Why should we worry about lead and cadmium?

Why should we worry about lead and cadmium?

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The California Office of Environmental Health and Human Hazard Administration (OEHHA) has listed cadmium and lead as chemicals known to cause birth defects or other reproductive harm.1

Lead has been widely recognized as the single most significant environmental health threat to children.2 As noted by the U.S. Center for Disease Control, no safe lead level in children has been identified. Lead exposure has been a significant public health issue for decades and is associated with neurological impairment such as learning disabilities and lower IQ, even when ingested at low levels.3, 4, 5

Chronic exposure to cadmium can cause kidney, liver, and bone damage in humans. Children are more susceptible to the effects of exposure to low doses of cadmium over time. Cadmium may also cause developmental problems, such as decreased birth weight, harm to neurobehavioral development, and male reproductive toxicity, all of which have been observed in animal studies.6, 7

Lead and cadmium accumulate in the body over time, increasing the total body burden of these heavy metals over decades. Ingesting even small amounts of these metals will add to existing body burdens and should be avoided.3, 4, 5, 6, 7

What are the sources of lead and cadmium?

Back to top. Lead and cadmium are toxic heavy metals that are released into the environment through manmade industrial processes including mining, burning fossil fuels such as coal or oil, incineration of municipal waste (plastics/batteries), and manufacturing and smelting, the largest source of airborne cadmium, among others. Lead and cadmium also enter soil through the disposal of sewage sludge, or the application of pesticides or phosphate fertilizers (cadmium).4, 7

Once released into the atmosphere, respirable-sized airborne particles attach to dust, can travel long distances, and will be deposited onto the earth, where they move easily through soil layers and can be taken up into the food chain. Once mined and introduced into the atmosphere, these heavy metals can move from air to soil to water, but do not break down easily and will remain for decades.4, 7

How are we exposed to lead and cadmium?

Back to top. The main route of human lead and cadmium exposure occurs via ingestion from food as well as through contaminated water and soil.4, 7 Lead and cadmium in food are ubiquitous and do not seem to discriminate between natural, certified organic, and non-organic products. One or both of these metals have been found in various foods including baby foods (made with carrots, peaches, pears, sweet potatoes), dietary supplements, vitamins, protein powders, seaweed snacks, ginger cookies, packaged peaches/pears, various fruit juices, as well as chocolate.

Another way we are exposed to lead and cadmium is through inhalation from dust or pollution from industrial processes. Additionally, cadmium is present in cigarette smoke.

How do lead and cadmium get into chocolate products?

Back to top. Cadmium and lead may contaminate the chocolate product at many points through the “bean to bar” process; these sources may depend on the cacao growing, fermenting, processing, manufacturing, shipping, and packaging practices.

One significant source is manmade pollution created by industrial processes as described above. Due to the persistence of these heavy metals in air, soil, and water, they remain present even after the industrial source has been removed. Once in the environment, the metals can fall onto cacao leaves or beans, depose into soil and be uptaken by roots, contaminate water used to grow cacao. Another source of these heavy metals in chocolate is through direct application of pesticides (lead and cadmium), phosphate fertilizers (cadmium), as well as sewage sludge disposal (lead and cadmium).4, 7Contaminated water may also be a source.

Lead and cadmium contamination may also occur through one of the various processing steps a bean undergoes after the harvest. These steps include fermentation, drying of the cacao bean, and manufacturing processes such as grinding, refining, and conching. Other opportunities for contamination are shipping, handling, and finally, packaging. Studies have shown that much of the “lead contamination in (chocolate) products occurs after the beans are harvested and dried, during the shipping of those beans and/or the manufacturing of cocoa and chocolate products.”8, 9

How can manufacturers prevent lead and cadmium contamination in their products?

