Effects Sources of Contamination
Benzene – / 0.005 Cancer Gasoline, pesticides, paint, plastic manufacturing
Carbon Tetrachloride 0.005 / 0.005 Cancer Solvents
p-Dichlorobenzene – / 0.075 Cancer Room and water deodorants, mothballs
1,2-Dichloroethane 0.005 / 0.005 Cancer Leaded gasoline, fumigants, paint
1,1-Dichloroethylene 0.014 / 0.007 Cancer Plastics, dyes, paints
Trichloroethylene 0.05 / 0.005 Cancer Adhesives, metal degreasers
1,1,1-Tichloroethane – / 0.2 Affects liver and nervous system Adhesives, aerosols, paints, inks, metal degreasers
Vinyl Chloride 0.002 / 0.002 Cancer PVC piping, breakdown of solvents