Do you still wonder if there’s a link between the high mortality rate for the Lillooet Local Health Area and arsenic in the District of Lillooet’s wells?
It’s a topic that appears regularly in letters to the News and on social media.
It is commonly agreed that naturally occurring arsenic can have health effects as troubling as those associated with man-made substances. It’s also commonly agreed that levels of arsenic in groundwater sources i.e. wells are generally higher than in surface water sources i.e. lakes, rivers and creeks.
According to the Dartmouth Toxic Metals Superfund Research Program, arsenic is the number-one naturally occurring chemical of environmental health concern worldwide. That research program, led by Dr. Joshua Hamilton, recently discovered that arsenic acts as an endocrine-disrupting chemical; Hamilton and his colleagues are now focusing on whether these alterations may contribute to arsenic’s ability to increase the risk of diabetes, vascular diseases and certain cancers.
Given that, why did an Interior Health Authority official write a letter to the Lillooet News (June 13, 2012) saying it would be “misleading” and “incorrect” to link arsenic in the wells to local mortality rates? The letter also suggested Lillooet residents should educate themselves about the factors that influence mortality rates and separate that topic from current discussions of water quality and the solutions to that problem.
Digging a little deeper, the News contacted Dan Ferguson, the author of that letter, for more information on the topic.
Ferguson is Interior Health’s Assistant Director, Health Protection for Environmental Health Operations.
Higher than BC’s rate
He says mortality rates for the Lillooet Local Health Area “have been consistently higher than provincial rates throughout the 25-year time period rates have been available, and in every single year. The five year moving average rates are all statistically significantly higher than the provincial rate.”
According to a letter from Ferguson to a Lillooet resident in June 2011, a five-year averaging process allows for full information to be presented up to the year 2005. The mortality rate in 2005 was 1.45, compared to rates of 1.46 in 2004, 1.34 in 2003, 1.36 in 2002 and 1.34 in 2001. Those numbers indicate there were more deaths than expected in this health area, given provincial age-specific mortality rates.
While those rates for the Lillooet Local Health Area are higher than the BC average, Ferguson reiterated it would be a mistake to attribute those death rates to arsenic in the District’s wells.
For starters, Ferguson says residents should know that the District of Lillooet is only one part of the Lillooet Local Health Area (LHA). “Only about half of the population of the Health Area live in the area serviced by the District of Lillooet water systems,” said Ferguson.
The Lillooet Local Health Area shares the same boundaries as the former Lillooet School District 29. That means the Health Area – and its associated mortality rates - also includes the St’at’imc communities of T’it’q’et, Xaxli’p, Xwisten, Chalalth and Ts’kw’aylaxw, plus Seton Portage, Gold Bridge, Bralorne, Gun Lake, Yalakom Valley, Pavilion Lake, Texas Creek and Fountain Valley.
Studies have shown that chronic or repeated ingestion of water with arsenic over a person’s lifetime is associated with increased risk of cancer (of the skin, bladder, lung, kidney, nasal passages, liver or prostate) and non-cancerous effects (diabetes, cardiovascular and neurological disorders).
Ferguson says the key phrase in the preceding statement is “over a person’s lifetime.”
Over a lifetime
He provided the News with the documentation for arsenic from the Guidelines for Canadian Drinking Water Quality.
Ferguson said the Canadian guidelines for carcinogenics (cancer-causing substances) are based on the principle of a 70 kg. adult consuming 1.5 litres per day of water containing arsenic over a lifetime (80 years).
Ferguson added that if residents of a community were drinking 1.5L of water per day at the Maximum Acceptable Concentration (MAC) of arsenic, “We would expect to see one additional cancer for every 100,000 to 1,000,000 people.”
He said the two Lillooet wells that are the focus of concern (both located at Conway Park) have not been in operation for the length of time necessary to create worries about long-term arsenic exposure.
The Conway Park wells were constructed in 1994 because the municipality concluded Town Creek could not meet summer water demands. When the wells were installed, the MAC for arsenic was at 25 ppb (parts per billion) and the wells were under that limit and considered safe.
