Heavy Metals in Food and Water: Arsenic, Cadmium, Lead and Mercury
Four metals come up over and over in fertility and pregnancy nutrition: arsenic, cadmium, lead and mercury. They behave differently, they arrive by different routes, and the advice that actually follows from the evidence is much less dramatic than the headlines.
The pattern underneath all four is the same. Vary what you eat, know your water, and do not eliminate nutritious foods on the strength of a scary word.
Arsenic: is my water a problem?
It depends on where your water comes from, and that is a question with an answer rather than a worry. Public supplies are regulated under the Safe Drinking Water Act. Private wells are not, and testing one is the owner's job.
Arsenic also comes in two forms that behave very differently, which is why blanket warnings about arsenic in food are so often misleading.
The WHO recommended limit for arsenic in drinking water is 10 micrograms per liter, and private well water in the US is unregulated so testing is the owner's responsibility.
Multiple health authorities agree
Clinical review pending
More than one independent health authority states this.
The quality and safety of drinking water from private domestic wells are not regulated by the Federal Government under the Safe Drinking Water Act... Private well owners are responsible for delivering safe drinking water to their households.
Organic arsenic is relatively non-toxic while inorganic arsenic is highly toxic, and arsenic-contaminated groundwater is the most significant cause of human exposure.
Stated in a health authority's guidance
Clinical review pending
A health authority states this in its published guidance.
Arsenic is highly toxic in its inorganic form. In contrast, organic arsenic compounds...are less harmful to health...Human exposure to elevated levels of inorganic arsenic occurs mainly through the consumption of groundwater containing naturally high levels of inorganic arsenic
You do not need to eliminate arsenic-containing healthy foods from your diet; instead vary what you eat and avoid always eating one higher-arsenic food.
Stated in a health authority's guidance
Clinical review pending
A health authority states this in its published guidance.
it is not an additive and cannot be completely eliminated from food...If you eat a lot of rice or other foods higher in arsenic, eat them less often or vary with other types of food that are lower in arsenic.
Cadmium concentrates in specific tissues rather than spreading evenly through the food supply, so knowing the few places it collects is most of what there is to know.
Cadmium is found in some meats, especially organ meats like liver and kidney.
Multiple health authorities agree
Clinical review pending
More than one independent health authority states this.
The highest levels of cadmium in food are typically found in leafy vegetables...potatoes, grains, peanuts, and organ meats such as liver and kidney.
Lead is unusual on this list because the main routes are not food at all. Housing, dust and water pipes do most of the work, which changes what a useful response looks like.
Humans are exposed to lead mainly by inhaling lead particles and ingesting lead-contaminated dust, food, and water, including from leaded pipes and lead-containing food containers.
Stated in a health authority's guidance
Clinical review pending
A health authority states this in its published guidance.
"inhalation of lead particles generated by burning materials containing lead, for example during smelting, recycling, stripping leaded paint and plastic cables" ... "ingestion of contaminated dust, soil, water or food" ... water contamination "through plumbing systems containing lead pipes, solders and fittings" ... "L…
This is the one where the caution and the recommendation point in opposite directions, and it trips people up constantly. Some fish carry mercury and fat-soluble pollutants. Fish is also one of the better things you can eat before and during pregnancy.
The authorities resolve that tension the same way: eat fish, and be specific about which.
Dioxins bioaccumulate up the fish food chain and, being fat-soluble, concentrate in animal fat; a significant source of human exposure is eating animal fats in meat, full-fat dairy, and fatty fish.
Multiple health authorities agree
Clinical review pending
More than one independent health authority states this.
"they accumulate in the food chain, mainly in the fatty tissue of animals" ... "More than 90% of human exposure is through food, mainly meat and dairy products, fish and shellfish."
Pregnant women should eat low-mercury fatty fish at least twice a week (up to 12 ounces), or take a daily omega-3 supplement if concerned about mercury or averse to seafood.
Stated in a health authority's guidance
Clinical review pending
A health authority states this in its published guidance.
the FDA/EPA recommends limiting fish consumption to 2 servings (approximately 340 g or 12 oz of seafood) per week... Alternate sources of DHA include fish oil capsules... and are low in contaminants such as mercury. Many prenatal vitamins contain up to 200 to 300 mg of DHA.
One should aim to eat a 4-ounce serving of seafood (or shellfish) 2-3 times a week.
Stated in a health authority's guidance
Clinical review pending
A health authority states this in its published guidance.
Pregnancy and breastfeeding: 1 serving is 4 ounces. Eat 2 to 3 servings a week from the "Best Choices" list (OR 1 serving from the "Good Choices" list). ... Those who are pregnant or breastfeeding consume between 8 and 12 ounces per week of a variety of seafood from choices that are lower in mercury.