“Blasting” refers to different processes depending on the context. In construction and manufacturing, it means using pressurized material to clean or shape a surface. In medicine, it relates to immature blood cells called “blasts” that play a role in both normal development and serious diseases like leukemia. And in reproductive medicine, a “blastocyst” is an early-stage embryo. Here’s what each term means and why it matters.
Abrasive Blasting in Industry
Abrasive blasting, commonly called sandblasting, is the process of propelling a stream of abrasive material against a surface at high pressure. It’s used to clean rust from metal, smooth rough surfaces, remove old paint, and prepare materials for new coatings. The abrasive material can be actual sand, steel grit, glass beads, walnut shells, or other particles, depending on the surface and the goal.
The main health concern with abrasive blasting is inhaling fine dust, particularly crystalline silica. When sand or silica-containing materials are blasted against a surface, they shatter into microscopic particles that can lodge deep in the lungs, causing a condition called silicosis. OSHA sets the permissible exposure limit for respirable crystalline silica at 50 micrograms per cubic meter of air, calculated over an 8-hour workday. Workers doing abrasive blasting with silica-containing agents must use ventilation systems and respiratory protection. Many operations have switched to alternative abrasives to reduce silica exposure entirely.
Blast Cells in Blood and Bone Marrow
In medicine, “blasts” are immature blood cells at an early stage of development. Your bone marrow constantly produces new blood cells to replace old ones, and blast cells are part of that assembly line. A master stem cell in the bone marrow develops into one of two types of blasts: myeloblasts, which eventually mature into red blood cells, most white blood cells, and platelets, and lymphoblasts, which mature into a specific type of white blood cell called lymphocytes.
In a healthy person, blast cells stay in the bone marrow and mature before entering the bloodstream. Finding a small number of blasts in the marrow is completely normal. The problem arises when blasts stop maturing and start multiplying out of control. This is essentially what happens in acute leukemia. The bone marrow fills with immature cells that can’t do the work of normal blood cells, crowding out healthy red cells, white cells, and platelets.
Blast Counts and Leukemia Diagnosis
The percentage of blast cells in the bone marrow is one of the key criteria for diagnosing acute myeloid leukemia (AML). For decades, the threshold was 30% blasts in the marrow. In 2001, the World Health Organization lowered that to 20%, which remains the standard cutoff. More recently, updated classification systems introduced in 2022 recognize an overlap category for patients with 10% to 19% blasts when certain genetic mutations are present, reflecting a shift toward diagnosing leukemia based on molecular features rather than blast percentage alone.
When blast cells overflow from the marrow into the bloodstream, they displace the cells your body actually needs. This leads to the hallmark symptoms of acute leukemia: fatigue and weakness from too few red blood cells, frequent infections from a shortage of functional white blood cells, and easy bruising or bleeding from low platelet counts. Bone pain can also occur as the marrow becomes packed with abnormal cells.
Blastocysts in Embryo Development
In reproductive biology, a blastocyst is an embryo at about five to six days after fertilization. After a sperm fertilizes an egg, the resulting single cell (called a zygote) begins dividing. It first becomes a solid ball of cells, then hollows out into a fluid-filled sphere. That hollow sphere is the blastocyst.
The blastocyst wall is mostly one cell thick, except for one area where it’s three to four cells thick. That thickened cluster becomes the embryo itself, while the outer layer of cells eventually forms the placenta. About six days after fertilization, the blastocyst attaches to the uterine wall and begins implanting. By day 9 or 10, implantation is complete. Once a surrounding sac forms, around day 10 to 12, the blastocyst is officially called an embryo.
Blastocyst Transfers in IVF
In fertility treatment, clinics can transfer embryos to the uterus at different stages. A “cleavage-stage” transfer happens around day 2 or 3, when the embryo is still a small cluster of cells. A “blastocyst transfer” waits until day 5 or 6, when the embryo has reached the more developed blastocyst stage. Waiting longer allows the lab to identify which embryos are developing well, since not all fertilized eggs successfully reach the blastocyst stage.
Blastocyst-stage transfers generally produce higher implantation rates per embryo transferred. Across multiple studies, implantation rates for day 5 or 6 transfers ranged from about 4% to 56%, while cleavage-stage transfers ranged from 3% to 44%. The higher per-embryo success rate means clinics can often transfer fewer embryos, reducing the chance of twins or triplets while maintaining similar overall pregnancy rates. Embryologists grade blastocysts based on three factors: how expanded the fluid-filled cavity is, the quality of the inner cell cluster (which becomes the baby), and the quality of the outer cell layer (which becomes the placenta). Each component is rated good, fair, or poor.
Blast Injuries From Explosions
In emergency and military medicine, “blast” refers to the force produced by an explosion. Blast injuries are classified into four categories based on how the explosion harms the body. Primary blast injuries come from the pressure wave itself, which passes through the body and damages air-filled organs like the lungs, ears, and intestines. Secondary injuries result from debris and fragments propelled by the explosion striking the body.
Tertiary blast injuries occur when the force of the blast wind throws a person against a solid object, causing blunt trauma. Quaternary injuries are everything else: burns, chemical exposure, crush injuries from structural collapse, and inhalation of dust or toxic gases. Most blast victims in real-world events sustain injuries from multiple categories simultaneously.
BLAST in Genetics Research
In a completely different field, BLAST stands for Basic Local Alignment Search Tool. It’s a program run by the National Institutes of Health that lets scientists compare a DNA or protein sequence against massive databases of known sequences. If a researcher discovers a new gene, they can run it through BLAST to find similar sequences in other organisms, helping them infer what the gene does and how species are related to one another. It’s one of the most widely used tools in molecular biology and is freely available online.