Brass is a metal alloy used across industries, from musical instruments and decorative hardware to plumbing fixtures. While the primary metals in brass are generally safe, the risk of cancer or toxicity lies in specific trace elements frequently added during manufacturing, particularly in older alloys. This article examines the composition of brass, the element that poses the greatest toxicity risk, common exposure routes, and current regulatory measures.
The Components of Brass Alloys
Brass is primarily an alloy composed of copper and zinc, with their proportions determining the alloy’s specific properties, such as color, strength, and workability. Copper typically constitutes 60% to over 90% of the mass, while zinc makes up the remainder, usually 5% to 40%, increasing the alloy’s hardness and tensile strength.
Copper and zinc are essential trace elements required by the human body. In the limited exposure associated with solid brass objects, these two main components do not pose a health risk. However, small percentages of other elements are often intentionally incorporated to achieve specific manufacturing goals. These additional components, known as trace elements, introduce the potential for adverse health effects.
The Specific Risk Posed by Trace Elements
The greatest health concern associated with many common brass alloys is the presence of lead, which was historically added to improve machinability. Lead acts as an internal lubricant, making the metal easier to cut, thread, and shape during the manufacturing of items like valves and fittings. Before modern regulations, lead content in some plumbing brass could reach 8% by weight.
Inorganic lead compounds are classified as probable human carcinogens (Group 2A) by the International Agency for Research on Cancer (IARC). Lead is also a potent neurotoxicant that bioaccumulates in the body over time. Chronic exposure, even at low levels, is associated with serious health problems, including nervous system disorders, kidney damage, and developmental delays, particularly in young children.
While other contaminants like arsenic or cadmium can be present, lead remains the element posing the highest risk due to its toxicity and historical use as a common additive. The health hazard stems from the lead embedded within the alloy matrix that can be released under certain conditions, causing concern for older or unregulated brass products.
Routes of Human Exposure
The primary way the public is exposed to harmful elements from brass is through leaching, particularly in domestic water systems. When brass is used in plumbing components like faucets, valves, and fittings, water that passes through or sits in contact with the alloy can dissolve trace metals. This process is accelerated when the water is soft, corrosive, or acidic, or when water has been stagnant for several hours.
This leaching action contaminates drinking and cooking water, which is then ingested. Brass fittings can be a significant source of lead contamination in potable water, even in relatively new buildings. Exposure can also occur through direct contact and inhalation of metal dust, especially in occupational settings or when handling old or deteriorating brass items.
Manufacturing processes such as grinding, polishing, or welding brass generate fine dust or fumes that are easily inhaled or ingested. This type of exposure is generally limited to workers but can also occur during home-based restoration or repair of older brass objects.
Regulatory Standards and Safety Guidelines
Modern, regulated brass products have significantly mitigated the risk of lead exposure. The US Safe Drinking Water Act (SDWA) progressively introduced requirements to reduce lead content in plumbing materials. Subsequent amendments established a new “lead-free” definition for plumbing components.
This regulation, which took full effect in 2014, mandates that wetted surfaces of pipes, fittings, and fixtures intended for potable water must contain no more than a weighted average of 0.25% lead. This strict limit effectively eliminates traditional leaded brass in new plumbing installations in favor of safer, lead-free alloys. Consumers can look for products certified by third-party organizations, such as those meeting the NSF/ANSI 372 standard, which verifies the low lead content.
For individuals living in older homes with pre-2014 brass plumbing, testing drinking water for lead concentration is advisable. Running the cold water for a minute or two in the morning or after long periods of stagnation can flush out water that has been sitting in contact with old brass fixtures.