Chromium toxicity

Chromium Toxicity

Chromium toxicity refers to the harmful effects on the body caused by excessive exposure to chromium compounds. Chromium is a naturally occurring element found in various environmental media such as air, water, and soil. It exists in several oxidation states, but the most common and stable forms are trivalent chromium (Cr(III)) and hexavalent chromium (Cr(VI)). While Cr(III) is an essential nutrient in small amounts, beneficial for glucose, fat, and protein metabolism, Cr(VI) is highly toxic and carcinogenic to humans.

Sources of Exposure

Individuals can be exposed to chromium through different pathways including occupational exposure, contaminated food and water intake, and inhalation of polluted air. Occupational exposure is the most common route, particularly in industries involved in stainless steel welding, chrome plating, and the manufacturing of chromate-containing paints and coatings. Environmental exposure to Cr(VI) can occur near hazardous waste sites and areas with contaminated soil and groundwater.

Mechanism of Toxicity

The toxicity of chromium compounds is primarily due to Cr(VI), which can easily penetrate biological membranes due to its anionic nature. Once inside the cell, Cr(VI) is reduced to Cr(III), generating reactive intermediates such as Cr(V) and Cr(IV), as well as reactive oxygen species (ROS). These intermediates and ROS can cause cellular damage, including DNA damage, lipid peroxidation, and protein modification, leading to various health effects.

Health Effects

Acute Toxicity

Acute exposure to high levels of chromium (VI) can cause severe damage to the respiratory system, skin, and eyes. Inhalation of Cr(VI) compounds can lead to nasal irritation, nasal ulcers, and perforation of the nasal septum. Dermal exposure can result in skin ulcers, commonly known as "chrome ulcers," and allergic contact dermatitis.

Chronic Toxicity

Long-term exposure to Cr(VI) is associated with increased risk of lung cancer, and can also damage the liver, kidney, and immune system. Chronic inhalation exposure has been linked to respiratory tract cancers, including lung cancer. Ingestion of Cr(VI)-contaminated water has been associated with stomach tumors in animals and is suspected to increase the risk of gastrointestinal cancers in humans.

Diagnosis and Treatment

Diagnosis of chromium toxicity involves a detailed history of exposure, physical examination, and laboratory tests. Biomarkers of exposure include measuring chromium levels in blood, urine, and hair. Treatment is primarily supportive and includes removal from exposure, respiratory support for those with inhalation exposure, and skin decontamination for dermal exposure. In cases of severe systemic toxicity, chelation therapy with agents such as dimercaptosuccinic acid (DMSA) may be considered.

Prevention

Preventing chromium toxicity involves controlling exposure through the use of personal protective equipment (PPE), proper industrial hygiene practices, and environmental regulations limiting chromium emissions into the environment. Public health measures include monitoring and remediation of contaminated water supplies and soil.