Childhood Exposure to Mercury from Baby Food and Fish Sticks

Amos, J*, DeSanto, D*, Kiry, P, Ashley, JSchool of Science and Health, Philadelphia University, 4201 Henry Ave, Philadelphia, PA, 19144

The Academy of Natural Sciences of Drexel University, 1900 Benjamin Franklin Parkway, Philadelphia, PA 19103

Abstract

Increasing fish in children’s diets increases their levels of valuable nutrients such as omega-3 fatty acid and vitamin D. However, the benefits of eating fish may be overshadowed by the presence of mercury in fish products. Once in the human body, mercury acts as a neurotoxin, resulting in negative impacts on cognitive thinking and memory in infants and children.5 To assess the levels of mercury and estimate subsequent daily exposures to this toxin, various baby foods containing fish oils and frozen fish sticks were analyzed using flow injection cold vapor atomic spectrometry. The EPA recommended daily limit of mercury for a child (45 lbs) is 2.05 µg and 0.68 µg for an infant (15 lbs)7. Total mercury, defined as the sum of the elemental and methylated forms of this element, was present in all samples, ranging from 0.002 to 0.003 µg/g in baby food and 0.018 to 0.059 µg/g in fish sticks. Baby food products in this study did not exceed this guideline. However, 88% of the fish stick brands studied resulted in mercury exposures over the EPA guideline. Because this study was limited in the number of samples analyzed (n=14), to ensure safe consumption levels further research should be conducted to determine the amount of mercury in all types of food containing fish products targeted towards babies and children.

IntroductionFish oil is a natural source of vitamin D and omega-3 fatty acids such as EPA and DHA, compounds known to benefit proper brain development in infants and young children.1 Many consumer products, such as fish sticks and baby food, now contain fish/fish oils supplying these nutrients (See Figures 1 and 2). However, the benefits of consuming fish can be overshadowed by the presence of mercury, a well known neurotoxin that bioaccumulates in fish and is found in products containing fish and fish oil (See Figure 3).5 Mercury may interfere with brain development of children and infants, impairing memory, speech development, and critical thinking.5 The goal of this study was to assess the levels of mercury in baby food and fish sticks and to calculate daily exposures to this toxin. This is the first known study to report the levels of mercury in baby food fortified with fish oil.

Materials And Methods Results & Discussion

Figure 6. The highest concentrations found were in Apples and the lowest in Pears Stage 1. All of the samples contained mercury yet all were below the EPA recommended limit.7

Figure 7. The highest concentrations were found in Gorton’s Fish Fillets and the lowest in Shindler’s Pollock. All of the samples contained mercury, however only one was under the EPA recommended limit.7

Nitric acid was added to samples of baby food and fish sticks (Table

1)

Microwave digestion was used to solubilize samples using EPA

method 3052 (Figure 4)

Digested samples were diluted to 100 mL by deionized water

Potassium permanganate was added to samples that had not

completely solubilized

Sodium Chloride and hydroxylamine was added to

remove the potassium permanganate

Mercury cold vapor atomic absorption spectrometer was used to determine mercury concentrations (Figure 5)

Figure 4. Example of MARS microwave digestion unit.4

Figure 5. Example of Mercury cold vapor atomic absorption spectrometer.6

Shindler's

EPA Rec-om-

mended Level

Dr. Praeger

Gorton's Tenders

SeaPak Shrimp

Co.

High-liner

Kosherific

Mrs. Pauls

Gorton's Fish Fil-

lets

0.00

1.00

2.00

3.00

4.00

5.00

6.00

Mercury Exposure Per Serving via Fish Sticks for a 20.45 kg Child

Conce

ntr

ati

on (

µg/s

erv

ing)

Pears Stage 1 Apple Blackberry Sweet Potato Pears Stage 2 Carrots Apples EPA Recom-mended Level

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

Mercury Exposure Per Serving via Baby Food for a 6.8 kg Infant

Con

cen

trati

on

(µ

g/s

erv

ing

)