Back to top. There may not be a single remedy to remove lead and cadmium in chocolate products. Chocolate manufacturers must be vigilant about monitoring the full chocolate production process -- from growing cacao beans, to processing the beans, through the transport, manufacturing, and packaging steps -- testing for possible sources of contamination in that process and taking steps to reduce contamination where it is identified. For example, the equipment used to process chocolate could be a primary source of lead or cadmium. Similarly, water used in processing or containers used in shipping, may be high in lead. Amendments used to grow the cacao trees may cause metals to be uptaken. Or lead may fall on beans growing on the trees or drying on the ground. Once the source(s) are identified, suppliers and manufacturers can improve their practices; increase supply chain transparency; and effectively remove or reduce lead and cadmium from their final product.

Another protocol many agree on is for the cocoa bean growers to test the soil in which they grow the cocoa beans before planting the beans, and avoid the use of lead/cadmium-laden pesticides, as well as avoiding phosphate fertilizers, which often contain high levels of cadmium, or to otherwise address metals-uptake in plants.

How does As You Sow test products and what do the results mean?

Back to top. Chocolates for testing are obtained from retail outlets throughout the state or ordered on-line. Heavy metals testing is conducted by independent, state-certified laboratories with special accreditation in food testing. Measurements of lead and cadmium are conducted using ICP-MS following EPA protocols or similarly standardized methods. The laboratory results are reported in concentrations of lead and cadmium, expressed in parts per million (ppm). In addition, for ease of reference, we have also translated the laboratory results from concentration (ppm) into micrograms per serving size, a measure of exposure. To calculate micrograms per serving we take the reported concentration (ppm), and multiply that by the product’s suggested serving size, in grams. For example, exposure from lead from a 30 g serving size chocolate bar, with a testing result of 0.2 ppm lead, would be calculated as follows: 0.2 ug/g * 30 g = 6.0 ug/serving.

For your reference, listed below are a range of existing public health guidelines or warning requirements for lead and/or cadmium. As noted in the chart below, the settlement agreement described above provides interim levels for warnings for chocolate products participating in the settlement agreement.

Lead Cadmium
California Proposition 65 (OEHHA)1 0.5 ug/day 4.1 ug/day
FDA guidance for industry2 0.1 ppm ---
EPA Maximum Contaminant Level Goals in drinking water3 zero3 0.005 ppm

EU Commission (EU) 488/2014 (by cacao content)4

  • - Less than 30%
  • - 30% and greater, up to 50%
  • - 50% and greater
  • - Cacao powder, drinking chocolate


0.1 ppm
0.3 ppm
0.8 ppm
0.6 ppm

Current interim warning levels (by cacao content)

  • - Up to 65%
  • - Greater than 65% and up to 95%
  • - More than 95%

0.100 ppm
0.150 ppm
0.225 ppm

0.400 ppm
0.450 ppm
0.960 ppm
  1. OEHHA (1992). Lead and Lead Compounds. & OEHHA (1987). Cadmium. OEHHA has set a maximum allowable daily exposure level (MADL) for lead and cadmium in consumer products. The MADL for a given chemical is otherwise referred to as a “safe harbor level.” The MADL is a level at which a chemical would have no observable effect, even if an individual were exposed to 1,000 times that level. The MADL for lead is set at 0.5 µg/day for lead and cadmium at 4.1 µg/day for cadmium. Exposures levels below established safe harbor levels are exempt from the requirements of Proposition 65. In some instances, enforcement actions may have resulted in negotiated exposure levels relative to specific settlement agreements.
  2. FDA (2005, revised 2006). Guidance for Industry: Lead in Candy Likely To Be Consumed Frequently by Small Children.
  3. EPA (May 2009). National Primary Drinking Water Regulations. EPA sets “Maximum Contaminant Level Goal” (MCLG) and “Maximum Contaminant Level” (MCL) for each regulated contaminant in drinking water. EPA expresses the levels in milligrams per liter (mg/L), which is equivalent to parts per million (ppm).The MCLG is a non-enforceable public health goal, and reflects the level of a contaminant in drinking water below which EPA has determined there is no known or expected risk to health. The MCL is a legally enforceable level that is set as closely to the MCLG as feasible using the best available treatment technology and taking cost into consideration. For lead, the MCLG is zero, but the MCL is 0.015 ppm. The MCLG and MCL for cadmium are both set at 0.005 ppm.
  4. EU Commission (2014). (EU) No 488/2014 of 12 May 2014 amending Regulation (EC) No 1881/2006 as regards maximum levels of cadmium in foodstuffs.

