Recent research conducted by scientists at George Washington University reveals the levels of heavy metals in many dark chocolate products available in the US market. The study was published in the journal Frontiers in Nutrition.
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The study analyzed over 70 dark chocolate products sold across various major retailers including Amazon, GNC, and Whole Foods, over a span of eight years (from 2014 to 2022). The researchers did not disclose the specific brands or products tested.
43% of the dark chocolate samples exceeded California’s Proposition 65 limits for lead contamination. The study found lead levels ranging from zero to 3.316 micrograms per daily serving with California guidelines setting the maximum allowable level at 0.5 micrograms per day.
35% of the samples exceeded the Prop 65 limits for cadmium. Cadmium levels in the chocolate samples ranged from 0.29 to 14.12 micrograms per daily serving, whereas the maximum permissible level according to California standards is 4.1 micrograms per day.
The study also tested for arsenic contamination but found no levels in the chocolate products.
Lead and cadmium are naturally occurring elements in the Earth’s crust and are commonly found in soil.
As a result, they can be absorbed by cocoa plants during cultivation. Some regions have higher concentrations of these metals due to industrial pollution and the use of metal-containing fertilizers.
The study suggests that while cadmium is primarily absorbed from the soil lead contamination is likely introduced during the drying, processing and packaging stages of chocolate production.
This could be due to the use of contaminated machinery or materials that introduce lead during these stages.
The study found that organic chocolate products often contained higher levels of contamination compared to non-organic products.
Lead exposure is particularly harmful to children affecting brain development and leading to reduced intelligence quotient (IQ), behavioral issues and decreased educational attainment.
There is no safe level of lead exposure, according to the World Health Organization (WHO). In adults, lead exposure can contribute to cardiovascular issues, kidney damage and reproductive problems.
The Environmental Protection Agency (EPA) classifies cadmium as a probable human carcinogen. Chronic exposure can lead to an increased risk of cancer.
Cadmium is known to accumulate in the kidneys leading to renal dysfunction over time. It can also affect bone health and the respiratory and cardiovascular systems.
The research involved the analysis of 72 dark chocolate products from popular retailers such as Whole Foods Market, Amazon and GNC.
The study spanned an eight-year period, from 2014 to 2022, ensuring data on the levels of lead, cadmium and arsenic in these products.
Researchers assessed heavy metal contamination using California’s Proposition 65 as the benchmark, which sets stricter limits than those of the Food and Drug Administration (FDA).
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43% of the dark chocolate products tested exceeded California’s maximum allowable dose levels for lead.
Lead levels in the samples varied widely ranging from 0 to 3.316 micrograms per daily serving. According to Proposition 65, the safe threshold for lead in foods is 0.5 micrograms per day.
35% of the products surpassed the allowable levels for cadmium. Cadmium levels ranged from 0.29 to 14.12 micrograms per daily serving with a California limit of 4.1 micrograms per day.
The study found that organic chocolate products contained higher levels of both lead and cadmium compared to non-organic varieties.
Lead is a potent neurotoxin with no safe exposure level especially concerning for children and pregnant women.
Chronic exposure to lead can lead to serious health problems including cognitive impairments, developmental delays and organ damage.
Cadmium is classified as a carcinogen at high exposure levels and can cause kidney damage, bone loss and other health issues. It primarily enters the body through food, as it is absorbed from the soil by plants like cacao.
Arsenic is a known carcinogen and can cause skin lesions, cardiovascular diseases and diabetes when consumed in high amounts over time.
Cadmium is primarily absorbed from the soil by the cacao plant. Factors such as soil composition and regional farming practices can influence the levels of cadmium in cacao beans.
Lead can be introduced at various stages of the chocolate production process including harvesting, drying and fermenting. Environmental contamination and industrial processes may also contribute.
California’s Proposition 65 sets stringent limits for lead and cadmium in foods, which are more restrictive than federal standards.
Prop 65 aims to provide consumers with information about potential exposures to toxic chemicals and to help them make informed decisions.
For most healthy adults, consuming dark chocolate in moderation is not expected to pose health risks. A typical serving size of dark chocolate is about 1 ounce and occasional consumption is considered a minor risk compared to other sources of exposure.
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