Conclusion All of the samples analyzed contained some level of mercury. According to the EPA, the recommended limit for a child (45 lbs) is 2.05 µg and 0.68 µg for an infant (15 lbs)7.  Out of the eight fish stick samples, only one did not exceed the recommended daily limit; none of the baby food samples exceeded the level of mercury that is considered safe for consumption.7 For Shindler’s, 1.38 of a recommended serving size can be eaten without exceeding the EPA limit of 2.05µg, which allows fish sticks intake greater flexibility by 30.98g. Only 0.36 of a serving of Gorton’s Fish Fillets can be eaten without exceeding the EPA limit, which limits consumption to 35g. Our findings have been observed in previous research.3 Contrary to previous research on mercury dietary levels2, our study showed that fish sticks exceeded the EPA recommendation. This justifies a need for further testing using a larger sample size.

Sources1. Environmental Protection Agency. What You Need to Know about Mercury in Fish and Shellfish. http://water.epa.gov/scitech/swguidance/fishshellfish/outreach/advice_index.cfm (accessed Apr 4, 2012)2. Food and Drug Administration. Mercury Levels in Commercial Fish and Shellfish. http://www.fda.gov/Food/FoodSafety/Product-SpecificInformation/Seafood/FoodbornePathogensContaminants/Methylmercury/ucm115644.htm (accessed Apr 4 2012)3. Food Quality News. Arsenic, mercury levels in baby food below limit, says regulator. http://water.epa.gov/scitech/swguidance/fishshellfish/outreach/advice_index.cfm (accessed Apr 4, 2012)4. Fordham University. MARS microwave digestion system. http://www.fordham.edu/academics/programs_at_fordham_/chemistry/facilities/mars_digestion_81356.asp (accessed Apr 4, 2012)5. MedicineNet, Inc. Mercury Poisoning. http://www.medicinenet.com/mercury_poisoning/article.htm (accessed Mar 15, 2012).6. Mississippi State University. Analytical Services Laboratory of ICET. http://www.icet.msstate.edu/historic/cap/Analytical%20Services%20Laboratory%20Web%20Page%20August%202006.html (accessed Apr 4, 2012)7. PBS. The Mercury Story. http://www.pbs.org/now/science/mercuryinfish.html (accessed Mar 9, 2012)8. University of Calgary. How Mercury Causes Brain Neuron Damage. http://www.youtube.com/watch?v=XU8nSn5Ezd8 (accessed Apr 4,2012)

Figure 3. The effects of mercury on tubulin and actin.8

Figure 1. Nutrition label from baby food stating the presence of 18 mg of DHA.

Figure 2. Nutrition label from baby food listing tuna fish oil as an ingredient.

Table 1. Characteristics of different fish stick brands used in this study.Fish Stick Brand

Species 

Serving Size (g) 

Concentration (µg/g) 

DHA Content 

Hg Exceedence Factor*** 

Daily Allowance (g)***

Shindler's Pollack 81 0.018 N/A 1.38 111.98Dr. Praeger Pollack 81 0.029 N/A 0.86 70.06Gorton's Tenders

Alaska Pollack

98 0.029 120 mg0.72 70.93

SeaPak Shrimp Co.

Tilapia 113 0.028 N/A0.65 73.26

Highliner Various Species*

85 0.046 32 mg0.52 44.47

Kosherific Various Species**

88 0.053 N/A0.44 38.92

Mrs. Pauls Haddock 113 0.043 N/A 0.42 47.34Gorton's Fish Fillets

Flounder 98 0.059 N/A0.36 35

           

Baby Food Flavor

         

Stage 1 Pears Tuna Oil 71 0.003 18mg 3.29 233.62Apple Blackberry

Tuna Oil 99 0.002 18mg 3.27323.91

Sweet Potato Tuna Oil 99 0.002 18mg 3.18 314.41Stage 2 Pears Tuna Oil 99 0.002 18mg 3.06 302.46Carrots Tuna Oil 71 0.003 18mg 2.76 195.86Apples Tuna Oil 99 0.003 18mg 2.46 243.79

*Whiting, Sole, Pollack, Cod, Blue Whiting, Tilapia, Flounder, Plaice, Burbot**Whiting, Pollack, Mullet, Carp*** Number of Servings to Reach Daily Limit**** Limit of Grams to Reach Daily Limit