How can I tell if lead or cadmium is in the chocolate product I purchase?

Back to top. The only way to tell if lead or cadmium is in a product is to test the product for heavy metals at a certified lab.

Doesn’t the government protect us from chemicals like lead and cadmium in the products we buy?

Back to top. The FDA does not consistently monitor food for lead and cadmium contamination. California has the most health protective standards in the country for the presence of lead and cadmium in consumer products, and requires the manufacturer to warn consumers if a product contains chemicals known to cause cancer and/or birth defects or other reproductive harm.

Will I get sick if I eat chocolate products with cadmium?

Back to top. It is difficult to predict which chemical exposure(s) will trigger an adverse health effect in a person, due to individual variation (depending on biological and/or genetic factors). What we do know is that lead and cadmium are toxic heavy metals that accumulate in the body where they remain for decades. The first step in preventing exposure is to identify the chemical itself and then try to avoid it. With all chemical exposures, the most vulnerable populations are developing fetuses, children, the elderly, and those most impacted from working or living near industrial and manufacturing plants.

What can I do to help make sure the chocolate products I buy are free of lead and/or cadmium?

Back to top. Check the lists that we have published on our web site and buy the product that do not require a warning. You can also write to your favorite chocolate manufacturer(s) and ask them to fix this problem.

What is Proposition 65 and how is As You Sow enforcing it?

Back to top. California Safe Drinking Water and Toxic Enforcement Act of 1986 is a consumer-right-to-know law voted into existence in 1986 by California citizens. It protects Californians by requiring the manufacturer to warn consumers if a product contains chemicals known to cause cancer and/or birth defects or other reproductive harm. While the law is California specific, the enforcement of the law can have a positive impact on all of the consumer products available across the U.S. Many product manufacturers, when reformulating to reduce toxins for the California market, will sell the reformulated product across the U.S., and even globally, rather than make separate products for each market. For over 23 years, As You Sow has been successfully enforcing the California Safe Drinking Water and Toxic Enforcement Act of 1986 and has worked with manufacturers to reformulate hundreds of products in order to provide consumers with cleaner, healthier products. These include mercury in fish, toluene in nail polish, lead in herbal supplements, formaldehyde in portable school classrooms, and toxic chemicals in cosmetics and laundry detergent. You can see a list of some of these products on our Toxic Enforcement page.


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  1. California Office of Environmental Health and Human Hazard (OEHHA).
  2. National Research Council, Measuring Lead Exposure in Infants, Children, and Other Sensitive Populations. Washington, D.C.: National Academy Press, 1993, p. 1. Centers for Disease Control, Preventing Lead Poisoning In Young Children, October 1991.
  3. EPA 2013 Integrated Science Assessment for Lead.
  4. Agency for Toxic Substances and Disease Registry (ATSDR). Toxicological Profile for Lead. August 2007.
  5. NRDC: Our Children At Risk, The Five Worst Environmental Threats to Their Health. Chapter 3: Lead.
  6. Agency for Toxic Substances and Disease Registry (ATSDR). ToxFAQs for Cadmium. 2012.
  7. Agency for Toxic Substances and Disease Registry (ATSDR). Toxicological Profile for Cadmium. September 2012.
  8. Rankin CW, Nriagu JO, Aggarwal JK, Arowolo TA, Adebayo K, Flegal AR. Lead contamination in cocoa and cocoa products: isotopic evidence of global contamination. Environ Health Perspect. 2005;113:1344–1348. [PMC free article] [PubMed]
  9. Yanus RL, Sela H, Borojovich EJ, Zakon Y, Saphier M, Nikolski A, Gutflais E, Lorber A, Karpas Z. Trace elements in cocoa solids and chocolate: an ICPMS study. Talanta. 2014 Feb;119:1-4. doi: 10.1016/j.talanta.2013.10.048. Epub 2013 Oct 28.