melamine's dilemma - an additional kidney stressor to consider

[Guest guest]

Comments hereinbelow are shared with permission, from a toxicologist who

wishes to remain anonymous. Note that melamine by itself (eg, in baby

food) won't happen as a single pollutant. Indeed, food-borne melamine

will be part of a toxic cocktail that includes many other pollutants

well documented in cord blood, breast milk, etc. Allowing ANY melamine

into the food chain seems the FDA's gift to the businesses whose staff

purchased melamine-tainted food. How many infants, toddlers, older

children, and others will be pushed beyond their body's detox capability

by " just a little melamine " ?

- - - - FWD:

Anyone looking at the melamine dilemma in the US may be challenged by

the lack of adequate scientific data in the published literature. The

only two chronic exposure studies are old - one from the US in 1983, and

research from Japan that is more recently, but still limited by current

standards. There are NO long-term exposure studies starting in early

life. While this gap is common in toxicological study arrays, it is a

severe limitation when exposures are occurring via infant formula and

foods that children consume.

The FDA's proclamation last week of a 1 ppm benchmark (of sorts), just

prior to the WHO meeting on this chemical and it's metabolite, is

questionable at best. Absent data on which to base this number, we can

ask why additional safety factors were not used, and we are left to rely

on existing data and protective concepts to pose additional questions

and consider safety versus hazard.

Many of us have worked on nephrotoxins, due largely to the fact that so

many petrochemicals and metals target the kidneys. Their prevalence in

the environment and foods raises serious questions about the wisdom of

allowing any melamine in food, especially infant formula.

The article below provides additional bases for discussion and concern.

It describes a study of physical stressors on the kidneys that are not

typically included in our chemical evaluations - dehydration and

hyperthermia. Given the difficulty of keeping an infant hydrated

during common illnesses, and increasing climate change-induced high

ambient temperatures, these additional stressors are important

considerations in evaluating any kidney toxin.

The potentially serious consequences of early sustained nephrotoxicity

and stressors are obvious. It is reasonable to request that FDA (or

another agency) conduct a full evaluation of nephrotoxic burdens and

stressors as an essential action prior to proclaiming any level of

melamine safe. With the number of nephrotoxins commonly encountered,

even at low (ambient) levels, condoning an additional nephrotoxin in the

diet of infants seems unwarranted and inadvisable. If there is

justification for this, the FDA must do a much better job of describing

and quantifying the kidney-damaging factors that infants are already

exposed to, and clarifying why an additional nephrotoxic burden would

not cause any infants who must rely on formula to reach a threshold of

kidney damage

leading to disease now or in the future.

Related - The WHO issued a data call in with the meeting, but it seems

likely that there are private studies that may not be submitted. If you

can identify unpublished studies that can help us to better understand

this chemicals behavior, please let us all know so we can do what is

necessary to make the information available to medical scientists.

_________________________________________________________

International Journal of Epidemiology 2008 37(6):1359-1365;

doi:10.1093/ije/dyn165

*The effect of heat waves on hospital admissions for renal disease in a

temperate city of Australia*

Alana L Hansen1, Peng Bi1,*, Philip 1, Monika Nitschke2, Dino

Pisaniello1 and Graeme Tucker2

1 Discipline of Public Health, School of Population Health and Clinical

Practice, Faculty of Health Sciences, The University of

Adelaide, Adelaide, SA, Australia.

2 South Australian Department of Health, Adelaide, SA, Australia.

* Corresponding author. Discipline of Public Health, School of

Population Health and Clinical Practice, Faculty of Health Sciences,

Level 9, Tower Building, 10 Pulteney Street (MPD 207), The University of

Adelaide, Adelaide, SA 5005, Australia. E-mail:

peng.bi@...

Abstract

Background A rarely investigated consequence of heat exposure is renal

dysfunction resulting from dehydration and hyperthermia. Our study aims

to quantify the relationship between exposure to extreme high

temperatures an renal morbidity in South Australia.

Methods Poisson regression accounting for over dispersion, seasonality

and long-term trend was used to estimate the effect of heatwaves on

hospital admissions for renal disease, acute renal failure and renal

dialysis over a 12-year period. Selected comorbidities were investigated

as possible contributing risk factors.

Results Admissions for renal disease and acute renal failure were

increased during heat waves compared with non-heat wave periods with an

incidence rate ratio of 1.100 [95% confidence intervals (CI)

1.003-1.206] and 1.255 (95% CI 1.037-1.519), respectively.

Hospitalizations for dialysis showed no corresponding increase. Comorbid

diabetes did not increase the risk of renal admission,however 'effects

of heat and light' and 'exposure to excessive natural heat'

(collectively termed effects of heat) were identified as risk factors.

Conclusion Our findings suggest that as heat waves become more frequent,

the burden of renal morbidity may increase in susceptible individuals as

an indirect consequence of global warming.

_