Predictors of Blood Mercury Levels in Older Urban Residents

Pollution by metals: Is there a relationship in glycemic control?

There are evidences of environmental pollution and health effects. Metals are pollutants implicated in systemic toxicity. One of the least studied effects, but which is currently becoming more important, is the effect of metals on glycemic control. Metals have been implicated as causes of chronic inflammation and oxidative stress and are associated to obesity, hyperglycemia and even diabetes. Arsenic, iron, mercury, lead, cadmium and nickel have been studied as a risk factor for hyperglycemia and diabetes. There is another group of metals that causes hypoglycemia such as vanadium, chromium, zinc and magnesium by different mechanisms. Zinc, magnesium and chromium deficiency is associated with increased risk of diabetes. This review summarizes some metals involved in glycemic control and pretends to alert health professionals about considering environmental metals as an important factor that could explain the poor glycemic control in patients. Further studies are needed to understand this poorly assessed problem.

Toxicity biomarkers among US children compared to a similar cohort in France: a blinded study measuring urinary porphyrins

The purpose of this blinded study was to evaluate potential environmental toxicity in a cohort of neurotypical children (n = 28) living in a suburban area of north-central Texas in the United States (US) with a comparable age- and gender-matched cohort of neurotypical children (n = 28) living in a suburban area of southeastern France using urinary porphyrin testing: uroporphyrin (uP), heptacarboxyporphyrin (7cxP), hexacarboxyporphyrin (6cxP), pentacarboxyporphyrin (5cxP), precoproporphyrin (prcP), and coproporphyrin (cP). Results showed significantly elevated 6cxP, prcP (an atypical, mercury-specific porphyrin), and cP levels, and increasing trends in 5cxP levels, among neurotypical children in the USA compared to children in France. Data suggest that in US neurotypical children, there is a significantly increased body-burden of mercury (Hg) compared to the body-burden of Hg in the matched neurotypical children in France. The presence of lead contributing to the higher levels of cP also needs to be considered. Further, other factors including genetics can not be completely ruled out.

Environmental toxins, a potential risk factor for diabetes among Canadian Aboriginals

OBJECTIVES

To review the current literature to determine if there is a case for examining the presence of toxins in traditional foods and the environment as a possible risk factor for type 2 diabetes in Canadian Aboriginal populations.

STUDY DESIGN

Literature review. METHODS. The scientific literature on possible causes of type 2 diabetes in Aboriginal populations in Canada was reviewed. Potential exposure through food and water to environmental toxins such as methylmercury, arsenic, persistent organic pollutants (POPs), including bisphenol A and phthalates, as well as Aboriginal lifestyle and composition of the traditional diet is discussed. RESULTS. There is growing evidence to suggest that environmental toxins may be associated with noninsulin-dependent diabetes mellitus (type 2 diabetes), which many consider to be endemic worldwide. In Canada, diabetes has reached epidemic proportions, especially among Aboriginal populations. Based on both molecular and pathological findings, some toxins found in the environment interfere with the functioning of the pancreas' islets of Langerhans cells, and consequently they affect insulin production. In addition, there is new evidence suggesting that obesity may be linked to endocrine disruptors, thus increasing the likelihood that obesity in itself may not be a chief risk factor for diabetes.

CONCLUSIONS

Diabetes prevalence rates among First Nations, Inuit and Métis populations are 3-5 times higher than the general population. Accepted risk factors such as diet, lifestyle and genetics do not fully explain this phenomenon. However, as many environmental toxins bioaccumulate in the food chain and are found in wild game and fish traditionally harvested and consumed by Aboriginal peoples, these chemicals could present health risks not yet fully explored. As there is not enough evidence to rule out this possibility, further studies are suggested. If correct, such environmental risk factors, especially if they are encountered early in life, would have implications on Aboriginal public health.

Omega-3 fatty acids and risk of dementia: the Canadian Study of Health and Aging

BACKGROUND

Omega-3 polyunsaturated fatty acids (n-3 PUFAs) may protect against dementia, although epidemiologic studies have yielded inconclusive results. Fish is the main dietary source of n-3 PUFAs and is sometimes contaminated with mercury. This neurotoxicant may modify the association with dementia.

OBJECTIVE

We evaluated the association of erythrocyte membrane total n-3 PUFAs, docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), and blood mercury with the incidence of dementia and Alzheimer disease (AD) in the Canadian Study of Health and Aging (CSHA) with adjustment for confounders including apolipoprotein E epsilon4 (APOE epsilon4) status.

DESIGN

The CSHA is a cohort study of a representative sample of persons aged > or =65 y, conducted from 1991 to 2002. A subsample of 663 nondemented CSHA subjects with a complete clinical examination, blood samples, and follow-up information was eligible for prospective analyses on laboratory measurements. Of these, 149 were incident cases of dementia, including 105 with AD.

RESULTS

In adjusted Cox regression models with age as the time scale, there were no associations between total n-3 PUFAs, DHA, or EPA and dementia or AD. In contrast, a mercury concentration in the highest quartile was associated with a reduced risk of dementia (hazard ratio: 0.53; 95% CI: 0.33, 0.88). However, significant risk reductions were limited to subjects with concentrations of both n-3 PUFAs and mercury that were above the median. There was no modification of risk by APOE epsilon4 status.

CONCLUSIONS

No associations between n-3 PUFAs and dementia or AD were found. The results regarding mercury may indicate a spurious association.

Sulfhydryl-reactive metals in autism

This study examined the difference between sulfhydryl-reactive metals (mercury, lead, arsenic, and cadmium) in the hair of 45 children with autism (1-6 yr of age) as compared to 45 gender-, age-, and race-matched typical children. Hair samples were measured with inductively coupled mass spectrometry. Some studies, such as Holmes et al. (2003), suggested that children with autism may be poor detoxifiers relative to normally developing children. Metals that are not eliminated sequester in the brain. Our study found that arsenic, cadmium, and lead were significantly lower in the hair of children with autism than in matched controls. Mercury was in the same direction (lower in autism) following the same pattern, but did not achieve statistical significance. The evidence from our study supports the notion that children with autism may have trouble excreting these metals, resulting in a higher body burden that may contribute to symptoms of autism.