Cancer treatment and chemical hazards
Cytostatic chemicals in chemotherapy are not so harmless.
Chemotherapy is a chemical method for treating cancer tumors. Cocktails of adapted chemicals are injected into the patient to treat the tumor and its potential metastases in a targeted manner.
As they are intended to react with cancerous cells, injected solutions contain chemicals which may also have an impact on healthy cells. Secondary effects of such therapies can be important.
Handling chemotherapy solutions or endure chemotherapy induce a risk of exposure to those chemicals and to harmful consequences on health. Patients and health professionals are at risk. Accidental contamination with cytostatic drugs comes mainly from cutaneous exposure or from exposure by inhalation or ingestion.
What is the composition of chemotherapies?
Cytotoxic substances are used in hospital for chemical treatment of cancers. Some chemotherapies can be performed at home. Chemotherapies are mostly injectable solutions. These chemicals can be cytotoxic (toxic for cells) or cytostatic substances.
Under the appellation “cytostatic substances” is gathered a wide number of chemicals used in chemotherapy. They all have a common property: they inhibit cell proliferation.
It is this property which makes them useful in chemotherapies against various cancers. Cell proliferation is characteristic of tumorous tissues. This explains the impact of such products on environment and health.
Cytostatic substances can be of different nature: from small molecules in classical non-targeted therapies to antibodies in a targeted therapy strategy.
Due to their large number and great variety, cytostatic molecules can present various chemical properties (electrophilic sites, acidic or basic functionalities, alcohol or amine function…) and are cytotoxic. A cytostatic substance can thus be irritant or corrosive.
A large proportion of cytostatic substances are carcinogenic, mutagenic and/or toxic for reproduction (CMR).
During chemotherapy, a mixture of several cytostatic molecules is used. Effects on health can be combined effects of each chemical contained in the injected solution.
What cytostatic molecules are commonly used and what is their impact on cells?
The great diversity of cytostatic molecules can be explained by the numerous cell components’ targets they have.
Generally, non-targeted cytostatic molecules can act:
- On DNA: by modification of DNA structure or synthesis (alkylating agents, platinum salts, 5-fluorouracile, gemcitabine, antimetabolites that are analogues for DNA bases) or by topo-isomerase inhibition (anthracyclines, etoposide, camptothecines…)
- On the mitotic spindle : by polymerisation or depolymerisation inhibition (vinca-alcaloids or taxanes) to prevent cellular replication.
Among cytostatic molecules for targeted therapies are specific protein inhibitors (STI 571, cetuximab) and angiogenesis inhibitors.
What is the impact of exposure to cytostatic chemicals for health professionals?
Health professionals’ exposure to cytostatic substances can occur at different stages of their manipulation: mainly during elaboration and reconstitution of chemotherapy drugs or during their administration to the patient.
Several studies on health professionals’ exposure to cytostatic molecules have been conducted since the end of the 1970’s. According to study conducted by the French National Institute for Research and Safety (INRS) in 2002-2003, 8.2% of health professionals (49000 people) are likely to be exposed to cytostatic drugs in France
The US national Institute for Occupational Safety and Health (NIOSH) issued an alert on cytostatic chemicals hazard. From a compilation of studies on this subject, NIOSH gives advice on recommended or requisite behavior for safe manipulation of cytostatic drugs. The Occupational Safety and Health Administration (OSHA) also considers this subject for prevention of chemical risks at workplace.
A study from the French National Institute for Research and Safety (INRS) showed that health professionals handling cytostatic chemicals or being in contact with a treated patient result in exposure. Cytostatics metabolites have been found in concerned health professionals’ urines. The study also highlights the fact that pregnant women that manipulates cytostatic chemicals will be more prone to enduring spontaneous miscarriage and foetus will have more chances to be malformed (teratogenic effects). Infertility is also possible. Most frequent symptoms among health professionals are metallic taste in the mouth, cold-hand feeling or chemical skin injury feeling.
As individual consequences of a chronic exposure to cytostatics are still difficult to evaluate, it is important to take individual and collective preventive and protective measures to protect the manipulating workers and prevent contact with CMR agents (carcinogenic, mutagenis and toxic for reproduction).
What are the protective measures to be taken ?
A lot of protective measures have been implemented in hospitals in which cytostatic substances are used.
Protection of health professionals starts with designing work environments and protocols that are adapted to cytostatic agents’ manipulation. This allows limitation of air and surface contamination and helps safe manipulation.
Handling of such chemicals in dedicated laboratories inside the hospital equipped with fume hoods or glove boxes is recommended. Centralized preparation of chemotherapies in such laboratories prevent dispersion of cytostatic chemicals through the hospital.
Added to collective protection measures, individual measures are of prime importance.
Equipment of health professionals who manipulate cytostatic products should be adapted and contain (according to INRS recommendations):
- Lab coats
- Long nitrile gloves
- FFP25 masks
- Individual protection goggles
- Head gear
Safety equipment is also necessary:
- Specific syringes
- Air filtration with hydrophobic filters
- Dedicated trash for contaminated products
These measures limit contact with CMR cytostatic substances.