(1) GMO foods
(2) chlorinated hydrocarbons
(3) heavy metal hazardous waste
(4) nanoparticle contamination
(5) petrochemical pollution
(6) radioactive fallout
… are not the greatest threat to global human survival.
The two greatest threats are …
(1) recycled water
(2) processed sewage
These provide “lending libraries” for antibiotic-resistant genes (ARGs).
UV light has no effect on these genes, and chlorine actally supercharges them. 
(1) GRAY WATER is recycled water (the leftover water from baths, showers, wash basins, and, sometimes, kitchen sinks and washing machines).
(2) BLACK WATER is sewage water (water containing human feces).
(3) WHITE WATER is potable water.
A world expert on ARGs lives right here in Montecito, California.
Medical geo-hydrologist Dr. Edo McGowan warned …
“In the late 1970s, the US/EPA did a major study that documented that sewer plants were a principal factor in putting resistant bacteria into the aquatic environment of the nation. That paper cited other works stretching back to the 1960s that said the same thing – sewer plants make antibiotic resistance. The EPA study for some reason, including all data associated with it was removed from the EPA data base. There was nothing wrong with the study, but I suspect it would raise questions about antibiotic resistant pathogens being in sewage sludge. The question would draw attention to the promotion of land applied sewage sludge and the potential for sewage sludge to spread resistance across the nation’s farmland. That would interfere with the promotion of sewage sludge by both US/EPA and USDA. The issue with reclaimed water is not dissimilar because we are discussing resistance. Once in the human gut, the genes can be kept for quite long periods (years) and thus act as a lending library to incoming pathogens. Maria Sjolund (2005) indicated that resistance in the normal flora, which may last years, might contribute to increased resistance in higher-grade pathogens through inter-species transfer. Sjolund et al go on to note that since populations of the normal biota are large, this affords the chance for multiple and different resistant variants to develop. This thus enhances the risk for spread to populations of pathogens. Furthermore, there is crossed resistance. Thus, with resistant organisms and the capacity of the gut biota to take in genes and multiply bacteria, the old paradigm of infective dose may no longer be applicable here.”
Dr. McGowan warned the California State Water Control Board …
“It has been held by some industry pundits that acquired resistance (lateral gene transfer) is a sometime, short time thing. Such is not the case. Lawrence [R. Curtis] notes that incorporation of DNA fragments conferring resistance or virulence can transform a benign strain into a pathogen in but a single step. Horizontal transfer of genes is often accomplished by phages while in a lysogenic state. Phages are abundant in sewage and within sewage plants. For example, the transfer RNA locus leuX operates as an integration site for pathogenicity islands in uropathogenic E. coli. Acquired horizontally transferred genes do last for some time, Lawrence suggests, however, that very few are maintained more than 10 million years (Myr).” 
Compliments of gray water and black water, ARGs are now commonly found in white water.
 Chlorine is a contributing factor to the worldwide proliferation of MRSA (methicillin-resistant Staphylocccus aureus).
 Regular readers of Atom’s Blog know a lot more about horizontal gene transfer than the general public.