In 2006, the federal government revised its guidelines and the MAC dropped to 10 ppb.
Although the wells exceeded the limit after the 2006 change in guidelines, Ferguson said neither the District nor IHA sampled the wells regularly because they were used infrequently and primarily to satisfy summer irrigation demands.
Because of concerns raised by the Lillooet Ratepayers Association and others, the subject of arsenic in the wells came under closer scrutiny in subsequent years.
In 2009, Ferguson says the wells were pressed into service because Town Creek was experiencing high NTU (turbidity) levels as a result of the forest fire in the watershed. The creek was taken off line at that time.
“The District continued to sample the wells for arsenic on a weekly basis for some time to see if the arsenic levels would decrease with use, increase with use or remain constant,” Ferguson continued. “Sampling was discontinued as the wells were not being utilized and the value of reporting was questioned.”
The two Conway Park wells were taken offline in September 2010 and have not been used since then.
He says his understanding is that use of the wells “could be described as intermittent at best.”
“So in summary,” Ferguson stated, “the wells have been used infrequently since they were constructed, use would certainly not meet the criteria of a lifetime (80 years), and there are many other social, economic, educational and lifestyle issues that affect the Lillooet mortality rate.”
Significant causes of death
He referred the News to the significant causes of death listed in the IHA’s April 2009 Lillooet Local Health Area Profile. The top five causes of death within the Health Area were malignant neoplasms (cancer), diseases of the circulatory system, alcohol-related deaths and diseases of the respiratory and digestive systems. Motor vehicle accidents were also a significant cause of death in this health area.
The Profile says non-medical determinants of health such as behaviours, living and working conditions, employment status, income inequality, personal resources and environmental factors all have the potential to influence human health.
According to the Profile, Lillooet LHA residents had a lower median share of income than the residents of the Thompson Cariboo Shuswap Health Services Area (HSA) and Interior Health overall. The Lillooet LHA also had a lower proportion of residents who graduated high school than Interior Health, but a higher proportion than the Thompson Cariboo Shuswap HSA.
For reference, the Thompson Cariboo Shuswap HSA is one of four service areas within Interior Health and includes the Lillooet Local Health Area.
The Lillooet LHA’s unemployment rate of 12.7 per cent was also higher than the Thompson Cariboo Shuswap HSA (12.0 per cent), Interior Health (10.6 per cent) and British Columbia (8.5 per cent).
The report states, “Research has shown that income inequality is a predictor of health and a major contributor to health inequities.” It also says unemployed people tend to experience more health problems.
How we measure up
The 2009 Profile says Thompson Cariboo Shuswap residents have a lower percentage of the population who are physically active in their leisure time and a lower percentage of people who eat healthy when compared to Interior Health and BC. The TCS HSA also has a higher rate of tobacco use than Interior Health and BC and higher rates of obesity than Interior Health and BC.
The report says 30 per cent of cancer and diabetes cases and 20 per cent of cardiovascular disease can be attributed to poor nutrition. Obesity is a major risk factor for many chronic illnesses, including cardiovascular diseases, type 2 diabetes and some types of cancer. The report says cigarette smoking is the primary risk factor for diseases of the circulatory system, lung cancers and respiratory disease.
In other words, the factors that contribute to mortality rates are complex and often interrelated.
Ferguson states, “There are more immediate and significant health indicators in Lillooet than the arsenic levels in the wells. We can make a positive shift in the health of the population by individually and collectively doing simple things such as walking/exercising for 30 minutes a day, eating more fruits and vegetables, reducing our sodium and sugar intake, quitting smoking and reducing alcohol consumption.”
Editor’s Note: I was a member of the Village of Lillooet’s municipal council in 1994 when the Conway Park wells were constructed. I also served as vice-chair of the Lillooet District Hospital Board, chair and vice-chair of the Lillooet Community Health Council and as Lillooet’s representative on the South Central Union Board of Health during the 1990s. I recall the Lillooet Local Health Area had a high mortality rate in those years, for many of the same reasons cited today by Interior Health.