Organic And Regular Dark Chocolate Contaminated By Lead And Cadmium， Study Finds

Dark chocolate and similar cocoa products are contaminated with lead and cadmium， two neurotoxic metals that are linked to cancer， chronic disease， or reproductive and developmental issues， especially in children， a new study found.

As natural elements in the Earth’s crust， lead， cadmium and other heavy metals are in the soil in which crops are grown and thus can’t be avoided. Some crop fields and regions， however， contain more toxic levels than others， partly due to the overuse of metal-containing fertilizers and ongoing industrial pollution.

However， despite growing on land with fewer pesticides and other contaminants， organic versions of dark chocolate had some of the highest levels， according to the study published Wednesday in the journal Frontiers in Nutrition.

Dark chocolate is known for being rich in plant nutrients called flavonoids， antioxidants and beneficial minerals and has been linked to improved cardiovascular health， cognitive performance and less chronic inflammation.

The research team examined only pure dark chocolate products as they contain the highest amount of cacao， the raw， unprocessed part of the cacao bean. Candies or baking chocolates with other ingredients were eliminated. The study did not disclose the names or manufacturers of the tested products.

The new study analyzed 72 consumer cocoa products for levels of lead， cadmium and arsenic. Compared with prior studies， which have looked at heavy metals in chocolate during a snapshot of time， the latest study tested the products over an eight-year period， in 2014， 2016， 2018 and 2020.

Of the six dozen chocolate products tested over the course of the study， 43% exceeded the maximum allowable dose level for lead as established by California’s Proposition 65， while 35% exceeded the Prop 65 maximum allowable level for cadmium， researchers found. The study found no significant levels of arsenic.

Over time， consuming low levels of cadmium can damage the kidneys. The Environmental Protection Agency calls the metal a probable human carcinogen.

There is no safe level of lead， especially for children， according to the World Health Organization.

“In particular， lead can affect children’s brain development， resulting in reduced intelligence quotient （IQ）， behavioural changes such as reduced attention span and increased antisocial behaviour， and reduced educational attainment，” WHO states on its website.

However， for healthy adults， risk analysis found little to worry about choosing to indulge in 1 ounce of dark chocolate now and again.

一项新研究发现，黑巧克力和同类的可可产品受到铅和镉这两种神经毒性金属的污染。过量摄入这两种金属会引发癌症、慢性疾病或生殖和发育问题，对儿童尤其有害。

作为地壳中的自然元素，铅、镉和其他重金属存在于农作物生长的土壤中，因此无法避免。然而，一些农田和地区由于持续的工业污染和过度使用含金属的肥料，其毒性水平比其他地区更高。

7月31日发表在《营养前沿》期刊上的研究指出，尽管有机黑巧克力产自农药和污染物较少的土壤，但是所含的几种重金属水平却是最高的。

黑巧克力因富含植物营养素类黄酮、抗氧化剂和有益矿物质而闻名，并被证实能改善心血管健康、认知表现和减少慢性炎症。

研究团队只检测了纯黑巧克力产品，因为它们的可可（即未加工的可可原豆）含量最高。含有其他成分的糖果或烘焙巧克力不在检测范围内。研究没有透露被检测产品的名称或制造商。

这项新研究分析了72种巧克力产品中的铅、镉和砷含量。过往的研究只在某一特定时间点检测了巧克力产品的重金属含量，而这项新研究分别在2014年、2016年、2018年和2020年对巧克力产品进行了检测，时间跨度长达8年。

研究人员发现，在研究过程中检测的72种巧克力产品中，有43%超过了美国加州65号提案规定的铅含量的上限值，有35%超过了该提案规定的镉含量的上限值。该研究没有在这些巧克力产品中发现砷含量超标的现象。

长期摄入微量镉元素会对肾脏造成损伤。美国环保署将镉元素称为一种人类致癌物。

世界卫生组织表示，铅是没有安全摄入量的，尤其对儿童来说。

世界卫生组织在其官网上写道：“铅尤其会影响儿童的大脑发育，导致智商降低、行为改变，比如注意力下降和反社会行为增加，以及学习成绩退步。”

不过，风险分析发现，健康的成年人偶尔吃一点黑巧克力几乎没有什么可担心的。