Cadmium Toxicity

Cadmium is a non-essential element that is found in naturally occurring high abundance in fertilizers. Cadmium has been able to monopolize similar reservoirs as mercury by collecting in tropic levels. This bioaccumulation is due to wide use of cadmium rich fertilizers, sewage sludge and industrial uses of cadmium, as well as the plants possessing a naturally high tolerance for the substance, unlike mercury. Similar to arsenic, cadmium moves readily within the soil, resulting in wide distribution and easy absorption into plants. The high tolerance in plants means their cadmium levels are greater than those found in animals or humans and thus only a small amount of contaminated plant matter needs to be ingested for a toxic dose (Satarug et al., 2003).

In 2003, Soisungwan Satarug and associates published a detailed paper discussing the effects of cadmium pollution and toxicity in the non-occupationally exposed population. They reviewed several studies and trials that documented the effects of cadmium toxicity on the body, which was then compared with their own study on liver and kidney samples that had been exposed through major food groups. Tabacco, willow and the sunflower plant have all been found to have high tolerance levels against cadmium. This means their bio-reservoirs are larger and thus allow cadmium to be readily passed up the food chain. In Australia, a study in the early 90s found that sheep grazing on fertilized pasture had high levels of cadmium in their kidneys compared to those grazing on unfertilized pasture. Correspondingly, Taiwanese and Japanese rice grown on contaminated soils was documented as having 0.21-2.16 and 1.67-5.38 mg/kg of cadmium, respectively, compared with rice grown in Queensland which only had 0.05mg/kg of cadmium.

Satarug et al. (2003) moves on from a review of studies to look at WHO/FAO cadmium health regulations. They establish that any crop grown on coils that are either contaminated or naturally rich in cadmium are the main source of toxic exposure in the general population. In Australia, the recommended daily allowances of cadmium are 0.1 ug/kg body weight per day. The WHO and FOA recommend no more than 70 ug per day and considering that most indiciduals ingest and average of 30 ug per day (based on estimates typical food products and diets) this fall within safe limits. However, in some areas and products where food items were reported to contain higher levels, ingestion was estimated to be as high as 90 ug per day, way above the safe levels. These food products were identified as primarily vegetables and cereals.

A detailed list of problems that were caused as a result of cadmium exposure were included in the paper, these incorporated diabetic renal complications, hypertension, osteoporosis, leukemia and cancer in several other organs; lung, kidney, breast, bladder, pancreas to name a few. They conclude that cadmium has a profound effect on the burden of health and the connections have now been well established and documented. In Japan, cadmium exposure in contaminated areas was found to increase mortality by 40-80%. A follow up study, 15 years later, showed researchers that the higher standardized mortality rate for cardiovascular disease was higher in contaminated areas of the Kakehashi river basin in a sample size of 2840 residents, the large sample of residents in this area meant minimizing the risk of anomalies and give a clear picture of cadmium pollution in the basin.

The paper contains a plethora of example studies to reinforce the impact of cadmium on the human body at high levels. Many of the example studies are reinforced by multiple studies and have large sample sizes meaning a higher quality of results. It is comprehensive in its review of the risk cadmium poses to health burden and the consequences of cadmium exposure. Regions of the world including, Australasia, have been identified as having high levels of cadmium. On the other hand, despite the comprehensive overview and arguments for the significant role of cadmium in the non-occupationally exposed population, there is no mention of how these risks can be monitored, controlled or even prevented. The journal article is a good foundation for future developments in both research and policy.