User:Jonathan Cline/Notebook/Melaminometer/Toxicology Details

Toxicity Studies in Milk Products

• [Full Text] World Health Organization Epidemic and Pandemic Alert and Response (EPR) Questions and Answers on melamine.

In China, where adulteration has occurred, water has been added to raw milk to increase its volume. As a result of this dilution the milk has a lower protein concentration. Companies using the milk for further production (e.g. of powdered infant formula) normally check the protein level through a test measuring nitrogen content. The addition of melamine increases the nitrogen content of the milk and therefore its apparent protein content.

• [Full Text] U.S. FDA Interim Safety and Risk Assessment of Melamine and its Analogues in Food for Humans. FDA/Center for Food Safety & Applied Nutrition Hypertext updated by cjm October 3, 2008

As of September 21, 2008, FDA learned that a total of 52,857 cases of nephrolithiasis (and, in some instances, renal failure) had been reported in China linked to consumption of this contaminated powdered formula. There have been approximately 13,000 hospitalizations, and at least 3 deaths have been confirmed to date. The vast majority of illnesses involved children under the age of 3 years (82% < 2 years; 17% 2-3 years; 0.8% > 3 years; and no cases involved adults). The results of an investigation conducted in China indicated that Chinese-produced powdered infant formula was linked to these illnesses; no cases were associated with liquid infant formula.

We note that there are generally available analytical methods that can reliably detect a level of 1 ppm melamine in some food matrices.

Melamine and its analogues - cyanuric acid, ammelide and ammeline - are assumed to be of equal potency and are referred to collectively below as melamine-analogues. Since there is limited information about the toxicity or pathology of the analogues compared to melamine, it is deemed prudent to make an assumption that these analogues have equal effects.

FDA used a worst case exposure scenario in which one-half of a person's total daily dietary intake (typically estimated at 3 kg (composed of liquid [1.5 kg] and solid food [1.5 kg]) is contaminated with melamine and its analogues. The previously determined (see above) total amount of melamine and its analogues/person/day:

3.78 mg melamine and its analogues/person/day divided by 1.5 kg of food = the food contamination level that would provide this amount of melamine and its analogues to a 60 kg person per day. Thus, 3.78 mg melamine and its analogues divided by 1.5 kg of food = 2.5 mg melamine and its analogues/kg food.

Therefore, if 50% of the diet were contaminated at a level of 2.5 ppm of melamine and its analogues, a person's daily intake would equal 0.063 mg/kg bw/d.d

The current incident has focused on melamine contamination of milk and milk-derived ingredients from China. As illustrated in Table 1, U.S. consumers would be exposed to only 1.1 % of the melamine TDI/10 (0.063 mg/kg bw/d) if all of the major milk-derived ingredients listed below were contaminated at a melamine level of 2.5 mg/kg (2.5 ppm) assuming an average per capita ingredient intake.

• [Full Text] Risk assessment and referral levels for dairy foods and foods containing dairy-based ingredients adulterated with melamine. Food Standards Australia-New Zealand Fact Sheet 2008, (14 October 2008).

A maximum level of 1 mg/kg for melamine in infant formula is considered appropriate.

A maximum level of 2.5 mg/kg for melamine in dairy-based foods and foods containing dairy-based ingredients is appropriate and acceptable.

A level of melamine above 2.5 mg/kg is indicative of food adulteration.

For infant formula, even at relatively low levels of adulteration an infant will quickly exceed the Tolerable Daily Intake for melamine, if consuming formula only.

Foods with low levels of dairy-based ingredients, such as candies and biscuits, are likely to be infrequently consumed and in small amounts so they are not considered to be a high-risk food for potential dietary exposure to melamine even if the dairy ingredient has been adulterated.

Toxicity Studies in Pet Food

• Killer pet food ingredients identified. The New Scientist Volume 196, Issue 2631, 24 November 2007, Page 4
• [Full Text] Identification and characterization of toxicity of contaminants in pet food leading to an outbreak of renal toxicity in cats and dogs. Toxicol Sci. 2008 Nov;106(1):251-62. Epub 2008 Aug 9.

Melamine and cyanuric acid, have been tested and do not produce acute renal toxicity. Some of the triazines have poor solubility, as does the compound melamine cyanurate. Pathological evaluation of cats and dogs that had died from the acute renal failure indicated the presence of crystals in kidney tubules. We hypothesized that these crystals were composed of the poorly soluble triazines, a melamine-cyanuric acid complex, or a combination. Sprague dawley rats were given up to 100 mg/kg ammeline or ammelide alone, a mixture of melamine and cyanuric acid (400/400 mg/kg/day), or a mixture of all four compounds (400 mg/kg/day melamine, 40 mg/kg/day of the others). Neither ammeline nor ammelide alone produced any renal effects, but the mixtures produced significant renal damage and crystals in nephrons.

Several triazines, but predominantly melamine and cyanuric acid, were identified as the contaminants in a batch of wheat gluten that had been used as an ingredient in a number of brands of wet pet food. The total fraction of triazines in the contaminated gluten was on the order of 10¿13%. Assuming that wet cat foods contained up to 10% gluten and feeding according to manufacturer's guidance, this would have resulted in dosages of melamine and cyanuric acid in the 360¿430 mg/kg/day range, comparable to the 400 mg/kg/day used in the rodent experiments.

The nature of the toxicity may pose a challenge for traditional risk assessment methods, which are based on assessment of the toxicity of individual compounds. In this case, the toxicity of the melamine cyanurate complex is qualitatively different from that of melamine or cyanuric acid administered alone. The dose-response curve and no-observed adverse effect level for the mixture is almost certainly different from that of either compound alone. Recent press reports indicate that the use of melamine may be more widespread than thought in the animal feed industry. Given that ammeline, ammelide, and cyanuric acid are bacterial breakdown products of melamine, and could also be formed during melamine synthesis, it is plausible that exposures to mixtures of melamine and related compounds could happen again. Therefore, improving the risk assessment for melamine mixtures is a significant need.

• Ultrasonic extraction and determination of cyanuric acid in pet food. doi:10.1016/j.foodcont.2008.04.004