Advisory information has been issued by the United States Anti-Doping Agency (USADA) on the dangers of athletes testing positive for banned drugs at this year's Olympic Games in Rio de Janeiro due to the Zika virus or water pollution.
A special new "Games Related FAQs" has been added to the USADA website following a series of enquiries from concerned athletes.
Questions include: "Are there any anti-doping issues related to the Zika virus that Olympic and Paralympic athletes should be aware of?".
USADA answered: "Currently, USADA is unaware of any vaccination, treatments, or prevention measures for Zika virus that impact anti-doping at the Games.
"For the most up-to-date information, please visit the US Centers for Disease Control and Prevention."
USADA also list several common active ingredients in US brand name mosquito repellents that not prohibited.
Another question WADA has been asked is whether it is possible to ingest a banned substance by coming into contact with the water in Guanabara Bay, where much of Rio de Janeiro's untreated sewage flows into.
"The water quality issues in Rio are largely due to pollution from bacterial and viral sources, such as raw sewage and excess garbage or decaying animals and plants," USADA said on their website.
"Simply put, this is a health and safety issue.
"An athlete will not test positive for a prohibited substance as a result of falling into or ingesting water which has high bacterial or viral counts.
"However, should athletes fall ill, they should always be vigilant to check any medications or treatment methods against the WADA (World Anti-Doping Agency) Prohibited List."
There is also a question about the danger of testing positive for clenbuterol, an anabolic steroid often prescribed to for asthma patients but which can sometimes be found in meat because it is injected into cattle.
The most high-profile case came in 2011 when players of the Mexico national football team failed drugs tests for clenbuterolbut were acquitted by WADA after they claimed it came from contaminated food.
FIFA also claimed 109 players from multiple countries participating in the Under-17 World Cup in Mexico tested positive for this drug.
FIFA and the WADA declined to prosecute any cases because the weight of evidence pointed to contamination from Mexican meat.
USADA claimed, though, this should not be a danger during Rio 2016.
"Unlike Mexico and China, USADA is unaware of any reported positive anti-doping cases due to clenbuterol meat contamination in Brazil," they said.
"Still, it is important that athletes remain vigilant and only consume meat and protein from trusted sources, such as from the dining halls in the Olympic and Paralympic Athletes Villages."