Lead Content in Coffee

• Coffee

Coffee is a drink made from roasted coffee beans. The main ingredients of coffee are caffeine, tannin, fat, acid fat, volatile fat, protein, sugar, fiber, minerals and so on. Drinking coffee is a double-edged sword. On the one hand, it promotes skin metabolism, activates the digestive organs, and has a hangover function. On the other hand, it can aggravate high blood pressure, induce osteoporosis and affect sleep.

Figure1. Coffee

• Lead

As a metal chemical element whose chemical symbol is Pb, lead is a non-radioactive element with the largest atomic weight. Lead is a weak, ductile and weak metal that is toxic and heavy. On October 27, 2017, the World Health Organization’s International Agency for Research on Cancer published a preliminary list of carcinogens containing lead.

• The Harm of Lead to Human Body

Excessive blood lead levels may affect the metabolism of heme and decrease the rate of nerve conduction. Besides, calcium deficiency, zinc deficiency and hemoglobin synthesis disorders may occur, causing low immunity, difficulty in learning, inattention, and decreased IQ, physical retardation, variable personality, irritability, hyperactivity, aggressive behavior, movement disorders, vision and hearing loss, unexplained abdominal pain, anemia, arrhythmia and other symptoms of poisoning, kidney damage, encephalopathy and even death.

• Determination of Lead Content in Coffee

Beverage manufacturers are required that lead content is not higher than 1 mg/L because it’s easy for lead to accumulate and thus become poisonous. The traditional colorimetric method, however, can not meet the requirement. So the most commonly used method for the determination of lead content in coffee is atomic absorption spectrometry. Atomic absorption spectrophotometry is used to measure metal elements and some non-metallic elements in the atomic state. The minimum detection concentration is 0.01 mg/L, with a linear range of 0.5-10 mg/L, the correlation coefficient R of 0.9998, a recovery rate of 97.61% and the relative deviation of 1.79%. The method is simple and rapid, which can be a good option for simultaneous determination of multiple samples.

• Regulations of Lead Content

The lead content in different foods is different. According to regulations, the limit of lead is 0.2 mg/kg in cereals, beans, potatoes, poultry, fresh eggs and fruit wine, 0.1 mg/kg in fruit, 0.05 mg /kg in fruit juice, 5 mg/kg in tea, 0.05 mg/kg in fresh milk, and 0.5 mg/kg in fish.

• Normal Blood Lead Content

Lead poisoning is generally determined by measuring the amount of lead in the blood. The international diagnostic criteria for blood lead are as follows: Human normal blood lead levels are 0—99 μg/L, while the levels equal to or greater than 100 μg/L represents lead poisoning. Among them, 100—199 μg/L stands for lead poisoning, 200—249 μg/L for mild poisoning, 250—449 μg/L for moderate poisoning, and equal to or higher than 450 μg/L means severe poisoning.

• Related Regulations

1. Lead in food, foodwares, and dietary supplements

2. Does FDA establish heavy metal limits in food?

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